!e oenes, H, Baili?" ®(|E ^. ^. ^iU pbrarg ^mrtl; Carolina ^tate College 5MS This book is due on the date indicated below and is subject to an overdue fine as posted at the circulation desk. EXCEPTION: Date due will earlier if this item is RECALLED. 11 be I .ED. I XLbc IRural Science Series L. H. BAILEY, Editor THE SWEET POTATO Edited by L. II. Bailey The Soil. King. The Sprayikg of Plants. Lodeman. Milk and Its Products. Wiiiff. Enlarged and Revised. The Fertility of the Land. Roberts. The Principles of Fruit-growing. BwUey. 20th Edition, Revisfd. Bush-fruits. Card. Revised. Fertilizers. Voorhees. Revised. The Principles of Agriculture. Bailey. Revised. Irrigation and Drainage. King. The FaRiMSTEAd. Roberts. Rural Wealth and Welfare. FairchUd. The Principles of Vegetable-gardening. Bailey. Farm Poultry. Watson. Enlarged and Revised. The Feeding of Animals. Jordan. (Now Rural Text- Book.) The Farmer's Business Handbook. Roberts. The Diseases of Animals. Mayo. The Horse. Roberts. Ho\v TO Choose a Farm. Hunt. Forage Crops. Voorhees. Bacteria in Relation to Country Life. Lipman. The Nursery-book. Bailey. (Now Rural Manual Series.) Plant-breeding. Bailey and Gilbert Revised. The Forcing-book. Bniley. The Pruning-book. Bailey. (Now Rural Manual Series.) Fruit Growing in Arid Regions. Paddock and Whipple. Rural Hygiene. Oyden. Dry-farming. Widtsoe. Law for the American Farmer. Green. Farm Boys and Girls. McEeever. The Training and Breaking of Horses. Harper. Sheep-farming in North America. Craig. Cooperation in Agriculture. Powell. The Faum Woodlot. Cheyney and Wentlvng. Household Insects. Berrick. Citrus Fruits. Coit. Principles of Rural Credits. Uorman. Beekeeping. Phillips. Subtropical Vegetable-gardening. Rolfs. Turf for Golf Courses. Piper and Oakley. The Pot.\to. Gilbert. Strawberry-growing. Fletcher. Western Live-stock Management. Porter. Peach-growing. Gould. The Sugar-beet in .Vmerica. Harris. Pork-production. Smith. The Development of Institutions Undee Ibbigation. Thomas. Landscape-gardening. Simonds. Commercial Apple Industry of North America. Folger and Thomson. The Sweet Potato. Hand and Cockerham. THE SWEET POTATO A Handbook for the Practical Grower BY T. E. HAND AND K. L. COCKERHAM ILLUSTRATED Jl3eto gotk THE MACMILLAN COMPANY 1921 All rights reserved ^^^\. <,^^ji Copyright, 1921, By the MACMILLAN COMPANY Set up and electrotyped. Published January, 1921. CONTENTS CHAPTER I PAGES Origin and Descbiption of the Swb:et Potato ... 1-7 Description 3-5 Botanical classification 5-7 CHAPTER II Impobtance and Distribution 8-19 Distribution 10-15 Climatic requirements and soil types 16-19 CHAPTER III Utilization of the Sweet Potato 20-53 As food for man 21-25 Composition and food value 21-25 As food for domestic animals 25-33 Sweet potato silage 28-30 Roots 30-32 Vines 32-33 Manufactured products of the sweet potato . . 33-46 Dehydrated and desiccated sweet potatoes . . 34 - 3S Sweet potato flour 38 Sweet potato pie product 38 Sweet potato chips 39 Sweet potato sugar 39 Starch manufacture 39-41 Alcohol manufacture 41-42 Sirup from sweet potatoes 42-45 Canned sweet potatoes 45-46 Domestic cooking of sweet potatoes 46-53 Baked sweet potatoes 47 Browned sweet potatoes 47 Fried sweet potatoes 47 Candied sweet potatoes 48 Sweet potato biscuit 48 Sweet potato bread 48 Sweet potato muffins 49 N. C. State College vi Contents PAGES Sweet potato salad 49 Sweet potato peanut croquettes 49 Baked sweet potato custard 50 Sweet potato a la Agnes 50 Sweet potato with raisins and- marshmallows 50 Sweet potato devil's food 50-51 Sweet potato drop cookies 51 Boiled sweet potatoes 51 Sliced and baked sweet potatoes 51 Riced sweet potatoes 51 Sweet potato flour 52 Flour No. 1 from tlie raw potato 52 Flour No, 2 from cooked potatoes 52-53 Flour No. 3 from pulp 53 Sweet potato starch 53 CHAPTER IV Pbopagation 54-89 Selecting seed (tubers) 56-61 For disease control 57-58 For yield and quality 58-60 Production of seed potatoes 60 Seed treatment 60-61 The plant-bed 62-80 Location 62-63 Preparation of the plant-bed 63-64 Open beds 64-65 Coldframes 65-67 Hotbed — manure-heated 67-69 Hotbed — flue-heated 69-71 Hotbed — pipe-heated 71-72 Other types of hotbeds 73 Bedding '^^ " I* Covering for seed-beds 75-76 Care of the plant-bed 77-80 Drawing the plants 80-82 Use of vine-cuttings 82-84 The commercial plant business 85-89 Field methods 86-87 Office methods 87-88 Advertising 88-89 CHAPTER V TILJ.AQE, Fertilizing and Rotation 90-119 Preparation for planting 90-91 Distance and method of planting 91-92 Contents vii PAGES Setting the plants in the field 92-93 Cultivation 93-96 Irrigation 96 Fertilizers 96-112 Kinds of fertilizers 99 Function and form of plant-foods 99-103 Commercial fertilizers 103-105 Home-mixing of fertilizers 105-107 What fertilizer to apply 107-108 Humus 108-109 Green-manures 109-110 Other materials as fertilizers 110-112 Application of fertilizers 112 Rotation 112-118 Plant-food 113-114 Root excretions 114-115 Mechanical effect on soil 115 Insect, fungous and weed enemies 115-116 Rotation to be used 116-118 Conclusion 119 CHAPTER VI Vabieties 120-136 CHAPTER VII Insects Affecting Sweet Potatoes 137-154 The sweet potato flea-beetle 137-139 Tortoise beetles 139-143 The two-striped sweet potato beetle 140 The black-legged tortoise beetle 140-141 The golden tortoise beetle 141-142 The mottled tortoise beetle 142 The argus tortoise beetle 142-143 Control of tortoise beetles 143 Saw-flies 143-145 Sweet potato weevil 145-154 Description 147-148 Life history 148-152 Control 152-154 CHAPTER VIII Diseases of the Sweet Potato 155-169 Stem-rot (wilt, blue-stem) 156-158 Control of stem-rot 157-158 iii Contents PAGES Foot-rot 158-159 Root-rot 159-160 Black-rot (black-shank) 160-162 Scurf (soil-stain, rust, Jersey mark) 162-163 Leaf-bliglit 163 Leaf-spot 163-164 White-rust (leaf-mold) 164 Soft-rot 1G5 Ring-rot 165-166 Dry-rot 166 Java black-rot 166 Charcoal-rot 167 Control of storage rots 167-169 CHAPTER IX Insecticides, Fungicides and Spray Machinery . 170-176 Insecticides and fungicides 170-173 Spray machinery 174-176 Dusters 175-176 Nozzles, hose, and fixtures 176 CHAPTER X Harvesting and Storage 177-206 Storage 179-206 Essentials in keeping sweet potatoes 180-184 Advantages of the storage-house over the bank . . 185-189 Construction of the storage-house 189-198 Operation of the storage-house 198-201 Outbuildings for storage-houses 201-202 Commercial curing-houses 202-203 Banking 203-206 CHAPTER XI Preparation for Market 207-237 Market requirements 207-221 Varieties 208-210 Selling period 210-212 Containers 212-221 Proper production 221-226 Quality 222-223 Grading 223-225 Quantity 225-226 Storage 226 Packing operations 226-229 Contents ix PAGES Proper transit 229-237 Choice of car 230-233 Packing in car 233-237 CHAPTER XII COMMEKCIAL DiSPOSAI, OF THE SWEET POTATO .... 238-256 Markets 240-247 Home markets 241-243 Foreign markets 243-246 Advertising 246-247 Selling agencies 247-252 Commission house 247-251 Cooperative shipping 251-252 Selling methods 252-256 Acknowledgments It is desired to give acknowledgment to the following sources, from which figures have been adapted for use in this book: The United States Department of Agriculture for Figs. 2-7, 14-34, 40- 50; John Deere Plow Company, Figs. 8-11; Virginia Truck Ex- periment Station, Figs. 12-13; B. C. Jarrel Company, Figs. 35-38; Mississippi Experiment Station, Fig. 39. i PLATES Plate I. A commercial sweet potato bed in Texas Frontispiece FACING PAGE Plate II. Fifty-acre field of sweet potatoes, Thomasville, Georgia. (Courtesy Clark Plant Co.) . . 30 Plate III. Sweet potato field operations 56 (After U. S. Dept. Agr.) Plat^" IV. Varieties of sweet potatoes 86 y (After U. S. Dept. Agr.) Plate V, Diseases of sweet potatoes 126 (After U. S. Dept. Agr.) Plate VI. Sweet potato foot-rot 15S (After U. S. Dept. Agr.) Plate VII. Sweet potato diseases 188 (After U. S. Dept. Agr.) Plate VIII. Sweet potato diseases 214 (After U. S. Dept. Agr.) X THE SWEET POTATO CHAPTEE I ORIGIN AND DESCRIPTION OF THE SWEET POTATO Foe many centuries the inhabitants of the warmer countries of the world have recognized the usefulness of the sweet potato as a source of food. Thus Bret- schneider writes ^ that the plant " was described in Chinese books a long time before the discovery of America," in the third or fourth century of our era. It was early an important cultivated plant, the roots of which supplied the place of com in Southern China. The root was said to be reddish and as large as a goose egg. Bretschneider identifies the plant with the sweet potato. Although the exact origin of the sweet potato is doubtful, its widespread cultivation, which in range compares favorably with that of such plants as tobacco and maize, argues for it antiquity of many centuries. The aborigines are said to have recognized such marked similarity between the sweet potato and the Irish potato that they called them by the same name, though they are not only very different species, but the 1 Bretschneider, " Study and Value of Chinese Botanical Works," p. 13. 1 2 The Sweet Potato sweet potato is a true enlarged root while the Irish potato is a tuber of underground branches or rhizomes.^ Although cultivated perhaps more widely in the New World than in the Old, the sweet potato now plays a part in the vegetable calendar of gardeners in every country within or near the tropics and of recent years has become of considerable commercial importance in several regions of both North and South America. The definite origin of the sweet potato has been much investigated and discussed for many years and there is much diversity of opinion on the subject. Although there are arguments for both its American and Oriental origin as well as the possibility of its being indigenous to both the eastern and western hemispheres, much must be learned before the question can be definitely and con- clusively decided. The available evidence in favor of American origin at the present time seems to be pre- ponderant, and this theory is the one most popular among American agriculturists. The tuber is now widely distributed in all tropical regions and is being considerably used in the eastern countries, and by some writers who contend that it belongs to both hemispheres is " thought to have been much used by the ancient Chinese," although the food article referred to may have been the Chinese yam. De Candolle says that Clusius (about 1600) was one of the first writers to mention the sweet potato and he quotes the latter as saying he had eaten the product in the south of Spain, where it was supposed to come from the New World. ^ Historians tell us that Columbus 1 De Candolle gives Turpin in " Mem. du Museum," Vol. XIX, Plates 1, 2, .5, credit for having clearly shown these facts. 2 De Candolle, " Origin of Cultivated Plants," 54. Origin and Description of the Sweet Potato 3 carried sweet potatoes to Queen Isabella among his other collections from the New World. The sweet po- tato is not mentioned among the agricultural products of the anciently famous valleys of the Tigris and the Euphrates rivers. It is hardly possible to suppose, had it been indigenous to the Old World, that the plant would not have been grown in these regions when its characteristically hardy reproduction and ease of trans- portation are considered. Furthermore, philologists have found no definite Sanskrit name for the plant and although cultivated in India at the present time few kinds are known there and those that are cultivated seem to differ somewhat from the plant as known by us. The plant was not cultivated by the Arabs, Romans or Turks even a century ago. DESCRIPTION The sweet potato plant is a perennial, although com- monly grown as an annual. It is a trailing vine of the morning-glory family which strikes root freely at the joints, bearing leaves that vary greatly in shape accord- ing to the variety. This characteristic variation in leaf shape furnishes an important means for the classifica- tion of varieties. Although in general contour re- sembling those of the common morning-glory, the leaves are of three types, entire and not lobed, shoul- dered and lobed, and deeply cut and lobed. The length of the vine varies greatly, some varieties produc- ing very long luxuriant stems while others have a decided bushy or " vineless " habit of gro"wth. Var- ietal influences also cause considerable variation in color tint of vines, leaf-stems and in structure of the 4 The Sweet Potato leaves themselves. Variation is also common in the prominence and abundance of leaf-veins. Flowers and seed. — Although rarely producing flowers and less frequently maturing perfect seed in the sweet potato producing areas of the United States, occa- sionally a small bell- or morning-glory-shaped bloom, with a purple throat and white margin, may be noticed in commercial fields. Matured seed may be produced if the gTowing period "is prolonged by the use of artificial means. These seeds, however, are unreliable for use in perpetuating varieties as the resulting plants cannot be depended on as coming true to the mother plant. In fact, they may differ widely among themselves. This characteristic enables the production of new varieties by selecting strong and prepotent offspring. Tubers. — The sweet potato as known to commerce is an enlarged tuberous root. In nature this root serves as an organ for the storage of food, to be used in nour- ishing the young shoots from which the plant is ordinar- ily propagated, but man has converted this stored mate- rial to his own use. This edible tuber is much prized throughout the warmer parts of Asia and the Americas as well as to considerable extent in other semi-tropical and tropical countries as a staple article of food.^ The tubers are variable in shape, size and color as well as in food value and chemical constituents. Some are long and cylindrical while others are short, thick and blunt at the ends. (Plate IV.) The skin may be pink, yel- lowish or dull straw color, purple, red or whitish in color. The flesh is variable also in color, quality, moisture and texture. These tubers (unlike the com- mon or Irish potato) do not bear definite eyes, but are formed in underground clusters immediately beneath Origin and Description of the Sweet Potato 5 the crown of the plant. Though these tubers are botan- ically enlarged roots, they are seldom spoken of as such because of the confusion that may arise from the fact that the word " root " may denote either the slender fibrous feed-roots, the culls or " seed potatoes," or th(3 enlarged edible root. The word " potatoes " is the uni- versal term in the southeastern states while outside this territory " sweet potato " is used in contradistinction to the " Irish," " round " or " white " potato. BOTANICAL CLASSIFICATION The sweet potato belongs to the Convolvulaceae or Morning-Glory family. The Convolvulaceae is a very large and widely distributed family, making the problem of proper classification rather difiicult. The sweet potato is an Ipomcea, a genus that, according to House in Bailey's Standard Cyclopedia of Horticulture, comprises " over 400 species of which more than 200 occur in Tropical America, chiefly in Mexico." Two species are native in the northeastern states, and others are run wild. The sweet potato has been accorded dif- ferent designations in the divisions of this rather com- plex family, by various botanists. Linnaeus gave the plant the name Convolvuhis Batatas, and Choisy the name Batatas edulis, while Poiret put it into the genus Ipomoea, as I Batatas, the name it now holds. De Candolle (Origin of Cultivated Plants) says that the word Batatas is American, coming from a mistaken transfer of " potato," and he mentions Humboldt as using the Mexican name of Camote, Clusius the words Batatas, Camotes, Amotes, Ajes, all supposed to be of American origin or at least foreign to the Old World and none referring to any of the Ipomoeas, This writer 6 The Sweet Fotaio also concludes that there is no Sanskrit name for the plant and the Uengalee name of ruktalu (which he says, though being derived from Sanskrit has been mistaken for a pure. derivative of that ancient language), indicates in modern langiiages yam and potato. Attempts have been made to connect the word Batatas with oriental languages but with indifferent success. Although the sweet potato appears to have been known in China as early as the second or third century, this fact does not prove an eastern origin. It appears to have been widely distributed by primitive Pacific peoples. Probably it is derived, by a long process of do- mestication, from the tropical American Ipomoea fasti- giata. This latter plant is described by Cook and Collins (Economic Plants of Porto Rico) as '' Bejuco de puerco ; a twining vine found in waste places ; the tuberous roots are called wild potatoes in Jamaica." The word yam is commonly applied to forms of the sweet potato, although it properly belongs only to species of Dioscorea, a very different plant. Various varieties of s^veet potato yams are grown in India, Japan, Sum- atra, Java, Philippines, and numerous Pacific Islands. Some of them have pyriform spindles while others assume the form of spherical rhizomes. Several species are also found in countries of South America. The word yam is supposed to have originated in Africa and in several African dialects is said to mean, " to eat.'' Whether the fondness of the southern negro, for " Yam Taters " offers any clue to the intricacies of this early history, is not known. But the word is used with such indefinite and variable meaning by people of the United States in referring to the sweet potato, that it had best Origin and Description of the Sweet Potato 7 be dropped. It is not only botanically incorrect but causes considerable confusion in markets which hinders or prevents stabilization of varietal trade demands. CHAPTER II IMPORTANCE AND DISTRIBUTION The growing of the sweet potato has become one of the most important food-producing industries. The extension of this crop has been continually on the in- crease for the past several years and it now ranks sec- ond only to the Irish potato as a vegetable in the United States. The value of the crop in 1917 reached the hitherto unparalleled sum of $96,121,000 and that of 1918 was estimated at $116,867,000. Although always groMTi to a limited extent by prac- tically every farmer in the cotton-belt, the sweet potato until recently has been accorded a secondary place in the average southern rotation. The increasing demand for the crop is, however, revolutionizing former cul- tural and storage methods and with its wide adaptabil- ity to various climatic and soil conditions, its ease of production, and with an increasing appreciation of its value as food resulting in its introduction into new sec- tions, within the last few years there has been a rapid increase in popular favor of the crop. Alabama, pro- ducing only 6,290,000 bushels in 1916, almost doubled this yield in 1918 when it produced 14,688,000 bushels. (Tables I to V.) With the exception of certain western sections, a similar though perhaps less increased interest in production has been experienced over almost the entire sweet potato area. (Tables I toV.) Importance and Distribution Table I. — Sweet Potatoes : Estimates of Acreage, Yield PER Acre, Total Production, Price to the Bushel, Total Farm Value and Value to the Acre by States in 1918. State Acreage (000 omitted) Yield per Acre Produc- tion (000 omitted) Price per Bu. Dec. 1 Total Value (000 omitted) Value Acre New Jersey .... Pennsylvania . . Delaware Maryland Virginia West Virginia.. North Carolina. South Carolina. Georgia Florida Ohio Indiana Illinois Iowa Missouri Kansas Kentucky Tennessee Alabama Mississippi .... Louisiana Texas 23 1 5 11 28 2 81 80 130 36 1 3 8 3 8 4 13 30 153 89 65 87 15 38 2 6 125 120 120 130 120 106 110 95 92 110 96 108 82 93 91 80 95 98 96 95 75 58 65 90 125 170 2,875 120 6Q0 1,430 3,360 212 8,910 7,600 11,960 3,960 96 324 656 279 728 320 1,235 2,940 14,088 8,455 4,875 5,046 975 3,420 250 1,020 190 185 125 150 145 204 132 142 125 125 175 195 175 210 186 222 175 136 115 104 128 175 220 138 250 150 5,462 222 750 2,145 4,872 432 11,761 10,792 14,950 4,950 168 ,632 1,148 586 1,354 710 2,161 3,998 16,891 8,793 6,240 8,830 2,145 4,720 625 1,530 237.50 222.00 150.00 195.00 174.00 216.24 145.20 134.90 115.00 137.50 168.00 210.60 143.50 195.30 169.26 177.60 166.25 133.28 110.40 98.80 96.00 101.50 Oklahoma Arkansas New Mexico. . . . California 143.00 124.20 312.50 255.00 United States.. 922 93.6 86,334 135.4 116,867 126.75 The farm value of sweet potatoes, which has more than doubled in the past ten years, has increased more rapidly than acreage or production. This tuber is now one of the principal vegetable foods of the southern states, and its use can be enormously increased in all 10 The Sweet Potato sections of the United States, especially in the northern and western areas. DISTRIBUTION Although the sweet potato is gro\\Ti as a garden crop as far north as scmthern New York, northern Illinois, central Iowa and Nebraska, its commercial production, is confined very largely to the South Atlantic and Gulf Coast states. A fair commercial crop is produced west- ward along the border line between the United States and Mexico extending into central California. (Fig. 1-) The commercial crop is raised mainly in eighteen states: the Southeastern group, comprising Virginia, North and South Carolina, Georgia, Florida, Alabama, Louisiana and Mississippi. Sweet potatoes are grown Figure 1. — Map showing range of production of sweet potatoes. The shaded portion represents the area adapted to commercial growing. The dark line represents the northern limits of sweet potato culture for home use. Importance and Distribution 11 quite extensively in Texas, Oklahoma, Tennessee, Ar- kansas and California, while the northern crop which figures very largely in car-lot shipments, is produced chiefly in jS'ew Jersey, Delaware, Maryland, Illinois and Iowa. Production has increased rapidly in some states, having nearly doubled between 1915 and 1918 in Ala- bama which gives it the leading place among the sweet potato growing states, while Georgia with an increase nearly as rapid takes second place in produc- tion. Northern and western producing sections as a whole show many decreases during recent years. How- ever, a few small localities in these areas have developed a considerable industry by the use of large curing- houses and it is very probable that these sections will rapidly increase their acreage and yields within the next few years. Tables TI, III and IV give in complete form the geographic distribution and the economic value of the sweet potato in the various sections of the United States since 1899. Table II. — Production and Value op Sweet Potatoes and Yams in the United States, by Divisions and States IN 1899 and 1909, as Eeported by the Twelfth and Thirteenth United States Censuses. Division or State. Production. Value. 1909. 1899. 1909. 1899. Geographic Divisions: Bushels. Bushels. Dollars. Dollars. New Eiifrland Middle Atlantic... East North Central West North Central South Atlantic East South Central West South Central 4.818 3,326.190 1.364,2.i6 1,696,111 29.628.153 13,573,580 9,025,928 567 2,662,046 1,004,277 1,491,275 21,881,977 8,772,133 6,439,547 4,543 1,638,902 751,929 1.095,724 16,146,222 9,116,510 6,265,750 346 1,349,588 619,833 805,669 9,183,650 4,536.187 3,220,595 13 The Sweet Potato Division or State. Production. Value. 1909. 1899. 1909. 1899. Geoj^raphic Divisions: Bushels. Bushels. Dollars. Dollars. Mountain ... 38,877 574,157 19,064 246,526 52,596 357,000 14,207 139,765 Pacific Principal States. Middle Atlantic: New Jersey 3,186,499 2,418,641 1,527,074 1,213,010 Pennsylvania . . . 128,770 234,724 104,434 130,990 East North Central Ohio 133,798 249,767 104,181 139,886 158,103 155,585 Indiana 178,300 239,487 Illinois 1,050,932 511,695 506,760 303,638 West North Central : Iowa 232,413 224,622 125,763 128,981 424,470 Missouri 876,2.34 743,377 567,413 558,021 474,810 373,432 224,049 South Atlantic: Delaware 733,746 222,165 276,679 96,566 Maryland 1,065,956 677,848 483,751 317,462 Virginia 5,270,202 4,470,602 2,681,472 1,720,188 West Virginia. . . 215,582 202,424 170,086 125,523 North Carolina.. 8,493,283 5,781,587 4,333,297 2,119,956 South Carolina. . 4,319,926 3,369,957 2,606,606 1,538,205 Georgia 7,426,131 5,087,674 4,349,806 2,354,390 Florida 2,083,665 2,049,784 1,231,238 898,282 East South Central : Kentucky 1,-326,245 925,786 839,4.54 507,038 Tennessee 2,-504,490 1,571,575 1,625,056 883,620 Alabama 5,314,857 3,457,386 3,578,710 1,687,039 Mississippi 4,427,988 2,817,386 3,073,290 1,458,490 West South Central: Arkansas 1,685,308 998,767 1,359,669 534,616 Louisiana 4,251,086 1,805,482 2,357,729 859,733 Oklahoma 3-59,451 a 276,163 350,-553 a 137,231 Texas 2,730,083 3,299,135 2,197,799 1,689,015 Pacific : California -572.814 239.029 355,624 135,612 All others 106,290 107,539 109,414 68,048 United States.. 59,2.32.070 42,517,412 35,429,176 10,S69,840 a Includes Indian Territory. Importance and Distribution 13 coosint- lO (M O O O PJ inoriioco in T). 0!0(N OO05OC tH ■ t-o>ot> a> OOOOlO rH CO O5 00 05-f in t-cooom "* t-005T).cg 00 OS |f-i CO 05 Mr)." •5.(0 tX rHOOtOSt- rfcO-Tf-rH irsNco CHOlNrfcO rHt'cO >nQocoTi.c co'co" rn'rH i 1 ^' "-"S s l|£i OOOQOOOO t-lO t-rH t- COCOIrtTl.M O 00 to CI t- QOOOHCDC Tt. tH •rH05 0CO(N O00(N,HrH OOTI.050 rHC0 050IN in o o CI cc (O 05 no rH 05 00(0 to t- 050000 M \r^ rH rH rH O S-^ 05 5 < P. .S 0) " => l°1 r).u5oocou:i OiNOOOcO t- o> io CO lo CO in C^l rH 1?) inTt.050-.* (O 1 05 r'"'- 05«(DOt- 00 00OOC5 O00t-t-<0 (00005 1? rHrH ?2 fS mouocot. (MOO-^O oooooco oinooc OO^OC t- t~rH l:-(M«0 CO 00(M rH 0)t-;Dtoco int-oino5 oooooca m CO ^rHrHtOrHlO rHotocaco lOrHCO Cq«OtD5DCO rHOCOOOO o El '5' HI rH COr).-t-"(N rH CO ion. 05 lo rHr^CCOOCq 05rHOOTl. OO(D00cr 05 -jt-iH t0005 Mt-OINCO tOU5t-'(N wHt-Hin Tl. X 00 C-] c rH-(0V t-t-coinc o in III 2 iz fi;p s '^ ^;z;otc; £ C M»^ s f^ " ^ e 5 ^ ^' e c C 14 The Sweet Potato ■*CI5t-OCO Ol-HOt--* •^ t- O rtin O) rH O m to rH Tt •^" c^' ■^"rn'M OOOOOO 3o ■* t->H 00 ■'I' in CO (M rH -J" 00 to 00 tcooo-t " oos coin c r-l «OlM ■ lOQO t-oo 00 win inc oo«t-in ooeoiHO ot-ininio u>t-t-INin 5iM i-l(N 0000)0 coocOi i4iN''inTj<' in in th in in in oo in OCOCOr-l lOinino oo'<*0' 11 ■ P. - "coO'^Tjico ^lOHu>l^^ iotjiostji co lirt IO0XN-* oin f^.«^. cJco'®" oociin -o •^Oi dOiOi Oi C 03 00 OOQOt- 003'*>-l • O (NO oinio tcooocooo -"tiNooin iN-*>noiN« r-lCOinOO « -a ^ Co, .s a Islll IIJII Hill sjill lil^l^ ;^;2;qs> ^;^<^oS o>555§ MWh^S ^e^o<:S5 16 The Sweet Potato CLIMATIC EEQUIKEMENTS AND SOIL TYPES A liberal rainfall, with warm nights and abundant sunshine, lasting throughout the growing season, with less moisture during the two months preceding matur- ity, constitute ideal weather conditions for sweet pota- toes. A gi-owing period of at least 130 days is essential for the production of maximum yields. While requiring a heavy rainfall during the late spring and summer to insure vigorously growing plants and the formation of an abundant and well-shaped tuber crop, considerably less rain is needed as the time of harvest approaches. In fact, much rain at this time may result in a considerable loss to the grower by injur- ing the flavor of the potato and greatly impairing its keeping and shipping quality. An unusually long con- tinued spell of wet weather in the fall has often resulted in great loss to growers along the Atlantic and Gulf coasts, sometimes causing the entire crop to rot in the field and more often causing a souring of the potato which makes it easily susceptible to disease attack on the slightest bruising, and rendering it practically im- possible of successful storage. This condition occurred throughout all the counties bordering the Gulf of Mexico in the fall of 1918 and in the same year the crop was more or less injured all along the Atlantic coast. (The handling of the crop under these conditions is fully treated under Chapter X.) It is also believed by some growers that heavy late rains increase the tendoncy to cracking or splitting in the tubers, although the scien- tific reason for this common occurrence has not yet been satisfactorily determined. Such late rains following a dry season, though not excessive, tend to create a re- Importance and Distribution 17 newal or second growth of the tubers which causes ex- cess sappiness and makes handling in transit more difficult. On the other hand, severe drouths late in the season make harvesting tedious. Where irrigation must be practiced, as will be nec- essary in some parts of Texas, New Mexico and Ari- zona, most of the water should be applied between the time the plants are set and the ground becomes covered with vines. The water is withheld altogether for several Avceks preceding harvest, to permit the proper ripening of the tubers. A climate with an abundance of sunshine and warm nights is necessary for thrift. A temperature ranging from 70 to 100 degrees F. during the summer growing period is a good average for maximum yield, although in a small way *' sweets " may be produced under a wide range of temperatures as well as soil types. ISTorth of the cotton-belt, the sweet potato is commonly re- garded as a garden crop. The sweet potato crop is exceedingly sensitive to frost and growth is noticeably checked by cool weather. Growers in the southern Gulf states have found it profitable to set their plants in the field a little later in the spring rather than have them stunted by the cool nights. The sweet potato is strictly a summer crop and grows best in the hottest part of the year. It requires about four and one-half months for the sweet potato to reach normal maturity. A potato that is immature is harder to keep in storage and shrinks more than one fully mature. The amount of starch, sugar and other constituents as well as their form and availability differ materially at various periods of growth. The relative length of the growing period is 18 The Sweet Potato the limiting factor of production as the line indicative of profitable growth is moved northward. The sweet potato finds its most desirable soil en- vironment when planted on light friable loam or sandy soil with a yellow clay subsoil. A well-drained soil that is warm and loose with a gftod proportion of sand in the top soil and a subsoil fairly retentive of moisture provides ideal conditions. A moderately fertile sandy loam lacking an excess of undecayed organic matter is preferable, although a fairly good yield can often be obtained on soils too poor for the production of most farm crops. Large yields of the most desirable market type of potatoes are sometimes produced on some of the driest and most sandy soils when the growing condi- tions are favorable, but care in the selection of suitable areas usually pays in greatly increased returns. The depleted cotton and tobacco lands of the South can be made to give excellent returns in sweet potatoes when intelligent care is exercised to provide a supply of humus in the soil by a leguminous crop in the rotation. The loams and mixed sandy soils of northern Louisi- ana, the friable chocolate loams of northeast Texas, the cut-over long-leaf yellow pine lands of Mississippi, Alabama, Georgia, and Florida, northern and eastern South Carolina, the lower sand hills and coastal regions of North Carolina, eastern Virginia, lower New Jersey and Delaware, the sandy localities of the Kaw and Arkansas valleys in Arkansas and eastern and southern Tennessee, all afford soil types well suited to the com- mercial production of this important food crop. Other sections of these same states, as the Piedmont regions of northern Georgia and North Carolina, supply soil conditions possible of profitable development but re- Importance and Distribution 19 quiring different treatment and handling. The custom, of planting on high ridges is for the purpose of facili- tating drainage. A porous clay subsoil not only sup- plies drainage without the leaching of plant-food but it is an important factor in the production of well- shaped tubers. A very deep sandy soil without a sub- stantial foundation permits the loss of valuable fer- tilizing elements by leaching and often produces long ill-shaped potatoes that do not bring the highest prices on discriminating markets. The surface soil should be six or eight inches deep and the subsoil should provide drainage without leaching. A stiff soil favors excessive vine growth and the production of rough irregular po- tatoes. Such soils also are usually cold and in the end will prove unprofitable for commercial plantings. The sweet potato is possible of profitable growth on a wider range of soil than perhaps any other of the common field crops. CHAPTER III UTILIZATION OF THE SWEET POTATO The most important use of the sweet potato is as a food for man, either in its original form or as manu- factured into a flour or starch. It may also have an important place in the rations for live-stock. T. E. Keitt ^ of South Carolina gives the chemical analysis of the sweet potato vine (average of four varieties) and tubers (average fourteen varieties) re- spectively to be : Table VI. — Analysis of Sweet Potato Tubers and Vines. Dry Matter Protein Nitro- Pfe^ Extract Fat Fiber Ash Water Sweet Potato Tubers.... 39.1 1.6 27.9 0.5 0.9 1.0 C8.1 Sweet Potato Vines — Fresh ' 17.0 2.1 9.5 0.8 3.1 1.5 83.0 Attention is called to the fact that the nitrogen-con- tent of the sweet potato occurs in the readily avaihible form of albuminoids which render this food element capable of full utilization in digestion processes. This is an important item to be considered in calculating the comparative food value of this crop with that of some other crops which, although containing a higher percent- 1 Bull. 146, S. C. Exp. Sta., 1908. 20 utilization of the Sweet Potato 21 age of nitrogenous substances, are not worth so much in actual feeding value because of the unavailable form in which they occur. AS FOOD FOR MAN As a food for human consumption, the sweet potato has always been held in very high esteem by the peoples of the southern United States, South America, parts of Asia and many of the tropical islands. In the Philip- pines and Hawaiian Islands, it furnishes one of the main sources of food supply, notwithstanding the fact that there is no trade in the crop aside from purely local markets. The sweet potato is highly nutritious and contrary to the common belief is easily digested. If ingenuity is employed in its utilization, many palatable ways of serving it are available, such as baked, boiled, served with meats, in soups, candied, in salads, desserts, and even for the production of sirup and as a flour substi- tute. Its use is also developing in making desserts, cereals, cakes and various drinks. Composition and food value. Although the sweet potato differs botanically from the Irish potato, in general chemical composition the root resembles very closely the tubers of the white po- tato. There are, however, some important differences as shown in Table VII. It will be noted that the sweet potato as purchased has a fuel value in calories equal to approximately one- half more than does the white potato. The water con- tained is less than that of the white potato and although 22 The Sweet Fotato Table VII. — Composition of the Sweet Potato and Irish Potato Coaipaueu. Kind OF Potato Refuse Per cent. Water Per cent. Pro- tein Per cent. Fat Per cent. Carbohydrates Ash Food Values Sugar, aturch, etc. Crude Fiber Per Pound Calories Sweet potato (edible poilion). 69.0 1.8 0.7 26.1 1.3 1.1 560 Sweet potato (as pur- chased) . . 20.0 55.2 1.4 0.6 21.9 .9 450 Sweet potato (cooked) 51.9 3.0 2.1 42.1 .9 905 Sweet potato (canned) 55.2 1.9 .4 40.6 .8 1.1 800 White pota- to — for compari- son (edible portion). 78.3 2.2 .1 18.0 .4 1.0 375 White pota- to — for compari- son (as purchased) 20.0 62.6 1.8 .1 14.7 .8 305 the percentajje of crude fiber is slightly higher, it is about that commonly found in most vegetables (see Table VIII). Although it would seem that the white potato is slightly higher in protein, actually the sweet potato contains more available protein. This is ex- plained by the fact that a large part of the protein in the white potato occurs in the form of amides which are not available as food. The sweet potato is consider- ably richer in fat and contains a perceptibly greater per- centage of available carbohydrates than does the white potato. The ash-content is approximately the same and about the same waste occurs in peeling. As indicated utilization of the Sweet Potato 23 bj the table, sweet potatoes contain considerable quan- tities of sugar. This sugar-content is influenced to a marked degree by the climatic conditions under which the roots are grown, tropical varieties often containing as much sugar as starch, while those grown in the northern areas of the United States often average less than 7 per cent sugar, or less than one-fourth of their total carbohydrates. Few crops will yield an equal amount of valuable food stuff with as little expense of production. The sweet potato is especially rich in nitrogen free extract which consists primarily of sugar and starch. Both of these food elements are producers of heat and energy. Fats and carbohydrates, containing carbon as the essen- tial element, are only valuable for fuel. On the other hand, protein, containing nitrogen, is the essential ele- ment in tissue building and is necessary in any balanced ration whether for man or other animal. Lean meat, the white of egg, milk, beans and peas furnish the most familiar examples of foods high in protein. Sweet po tatoes in any ration must be supplemented by such foods. About 10 per cent of the total number of heat units consumed in any human ration should be protein. This does not mean 10 per cent of the total weight or bulk but 10 per cent of the total nutriment. In other words, out of every 100 calories of food consumed only ten calories of protein are needed. A diet containing 10 per cent protein, 30 per cent fats and 60 per cent carbohydrates is a well balanced one. In the prepara- tion of a palatable wholesome and well balanced meal, the housewife will find no more economical and satis- factory source of carbohydrates than in the sweet po- 24 The Sweet Potato tato; pound for pound the sweet potato contains about one-half more available food than does the more com- monly used Irish potato. Aside from the purely chemical food value of the sweet potato, it supplies valuable mineral salts which are not obtained in cereal carbohydrates. These min- eral salts, which are composed largely of potassium compounds, are very valuable in offsetting the acid effect brought about by meats and other common pro- tein foods in the body. To maintain the system in a- state of vigor and efficiency, the general diet should be neutral or slightly alkaline rather than overly acid. ISTothing is so valuable as an alkaline medicine as fresh vegetables and in supplying these mineral salts the sweet potato, because of its many ways of preparation and palatability, will be found to rank well in the list of cheaply available vegetables. The sweet potato is easily prepared and has the goods points of a cereal plus the advantages of a vegetable. Although containing less fat and protein than most cereals, it furnishes the body a large proportion of mineral substances. A cupful of boiled potatoes would furnish the body with about as much energ}^ as a cupful of boiled rice. Although the available protein in the sweet potato may be a little more easily digested than that of the Irish potato, yet the difference is so small as to be negligible. All experi- mental data available indicates a degree of digestibility equal to that of white potatoes.^ C. F. Langworthy says, " It is a matter of common experience that sweet potatoes are wholesome, and they are ordinarily di- gested without distress. Many persons find the starchy 1 Bull. 468, U. S. Dept. Agr., page- 21. Utilization of the Siveet Potato 25 varieties so dry that they do not relish them without large quantities of butter. This makes a rather rich mixture and is perhaps accountable for the digestive disturbances occasionally experienced. Considering both composition and digestibility, it may be said that the nutritive value of sweet potatoes is much the same as that of white potatoes and that they are well fitted to occupy the same place in the diet and furnish a palatable substitute for white potatoes. The characteristic and pleasing flavor has the advantage of giving variety to the diet. In the North they frequently cost somewhat more than white potatoes, but are still among the cheaper vegetables. In the South they are usually cheaper than white potatoes and merit their extensive AS rOOD FOR DOMESTIC ANIMALS In consideration of the great need with which this country is confronted, and especially the South, for a cheaper and more easily produced carbohydrate than corn, sweet potatoes might well be considered as a source of this food element for all domestic animals. Owing to the ease with which it is produced, the ex- ceptional food value and the readiness with which it is consumed by practically all domesticated animals, it is natural to expect that the sweet potato will play a more important part in food rations as its general produc- tion is increased. Heretofore, when the consumption of this crop has been limited to a few weeks in the fall when the hogs were turned on the fields to dig up the roots left by oversight, little attention was paid to feeding it and little was thought of its feeding value. With the advent of improved storage houses from which 26 The Sweet Potato the tubers can be taken at any season of the year as conveniently as corn from the crib, farmers are rap- idly giving more attention to the possibilities of the crop as a source of nutritious, succulent and palatable food- stuff for their live-stock. At present sweet potatoes cured in the storage-house bring midwinter prices, which makes them prohibitive for feeding purposes when con- venient transportation facilities are available. How- ever, many farmers live t oo far from the railroad to make hauling to market of such a bulky crop profitable and they will always find it a good policy to preserve the crop for feeding purposes. The very interesting results recently obtained by the Florida Experiment Station with the feeding of sweet potato silage to dairy cattle opens up a new field in the feeding of the crop. Feeding to live-stock will always be a profitable way of marketing the culls, the bruised and ill-shaped crop. All kinds of stock relish them and because of the high content of dry matter, they possess a decided advantage over the other root-crops. They can be depended on to contain an average of 10 per cent more dry matter than the Irish potato, and more than 20 per cent more than common beets, mangels, turnips, rutabagas, car- rots or parsnips. (Table VIII.) The yield in many sections is larger than that of the Irish potato and the " sweets " are not so subject to disease and insect en- emies in the field, nor are they so expensive to fertilize, propagate and cultivate. The following table ^ gives the average feeding stuff analysis of several similar crops and also that of corn : 1 Bull. 146, S. C. Exp. Sta. utilization of the Sweet Potato 27 Table VIII. Irish potato. . . . Beets, common. . Beets, mangels. . Beets, sugar .... Turnips Rutabagas Carrots Parsnips Artichoke Sweet potato. . . Corn Showing Analysis of Various Feedikg Stuffs.^ Per cent. Water Per cent. Ash Per cent. Protein Per cent. C. Fiber Per cent. N. Free Extract 78.9 1.0 2.1 0.6 17.3 88.5 1.0 1.5 0.9 8.0 90.9 1.1 1.4 0.9 5.5 86.5 0.9 1.8 0.9 9.8 90.5 0.8 1.1 1.2 6.2 88.6 1.2 1.2 1.3 7.5 88.6 1.0 1.1 1.3 7.6 88.3 0.7 1.6 1.0 10.2 79.5 1.0 2.6 0.8 15.9 68.1 1.0 1.6 0.9 27.9 10.6 1.5 10.3 2.2 70.4 Per cent. Ether Extract 0.1 0.1 0.2 0.1 0.2 0.2 0.4 0.2 0.2 0.5 5.0 Keitt says concerning the analysis of the above crops : " On land in this State (meaning South Carolina) which under the ordinary system of cropping, yield 20 bushels of corn, we should be able to produce about 200 bushels of sweet potatoes. The potatoes would furnish more than three times as much nitrogen free extract and as much or more of each of the other proximate constituents contained in the corn. From the preced- ing table, we will note that the Irish potato contains 2.1 per cent, of protein, which is more than the amount contained in the sweet potato; but about one-half of the calculated protein of the Irish potato is really nitrogen present in the form of amides, which do not have the feeding value that the albuminoids have. In order to determine whether or not any of the nitrogen present in the sweet potato was present in the form of amides, 1 All of the analyses were taken from Henry's " Feeds and Feed- ing " except that of the sweet potatoes, which represent the aver- age analysis of fourteen varieties by T. E. Keitt, chemist of the S. C. Exjp. Sta. 28 The Sweet Potato we made determinations on all of the varieties and found that there were no amides present." Importance in the proper balancing of the farm ani- mal's ration cannot be over-emphasized. The proper proportion of heat and eneray producing foods with muscle builders must be fed for economy as well as for the well-being of the animal. It is too often neglected to give a sufficient amount of fat and carbohydrates with- the protein feed. Although protein when supplied in over-abundance will partly do the work of carbohydrates, it is an expensive means of supplying it. One part of protein in the food should be supplemented with six parts of fats and carbohydrates for a milk cow. When much more protein than this is used, it cannot be assimilated by the animal and so is lost in the manure. As Keitt points out, a mixture of 8 pounds of sweet potatoes to 1 pound of cotton-seed meal would give a nutritive ratio of approximately six to one. Such a ration if periodically supplanted by other rations to avoid getting the animal " off-feed " will give good results. The value of this crop in the production of milk has been aptly illustrated in recent tests with the ensilage. Sweet potato silage. The first record of making the crop into silage was in 1912 when the Florida Experiment Station con- ducted feeding experiments with sweet potatoes. The roots were run through the ensilage cutter and handled the same as any other crop. The comparative analysis of corn and sweet potato silage was as follows : utilization of the Sweet Potato 29 Table IX.— Showing Comparative Analysis Sweet Potato Silage. OF Corn and Crop Water Cnide Protein Nitrogen P. Extract Fiber Fat Ash Sweet potato silage Well matured corn silage 54.87 73.7 1.82 2.1 39.41 15.4 1.48 6.3 .66 .80 1.85 1.7 Attention is called to the fact that there is very little difference in apparent feeding value. There is, however, about two and one-half times as much nitro- gen free extract and considerably more dry matter in the potato silage; and experience showed the potato silage to be from 50 to 100 per cent more valuable. In a test lasting forty-three days, divided into twenty- day periods with three days between periods for the purpose of changing feeds, the following results were secured ^ : " Ten cows were used in the test and were divided into two lots of five cows each. During the first period each animal in lot one was given the follow- ing daily ration; wheat bran 8.4 pounds, cotton-seed meal 2.8, and sweet potato silage 10,6 pounds. Each animal in lot two v^as given the following daily ration : Wheat bran 8.4 pounds, cotton-seed meal 2.8, and sorghum silage 15.2 pounds. " During the second period feeds were reversed, that is, the cows in lot one were given the feed that lot two had received and those in lot two were given the feed that lot one had received. " During the experiment the cows fed sweet potato silage, wheat bran and cotton-seed meal produced 2641 pounds or 307.1 gallons of milk. During the same 1 Jno. M. Scott, Press Bull. 274, Fla. Exp. Sta. 30 The Sweet Potato length of time the cows fed sorghum silage, wheat bran and cotton-seed meal produced 2415.8 pounds or 280.9 gallons of milk, a difference of 225.2 pounds or 26.2 gallons of milk in favor of sweet potato silage. '' One noticeable fact in this experiment is that the cows ate one-third less sweet potato silage than sorghum silage. This is quite a saving in the amount of feed consumed by a herd during the year." Scott of the Florida Station is very enthusiastic over the silo as a means of preserving the crop for the dairy cow. He gives the advantages of preserving as ; " No loss in storage ; they require less space for storage ; and there is no waste in feeding." It is possible that this form of silage will come into more general use throughout the South when more is known of its feeding values. Roots. The roots without any special preparation are grown extensively throughout the South for feeding purposes, especially for hogs. The Tuskegee Experiment Sta- tion of Alabama found that hogs put on almost as much fat with sweet potatoes alone as with wheat shorts alone. ^ This station also found that a grain ration of corn could very economically be cut in half by sub- stituting from 2% to 3V2 pounds of potatoes for l^A pounds of corn in feeding mules doing heavy work. Four mules were used in the test. They kept in as good condition and were able to do as much work as the four check animals which were fed corn exclusively. Planted in June and early July, they will be ready 1 Geo. W. Carver, Bull. 30, Tuskegee Normal and Ind. Inst., p. 1. Utilization of the Siveet Potato 31 for hog-grazing in October. An acre of sweet potatoes should feed eight or ten hogs weighing 200 pounds for a period of two months, provided supplemental feeds are used to balance the ration. Hogs will often root up more than they will eat immediately but little or no loss results. It has been found that some of the heaviest yielding varieties, such as the Yellow Strasburg, Eed Bermuda, Southern Queen and White Belmont, may be left out in the field with but slight injury, for feeding purposes. Care should be taken in feeding frost-bitten potatoes tO' horses, mules and cattle as they are very sweet at this time and stock eat them ravenously. They should never be fed to any stock other than hogs after they have become sour. Hogs eat them, however, with no apparent bad results. For fall and early win- ter grazing, the sweet potato is preeminently the best crop for hogs that can be grown in the South. The cut- over pine lands of that region will doubtless owe their development as a hog-raising country largely to the fact that these soils are ideally suited to the growth of sweet potatoes, which furnish excellent grazing during the period when other grazing crops are getting a start be- fore severely cold weather ; and to the perfectly balanced ration secured when supplemented with other easily grown grazing crops, such as peanuts, soybeans, and cowpea pastures. Such a combination will certainly result in the production of economical pork, Beattie ^ has suggested the production of excellent stock feed by growing some of the heavy yielding vari- ties of sweets, drying and pulverizing them and adding enough concentrates to form a balanced ration. As 1 Farmers' Bull. 324, U. S. Dept. Ajrr. 33 The Sweet Potato yet no means have been perfected by which they may be converted into a condensed stock food on the fann economically. It will be noted (Table VII i) that both the protein and fat-content are relatively low. If pea- nuts, which are rich in these two elements, are ground in the shell and mixed 1 bushel to 3 of sweet potatoes, a well-balanced ration will be secured. Three bushels of sweet potatoes are usually considered equal in feed- ing value to 1 bushel of com ; but experience has shown that supplemental concentrated feeds and especially ones rich in protein should be used if a satisfactory feed is obtained. Vines, The vines of the sweet potato when properly cured make a fair quality hay for feeding cattle and sheep. Though the vines turn black when dried, they are greed- ily eaten by all kinds of stock. The principal objec- tion to saving vines for hay is the difficulty of harvest- ing. They not only lie flat on the ground but root freely, making them very tedious and expensive to gather. Cattle, hogs and sheep readil}-- eat the green vines in the field but the food value is relatively small in this state. In chemical analysis, however, the cured vines compare favorably with some of our prominent hays. Keitt ^ gives the following compari- son of the average analysis of red clover, crimson clover, cowpoa and soybean hays with that of hay made from sweet potato vines. The analysis of the potato vines represents an average of four varieties ; Brazilian, Polo, Southern Queen and l^ancy Hall. 1 T. E. Keitt, Bull. 146, S. C. Exp. Sta., p. 16. utilization of the Sweet Potato 33 Table X. — Comparative Analysis of Sweet Potato Vines. WATER-rEEB Protein Fat Fiber Ash Nitrogen Extract Red clover hay Crimson clover hay . . . Cowpea hay Soyabean hay 14.52 10.81 18.50 17.36 3.90 3.08 2.46 5.86 29.28 30.09 22.51 25.14 7.32 9.51 8.40 8.12 44.98 40.51 48.14 43.52 16.82 12.48 3.83 4.80 26.76 18.22 8.34 8.73 44.25 Sweet potato vines. . . . 55.71 The plants with which the potato vines are compared in the above table are among our most nutritious hays and attention is called to the fact that they are all legumes. Although the average protein-content is about 4 per cent greater than that contained in the potato vines, the percentage of both fat and nitrogen free ex- tract is decidedly in favor of the latter. It will also be noticed that the fiber-content is relatively high in all of these hays compared, which is of course the least valuable of any food constituent. Although analysis shows a very favorable comparison, the actual value as a hay in practical feeding is yet to be demonstrated by determining the real digestibility and power of utilization by animals of the food con- stituents. Unless cheap labor is available and the cost of har- vesting thereby reduced, it will often be more profitable to leave the vines on the ground to decay and supply organic matter than to undertake their manufacture into hay. MANUFACTURED PRODUCTS OF THE SWEET POTATO The manufacture of sweet potatoes into various food forms which can be more systematically handled in 34 The Sweet Potato commerce than can the product in the natural state in- cludes canning, desiccating or dehydrating, from which process of reducing the water-content such by-products result as potato flour and chips. All of these processes are means of changing the same food into a dif- ferent form that marketing may be facilitated. In addition to these strictly food manufacturing indus- tries, at least two other side-line or strictly speaking by-product commercial endeavors are possible of con- siderable development ; one of these is the manufacture of starch and the other is the possibility of alcohol manufacture from the fermentable carbohydrates con- tained in the roots. Dehydrated and desiccated sweet potatoes. (Figs. 2-5.) In recent years the dehydration of various vegetables has been undertaken extensively in certain sections by numerous manufacturing concerns, and to a more lim- ited extent on a small scale in the home. This process consists in remov- ing the water from the products by means of heat- ing after the vege- tables have been first sliced or cut into small pieces. Perhaps no other one vegetable of- fers better possi- FiGURE 2. — Showing possible oon- bilities of develop- struction of a commercial sweet potato ^ r ^ desiccating plant. ment as a food utilization of the Sweet Potato 35 t li r u g li this means than does the sweet potato. The dehydrated potatoes, ready for use, appear in two forms, i. e., sliced and the " riced " or granulated forms. The sliced pieces are 1 to 3 inches Figure 3. — A rotary slicer that may- be used in slicing sweet potatoes. long, Vi to y2 inch wide and about Ys inch in thickness. The " riced " product appears as small grains about the size of a grain of rice. The sliced article is very hard and usually requires soaking overnight before using. Some of the granulated kinds require soaking while others may be boiled immediately. Both of these forms are used largely in making pies and for seasoning soups. Dehydrated potatoes may be purchased commercially in packages ranging from one pound and upward. Al- though the dehydrating industry is still in its infancy, it bids fair to furnish an excellent medium through which sweet potatoes may be exported and thus become of use in regions where it is now impossible to obtain them. The dehydrated product may be kept indefinitely and handled as any other staple article of food. Dried sweet potatoes have for many years been pre- pared at home by hanging strings of them from the rafters in the kitchen together with other drying fruits and vegetables. This practice has, however, been 36 The Sweet Potato \ fN-^ • ^^^ \ • _ mP^ Figure 4. — A portable out- door evaporator to be heated by an ordinary stove. largely supplemented by preservation in the modem farm storage-bouses. Many special devices for evapo- rating fruits and vege- tables are on the market which can be used eco- nomically for sweet pota- toes. Desiccated sweet potatoes prepared in much the same way as desiccated white potatoes are now sold to some ex- tent in everyday com- merce.^ For meeting the needs of the ordinary family, there are a considerable number of small driers, both patented and unpatented, intended to be operated over the cook- stove and in con- nection with the usual routine of the kitchen.^ Very simple dry- ing devices may be made at home by providing sin- gle racks or trays Figure 5. — A home-made drier con- made of wire structed of sheet iron in operation over a , ,, , , small stove. cloth secured to ^^= 1 ^ • ; : -• ^ 1 Bull. 468, U. S. Dept. Agr., page 20; Bull. 71, S. C. Exp. Sta., 1903, page 6; Farmers' Bull. 16!), U. S. Dept. Agr., 1903, page 25. 2 For full description of various tvpes of driers, see Farmers' Bull. 984, U. S. Dept. Agr. utilization of the Sweet Potato 37 wooden frames of the desired size, and suspended above the cookstove. Fig. 4 shows a very efficient but inex- pensive cookstove drier which is well adapted to the desiccation of sweets. A somewhat similar drier is shown in operation in Fig. 5. The housewife will fre- quently find it convenient to dry sweets in the stove oven without any special apparatus. The desiccation of sweet potatoes is especially valu- able in disposing of the small, extra long or ill-shaped roots. In preparing for the drying process, they should be washed and peeled with as little waste as possible, after which they are cut into slices or split lengthwise into quarters or eighths according to size. Peeling must ordinarily be done by hand or with a rotary slicer (Fig. 3). The rotary peelers sometimes used for Irish potatoes are not satisfactory for the sweets. The slices should be as near the same thickness as possible to insure uniform drying. As the potatoes are sliced, they should be blanched by dipping into boiling water from six to ten minutes. The sliced pieces are placed in a wire basket, or wire-bottom box, to a depth of not over 6 inches and plunged into the water, which should be boiling violently enough to stir and separate the slices. If cut into slices y^ inch thick, six to eight minutes is sufficient for blanching, but when cut into larger pieces ten minutes is necessary to secure the de- sired results. Blanching is done to prevent darkening and it is desirable to prolong the blanching process until partial cooking results. As soon as blanched, they should be drained quickly and placed in the drier. A begiiming temperature of 145° to 150° F. should be used and as the product loses moisture, this should gradually be raised to around 160° F. Drying is com- 38 The Sweet Potato plete when the slices become brittle and break readily under pressure. The dried material is used for cook- ing iu the same way as other dried root-crops. Sweet potato flour. With the beginning of the War, every effort was made to determine the most economical and convenient substitutes for wheat flour in making bread. Among the many important wheat substitutes derived was sweet potato flour. There are several grades of this flour and quite as many ways to manufacture it. Flour may be made from the raw potato, from the cooked product and from the pulp resulting from the by- product manufacture of starch (page 39). Sweet potato pie product. Sweet potato pies are considered a delicacy in all sec- tions of the South. As a result of the widespread use for this purpose, canning factories in some sections are manufacturing a special pie product. This pie filler is put up in two- and three-pound tins and is ready to be used without further preparation. It is commonly man- ufactured by peeling, mashing and then cooking the po- tatoes, after which a sufficient quantity of ribbon cane sirup is mixed with it to form a thick semi-fluid sub- stance. The natural sugar of the potato and the cane sirup combined furnish a delicately sweet pie filler which is rapidly becoming popular over a wide area. The red or yellow varieties which have a relatively high sugar-content are preferred to the mealy and less sweet kinds in making this product. utilization of the Sweet Potato 39 Sweet potato chips. Sweet potato chips are now manufactured to a lim- ited extent by some dehydrating concerns. They are put on the market in much the same form as the com- mercial Irish potato chips, which are packed in waxed paper boxes. The sweet potato chips, however, usually require other preparation before using. Sweet potato sugar. In addition to its high starch-content which is largely capable of being converted into sugars, the sweet po- tato also contains several per cent of free sugars (more than 4 per cent of sucrose has been found in the roots). The fermentation of this saccharine matter is embodied in the manufacture of alcohol. Though the commercial manufacture of sugar from this crop has not yet been undertaken, it is possible that the next few years will witness concerted effort in this direction. Starch manufacture. Carver ^ has described the home manufacture of starch as follows : " This is very easily made ; all that is necessary is to grate the potato, the finer the better, put into a cheese cloth or thin muslin bag and dip up and down in a vessel of water, squeezing occasionally. Continue washing as long as the washings are milky. xVllow it to settle five or six hours or until the water becomes clear, pour off ; re wash the starch, which will be in the bottom of the vessel, stir up well, allow to set- tle again, pour off the water and let it dry. Keep the same as any ordinary starch." Starch made in this 1 G. W. Carver, Bull. 37, Tuskegee Normal and Ind. Inst. 40 The Sweet Potato way was equal if not superior to com-stareb in cooking and it was found that an excellent quality of library paste having powerful adhesive power could be manu- factured from it. A theoretical yield of approximately ten pounds of pure starch to each bushel of sweet potatoes has been secured in the laboratory with scientific methods. The following table gives the analyses of fourteen varieties and shows an average of 18 per cent starch, although it will be noted the starch-content varies considerably with different varieties. The analyses were made by Keitt of the South Carolina Station who calls attention to the fact that " one indication which appears worthy of note is that the water content as a rule varies from Table XL — Showing Calculated Eate of Yield per Acre, Water-Content, Starch-Content, and Yield in Pounds per Acre. Variety Rate of yield per acre in Bu. Per cent. Water Per cent. Starch Pounds of Starch per Acre Nancy Hall Polo Southern Queen White Spanish General Grant Brazilian . . 270.0 281.0 416.0 141.0 191.0 450.0 158.0 281.0 214.0 180.0 270.0 174.0 141.0 326.0 68.75 72.53 68.38 67.27 06.52 65.45 72.80 68.87 72.12 65.57 62.20 65.82 69.84 67.74 17.82 14.85 19.07 20.05 17.30 10.46 14.43 16.71 13.50 19.40 20.63 23.89 19.22 18.72 26.94.0 23.37.0 44.43.0 15.83.0 18.50.0 41.48.0 Arkansas Beauty Tenn Notch Leaf Yellow Nansemond .... Purple Yam Pumpkin Early Yellow Yam Shanghor Yam Vineless Bunch Yam. . . Fullerton Yellow Yam. 12.77.0 26.29.0 16.18.0 19.56.0 30.48.0 23.28.0 14.83.0 34.18.0 Average 249.5 8.11 18. 24.86.5 Note — The bushel per acre yield being calculated from small areas can be taken only as comparative. utilization of the Sweet Potato 41 65.0 and 69.0 per cent and it seems that any consider- able increase of this percentage is accompanied by a corresponding decrease in the starch content — the per- centage of starch being about as many per cent below the average as the water content is above the average. There are three striking examples of this, — the Polo, the Arkansas Beauty and the Yellow Nansemond ; all of these varieties containing over 72 per cent water and below 15 per cent starch." White-fleshed varieties would probably be better suited to commercial starch manufacture, since yellow kinds might discolor the starch. It is possible that with care in selection, the starch-content of specific varieties could be increased. This possibility and other phases of starch manufacture from the sweet potato offer a wide field of study for the scientific investigator. Alcohol manufacture. When a solution of sugar is fermented by mixing with a certain kind of yeast (Mycoderma cervisiae) and kept at a certain required temperature until carbon diox- ide ceases to be given off, there is formed the familiar substance known as alcohol. The sugars necessary for the fermentation of alcohol may be obtained from a large number of possible sovirces. In the commercial manufacture of this product, no cheaper means of pro- duction has been found than by making use of the fermentable saccharine matter contained in such crops as rye, barley, wheat and other grains. A number of fruit juices and vegetables may be made to yield alco- hol by fermenting. In addition to about 18 per cent starch which is capable of fermentation by first con- 43 The Sweet Potato verting into sugars, the sweet potato also contains an average of about 4 per cent actual sugar, making an average of about 22 per cent of alcohol-producing ma- terial. Keitt found that a bushel of sweet potatoes would produce on an average a little more than a gallon of commercial alcohol. As varieties differ materially in starch and sugar-content, the amount of alcohol pro- duced by a given quantity of sweet potatoes would naturally be influenced by varietal kind. With the in- creased demand for denatured alcohol in art and science, it is probable that this crop will furnish an important source of raw material for manufacture. Sirup from sweet potatoes. Experiments conducted in the Bureau of Chemistry, United States Department of Agriculture, have pro- duced a palatable and wholesome sirup from sweet po- tatoes. The method is recommended particularly for home use when there is an over-supply of sweet po- tatoes that cannot be marketed to advantage. It is not advocated at present for commercial use, because it is believed that sweet-potato sirup cannot compete on a commercial basis with grain sirups. The process of manufacture is described as follows : ^ " The sweet potatoes should be washed, any decayed portions or other blemishes removed, and then weighed. They are then placed in a kettle with plenty, of water and boiled until thoroughly soft. From II/2 to 2 hours' boiling is required. The potatoes are then mashed in the kettle in the water in which boiled, with sufficient water, adding more if necessary to form a thick, smooth, mushy liquid. The temperature of the mixture is then 1 " Weekly News Letter," U. S. Dept. Agr., Feb. 12, 1919, p. 6. utilization of the Sweet Potato 43 brought to 140° F., and a quantity of ground malt added equal to 31A per cent of the weight of the orig- inal sweet potatoes. The mixture is thoroughly stirred and allowed to stand for a few minutes at a temperature of 140° F., and the temperature is then brought with constant stirring to a temperature of 150° F., the source of heat removed, and the mass allowed to stand with occasional stirring for an hour. The mixture, known technically as the ' mash,' is now pressed in cloths to separate the liquid and solid portions. The material is placed in cloth bags, which are closed, and the bags subjected to gentle pressure while kneeding. The juice flows out readily, leaving the pulp behind. The juice is now boiled down to sirup in an ordinary kettle. " Any of the common varieties of sweet potatoes can be used. Freshly harvested stock will yield a sirup somewhat less sweet than sweet potatoes which have been harvested for some time. " The sweet potatoes should be cooked with plenty of water. It is necessary to obtain a fluid, mushy mass which can be mixed readily with the malt. " Great care must be taken that the temperature of the mass be uniform throughout during the action of the malt. " Ordinary brewer's or distiller's malt of good qual- ity gives excellent results, or the malt can be made by sprouting barley under proper conditions. In prepar- ing malt from barley the following method will give satisfactory results: The grain should be soaked in water for 12 hours. The water is then drained off and the grain allowed to stand for 12 hours, and the opera- tion of soaking and standing repeated during the next 44 The Sweet Potato 24 hours. At the conclusion of the steeping, the in- terior of the grain should be soft and chalklike. The grain is then spread upon a tray in a layer not over 6 or 8 inches deep. The temperature at which the sprouting grain is kept is of great importance in the successful manufacture of malt. It should be kept as near 60° F. as possible. After the grain has grown for six or eight days the sprout forces its way out at the end of the grain opposite to the rootlet, and the malt may be used with excellent results at this time. Sprout- ing, however, may be allowed to continue slowly for another six or eight days, or even longer, until the sprout has attained a length from three to four times that of the grain. The grain must be kept moist, so that the rootlets do not wither during the sprouting period and should be turned over and thoroughly mixed at least once a day and kept covered with a wet cloth and in the dark. The product is known as ' green malt.' It should have a fresh odor and be free from any sour smell, and should be free from mold. Immediately be- fore use the green malt should be finely ground in an ordinary meat chopper or other suitable machine. When so ground it forms a pasty mass and may be added directly to the boiled mashed sweet potatoes and the mixture thoroughly broken up by stirring until the malt is thoroughly disseminated. " On a small scale this is most readily accomplished as described. On a large scale an ordinary cider press, using racks and cloths, can be successfully employed. The liquid obtained is slightly sweet and rather turbid. Plenty of water should be used in order to produce a mash from which the liquor will freely flow and in which a large proportion of the sugars may be easily utilization of tlt.e Sweet Potato 45 removed by a single pressing. The total quantity of water used should be two or three times the weight of the potatoes. The sweet-potato sirup can be boiled down to as thick a consistence as desired. The pulp which remains can be dried and used for feed, or it can be fed while fresh." Canned sweet potatoes. The commodity in this form is now finding a wide and ready sale over the entire country. There are many canning factories in the South and Southeast, especially along the coast lines where fish products may be obtained during the season when potatoes are scarce. These industries are opening up an extensive trade which has not been developed before. Practically every town along the Gulf Coast has one or more canning fac- tories which handle sweet potatoes exclusively during a large part of the year. The commercially canned product appears in two- and three-pound tins. They may be cooked in any way except baked, as they are peeled and somewhat mashed in the canning process. The red or yellow varieties are preferred for canning because of the dark color assumed by the white po- tatoes after cooking. J. H. Barrett and Son, manufacturers of canned goods at Westminster, South Carolina, who are among the most successful eanners of sweet potatoes in the South, have given the following method for steam can- ning: " I have been packing sweet potatoes for over ten years and I lose very few cans, not over one or two to the thousand. I peel the raw potatoes on an Imperial machine, cutting the large potatoes in several pieces, 46 The Sweet Potato making them a uniform size so that the entire cooking will be thoroughly done at the same time. I cook in a copper kettle using steam, without any water as the steam makes enough moisture. After the potatoes are thoroughly cooked I remove them from the kettle and pack them in cans, filling the can full of soft cooked potatoes, then I cap and cook the potatoes one hour at 2(30 dgrees of heat, then remove the potatoes from cooker immediately and let them cool. If you will carry out this method your potatoes will keep all O.K., but do not let your potatoes remain out too long from the first cooking in the kettles until you cook them the second time — not over one hour." Other canning recipes with steam pressure canning machines and tin cans are : ^ Eecipe No. 1. — Boil or steam potatoes until three-fourths done; peel and pack dry into No. 3 cans, being sure to get full pack, then seal. Exhaust 8 to 10 minutes at boiling tem- perature and tip. Cook or process these cans 70 minutes at 10 pounds pressure. Recipe No. 2. — Cook potatoes until thoroughly done; skin and mash with an ordinary masher. Pack solidly into cans and finish as in recipe No. 1. If No. 2 cans are used for the mashed potatoes, they should be cooked 55 minutes instead of 70 minutes. Canning with glass jars and hot water is not so satisfactory as when steam canning facilities are avail- able. DOMESTIC COOKING OF SWEET POTATOES It is thought by many that sweet potatoes are at their best when prepared in the simplest way, that is, cooked 1 Miss Cornelia Simpson, canning specialist, Tex. A. & M. Coll. utilization of the Sweet Potato 47 or boiled. Even so, a very wide variety is possible, for it lias been said that sweet potatoes may be prepared in more than a hundred ways. Specific ways of prepa- ration will be given as briefly as possible. The recipes contained herein have been carefully selected from the great bulk of information published because of their practicability and ease of execution; these have been thoroughly tried out and recommended by the United States Department of Agriculture and food specialists of the various state departments of agriculture. Northern and southern tastes differ as to what is a desirable quality in a sweet potato. The moist sweet varieties are preferred in the South while the North generally prefers a dry mealy root. Long cooking will, however, make any sweet potato moist. (" T " indicates tablespoons.) BAKED SWEET POTATOES Wash the potatoes and bake the same as white potatoes. Small ones will bake in half an hour, while very large ones will require an hour or more. If the potatoes are desired very moist and sweet, bake from 1 hour to 2 hours depending on size. BROWNED SWEET POTATOES Boil medium-sized sweet potatoes 45 minutes. Peel them and cut in halves lengthwise. Put them in a baking pan and baste with savory drippings, and season with salt. Cook them in a hot oven for 20 minutes. FRIED SWEET POTATOES Parboil the potatoes, peel, cut in slices, and fry to a nice brown in boiling lard. They can be fried without boiling, though it will require a longer time and more lard or butter. 48 The Sweet Potato CANDIED SWEET POTATOES Candied sweet potatoes are very popular on southern tables, and are extremely palatable when well prepared. Cut boiled sweet potatoes into long slices, place in an earthen dish, put lumps of butter on each slice, and sprinkle with sugar. Some cooks add a little water also. Bake until the sugar and butter have candied and the potatoes are brown. SWEET POTATO BISCUIT V2 cupful mashed sweet potatoes, 1 cupful flour, 4 tea- spoons baking-powder, V2 teaspoon salt, 2 tablespoons butter or lard, milk sufficient to make a soft dough. Sift the flour, salt, and baking-powder together several times; add these to the potatoes, mixing in with a knife. Now work the fat into the mixture lightly; add the milk; work quickly and lightly until a soft dough is formed; turn out on a floured board; pat and roll out lightly until about one-half inch thick; cut into biscuits; place on buttered or greased pans, and bake 12 or 15 minutes in a quick oven. SWEET POTATO BREAD (Enough for two large loaves). G cups sifted flour (more if flour is soft), 2 cups mashed sweet potato (luke-warm), y2 cup lukewarm water (this will not be required if liquid yeast is used), 1 cake yeast, dry or compressed or Vo cup liquid yeast, 1 T sugar, 1 T salt, 2 T shortening, if desired. To the cool mashed potato add the salt, the sugar, and about 4 ounces of the flour (1 scant half pint of sifted flour), and mix thoi'oughly. Next add the yeast, which has been rubbed smooth in a cup with 4 tablespoons of lukewarm water. To get all the yeast, rinse the cup with the remainder of the half cup of water and add this also to the potato. Cover and place the bowl out of the way of drafts and at a temperature of 80° to 88° F. Allow this mixture to rise for two hours or until very light. To this sponge add the melted shortening and the re- mainder of the flour, kneading thoroughly until a smooth and elastic dough has been formed. Do not add more water utilization of the Sweet Potato 49 to the dough unless it is absolutely necessary in order to incorporate all the flour. Set the dough back to rise again for 1 hour or until light. Bake allowing it to rise in the pans only until two and one-half times the original volume. If desired the sponge for this bread may be set in the evening using only one-fourth as much yeast as directed for the quicker method. In warm weather keep this sponge cool. Rolls may be made from this mixture. SWEET POTATO MUFFINS IV2 cups cooked sweet potato (Irish potatoes may be used instead, with or without the sugar), IV2 cups sifted white flour, 1 teaspoon salt, 2 teaspoons baking-powder, 2 T sugar, 2 eggs, 2 T shortening, liquid sufficient to make a rather stiff batter (about Vs. cup). Boil the potatoes in the skins until tender, drain, peel and mash fine. Putting the potato through a ricer or colander is better than mashing. Sift together the flour, salt, sugar and baking-powder twice. Beat the eggs until light and add to the cool mashed potato. Next add the melted shortening, then the flour mixture, alternating with portions of the liquid, until a batter is formed somewhat stiffer than for ordinary flour muffins. Drop by spoonfuls into greased muffin pans until half filled and bake 20 to 25 minutes in a fairly hot oven. SWEET POTATO SALAD Cut hot boiled sweet potatoes into very small pieces. To 1 cup diced potatoes add Mj cup chopped peanuts and 1 T of thin mayonnaise or French dressing. Arrange on lettuce leaves and garnish with stiff mayonnaise. SWEET POTATO PEANUT CROQUETTES 3 cups mashed potato, IV2 teaspoons salt, 2 T fat, 1 egg (beaten slightly), % cup chopped nuts, and a little milk if mixture is too stiff. Shape into croquettes. Dip in crumbs, beaten egg, into crumbs again and fry in deep fat. Drain and serve hot. 50 The Sweet Potato BAKED SWEET POTATO CUSTARD 1 egg, IV2 cups scalded milk, ^2 cup mashed sweet potato, I/2 teaspoon vanilla, 2 T sugar. Beat egg, add sugar, mashed potato and scalded milk. Pour into greased individual bak- ing dishes, place in pan of hot water and hake until set. Raisins or nuts may be added. Serve with caramel sauce. SWEET POTATO A LA AGNES If you use grate or open wood fires, this will prove an attractive supper dish. Bury the sweet potatoes in the ashes and cover with coals or allow to stand under grate. Roast for about two hours. The skin will be very dark when fin- ished. Remove from ashes, wipe off potatoes, open the skin and take out potato. Serve hot with a spoonful of mayon- naise dressing on each potato. SWEET POTATO WITH RAISINS AND MARSHMALLOWS 2 cups mashed, boiled, or baked sweet potato, 3 T butter, 1/2 teaspoon salt, hot milk enough to moisten. Beat, adding % cup chopped raisins or prunes. Pour into greased baking dish, brush top with milk, and brown in oven. Just before removing from oven stick marshmallows half way into mix- ture and keep in oven until marshmallows have toasted. Serve hot. The marshmallows and raisins may be omitted and the potatoes served as mashed potatoes. The mashed potatoes may be varied by adding a sirup of 2 T molasses and 1 T butter cooked together for five minutes. This can be poured over the mashed potatoes, and bake until they are very brown. SWEET POTATO DEVIL's FOOD 1 cup mashed sweet potato, ^A cup sugar, y^ cup fat, 2 tea- spoons milk, 1 egg, I/4 cup raisins, V-i cup hickory-nuts, 1 cup flour, 4 teaspoons baking-powder, 2 teaspoons melted choco- late, 1 teaspoon cinnamon, I/2 teaspoon cloves, V2 teaspoon nutmeg, Va teaspoon salt. Cream fat, sugar, add beaten egg, mashed potato, melted chocolate, milk. Sift flour and measure. Add other dry in- utilization of the Sweet Potato 51 gredients to flour and sift into mixture. Add nuts and raisins. Bake in greased pans and combine in and frost two layers with the following frosting: Vs cup water, 1 cup sugar, 1 egg, Vo teaspoon vanilla. Cook water and sugar to- gether until the sirup threads when dropped from a spoon. Eemove from fire and beat into stiffly beaten egg-white. Add vanilla and beat until consistency to spread. SWEET POTATO DROP COOKIES 2 cups mashed sweet potatoes, iVi cups sugar, 4 teaspoons baking-powder, 1 teaspoon cloves, V2 cup raisins, 1 egg, I/2 cup fat, 2 cups flour, 1 teaspoon cinnamon, V2 teaspoon nut- meg, 1 teaspoon salt. Cream fat and sugar. Add beaten egg, mashed potatoes, dry ingredients sifted together and raisins. Drop from spoon on greased tin and bake in moderately hot oven. BOILED SWEET POTATOES The roots are washed and boiled as Irish potatoes, but with- out peeling. When sufficiently done to permit piercing with a straw, take up and peel; when large, cut lengthwise; place in covered dish and pour melted butter over them. Boiling is especially popular in the North where the varieties grown are commonly dry and mealy. SLICED AND BAKED SWEET POTATOES Slice roots that have been boiled until nearly done, place butter sprinkled with sugar between slices; continue layer of butter and sugar and potato slices alternately until baking dish is full. Add a small quantity of water and bake thoroughly. RICED SWEET POTATOES Force boiled sweet potatoes through a ricer, or a coarse strainer into a hot vegetable dish. Avoid rehandling in order to keep the potatoes light and attractive in appearance. Eiced sweet potatoes are particularly appropriate with roast beef, roasted chicken or any meat served with gravy. 52 The Sweet Potato SWEET POTATO FLOUR There are several grades of this product and quite as many- ways to manufacture them. Each one of these flours or meals (as most millers insist on calling them) has a particu- lar character of its own and is therefore adapted to certain uses the other products are not. The sweet potato flours are, generally speaking, of three kinds : (1) Those made from the uncooked potato; (2) those made from the cooked potato; (3) those made from a careful system of roasting, or from the starch making process. The first two will be of most interest to the housewife. FLOUR NO. 1 FROM THE RAW POTATO Here all that is necessary is to wash, peel, and slice the potatoes very thin, dry in sun, oven or dryer until the pieces are quite brittle, grind very fine in a coffee or spice mill, or any type of mill that will make wheat flour or corn-meal; bolt through fine cloth in the same way as for other flours. The fine flour-like particles will pass through, and the coarse granular meal left on the bolting cloths. This kind of flour is good for making mock rye bread, ginger snaps, wafers, waffles, batter cakes, custards, pies, and the like. Bread can be made with it, but it makes a dough deficient in elasticity, bread dark in color and a loaf which dries out quickly. The coarser meals can be cooked in a great variety of ways and make very palatable dishes; they are to be soaked in warm liquid (whatever is desired to cook them in), when soft proceed as for grated potatoes. FLOUR NO. 2 FROM COOKED POTATOES For the making of this flour the potatoes are boiled, or steamed (preferably the latter) until done, sliced or granu- lated by mashing or running through a food chopper and dried until they become very brittle. They are made into flour and meal exactly the same as given for Flour No. 1. This kind of flour is especially good for bread, cakes, pies, puddings, sauce, gravies, custards, and so on. A loaf may be made in the proportion of one-third sweet potato flour to utilization of the Sweet Potato 53 two-thirds wheat flour. Many experiments have proven that either the maslied sweet potato or the sweet potato flour may be used in bread as high as 50 per cent but at this point it becomes decidedly potato-like in texture and flavor but not unpalatable or unwholesome. FLOUR NO. 3 FROM PULP This flour is make from the pulp after the starch has been removed. It is dried without cooking, ground and bolted exactly the same as recommended for the other flours. When made into puddings, pies, blanc-mange, and the like, the same as shredded eocoanut, it resembles it very much in taste and texture and is very palatable and is a most welcome addition to the dietary. It can also be used in the making of bread and is especially valuable when a loaf is desired with- out the least sweet taste, and with as little starch and sugar as possible. SWEET POTATO STARCH This is very easily made, all that is necessary is to grate the potato, the finer the better, put into a cheese-cloth or thin muslin bag and dip up and down, in a vessel of water, squeezing occasionally, continue washing as long as the wash- ings are very milky. Allow it to settle five or six hours or until the water becomes clear, pour off; rewash the starch, which will be in the bottom of the vessel, stir up well, allow to settle again, pour off the water and let dry; keep the same as any ordinary starch. Used exactly the same as corn- starch in cooking. As a thickening agent, 1 tablespoon of sweet potato starch thickens 1 cup of licpiid to the consistency of a tliiek sauce or makes a pudding of the proper con- sistency for molding. CHAPTER IV PROPAGATION The sweet potato produces seed in ISTorth America only when the growing season is prolonged by artificial means. The more common varieties are propagated by means of sets taken from the tubers (called " seed ") themselves and from cuttings or vines from the growing crop. The " draws," as they are commonly called in the South, are produced by bedding the tubers in a specially prepared bed where they are sprouted and the young plants removed three or four times as they appear, being set in the field as would the seed- lings of cabbage, tomatoes or similar plants. This practice furnishes the most economical method of propa- gation. The tubers themselves are sometimes planted directly in the field where they are to grow in much the same way as with the common potato. When this method is employed, several plants often appear in one hill, which necessitates thinning. Its use is restricted to special areas or to cases influenced by peculiar con- ditions. Propagation by vine-cuttings has been prac- ticed quite extensively and very satisfactorily in all of the southern states. This practice is especially popu- lar for the late crop and there are several arguments in favor of its more extensive use in controlling disease, in the production of potatoes to be stored, and in render- ing production more economical. At a sweet potato rropagaiion 55 conference held in connection with the annual meeting of the Association of Southern Agi-icultural Workers in Birmingham, Alabama, in 1919, the terms " slips," " sprouts," " draws " and '' plants " were officially de- cided on as designating plants derived from bedded po- tatoes, while " cuttings " and " vine-cuttings " should refer to the cut ends of vines used for rooting. In the extreme southern part of the United States, notably in southern Florida and also in some of the neighboring tropical islands, the potatoes are sometimes left in the ground from one year to another. This practice would be more widely followed but for the excess water often present in the soil in these southern areas, which causes the tubers to rot. In a dry season or on high ground even near the water where the winters are always mild, as in southern Florida, the crop may remain in the ground without injury. In such cases, the tubers are removed for use as needed and in the spring those which are left sprout and produce slips which may be transplanted or allowed to remain on the same ground. By far the most important method of propagation and that which is primarily depended on by practically all commercial growers of this country, is the use of plants produced in the artificial or preliminary seed- bed. In fact, the recent gain in popularity of the sweet potato as a food crop has created such a demand for sweet potato plants of pure varieties by the general public, that individual growers have found the " slip " business a very profitable commercial enterprise. In many sections individuals have developed this business into an industry of no mean economical importance. Several dealers in the Central West bed annually more 56 The Sweet Potato than 10,000 bushels of tubers, selling the plants to smaller growers at a good profit. This specialization has not only been made remunerative by ingenious and industrious planters, but, because of the economy pos- sible in handling large quantities, has been of real service to the smaller planters. The larger number of farmers who plant less than an acre usually find it more convenient and economical to purchase their plants than to grow them at home. Planters growing more than an acre usually prefer to prepare their own seed- bed and grow their sets at home. From 6 to 8 bushels of seed potatoes are required to produce enough plants to set an acre at one drawing. Usually three or four drawings may be made, 3 or 4 bushels of seed producing enough plants for an acre. It requires from 8,000 to 10,000 plants to set an acre (Plate III). Although as many as 4,000 plants have been produced from a single bushel of seed, the average production ranges from one- third to one-half this number with three or four draw- ings. The question of proper seed selection with refer- ence to the influence on yield and quality of the field product and the control of disease is now known to be of more importance than was formerly thought. SELECTING SEED (l. E., TUBERS FOR PROPAGATING) Although the value of individual hill selection has been fully demonstrated with the common potato, ex- perimental data available on the same subject with the sweet potato is not so complete. The commonly fol- lowed practice of using the culls and stringy tubers for seed has been the subject of much controversy with little conclusive data substantiating either side of the argument. However, practical growers have long Platk III. — Sweet potato field operations, a, A field of sweet potatoes after the vines have practically covered the ground, b. Droppincr and setting draws by hand. c. A horse- drawn fertilizer distributor in operation. Propagation 57 recognized the importance of seed selection as a means of controlling disease and popular opinion seems to have indicated merit in the theories commonly advanced with reference to the influence of more careful selec- tion over yield and characteristics of the resulting crop. Eecent experiments on the eastern shore of Virginia have strengthened this belief. There are several con- siderations in selecting seed which plain judgment would dictate as being worthy of practical execution for the sake of a conservative system on the farm if for no other. One of the greatest hindrances to systematic marketings, especially from the more southern areas, is the mixed condition of the varieties. As the only means of mixing is by mechanical mixture of the tubers themselves, this condition is inexcusable. It can be entirely eliminated by careful selection and handling of the seed stock. Selecting "seed" (tubers) for disease control. Seed selection is of the very first importance in sweet potato growing from the standpoint of controlling dis- eases. A number of diseases seriously affect the crop in the field and unless care is taken to choose clean healthy seed, these diseases may be carried into storage and later into the seed-bed where they are transmitted to the propagating plant stock. One of the greatest troubles in the way of a successful storage is the bring- ing in from the field of decay organisms which would never have been present had proper precautions been taken in selecting the seed which produced the field crop. A comparatively short time ago sweet potato diseases were practically unknown, but now it is often difficult to secure disease-free seed. Many of the dis- 58 The Sweet Potato eases, such as soil-stain and foot-rot, can be controlled eifectively by selection and the danger even from soft- rot and black-rot can be greatly lessened by careful culling and the use of proper disinfecting agencies on the seed to be bedded. (Chapter VIII.) Only sound potatoes free from soft spots should be selected for bed- ding. Tubers with suspicious looking spots should be avoided for seed purposes. It is best to obtain these seed from plots known to be free from field diseases. Freedom from disease should be the governing factor in selection rather than disease resistance. The tubers for bedding should be selected at time of harvesting, carefully handled to prevent bruising and consequent infection by disease, and carefully stored to prevent freezing and injury from other sources. For yield and quality. It is now commonly recognized that the only basis for the improvement of the sweet potato is the hill unit. Bin selection is not sufficient. Hill selection, followed for two years on the eastern shore of Virginia, practically doubled the yield. ^ The practice in Vir- ginia is to select from hills with five or more marketable potatoes. Quicker results will be secured if the stand- ard is placed higher and selection made from hills show- ing ten or more marketable potatoes. The market de- mands a smooth, medium-sized, spindle-shaped potato; and this standard should be kept in mind in selecting the seed stock, although use of the small tubers from high yielding hills seems to have no bad effect. 1 Report of the conference on sweet potato problems and on diseases of cotton, corn and tomatoes, Birmingham, Ala., Feb., 1919. Propagation 59 Small or medinm-sized roots are usually selected for seed purposes since the small roots produce many more plants to a bushel of seed than do larger potatoes. It would seem reasonable to believe that continued use of small seed would tend toward the production of a field crop of small tubers but this theory has not been sub- stantiated in practice. The question has been raised whether, because the smaller potatoes are usually formed later in the season, the practice of using these small potatoes for seed would tend to produce a late strain. For all practical purposes, the tendency in this direc- tion, if present at all, would be so slight as to be negli- gible. As the sprouts come only from the neck of the potato and as the greater number of smaller potatoes contained in a bushel provides a much larger total sur- face area from which the buds may grow out, it is quite evident that economy would result from the use of small tubers in so far as the number of plants pro- duced is concerned. This fact is further augmented by the difficulty of disposing profitably of the small potatoes on the market for any other purpose than for seed. Although some growers maintain that more vigorous plants are produced from the larger tubers, more sub- stantial evidence will have to be secured before dis- continued use of the small tubers is warranted, espe- cially if they are chosen from high yielding hills. It is probable that certain varieties have a greater tendency to produce stringy potatoes than do other kinds under the same conditions. It is evident that in case of a mechanical mixture of two such varieties, continued selection of the small tubers would result in the in- ferior variety becoming dominant over the more de- sirable one. As has been stated, however, the tubers 60 llie Sweet Fotaio of different varieties slioiild never be mixed. In gen- eral, it may be said that painstaking hill selection should be practiced in the fall at digging- time, the po- tatoes selected being carefnllj- saved in a storage-house and culled over in the spring. Medium-sized or small tubers are preferred. Production of seed potatoes. Some growers have adopted a systematic method of producing their seed stock with a view to the elimina- tion of disease, improvement in quality and economy and convenience of growth without going through the entire field each year. One system is managed on the same principle as the " ear-to-row " test in seed-corn selection. A special seed patch is prepared. Medium- sized well-shaped potatoes are selected from high pro- ducing hills and enough are bedded to produce slips for the seed patch. The following year the same care- ful hill selection is made from the seed patch for tubers to bed for select plants the next year, the remainder of the seed-patch potatoes, whether from high yielding hills or not, being used to bed for the main field crop. This practice is probably justifiable when planting is done on a large scale and when wholesale selection of tubers for the entire field crop would have to be trusted in the hands of unreliable farm labor. The specialized production of seed stock from vines has been found of value, especially in the control of disease and in the better keeping quality of potatoes produced in this way. Seed treatment. Even though careful culling of bruised and diseased Propagation 61 potatoes has been practiced, mncli may be accomplished toward preventing trouble in the seed-bed by dipping the seed from five to eight minutes in a solu- tion made by dissolving 1 ounce of corrosive sublimate in 8 gallons of water. (Fig. 6.) An old lard or molasses barrel may be used conveniently for the solution and the seed emersed in any con- venient container which will permit the escape of the water back into the barrel. It is not necessary that the seed be rinsed in clean water before bedding. After treating three or four lots of seed, the solution should be discarded or more corrosive sublimate added. This treatment is designed to kill the disease spores on the surface rather than to reach those that may be present within a partly decayed tuber. Although having no effect on stem-rot, this treatment is helpful in controlling black-rot and soft-rot, if the tubers are not already affected. It has also been re- ported that soft-rot may be prevented by dipping the seed in equal parts of sulfur and air-slaked lime.^ 1 Report of the conference on sweet potato problems and on diseases of cotton, corn and tomatoes, Birmingham, Ala., Feb., 1919. Figure 6. — Dipping sweet po- tato seed in mercuric-chloride 1:8 for eight minutes just before bedding. 62 I'he Sweet Potato THE ri-ANT-BED The kind of plant-bed to be used will depend on the area to be planted, climatic conditions and the facilities at hand for its preparation and operation. The grow- ers of the Atlantic Coast area usually provide for one large sash or an area equal to about 32 square feet for each bushel of potatoes to be bedded. From 15 to 20 square feet of surface are required for a bushel of medium-sized tubers, while an equal amount of small roots will cover 25 to 30 square feet of bed, when they are placed as close together as possible without touching. Location. The first and one of 'the most important considera- tions demanded by the plant-bed is its location. ]^o other one factor is so important as the choice of a good site. Especially is this true when strong plants are desired to provide the early crop. A high well-drained spot should be selected, and in the regions north of South Carolina a windbreak protecting the bed on the north is very desirable. In any case, cold windy places should be avoided, and unobstructed sunlight is essen- tial. The southern or southeastern slope of a hill or a location protected on the north and northwest by thick woods or a large building is desirable. Where no nat- ural protection is possible, growers often provide arti- ficial windbreaks by the use of some thickly growing hedge such as privet or arbor-vitae thickly planted. In the more northern areas, a tight board fence is some- times constructed around the bed, but usually when only sweet potatoes are grown, protection on the north side is sufficient. Propagation 63 The plant-bed will require frequent and careful at- tention and should be so situated as to be easily ac- cessible at all times. Proximity to the field is not so important as nearness to the residence, as transporta- tion of the plants is comparatively easy. Many large growers have found it convenient to provide a small shed where the plants may be placed temporarily in the shade while waiting to be carried to the field for plant- ing. Convenient watering facilities are an absolute neces- sity and this should be borne in mind when selecting the site. If the home place is located on a hill and the plant-bed is on lower ground nearby, a very convenient and economical watering system can often be provided by piping water from the home well to a barrel placed on a platform at the bed. When such a system is used, the water is convenient both for watering the bed and for filling the planter when it comes for a supply of plants. An open trough may often be used to convey the water instead of pipe when the former is more economical. Thoughtful care in locating the plant-bed will be repaid many times in profits received. Preparation of the plant-hed. The proper preparation of the plant-bed is very im- portant for it is here in a comparatively small space that plants are to be produced to set the whole or a good part of the entire acreage. The plant-bed is the medium of a very intensive form of production. If the plants do not receive a good start in life, their growth will be greatly hampered. Therefore, no pains should be spared in preparing the plant-bed in the most thorough manner consistent with economy. The kind 64 The Sweet Potato of seed-bed to be used and the manner in which it is to be prepared will be goveraed very largely by prevailing climatic conditions, the number of plants to be produced and peculiar conditions that may be present in indi- vidual cases. In the Gulf states, plants are either grown in the open or in coldframes, while a little far- ther north hotbeds are employed quite extensivel^v. These may be heated with decaying manure, a coal or wood furnace with flues running under the beds or with a hot-water system. Open beds. By far the greater number of sweet potato plants in the South are produced in open beds. Farmers who grow an acre or two for home use and who bed out a few bushels of seed instead of ordering their plants from a dealer, seldom go to. the trouble to provide a permanent plant-bed of any kind. Nor would they be justified in so doing when such a small acreage is in- volved and since frequently the bed would be used for no other purpose than for the potatoes. Even when a considerable acreage is to be planted, the open bed method is often preferable in the more southern areas. Because of the longer growing period in this section, extra early plants are not always desired, consequently the seed may not be bedded until late when the gTound has become sufficiently warm to make bottom heat un- necessary. The growing of plants in the open is very widely resorted to as being most consistent with con- venience and economy. The open bed must be so located as to allow thor- ough drainage. Although an excavation is usually de- sirable to provide room for the extra sand that is Propagation 65 added without raising the level of the bed too high above that of the surrounding ground, under no cir- cumstances should the bed level be lower than the general land contour. The general practice is to make an excavation 5 or 6 inches deep, 5 or 6 feet wide and as long as is needed for the quantity of potatoes to be bedded. About 4 inches of clean sand is placed in this excavation. The tubers are put on top of this sand as close together as possibla without touching, after which they are covered with 2 inches of sand. This bed is kept damp by sprinkling daily until the plants appear. As soon as the young shoots may be seen, another inch of sand should be added to insure the development of a vigorous root system. The importan'ca of using pure sand in the seed-bed cannot be over-emphasized. The practice sometimes followed of placing the tubers on top of a thin layer of manure is unjustified. The sprouts grow from material stored in the potatoes and rich soil is not required. 'Npt only is manure unneces- sary (except in the sub-layer for bottom heat) but it is a carrier of disease. Pure sand about the potatoes is most certain to produce a large crop of strong, healthy, well-rooted plants. Such a bed may be covered with straw, hay or leaves to protect it from cold early in the season. Old burlap sacks are also sometimes used for this purpose. Such coverings may be valuable in pre- venting too rapid drying out of the surface. Coldframes. Some of the largest commercial plant-growers in the South and Southwest gi'ow their slips in glass and can- vas-covered coldframes. When potatoes are produced as an early truck crop, some means of protection so 66 The Sweet Potato as to allow earlier planting is necessary even in the region bordering the Gulf. The commercial growers are particularly desirous of producing early plants which bring the best prices, and in the lower South the coldframe answers this purpose. The location of the coldframe should be considered with the same care as for an open bed; Plate II shows a location well protected from cold winds by a natural forest wind- break. Although coldframes may be constructed entirely above the ground or only partly so, the former method is usually employed because of convenience and thor- ough drainage which is afforded. (See Plate I.) Or- dinarily a frame is made, using 14-inch boards on the north or west side and 8- or 10-inch boards on the south or east side, the ends being boxed up. The sides of the frame are held rigidly in place by cleats which are spaced at intervals of about 6 feet, the side boards being nailed to these. Brace-strips of 1x4 or 2x4 material extend from one side to the other at every place where the side boards are nailed to the cleats. If the bed is below the ground surface, the frame should, of course, be made to fit in the excavation. When built above the ground, the frame is hereby nailed together and set on the surface, being held rigidly tcf the ground by means of the cleats above mentioned which may be extended into thc' soil. Further protection from coid may be secured by banking dirt against the. north side and the ends. The standard width for either a cold- frame or hotbed is about 6 feet. The length will of course be determined entirely by the quantity of po- tatoes to be bedded. The coldframe is ordinarily cov- ered with canvas (Plate I), although hotbed sash Propagation 67 are sometimes employed. The cross-brace pieces are more conveniently spaced every 3 feet if sash are used. They thereby act as supports for the sash and facilitate adjusting the ventilation. Clean sand is used in the coldframe and the tubers are bedded just as in the open bed method. Hotbed, — manure-heated. The commercial sweet potato crop of this country is very largely gi'own from plants produced in hotbeds. This is because the states of New Jersey, Delaware, Maryland and Virginia, which at this time grow the greater part of the crop put on the market, have growing seasons too short to allow the plants to be started in coldframes; because of the increased price which the early crop brings ; and the possibility of growing earlier plants in hotbeds than could be produced otherwise. The tubers are ordinarily bedded six to eight weeks before weather conditions permit the plants to be set in the field. In bedding so early, artificial bottom- heat is necessary to overcome outside temperatures and to obtain a quick growth of large stocky plants. Fresh rapidly fermenting horse-manure, which is naturally bulky and contains a large amount of organic matter capable of creating considerable heat in the process of decomposition, furnishes the cheapest and simplest method of supplying this bottom-heat. In preparing a hotbed, the frame is made in the same way as in con- structing a coldframe, but an excavation must be made for the manure. The depth of the manure will be in- fluenced by the severity of the temperature to be over- come and the length of time heat will be required. The depth usually ranges from 12 to 18 inches. It is better 68 The Sweet Potato to have the hotbed extend east and west as the sun-rays concentrated bv the glass will be of substantial value in supplying- heat. Sash-bars or cross-rafters to slide the sash on may or may not be used ; if the walls are prop- erly supported at the comers and at intervals along the sides by 2 X 4 inch stakes driven into the ground, cross rafters are not essential. A layer of fresh horse^manure at least 12 inches deep is placed in the pit a week before bedding the potatoes and thoroughly packed by tramping. Manure which contains old sweet potato refuse or culls from the storage-house should be carefully avoided as dis- eases may be conveyed in this manner. Before using, the manure should be piled and forked over two or three times to insure uniformness throughout. In case the manure is dry, it should be watered, as moisture is an essential to the decomposition which produces heat. A layer of clean sand 3 or 4 inches deep is spread evenly over the manure as soon as heating starts. This sand should always be obtained fresh from the woods, a pit, or some place where it has had no chance to become infected with disease. Some of the most serious dis- eases develop in the plant-bed and every precaution should be taken against their introduction. Fresh sand should be used for bedding each season, as disease may remain in the sand and carry infection over until the next year. The woodwork of old beds should be sprayed each year as a precaution against disease. After the bed has been prepared, it is best to place the sash in position and allow the heat to become con- stant before the seed are bedded. When the tempera- ture has dropped to 80 or 85 degrees F., the tubers are Propagation 69 placed on the surface and covered with sand as has al- ready been explained. Hotbeds which are to be pennanent are sometimes made of brick, stone or concrete, but growers generally prefer the cheap practical bed just described. This can be used for a few years and when demolished by decay the expense of building new is not so great as to offset the advantage of being able to move the bed at will. Hotbed, — -flue-heated. In the more northern areas and where it is difficult to obtain a sufficient quantity of the proper kind of manure, heat for the hotbed may be secured from a stove or furnace through conduction pipes under the beds. The flue-heated bed may be constructed for one or two tiers of sash. When two tiers are used, they are elevated in the center and slope to each side. Hot- beds so equipped are frequently made of brick, stone or concrete as they are usually intended to be more or less permanent.- However, a temporary structure may be made of wood. J. C. C. Price, ^ gives the following discussion on the construction of a flue-heated hotbed; " A flue-heated hot-bed may be constructed of con- crete or boards for sides. The first is permanent, while the boards will rot out after a period of time. If the boards are treated with creosote they will last much longer. The frame should be located on a well-drained place, sloping to the south or southeast, so as to get the full benefit of the sun's rays and be protected from north and north-west winds. When possible, the frame 1 Circ. 15, Ala, Exp. Sta. 70 T/ie Sweet Potato is placed on a slight slope with the fire box at the lower end, thus giving the necessary slope to the floor. " The fire box is constructed of brick and should be arched. The di- mensions (as given in Fig. 7) are 18 inches wide (inside m e a s u r ements ) , 20 inches high, and 4 feet and 8 inched long. The terra cotta flue pipe leading un- der the bed is 8 inches in. diame- ter and should extend the entire length of the frame into the chimney at the other end. The first two or three joints of the flue should be covered with brick, as the blaze from the fire might cause it to become too hot and endanger the floor. The chimney may be made of brick or by nailing together four 12-inch boards in box fashion. The chim- ney should be larger than the flue under the floor as it will draw better. Figure 7. — Showing the construction of a fire-heated draw bod. Propagation 71 " The wooden floor should be built at least four inches above the flue, so as not to catch fire and to give better distribution of heat. The floor should have a slope of one inch to seven and one-half feet, or twelve inches in ninety feet. That is, the soil at the furnace end should be eighteen inches deep and at the chimney end six inches deep. The flue under the floor should have the same slope as the floor. The soil on top of the frame should be level. Any kind of rough boards may be used as flooring. They should be treated with creo- sote to make them more durable. " As shown in the drawing, the frame should slope toward the sun and should be six inches higher on the back than on the front side. The top of the frame should be level from east to west." Hotbed, — pipe-heated. A type of hotbed rapidly gaining in favor among the commercial plant-growers of the northern areas is one heated by means of hot water or steam pipe lines, which may be supplied from a greenhouse boiler or a separate heating furnace. The lines of pipe are commonly laid 4 or 5 inches below the bed surface. Miller ^ describes the method as follows : " Where a steam or hot -water boiler is used for heating a greenhouse, residence or other structure, it can often be employed to good ad- vantage in heating the sweet potato bed. In fact, where sweet potato plants are groMoi on a very large scale it might be advisable to install hot water or steam heat even if it is not used for other purposes. The tem- perature of the bed can be regulated more easily where 1 Farmers' Bull. 999, U. S. Dept. Agr., page 11. 72 The Sweet Potato steam or hot water is employed than where other meth- ods of supplying heat arc nsed. " When steam or hot-water pipes are nsed to heat the hotbed, the best results are secured when the pipes are placed near the bottom of the hotbed pit, the soil being put on a tile or board floor resting on pipe or wooden supports so as to leave a space of a few inches between the bottom of the pit and the floor. The num- ber and size of the heating pipes required depend on the rapidity of the circulation and on the temperature of the water or the pressure of the steam. When hot water is used, four 11/^-inch pipes will be ample in most cases for beds not over 50 feet long. For larger beds 2-inch pipes should be used. Two of the pipes serve as flow pipes and two as returns. The water enters at one end, makes the circuit of the bed, and leaves at the same end. The point where the pipes enter the bed should be the highest in the system, and the point where the pipes leave the bed the lowest in the system. The pipes should have a uniform grade and should be evenly spaced, with the flow pipes about a foot from each outside wall and the returns in the middle. When steam is employed the arrangement of the bed and pipes is the same, but smaller pipes may be used. With steam at 10 pounds pressure 1-inch pipes are large enough for 50-foot beds, and l^^'inch pipes are ample for beds up to 100 feet long." A general idea of the construction of a pipe-heated bed may be gained from Fig. 7. The same rules gov- erning greenhouse heating apply to piping beds of this kind. Propagation 73 Other types of Jiotheds. In the absence of stable manure and when the size of the bed is not enough to justif}^ the installation of one of the more elaborate heating systems just dis- cussed, other simpler heat-producing materials may be employed. A moderate hotbed may be heated by means of oak leaves, damp with fresh lime sprinkled through them as they are packed in the excavation (which should be at least 2 feet deep) under the frame. Such beds will produce moderate heat and will hold it longer than stable manure. An ordinary cotton cloth may be used for a cover. ]\fany growers use no cloth or glass, but often cover thickly with pine straw, raking it off on warm sunny days and covering again at night. Pine straw and mold have been used for bottom-heat but they are of practically no value. Bedding. In regions as far north as l^ew Jersey and New York, bedding is not ordinarily done before April 1st to 10th, while in the lower South the seed may be bedded in early ]\Iarch. A bed 100 feet long and 6 feet wide should furnish enough plants to set six acres at the first drawing and enough for three acres more ten days later. It will require about 35 bushels of average seed for a bed this size. The sand in the bed should be at a temperature of about 85 degrees F. at the time of bed- ding, and should be allowed to drop slowly to 70 degrees F. A minimum temperature of 60 degrees F. should be maintained during the entire bedding season. The seed should be handled carefully and not allowed to 74 The Sweet Potato chill in moving from storage to the newlv prepared bed. For convenience, burlap-lined baskets should be used and bedding is preferably done on a warm bright day. The seed should be carefully examined for disease and all suspicious tubers discarded. All the seed should receive the corrosive sublimate treatment already de- scribed. (Page 61.) After draining, the tubers are carefully laid by hand as closely together on the bed surface as possible without having them touch. (Plate I.) If the potatoes are crowded in the bed, dis- ease may be spread from one tuber to another and the sprouts will be so crowded that long spindling plants will be produced. If unusually large roots are em- ployed for seed, they may be split lengthwise and placed with the cut side down in the bed. Many growers have found that a thin layer of pine needles placed over the potatoes before the sand is applied aids materially in holding the tubers in place when the plants are pulled. Only part of the top sand should be applied when bedded, for if the tubers are covered too deeply some rotting may result. Ordinarily about 2 inches of sand is applied when bedded and an additional inch put on after the shoots appear. The covering sand should be evenly distributed, carefully smoothed and lightly packed by planking. Only clean fresh sand should bo employed. As has been stated, sand is as good as rich soil for the sprouts come from the material stored in the potato. Ilowever, the use of sawdust should be avoided. After the bed has been completed, it should at once be wet thoroughly with a fine spray from the hose or with a sprinkling-can. Propagation 75 Covering for seed-heds. Some kind of covering, if not always essential, is desirable for the protection of the young plants from cold nights and from the cool temperatures that often occur late in the season. With a moderate hotbed, sweet potato plants can be grown under cloth as well as glass. Many growers, from South Carolina and Tennessee southward, use no other cover than pine straw, which is raked off in the daytime after the plants are started and replaced at night. If the nights are cool, pine straw is frequently employed to cover the beds before the plants appear. The ordinary liotbed frame may be covered witli cot- ton twilled cloth. The kind of covering may materially influence the type of seed-bed to be employed. In re- gions south of North Carolina, light bottom-heat is often needed when a cloth covering is used, while in the same territory no bottom-heat may be required if glass sash is employed and properly managed. When cotton cloth is used, it should be treated with hot linseed oil to ren- der it waterproof and to lengthen its usefulness by pre- venting decay. Canvas covers should be tacked on one side and provided with poles on which they can be rolled up in the daytime to admit sunlight and secure ventila- tion. Handling the cloth cover will be greatly facili- tated by providing support lathes or wires at frequent intervals. Such construction will cause the water to drain off without forming puddles and dripping on the bed. In Texas, Oklahoma and Louisiana, commercial plant-gTowers frequently use coldframes, 6 feet wide, constructed of 8-inch strips for the sides. A thin cotton cloth is merely tacked over this flat bed and only re- 76 21ie Siveet Potato moved about once a week, the watering being done by sprinkling on top of the cloth. These coverings are so thin that considerable sunlight is given the plants with- out moving the cover. In these warm sections, this practice seems satisfactory although the cloth covers seldom last more than one season. If good canvas is used and properly oiled and cared for, it may last sev- eral years and makes a suitable covering even for the hotbeds as far north as Virginia. Glazed hotbed sash are more commonly used as cover- ings in the northern part of the sweet potato district, for both manure and fire-heated beds. The regular 3X6 foot sash is commonly employed. A cheap home- made sash is sometimes built by the use of scrap glass and suitable strips of lumber. Johnson and Kosa ^ de- scribe these home-made sash as having, " six rows of small panes of glass, supported on wide strips. These obstruct a large part of the light, which, however, is not a serious objection with sweet potatoes. These sash are cheap and if well made answer the purpose." Sash, when used, should slope toward the south or east, if the greatest benefit is to be derived from the sunlight. If carefully handled to avoid breakage and the wooden parts are painted each year, hotbed sash will last for many seasons and will in the end prove to be cheaper than cloth coverings. As they are always useful in any gar- den for producing all kinds of young plants early in the season, sash are perhaps the most popular among grow- ers for the sweet potato plant-bed. A board covering is sometimes used but because of the difficulty involved in handling and its inability to admit sunlight, it is undesirable. 1 Bull. 19, Va. Truck Exp. Sta., page 396. Fropagulion 77 Care of the plant-hed. When the plant-bed has been placed in an ideal loca- tion, the bottom-heat perfectly regulated, the top soil or sand carefully selected and applied for its purity and freedom from disease, and the tubers which have been carefully selected and treated for disease are evenly placed in the bed and covered, the task of producing strong vigorous plants which will vitally influence the crop yield is only half accomplished. A sweet potato plant-bed may be perfectly prepared but unless properly cared for discouraging results will be the' consequence. Maintaining temperature. — As has been stated, the temperature of the plant-bed should be between 80 and 90 degrees F. or around 85 degrees F. when the tubers are bedded. This heat should be allowed to decrease gradually until a constant uniform temperature of TO to 75 degrees is reached at the end of about six weeks. In no case should the temperature be allowed to go below 60 degrees F. as it is sure to cause injury to the growing shoots. The temperature of the bed should be noticed carefully every day for the first ten days. A ther- mometer should be kept continually in the soil. In these first few days a manure-heated bed may suffer considerable variation in temperature which will re- quire regulating. In case the bed is not well drained, excess water may find its way into the manure, destroy- ing the heat altogether or starting a new fermentation resulting in the production of heat too intense for the well-being of the young sprouting buds. In case of extreme heat, enough water should be applied thor- oughly to wet the surface sand. A double row of 3- inch holes, 1 foot apart, should then be worked along 78 The Sweet Potato the center of the bed through to the manure. This may be done by using a crowbar which is pushed into the ground and then removed. Such an operation, aided by the removal of any covering, will rapidly lower the tem- perature of the bed. It nearly always happens that after a few days some parts of the bed will become too hot and other parts too cold. The cooler places should have the sash left over them during the heat of the day so that the sun's rays may be concentrated on them while the hotter places may be shaded. Even though a ther- mometer is not used, an experienced grower carefully examines all parts of the beds every day by thrusting his finger into the sand between the potatoes and below their level. If a comfortably warm temperature can be maintained at this point, it is satisfactory. Watering. — Water should be applied abundantly as soon as the potatoes are bedded. After this the bed should be liberally watered two or three times each week until the plants begin to form leaves. After the leaves form, the bed will need water every day. It is best to water the bed about three or four o'clock in the after- noon so that the surface of the soil and leaves will dry off before night. If this is done, no trouble will be ex- perienced from the damping-off fungi. The method of heating will in a measure influence the amount of water necessary. A steam- or furnace-heated hotbed will re- quire more water than will an ordinary manure-heated bed. Water should always be applied in a spray rather than in a solid stream. This may be accomplished by means of a sprinkling-can, with the spray-nozzle on the hose or by means of regulating the spray with the hand as it comes from the hose without any nozzle. Many growers prefer regulating the water in the latter way, Propagation 79 claiming they can better place it where desired. Small growers who have seed-beds in the garden sometimes prefer to use lukewarm water containing soap-suds on their plants. The wash-water from the house is com- monly saved for this purpose. The merit of this prac- tice seems to be questionable. At all events, it is im- practicable and undesirable for the planter with more extensive beds. Ordinarily the beds may be allowed to take all rains. liardening-off. — It is recommended that the sprouts be allowed to reach a height of 4 to 5 inches above the surface of the sand before they are removed. A " hard- ening-off " process lasting a week or more, during which the ventilation is increased and the water supply shut off, should be employed before transplanting. This process must be brought on gradually as the time for drawing approaches. Toward the end of the period in which the plants are to remain in the bed, the ventila- tion should be increased by leaving off the cover entirely during the warm part of the day and even in the early morning and late evening considerable more ventilation can be given. When removed entirely, which is advis- able during the last few days before the plants are pulled, the cover should be kept close at hand where it can be put on quickly in case of a late cold spell. Sweet potatoes are very sensitive to frost and even though they have been accustomed to the air, the slight- est frosting will cause serious injury. Treatment of seed-bed for disease. — Disease may often appear in the plant-bed after the tubers have been bedded, especially if they have not received the cor- rosive sublimate treatment already discussed. W. F. Massey recommends spraying the bed with bordeaux 80 The Sweet Potato mixture in such cases, for the purpose of killing some of the causal fungi which may be present. However, pre- vention is far easier and more reliable. DEAWING THE PLANTS Sweet potato plants should not be set in the field until after all danger of frost is past. The plants will ordinarily be ready for drawing five weeks after the hot- bed has been put down, although seven or eight weeks are sometimes required for plants to reach proper devel- opment in a coldframe or open bed. The ground for planting should be ready and the plants promptly pulled when they are 5 to 6 inches high. The common prac- tice of waiting for a rain to transplant is unnecessary if one-half pint of water is applied to each plant when set. In fact, many growers claim the plants grow off better when set in this way. The plants should be drawn carefully one at a time. If the roots of several plants are grown together, they should be separated at the bed to avoid delay in the field. Drawing should be done by giving the plant a sidewise pull with the right hand while the left hand is employed in holding the ground firmly to prevent the mother potato from being disturbed or drawn up. As the plants are pulled, they should be placed in baskets or crates and covered with a burlap sack or with hay to prevent drying out while being carried to the field. It will often be convenient to have a small shed at the bed in which the plants may be stored with roots down until needed in the field. ]\Iany commercial plant-growers have a special shed for this purpose which is provided with a shallow pit in which the bundles of plants (100 or 200 in a bundle) may be stacked with the roots in Propagation 81 soft damp soil or a bed of saturated moss until they can be packed and shipped out. The plants do not develop uniformly, and in pulling many small plants must be left for further growth. A well-developed root system is very desirable and if the bed has been properly pre- pared with sand no difficulty will be experienced in this regard. Much time may be saved in the field if the plants are orderly and systematically handled at the plant-bed. All roots should be turned in the same direc- tion and if a machine is used for transplanting, it will often be necessary to trim off long or irregular tops with a knife. It is essential that draws planted by machine be in the best possible condition if they are to be effi- ciently handled by the boys who sit on the back and feed the plants into the machine. Nimbleness is necessary under the best of conditions and if the plants are ir- regularly arranged and grovm together, many skips in the field will be the result. In very dry weather or when a small area is to be set by hand-dropping the plants, growers sometimes have at hand a large tub containing a mixture of an equal part of clay and cow-manure mixed to the consistency of a thin slime wdth water. As the plants are pulled from the bed, they may be taken in small bunches and their roots dipped into this mixture. This " puddling " pro- cess, though of some value, is now seldom used because of the disagreeable feature of handling the plants with mud-covered roots. The plants should never be allowed to stand in such a mixture for any length of time, as they will shed their leaves. In preparing plants for shipment, commercial grow- ers usually tie them in bundles of 200 each with soft cotton twine. Perhaps the most economical method of 82 The Sweet Potato packing is in a burlap bag which has been split open and cut in half or for large bundles left whole. The sack is first split and laid on the ground or packing-table, placing on it an old newspaper which has been dampened with water. The bundles of plants are then placed roots down on top of the wet paper, putting them in a circle with a bundle in the center. A second and even a third layer of bundles of plants may be placed on top of the first. Each succeeding layer should contain fewer bun- dles than the first, thus building the pile up into a com- pact cone-shape. The package is tied by bringing the corners of the sack together in the center, much as a bundle of clothes would be tied in a sheet. Although the roots need moisture, the tops had best be kept dry. When packed in crates or baskets, damp moss is fre- quently placed around the roots. From 2000 to 4000 plants can ordinarily be packed in an average size bur- lap bag which has been split open and the plants ar- ranged as described above. When in crates or baskets, the plants are perhaps not bruised so much as when packed in burlap. USE OF VINE-CUTTINGS The value of vine-cuttings in the control of certain diseases is now universally recognized throughout the sweet potato area. When vines are cut from the grow- ing plants and transplanted in new fields free of disease, the potatoes produced will be disease-free. Practical growers have long since discovered the value of this means of propagation in the eradication of black-rot. For this reason, vines or " vine-cuttings " are widely used in producing tubers which are to be employed for Propagation 83 seed. Most sweet potato authorities now advocate grow- ing seed from vine-cuttings. The potatoes grown from vines are not only practically free from disease but they seem to keep better in storage and are about the proper size for seed. Frequently the main crop is grown from vine-cuttings, only enough sets being planted to pro- duce vines sufficient to set the required acreage. This practice is not only satisfactory in-so-far as disease con- trol is concerned, but is more economical than purchas- ing or raising enough plants for the entire acreage. When a machine is employed for setting such plants, all or most of the leaves must be stripped from the cut- tings to facilitate handling. The cuttings are made as soon as the vines are 3 or 4 feet long. Pieces 7 or 8 inches long containing about two joints are commonly used. These cuttings are usually made from the early vines grown from slips. Setting and handling is done the same as with slips. It is generally conceded by growers that after the vines have begun to run well, the use of vine-cuttings is much to be preferred to the slips, especially for the late crop. ITowever, except for the advantages already mentioned, experiments have shown practically no difference in yield. It has been found that too close pruning of the vines will decrease the yield of marketable potatoes by increasing the percent- age of smaller ones. ^ The effect of constant propagation by vine-cuttings and the influence on yield of constant selection of cut- tings from plants with the most vigorously growing vines are problems yet undetermined. Individual plants of the same variety growing side by side often 1 G. W. Carver, Bull. 30, p. 7, Tuskegee Normal and Ind. Inst. 84 The Sweet rotato show wide variation in hardiness, thrift and vigorous- ness of growth. It would seem reasonable to believe that continued selection of vine-cuttings from the best individual plants would in time give favorable results in the offspring. Vine-cuttings seem to be especially pop- ular for the very late crop. Fitz ^ cites a Georgia planter who with vine-cuttings planted July 18, which were given one hoeing and one plowing, produced a yield of 125 bushels to the acre, more than half of which were marketable potatoes. When planted especially for the production of seed potatoes, the vines are usually not set until July or the first of August. This late planting gives a good yield of small tubers which are easier to keep than potatoes from the earlier plants. It is preferable to plant out vine-cuttings just after a rain while the soil is wet, but if enough water is used they may be planted in dry weather about as successfully as draws under the same conditions. E. A. Miller ^ has given the following directions for storing sweet potato vines which he says has been used quite successfully in some western sections: " Take four boards, about eight inches wide, drill them full of holes and then nail them together to form a hol- low flue. 8et these up endwise in some protectetl place in such a manner as to form a flue, and then place the sweet potato vines around this flue, cover with straw and bank up around it with earth, to protect them from cold. The flue will permit a free circulation of air which will keep the vines alive through the winter." 1 Jas. Fitz, " Sweet Potato Culture," page 73. - Formerly specialist in potato storage of the Extension Service, Tex. A. & M. Coll. Propagation 85 THE COMMERCIAL PLANT BUSINESS In recent years there has been a large demand for sweet potato phints of pure varieties which are free from disease. The greater part of the sweet potato crop in the South is raised by small faraiers who produce just enough for home use and possibly a few to sell on the local markets. These growers usually prefer to buy a new supply of seed or plants each year for their small area. Recently a number of large sweet potato storage companies have been formed for the purpose of produc- ing, buying and storing the crop. These organizations require large supplies of plants to set their new area. These conditions and the continually increasing interest which has been taken in sweet potato production in re- cent years have given rise to the development of a num- ber of commercial plant industries. Two months will cover the time required to produce salable plants from seed. As a bushel of seed which can ordinarily be bought for $2,00 or less will produce from 2,000 to 4,000 plants worth as much a thousand as the original bushel of seed cost, there is opportunity to realize a good margin of profit in a comparatively short time if proper care is exercised. Often heavy rains will prevent the beds from " slipping " just at the season when the plants are most in demand, while later on an abundance of plants may be produced which can- not be disposed of on the later market. However, since some growers bed 10,000 bushels or more seed, assuming the risk of their disposal, it is evidence that the business can be made to pay if properly handled and unfortunate occurrences do not interfere. 86 The Sweet Potato Field methods. The commercial plant-grower ordinarily employs either coldframes or fine-heated or pipe-heated hotbeds, the former in the southern and southwestern areas and the latter farther north. Cloth covers are used on the coldframes commonly and the beds are prepared as de- scribed for ordinary coldframes. (See page 66.) An adequate supply of water must be provided by piping and hose connections, by running one or two pipes through the area covered by beds on which are numerous faucets for hose attachment. JMen must be kept busy continually, providing for the proper moisture require- ments of the beds. Drawing of the slips is done by negro women and girls who may be employed at a relatively low figure and can accomplish work satisfactorily. The slips are pulled and placed in piles, 200 plants to each pile. One or more of the hands is kept busy tying these bundles and putting them into containers to be transported to the packing-shed. A superintendent is necessary to see that the drawing is done carefully and that the counting is correct. At the packing-shed the plants are received by the packer in charge who stacks them roots down and one layer deep in a shallow pit, the bottom of which is covered with damp moss, the different varieties of course being kept separate. The packer will find it con- venient to work on a low platform on which the plants are packed in sacks, crates or boxes. To his right and above the packing platform is a roughly constructed board desk on which is kept in plain view the order- sheet, the corresponding shipping tags and miscellan- eous supplies. Hanging over the packing platform is a / Plate IV. — Varieties of sweet potatoes. Top : Typical speci- mens of some of tlie commercial moist-fleshed varieties of sweet potatoes: a, Yellow Belmont: b, Pumpkin; c, Porto Rico; d. Nancy Hall; e, Southern Queen; /, Dooley; g. Bunch. Bottom: Some of the important commorcial dry-floslied varieties of sweet potatoes: a. Big Stem Jersey; h, Triumph; c, Yellow Jersey; d. Yellow Jersey; e. Red Jersey. Note the two distinct types of the Yellow Jersey variety. Propagation 87 roll of soft cotton twine which is used for tying the plants and for tagging. This twine can be purchased in rolls of about fifty pounds each which are so made that they can be suspended on a stick placed through the cen- ter and unrolled as needed. The order-sheet is made out at the office by the owner or his bookkeeper. This sheet includes the purchaser's name and address and the variety and number of plants desired. Shipping tags are made out to correspond to each order and sent down with them by the bookkeeper. N^o bookkeeping is done at the packing-shed. The order sheet is kept in con- venient reach at the packer's right and as the orders are filled and tags attached to the packages, they are checked off the list. The work thus proceeds systematically and without confusion and lost motion. Office methods. If the grower is sufficiently well known throughout the territory which he supplies or desires to supply, and his stock has been properly advertised, the office force will be well occupied from the middle of April until July 1st. Many orders will be booked during the win- ter and early spring months and these will be tabulated for immediate attention when the first plants are ready to be drawn. A rush of orders will, however, begin to pile in with the beginning of early planting season and at this time the grower receives the best prices for his plants. These orders must receive prompt attention. Nothing is so valuable to a commercial grower as to have the reputation of giving his orders prompt and faithful attention. Many telephone and telegraph orders will be received by the progressive grower and these must be given the same courteous attention as the mail orders. 88 The Sweet Potato The business-like plant-dealer never sends a customer one variety of plant when another has been ordered without first asking whether the substitution is satisfac- tory. The very best business principles must be used in the office if satisfied customers are to be gained. The office force tabulates each order by making an order sheet in duplicate. One copy of this order-sheet is sent to the man in charge of the packing-shed together with corresponding shipping tags. One system of hand- ling money must be adopted and rigidly adhered to. It is best that all orders go through the office in the reg- ular prescribed way, and no plants sold directly from the beds without making a record of same. Of course the particular system to be used will be worked out in each case by the owner in such a manner as to fit his spe- cific conditions. As with any other business, there are many possible " leaks " that must be avoided if profit is to result. Advertising. Although a dealer may be able to grow the most per- fect plants at the proper time and season and with a minimum cost for production, unless he can dispose of them at a profitable price, his enterprise is a failure. It should not be concluded that advertising in its proper sense can be done in any one year or two years and through newspapers and farm journals alone. Any broadly successful business is gradually built up through long years of earnest and concerted effort, by fair deal- ing always and with the continued aid of the printed announcement. A satisfied customer is the best ad- vertisement. The classified ad columns of the leading farm weeklies seem to be one of the most popular and Propagation 89 efficient advertising mediums. Some growers have fonnd that large and more attractive advertisements in a few leading daily papers having a wide circulation are highly profitable. Small and less expensive adver- tisements should be run during the late winter and early spring months, announcing the varieties offered and the prices booked for delivery at a specified time. For a few weeks before the rush season opens, it will be profitable to run a good advertisement in every daily or weekly paper published in the immediate vicinity. At this time more than at any other, the advertising campaign should be pushed. CHAPTER V TILLAGE, FERTILIZING AND ROTATION The soil adapted to sweet potato culture is usually easy to prepare, in about the same way as for corn or cotton. It should always be borne in mind that very thorough preparation is repaid in the ease of cultivation to follow. The depth of cultivation has considerable in- fluence on the character of the product. If the soil has not been broken deeply before, a little more should be plowed each succeeding year rather than the entire depth the first year. The land may first be prepared either by flat breaking or by ridges thrown up to form rows. It is important that the land should be harrowed within a few hours after plowing. It should be thoroughly pulverized, and this may be done shortly after a shower while the lumps and clods are still soft. After this work has been completed, the soil should be mellow to a depth of 6 to 8 inches, and the surface smooth and even. Preparation for planting. After the land has been plowed and fitted for the sweet potato crop, it should be allowed to lie idle several days before planting. If potatoes are to be planted flat for level culture, only a harrow and a marker are necessary for planting. The harrow should be run both ways and the surface tlioroughly pulverized. The 90 Tillage, Fertilizing and Rotation 91 marking may be done either with a one-horse roller rake- toothed marker or a disk-marker. When the more uni- versal ridge method is used, the ridges or rows are made by means of a turning plow or disk. The ridges should be turned a few days before planting in order that the soil may have time to settle. Most farmers make the ridges whenever the land is in working condition, and then run over them with a drag or roller to level them, and leave a suitable place to set out the plants. By means of the roller or drag, from four to eight rows can be done at once, according to the nature of the machine. A drag can be built at home by nailing together several pieces of 2 X 4, or one or two 4X4 scantlings. In small patches for home use, ridges are often leveled by means of a field or garden hoe, all the preparatory work and cultivation being done by a one-horse plow. Distance and method of planting. (See Plate III.) When level culture is practiced, plants may be set from 24 to 30 inches apart in each direction. On the eastern shore of Virginia, Delaware and New Jersey, a part of the crop is checked 24 inches each way, therefore re- quiring about 11,000 plants to the acre. When the crop is grown in ridges, it is customary to have them from 30 to 40 inches apart, and the plants from 12 to 18 inches in the row. By this method an acre will require from 8000 to 12,500 plants, the average acre through- out the Gulf Coast region being set with about 10,000 plants. In planting for level cultivation, the location for the plants is indicated by cross marks made by running the marker in two directions across the field, the marker being at right angles. When planting on ridges, the 92 The Sweet Potato distance of the plants apart may he found by running the marker across the rows. An important operation to be watched is the proper setting out of the plants after they have been drawn from the seed-bed. It is a common custom throughout the sweet potato region to set just before a rain or as soon thereafter as the land will permit. It is essential to have the roots in contact with moisture, and the soil packed firmly around the plants. If the ground is not wet, it may be necessary to haul water to the field and pour about one-half pint around each plant. In the area where irrigation is practiced, the plants may be set and the water turned on which will insure the growth of practically all the plants. Setting the plants in the field. When only an acre or two is grown for home use, hand-planting will answer the purpose and is probably more economical. A trowel and dibble may be used to open and pack the earth around the roots ; after the roots of the plants are thrust into the hole in the ridge, the earth should be pressed firmly around them. For hand-planting, plants are dropped ahead of the setters, boys and girls being very useful for this work. Setting out one acre by hand is considered a good day's work for one man. A part of the undesirable work by hand may be avoided by the use of tongs. After the plants have been dropped on the rows, the root may be clamped with the jaws of the tongs and thrust into the ground. This saves the bending of the back and is practically as fast as the hand work. The tongs should be of wood and about 3 feet in length ; the jaws of the tongs should be made by sawing out a por- Tillage, Fertilizing and Ixotaiion 93 tioii down through the middle of the stick. This will leave jaws on either side that stand erect but are readily clasped together. On being released from the hand, thej assume their natural position. An instrument known as a shovel or punch may sometimes be used. This may be made from a narrow board with the ends somewhat sharpened, with which a hole is punched, the root inserted in the hole and the ground packed around it. When a large acreage is planted, hand-setting is too slow and expensive, and transplanting machines are used which are capable of setting several acres of plants in a day. With these machines it is not necessary to wait for a rain, as they automatically throw a small quantity of water around the roots of each plant as it is being set. These machines will set from three to five acres a day. Cultivation. (Figs. 8-11.) After the potato plants are set in the field, ordinary Figure 8. — Five-tooth cultivator. 94 The Sweet Potato methods employed for other crops arc all that are neces- sary for sweet potato cultivation. In the South it is customary to keep the weeds and grass from the row by FiGUKE 9. — Mulch harrow. giving at least one hoeing. The potatoes are plowed two or three times or until the ground is covered by the vines. Cultivation should cease when the vines have thoroughly covered the ground. In the small patches and fields, the one-horse plow or cultivator is ordinarily used, or sometimes the spring-toothed harrow. In flat lands on the coast where the soil is wet, farmers often use a plow to throw up a high ridge. While this assists in drainage, it is not thought to be of much value from the standpoint of cultivation. On larger farms where potatoes are grown for com- mercial purposes, cultivation is done by one- and two- horse cultivators. In this way a row is completed at Tillage, Fertilizing and Rotation Figure 10. — Diverse spring-tooth cultivator. one passage over the row, practically the same kind of plows being used as on the single-stock plow. It is customary in certain localities to throw two rows of vines to the same middle and cultivate the alter- nate middles thus left free or clean. In some sections the vines are turned from one side of the row to the Figure 11. — Five-tooth cultivator with banker attachment. 96 The Sweet Potato other while plowing, then turned back after the plowing is finished. It is not thought advisable to turn vines after the ground is thoroughly covered. After the vines have become large enough to shade the ground, the shade will kill out grass and weeds and keep the surface cool ; it is not necessary to cultivate later than this. Irrigation. In some arid regions where sweet potatoes are grown, it is necessary to supply moisture by means of irri- gation. The most practictil method is the open ditch, or furrow irrigation with water, the supply coming from some, stream or lake. The greatest quantity of water should be supplied between the time the plants are set in the field and when the vines thoroughly cover the ground. Too much water applied during the latter part of the summer or after the vines have covered the ground may result in an excessive growth and a small yield of stringy potatoes. It is preferable that the water be given at evening or on cloudy days. For some time before harvesting, water should be withheld altogether in order that the roots may properly ripen and mature. FERTILIZERS Manure is the foundation of successful agriculture.^ Any substance added to the soil to render it more fertile may properly be termed a fertilizer or a manure. The successful producer of sweet potatoes or of any other food plant secures crops that command a selling price in advance or in excess of their production cost 1 Miller, Farmers' Bull. 999. Tillage, Fertilizing and Rotation 97 and at the same time maintains or even increases the productivity of the soil, A most important factor in the determination of profits which mnst necessarily be considered by the business farmer of to-day is the rela- tion of the annual outgoing and incoming of plant-food. Sound business principles do not v^arrant the produc- tion of increased crops unless they can be grown at a genuine profit, which embodies more than a margin over and above the production cost in the way of manures and labor and should take into account the per- manent effect on the productive power of the soil. These facts have been realized in a practical way, per- haps without any special understanding of the scien- tific principles involved, by many of the sweet potato growers in the commercial producton centers. This is especially true of the New Jersey, Delaware and Vir- ginia growers who have by many years of practical pro- duction and observation learned that diligence must be exercised in the rotation of crops and the annual appli- cation of manures if the quality of their " Nansemond sweets " is to meet the expectation of discriminating markets and the productivity of their land is to be maintained. In areas where this practical observation has not been facilitated by systematic commercial pro- duction, a vast improvement in the proper manuring of the sweet potato crop must be effected by producers if they are to compete successfully with their more ex- perienced neighbors. This phase of production is of especial importance to the naturally favored areas of the cut-over pine-belt, and on the depleted cotton and tobacco farms of the South where the prevailing climate and soil conditions aided by intelligent and judicious use of the proper manures would make 98 The Sweet Potato possible enormous yields of a high-class quality product. Although fertilizers have become a necessity in the production of the sweet potato when maximum profit is derived, certain kinds of manures may result in actual injury to the quality and so reduce the selling value as to make the crop unprofitable. Some soils may yield profitably to the application of one food element while another may actually retard productive growth. For example, it has been found that liberal application of a fertilizer rich in potash and in phosphorous is es- pecially profitable on a soil filled with undecayed organic matter such as one that has had a green-manure crop turned under, while a heavy application of a nitro- genous fertilizer on such a soil might result in the growth of very luxuriant vines with practically no pro- duction of tubers. It is now believed that applications of potash on certain red clay soils of the South, although causing increased yield, do not produce an increase suf- ficient to warrant its use, notwithstanding that the sweet potato makes heavy demands on the potash-con- tent of the soil. Although the sweet potato responds readily to additions of organic matter to the soil, such as the liberal use of green-manures and barnyard fer- tilizers, these materials cannot be applied directly to the crop without reducing the quality and selling value but can best be supplied to the crop immediately pre- ceding the potatoes. It is now concluded that nitrogen can, other things being equal, be supplied most econ- omically in some organic form, such as cotton-seed meal, rather than nitrate of soda or sulfate of ammonia. To understand the proper manuring of a crop of sweet potatoes and the fertilizer requirements of a given rotation, a few fundamental principles involved in Tillage, Fertilizing and Rotation 99 fertilizer standards must be studied, the forms of plant- food required, the sources of supply, as well as present day methods of preparation, commercial sale and appli- cation. Kinds of fertilizers. Fertilizers may be direct or indirect ; complete or in- complete. A fertilizer that supplies available plant- foods directly to the soil is known as direct. Nitrate of soda is a good example of this type. A fertilizer that benefits growth through its effects on the availability of the plant-food already contained in the soil, through its action on soil acidity or by im- proving the mechanical condition of the soil, is known as indirect. Strictly in this sense, drainage, proper cul- ture or humus might be considered fertilizers. Lime is the most commonly used commercial fertilizer of the indirect type. Although plants ordiuarily require about fourteen different food elements for their normal growth, only four and usually only three ever need be applied arti- ficially. These three are nitrogen, phosphorus and potassium; the fourth is calcium in the form of lime. A complete fertilizer is one containing nitrogen, phos- phorus and potash while an incomplete one supplies only two of these plant-foods. Function and form of plant-foods. Nitrogen, phosphorus and potassium are known as the " essential " fertilizing constituents since they are the specific plant-foods most likely to be deficient in soils or more quickly exhausted by the production and removal of crops. Nitrogen functions most largely in 100 The Sweet Potato the production of vegetable growth. A soil overly rich in nitrogen tends to produce an excess growth of vines at the expense of the roots. Phosphorus and potash, while present in the vine growth and more or less es- sential to it, function more largely in the make-up of the edible roots, and in the case of other crops in the formation of fruit or seed. Nitrogen, which in commerce is the most expensive of the " essential " elements, exists in three distinct forms ; as organic matter, as ammonia and as nitrate. Organic nitrogen occurs in all plant and animal forms and its availability as plant-food depends entirely on the rapidity with which the various forms decay. In any case, its availability as plant-food comes about more slowly than the two other forms of occurrence, as nitrate or as anomonia. The organic forms furnish some of the more valuable sources of nitrogen and are of value where the more quickly available forms would be of relatively little importance. Cotton-seed meal, dried blood, fish scrap and tankage are valuable com- mercial sources of organic nitrogen. Nitrogen as ammonia is more readily available than the organic fonns. In fact, organic nitrogen in its pro- cess of decay passes through the ammonia stage in be- coming available ; it is one of the first products that results from the decay of organic substances. The commercial nitrogen in this form is obtain(>d almost en- tirely from sulfate of ammonia. It is readily converted into the nitrate form and quickly becomes available when placed in the soil. This form of nitrogen is es- pecially used as a rainy-weather-available fertilizer for, until it changes into the nitrate form, it has the power of combining with certain minerals and organic substances Tillage, Fertilizing and Rotation 101 in the soil which prevent its loss bv leaching-. Commer- cial nitrate of ammonia contains about 20 per cent ni- trogen. In the form of nitrate, nitrogen is directly available to the plant as food. It is the most soluble form. Ni- trate of soda, containing an average of about 15 per ceot nitrogen, is the most common commercially. Neither nitrogen as ammonia nor as nitrate is so widely used for sweet potatoes as are the organic forms. There are in- stances, however, when the more available forms are used, either because of their cheaper cost or because of some specific purpose ; as giving the plant a rapid start by the use of a quickly available form on very poor land.^ Cotton-seed meal, which contains on an average from 6 to 7 per cent nitrogen, is by far the most com- monly used form of nitrogen for sweet potatoes. When the cost of nitrogen a pound in this form is not greatly in excess of the cost in other forms, authorities are unan- imous in recommending it. The long hot season during the growing period furnish conditions best suited to its rapid decay. Phosphorus exists in the form of " organic " phos- phates and as mineral phosphates. The latter are so termed in contradistinction to the organic forms be- cause of their lack of organic or animal matter. As the organic phosphates are seldom used in sweet potato cul- ture, discussion will be confined to the mineral forms. The chief sources of mineral phosphates in this coun- try are the raw phosphate rock of Florida and South Carolina, phosphates from the mines of Tennessee and Thomas slag which occurs as a by-product from the 1 For more exhaustive study of forms of plant-food, see Farmers' Bull. 44. 103 The Sweet Potato manufacture of steel from pliosphatic iron ores. !N^one of these forms, however, is used in the raw state for sweet potatoes. Superphosphates, of which acid phosphate is the most common commercial form, are obtained from the in- soluble or very slowly soluble raw products just de- scribed. The process of manufacture consists in treat- ing the finely pulverized raw products with sulfuric acid which renders soluble the phosphorus which they con- tain. In this process the phosphoric acid obtained is a definite chemical compound and its composition is the same irrespective of its raw state. Any material con- taining soluble phosphoric acid as its chief constituent may, therefore, be termed properly a superphosphate. Acid phosphate, containing on an average 14 to 15 per cent of soluble phosphoric acid, is manufactured by treating 1000 pounds of raw phosphate rock with 1000 pounds of a dilute solution of sulfuric acid. The raw rock, containing about 30 per cent phosphorus which is very slowly soluble, is thereby converted into a com- pound having about one-half as much total phosphoras as did the raw rock but which is vastly more valuable as a fertilizer for ordinary crops because of the availa- bility of the plant-food. This phosphate is the form used almost exclusively on sweet potatoes. Potash exists chiefly in two forms, as chlorids or muratcs and as sulfates. Though the availability of the potash in these forms is about equal, the respective elements with which it is combined in the two forms exert considerable influence on its use for particular crops. Tt has been found that the potash combined with chlorin is not so valuable for potatoes as the sulfate Tillage, Fertilizing and Rotation 103 form. It seems that a combination of chlorin exerts an undesirable inflnonce on the quality of the crop. This behavior is perhaps more noticeable with Irish potatoes than with sweets. The supply of potash is obtained largely from the potash mines of northern Germany. Sulfate and murate of potash, kainit, sylvinit, high-grade sulfate of potash and double sulfate of potash are the most common forms. As with murate of potash, kainit also contains large amounts of chlorin, although in reality the potash is in the form of a sulfate. For sweet potatoes, potash is best applied in the form of sulfate. It gives largest returns on light sandy soils and on lands with a high humus-content. Clay soils are usually well supplied with potash. With a good clay subsoil, when the surface is sandy, sweet potato crops do not respond noticeably to applications of potash, especially when the sand is not deep and plowing has brought some of the clay to the surface. Potash is sometimes applied in the form of hard- wood ashes, which in the unleached state contains about 5 per cent potash. This, however, is usually an expen- sive medium and is seldom used except when the lime contained is decidedly unleached, when it contains in addition to 4 to 6 per cent potash, about 30 per cent lime and from 1 to 2 per cent phosphoric acid. Commercial fertilizers. Commercial fertilizers differ from farm and green- manures in that they exist in a form readily exchanged and handled in commerce. The following table ^ gives 1 Farmers' Bull. 44. 104 27ie Sweet Potato the most common commercial fertilizers and their re- spective contents of manurial constituents : Table XII. — Composition of the Principal Commercial Fertilizing Materials. Nitro- gen Phosphoric acid. Potash. Fertilizing material. Avail- able. Insol- uble. Total. Chlorin. Supplying nitrogen : Per cent. 15..5-1G.0 Prr cent. Per cent. Per cent. Per cent. Per cent. Dried blood (high grade). 12.0-14.0 10. 0-11. n 3.0- 5.0 l.C- 2.0 11.0-14.0 6.0- S.O 1.5- 2.0 1.0- 1.5 26.0-28.0 13.0-16.0 33 0-35 Concentrated tankage 5.0- 6.0 7 0-90 6.5- 7.5 5.0- e.o 2- 3.0 1- 1.5 Supplying phosphoric acid: South Carolina rock phos- 26-2S 1- 3 33 3."i South Carolina rock su perphosphate (dissolved South Carolina rock 12-15 Florida land rock phos- 2i;-32 1- 4 32-36 1- 2 1.5-17 16-20 2- 3 26.0-32.0 16.0-20.0 32.0-36.0 17.0-18.0 20.0-25.0 22.0-29.0 15.0-17.0 11.4-23.0 Florida superphosphate (dissolved Florida phos 14-16 Boneblack superphosphate (dissolved boneblack)... ■2.5-4.5 1.5- 2.5 2.0- 3.0 15-17 5- S 6- 9 13-15 Supplying potash: 4S-52.0 48-52.0 26-30.0 12-12.5 16-20.0 20-30.0 2- 8.0 1- 2 5- 8.0 45 0-48.0 Sulfate of potash (high .5- 1.5 Sulfate of potash and 1.5- 2.5 Kainit 30.0-32.0 42.0-46 7.0- 9.0 1.0- 2.0 1.0- 1.5 3.0- 5.0 Wood-ashes (unleached)2 ■VVnnfl-nsViun (\e"\rhpi\'\2 2.0- 3.0 1 In Kood Tliomas slag at least 80 per cent of the phosphoric acid should be soluble in ammonium citrate, i. e., available. 2 Cotton-hull ashes contain about 10 per cent of lime ; unleached wood ashes, 30 to 35 per cent; and leached wood ashes, 35 to 40 per cent. Tillage, Fertilizing and Eolation 105 The percentage of available plant-food elements in a complete fertilizer is usually marked on the container. State laws require this of manufacturers and state in- spection is usually very rigid. A 2-8-10 formula means 2 per cent nitrogen, 8 per cent phosphorus and 10 per cent potash. The nitrogen is often listed as ammonia, which in interpreting formulas is considered to be about ^/47 as valuable as nitrogen. Fertilizers should always be purchased on the basis of the available plant-food which they contain and not according to the price or brand of the fertilizer. The fertilizer lowest in price is often the most expensive medium through which plant- food may be purchased. In general, the actual plant- food contained in higher-grade fertilizers is least ex- Home-mixtng of fertilizers. Thorough familiarity with fertilizing constituents, better facilities for handling and the ability to pur- chase in large quantities, makes legitimate the commer- cial manufacture of complete ready-mixed fertilizers. In spite of this, many sweet potato growers can save money by mixing their manures at home and if intelli- gent care is exercised as good results can be secured with the home-mixed goods as with that purchased ready- mixed. In many cases there may be an actual improve- ment in results as well as saving in cost, since the " carriers " are known and mixing can be done to suit specific conditions. The approximate composition of the fertilizers de- sired must first be decided on and the form in which each constituent is to be applied must be determined 1 Bull. 392, N. Y. Exp. Sta., 1914. 106 The Sweet Potato by the convenience and availability of the possible materials which will supply the desired plant-food. For the northern commercial sections, Miller^ rec- ommends " a fertilizer analyzing 2 to 4 per cent of nitrogen, 8 per cent phosphoric acid and, when avail- able, 8 to 10 per cent of potash." Assuming that cot- ton-seed meal is the most convenient source of organic nitrogen (which is preferred to inorganic forms for sweets), and acid phosphate and sulfate of potash the best carriers of phosphoric acid and potash respectively, the following fertilizer may be mixed : Composition of fertilizers, 4 per cent nitrogen, 8 per cent phosphoric acid and 10 per cent potash: (1) Use cotton-seed meal containing 6.5 per cent of nitrogen. (2) Use acid phosphate containing 16 per cent phosphoric acid. (3) Use sulfate of potash containing 46 per cent potash. (4) 20 Cwt. (in one ton) X 2 per cent N = 40 lb. nitrogen -^ 6.5 (nitrogen) in c. s. meal = 615 lbs. c. s. meal 615 lbs. (5) 20 Cwt. (in one ton) X 8 per cent phos- phoric = 160 lbs. phosphorous -=- 16 (phos- phoric in acid phosphate) = 1000 lbs. acid phosphate 1000 lbs. (6) 20 Cwt. (in one ton) X 10 per cent K. 20 = 200 lbs. potash -f- 50 (potash in sulfate of potash) = 400 lbs. sulfate potash 400 lbs. 2015 lbs. By calculating the cost of such a fertilizer with local 1 Farmers' Bull. 999. Tillage, Fertilizing and Rotation 107 prevailing prices of the ingredients and comparing this cost plus labor of mixing with the manufacturers' price for a ready-mixed product of the same analysis, the economy of home-mixing could be determined. Some soils would, perhaps, require no nitrogen at all, in which case the calculation for the other two elements would be made exactly as before and the deficiency in making a ton would be made up by the use of a filler. Often in buying ready-mixed fertilizers, the producer has to pay freight on a " filler " which is of comparatively no value as a fertilizer. Mixtures adapted to the growing of sweet potatoes on most soils may be mixed in the following proportions: 1000 pounds of 16 per cent acid phosphate 600 pounds of cotton-seed meal 400 pounds of sulfate of potash. Total, 2000 pounds. 200 pounds of sulfate of ammonia about 25 per cent pure 200 pounds of dried blood 1200 pounds of acid phosphate about 10 or 12 per cent pure 400 pounds of muriate or sulfate of potash about 50 per cent pure Total, 2000 pounds. This last mixture should analyze about 4 per cent nitrogen, 6 per cent phosphoric acid and 10 per cent potash. The nitrogen may be left out or reduced. What fertilizer to apply. It is impossible to give any specific fertilizer ration best to use on a crop of sweet potatoes. Even a chera- 108 The Sweet Potato ical analysis of a specific soil would be of little practical value in determining- the " best " fertilizer. Every grower must make a study of his individual soil re- quirements by noting " results " rather than by theoret- ical calculations. For this reason it has been thought best to give as briefly as possible the fundamentals un- derlying fertilization and with this knowledge each grower can be guided in the intelligent manuring of specific fields. ' In the commercial sections of northern production areas where the growing season is comparatively short, more liberal application of manures will be profitable than in the South. When rapidity of growth, earliness and high quality are important factors, even the most fertile soils contain too little quickly available plant- food for maximum yields. In such cases, more liberal and careful application of commercial manures must be resorted to. Humus. It has been said that " humus is just as necessary to make soil fertility as water is to make lime and sand into plaster." This is especially true of land on which the best yields of sweet potatoes are to be secured. Al- though the chemistry of humus is not thoroughly under- stood, it is known to be a very powerful factor in ren- dering soil loose and friable (when well-drained) ; it supplies plant-food in the form of nitrogen ; it combines with many of the other fertilizing elements, making them available and effective; it is very important in con- trolling the moisture-content of the soil, in furnishing food for friendly bacteria^ in enhancing the physical Tillage, Fertilizing and Rotation 109 Condition generally and it has an important influence on soil temperatures. Although a liberal supply of humus is very desirable on sweet potato land, it should be well decayed, the soil well-drained, and it should not be acid or sour. Humus becomes worthless with many croppings and its supply in the soil must be renewed from time to time. This is best done by the application of barnyard manure and the use of green cover-crops turned under. However, such applications of humus should be made to crops pre- ceding the sweet potatoes in the rotation if it is to decay properly and be of most value. Green-manures. The question of providing in the rotation a legu- minous crop to supply needed nitrogen and humus has been briefly discussed under rotation. Even when these crops are removed from the land, an actual gain in nitrogenous fertility results. The Ehode Island Ex- periment Station, in a five-year pot experiment, found that cowpeas and soybeans grown on land resulted in a gain in nitrogen. " The approximate five-year net gain of nitrogen in the presence of these two crops and the vetch which was grown alternately with each, was a ton of nitrogen per acre, about seven-tenths of which was contained in the twenty-five tons of moisture- free summer crops removed, and the remainder in the soil itself. These quantities should be considered with reference to the following facts, namely : the soil in the pots Avas 10 inches deep, somewhat deeper than the surface soil in many localities; the winter vetch was grown in a heated greenhouse; and furthermore, suf- 110 The Sweet Potato ficient water was given to supply all needs of the plants," ^ In many sections of the South, the growth of leguminous crops in the sweet potato rotation would be a most desirable means of supplying both nitrogen and humus, which are much needed on many of these soils. If the crops in rotation are corn, cotton, oats or wheat, leguminous crops should be sown with these, or after they are harvested, in which case they might also be used as a winter cover-crop. Velvet beans, peas or clover may be planted with the corn, or clover may fol- low oats or wheat. Very good results are secured by turning under a heavy crop of crimson clover early in the spring. Green-manuring, however, consists of more than growing a leguminous crop which is removed from the soil. It means the growing of a crop on the land which is plowed under. Many fields of so called " worn- out " land could be made to produce bountiful yields of high quality sweets by the use of one or two crops of legume turned under as manures. Other materials as fertilizers. Stable-manure J though supplying organic matter in its most desirable form and also adding nitrogen and smaller quantities of other food elements to the soil, should never be applied directly to a crop of sweet potatoes. When so applied it has a tendency to cause too rapid growth, resulting in large rough tubers of poor quality. When applied excessively, vine growth is over-stimulated at the expense of the tubers. Stable- manure is best applied to the crop immediately preced- ing the sweets and even then it should be well rotted. Well-rotted stable manure may be used at the rate of 1 Bull. 147, Pv. T. Exp. Sta. Tillage, Fertilizing and Rotation 111 10 to 15 wagon-loads to the acre. It may be applied broadcast, and harrowed into the soil, or drilled into the rows before bedding. Peat, muck and leaf-mold. — Clay soils and others having a tendency to compactness and those deficient in organic matter can often be improved for the growth of sweet potatoes by an application of peat, muck, or leaf- mold. Sometimes these substitutes contain as high as 4 per cent nitrogen. Their chief value, however, is in the humus which they contain. The distance which such substitutes have to be hauled will determine the advisability of use. Poultry manure. — The value of poultry manure is too often unappreciated by farmers. This substance is rich in nitrogen and phosphoric acid. It is valuable as a fertilizer for sweets in the ISTorth where they are grown as a garden vegetable. If the full utility of this fertilizer is received, care must be taken of it, as a large part of the nitrogen may be lost by evaporation. Poultry manure, or any other barnyard manures should never be mixed with ashes since they contain alkalies which increase fermentation, causing a loss of nitrogen. Hardwood ashes may be applied to sweet potato land at the rate of 1200 to 2000 pounds to the acre. A good grade of wood-ashes should analyze from 6 per cent to 8 per cent of available potash. They also contain considerable lime. The food value may be reduced by excessive leaching. Lime is also applied to sweet potato land when a large amount of green material has been turned under for organic matter. This neutralizes the sourness that often is caused by the gi'een crop. From one to two tons may be applied to the acre. Lime present in the 112 The Sweet Potato soil hastens the maturity of the crop and increases the yield. On poor soil, lime and potash work together to produce uniform sizes and shape. Lime, for the best results, should be applied the year previous to planting- sweet potatoes. Application of fertilizers. (Plate III.) Since the sweet potato plant when transplanted in the field is ready to begin growth, all fertilizers are best applied sometime before the plants are set. The com- mon practice* is to apply commercial fertilizers in the drill at the time of making the rows. This is ordinarily done by distributing the fertilizer in the middles be- tween rows, mixing it with the soil by stirring with a scooter or bull-tong-ue, and then bedding on top of it by throwing two furrows together with a turn plow. It is very important that kainit (when used as source of potash) be thoroughly mixed with the soil before plant- ing, as cases have been reported in which this fertilizer injured the crop. ROTATION The growing of a series of crops on the same land in definite order throughout a period of years constitutes what is termed crop rotation. Proper rotation is now recognized to- be a necessity to maximum production and efficiency witli all crops. In fact, it is quite as important to the permanent welfare of the soil as to the yield and quality of the plants grown, and the kind of rotation practiced will have fully as much influence on both as docs cultivation or fertilization. A seed-bed may be perfectly prepared; plant-food Tillage, Fertilizing and Rotation 113 may be present in abundance ; the seasons may be ideal ; and still a complete failure or a greatly reduced yield may be the reward because each year the field has had to nourish the same kind of crop, supplying it with the same amount of the same food elements and receiving in return the particular toxin or poison which is given off by the plant in question. Each plant takes from the soil its special kind of food and throws off certain root excretions, corresponding to perspiration in ani- mals, which are poisonous to that particular plant but which perhaps would be unharmful to any other species. Each plant exerts a certain influence on the mechanical condition of the soil caused by the development of its peculiar root system which varies with different crops. Alternation of deep and shallow-rooted crops in the rotation require the use of other layers of soil. Each plant has certain insect enemies and is subject to certain fungous diseases which naturally become worse if the plant crop is grown in the same place year after year. Some crops are more exhaustive on the humus supply of soils than others, and rotation enables the main- tenance of this humus. Proper rotation facilitates diversification of crops which is essential to the proper distribution of farm labor. Plant-food. The demand on soil for plant-foods from year to year is varied by rotation. An " exhausted " soil is frequently depleted in some one food element due to growing continually some crop that uses more of that element than it does of other plant-foods. Such a soil is often exhausted only for the particular crop which 114 The Sweet Potato has been grown without alternation. A thousand pounds of sweet potatoes contain 2.9 pounds of nitrogen, .9 pounds of phosphoric acid and 5.1 pounds of potash, while a similar amount of Dent corn contains 16.2 pounds of nitrogen, 6.9 pounds of phosphoric acid and 4 pounds of potash.^ Thus it is seen that sweet potatoes remove from the soil about two-thirds more potash than nitrogen, while corn removes more than four times as much nitrogen as potash. It would appear that a con- tinuous cropping of corn would quickly exhaust the nitrogen supply, while successive crops year after year of sweet potatoes would tend to deplete the supply of potash more quickly than the other food elements. However, this consideration in favor of crop rotation is not considered of as much importance as formerly for the increased yields resulting will ordinarily take from the soil inore actual plant-food than would be used by the smaller crops were rotation not practiced. The fact, however, that plant-food in the soil is continually being made available and that deficient crops use the elements in varying proportions may be of importance. Root excretions. The accumulation in the soil of certain root poisons or toxins may be avoided by rotation. Frequently when the soil has been well fertilized and diseases kept out, small yields of sweet potatoes are secured on a piece of ground after several years continuous cropping. Although little definite information is available on the subject, it is known that the roots of a plant throw off waste matters and that these excretions seem to be self- poisoning to the plant. Other plants, however, are not 1 " Feeds and Feeding," Henry and Morrison. Tillage, Fertilizing and Rotation 115 noticeably injured by this poison and after a few years cropping in other varieties the toxid effect is destroyed by natural soil forces. Mechanical effect on soil. The prevailing opinion that " sweets " are hard on land is not without foundation. Not only are large amounts of nitrogen and potash removed but frequently the crop is not dug until late and the ground is often left bare all winter when the leaching rains rob the soil of its available plant-food. Hogs are often left in the potato fields in wet weather when their rooting causes the soil to become hard and baked when it is dried out. The soil should never be molested when muddy either by animals or otherwise. On heavy soils, the vines, especially when heavily manured, become very rank and when turned under cause too much acid in the soil. Under such conditions, an application of raw phosphate rock would be advis- able. Sweet potato land should be amply supplied with organic matter but it should be well decayed and the soil should be loose and mellow. Proper rotation of crops provides for sowing a winter cover-crop to prevent leaching; for the growth of legumes to be turned under and allowed to decay thoroughly ; and for the alternation of deep and shallow- rooted crops which will preserve and improve, the mechanical condition of the soil, making it easier and more economical to cultivate and allowing the produc- tion of a crop of the best quality. Insect, fungous and weed enemies. One of the most important advantages of crop rota- 116 The Sweet Potato tion with the sweet potato is the controlling of insect pests and fungous diseases which in sections seriously hamper the development of the industry. In speaking of control measures for the sweet potato weevil, which in Texas alone is exacting an annual toll of nearly 20 per cent of the crop, Chittenden ^ writes " Rotation of crops is a necessary measure in the eradication of this pest; indeed, injury may be prevented to a large ex- tent by the selection of the field for planting." (See Chapter VII.) Miller ^ says, "A rotation in which sweet potatoes are gro\vn on the land once in three or four years combined with seed selection and hot-bed sanitation, is effective in preventing loss from stem-rot, black-rot and other injurious diseases." The New Jer- sey Station recommends a rotation calling for sweet potatoes not oftener than once in four or five years for old sections and every three years for new ground if disease is to be controlled. Some crops are favorable to the growth of accom- panying weeds which are likely to become firmly estab- lished if the crop is continually grown on this same land. In the South, crops of the short-vined varieties of sweet potatoes may be almost completely choked out by Ber- muda-grass which can easily be held in check by the use of a heavy cover-crop such as cowpeas. Johnson- grass, " nut-grass " and " Kerless " weeds are obnoxious enemies of the sweet potato. All can be controlled and sometimes completely eradicated by proper rotation. Rotation to he used. The crop rotation with sweet potatoes will necessarily have to be determined by the individual grower. It will 1 F. H. Chittenden, Farmers' Bull. 1020, p. 18. 2 Fred E. Miller, Farmers' Bull. 999, p. 5. Tillage, Fertilizing and Rotation 117' be governed by the prevailing soil and climatic condi- tions ; by the kind of farming practiced ; by the demand and market for particular crops that might be grown; by the inclination, taste or preference of the individual ; by the land and equipment available ; by the condition of his land and other circumstances which can only be de- cided by the individual. The cut-over pine lands of the South are preeminently suited to the production of " sweets " and even the " worn-out " cotton and tobacco farms make good yields, when rotation includes leguminous crops for increasing the humus-content of the soil. Newly cleared land in this region produces heavy crops. As the clovers do not thrive on a large part of this la:nd when planted so late (sweet potatoes in this section are harvested in jSTovember), such crops as oats and rye have to be de- pended on for winter cover. In Virginia and regions farther north, when potatoes are dug for the early markets, crimson clover may be sown for a cover-crop provided the potatoes are off by September 1 to 15 in JSTew Jersey, Delaware and Maryland, and by Septem- ber 30 in southern Virginia. Where the potatoes oc- cupy the land too late for planting crimson clover, a cover-crop of rye or of oats and vetch should be used. The following suggested three- and four-year rota- tions are taken from Farmers Bulletin 999 of the United States Department of Agriculture : A. For the cotton-belt, where sweet potatoes are grown as a farm crop : 1. First Year, (a) Cotton, followed by rye for winter pas- ture or as a crop to turn under; or (b) Corn, with cowpeas or velvet beans planted as a soil-improving crops. 118 The Sweet Potato Second Year. Sweet potatoes followed by a winter cover-crop of rye or oats and vetch. Third Year. Oats, followed by peanuts or cowpeas. 2, First Year. Sweet potatoes followed by a winter crop of rye or oats and vetch. Second Year. Cotton, with rye sown between the rows for winter pasture or to turn under. Third Year. Corn with cowpeas or velvet beans planted as a soil-improving crop. AA. Four-year rotation for the southern sweet-potato section : First Year. Sweet potatoes. Second Year. Winter oats, followed by peanuts or cowpeas. Third Year. Cotton, with bur clover between the rows. Fourth Year. Corn, with cowpeas or velvet beans be- tween the rows. AAA. Three-year rotation for the eastern shore of Vir- ginia and Maryland: First Year. Sweet potatoes, followed by crimson clover or rye as a winter cover-crop. Second Year. Early Irish potatoes. In many farms corn is planted between the rows of potatoes at the last cultivation ; on other farms the potatoes are fol- lowed by fall vegetables. Third Year. Winter oats, followed by cowpeas for hay. These rotations are merely suggestive and will neces- sarily be changed according to the existing influences governing any case. Miller conchides, " In planning a sweet potato rotation, the importance of plowing under a soil-improving crop once every two or three years should be borne in mind. The crops to include in this rotation will vary according to local conditions. Wherever practicable a leguminous crop, such as cowpeas, soy- beans, velvet beans, or crimson clover should be used in order to supply nitrogen as well as humus." Tillage, Fertilizing and Rotation 119 CONCLUSION In growing sweet potatoes, quality, which is measured by size, shape and cooking, is a very important consid- eration. These characteristics are largely influenced by the soil, the rotation followed, and the fertilizer applied. An abundance of phosphoric acid and potash with smaller amounts of not too quickly available nitro- gen are essential. A yield of 200 bushels of sweet po- tatoes, not including vines, removes from the soil approx- imately 30 pounds of nitrogen, 10 pounds of phosphoric acid and 30 pounds of potash. Fertilizers containing a liberal supply of potash in comparison to the other elements seem to give best returns under average con- ditions, though clay soils do not respond so readily to this element. In general, the best growers have found a small amount of nitrogen and a larger percentage of phosphorus and potash to give most profitable returns. A quantity of each element somewhat in excess of the actual amount removed from the soil by the plant should be applied, as some will be lost by leaching. Twenty pounds of pure nitrogen to the acre is the maximum that should be used if high quality is not to be sacrificed to ex- cessive yields. The New Jersey Station has found that commercial fertilizers alone can be depended on to fur- nish plant-food, but barnyard and green-manures are valuable for supplying organic matter or humus. Or- ganic nitrogen is preferred to the more soluble forms. Commercial fertilizer is best applied in the drill before putting out the plants, while stable and green-manures should be applied to crops preceding the sweet potatoes in the rotation. Organic matter in the soil should be well decayed. CHAPTEK VI VARIETIES The question of varieties is largely a local problem depending on special conditions and on the require- ments of the market served. Considerable confusion exists both in this country and in the insular possessions with reference to varietal characteristics. This' is due in a large part to the fact that the sweet potato is sub- ject to sudden mutation or the appearance of sports giving rise to many new varieties, which may or may not continue in existence. Often even the name for well-known varieties is extremely local, varying for the same variety in different sections. Many growers have undertaken the improvement of some standard variety and after a few years' selection have given it an entirely new name. These influences combined have given rise to a vast number of varieties, many times differing from some other only in the local adoption of a par- ticular name. Eor instance, the Pumpkin yam, the Georgia Split-Leaf and the East Texas yam are identical but are sold from the different sections under the various names. In Porto Rico a great many varieties are found but only the Mamey varieties, namely the- Mameyona or large Mamey and the Mameyita or small Mamey, and also the Blanca or white, are known by the same name all over the island. Several tentative classifications for varieties have 120 Varieties 121 been suggested by various writers but no key has yet been made sufficiently complete to rely on in accurate classification.^ Roughly speaking, the distinguishing characterization of various varieties are included in: (1) the length of vine, which may be either long or bunch; (2) the shape of leaves, which are either deep cut, shouldered or entire; (3) the texture of the meat, which is either sirupy, mealy or intermediate; (4) the color of the flesh, which may be yellow, white or mottled white and yellow; and (5) the color of the skin, which is white, yellowish, light red or purple. Many minor characters may be noted, such as prominence of leaf- veins, color of leaf-veins, and tint of leaves. In order to make a treatise on varieties as practical as possible, it has been thought best to give all of the available in- formation on the better known kinds, even though some of these varieties are only known locally by the name given. The descriptions given below are in somewhat the form of notes as made by the authors from observation, elaborated in cases by descriptions from other authori- ties. All available descriptions of varieties except a very few well known ones are admittedly incomplete and the notes on characteristics and importance constitute only such information as is known to be reliable and ac- curate. A longer study and more systematic effort on the part of investigators is sure to give some very valu- able data on varietal characteristics in the future, and if the descriptions given here seem incomplete it is 1 A letter from Jno. H. Beattie of the Bureau of Plant Industry, Washington, D. C, to the author, dated July 30, 1919, says, " Dur- ing the present season we are planning to test our variety key out, and if it shows the same results as it did last year, we will publish the material." 122 The Sweet Potato hoped the reader will remember that only time and study can bring about a standardized varietal character- ization with any plant so subject to change by climate, mutation and selection as is the sweet potato. Anguilla. — This variety seems to have almost dis- appeared from the market. It was formerly well known on the eastern coast where it grew to great size. In this respect it was similar to the Peabody, but dif- fered in its white skin and white flesh. This variety is characterized by the immense size the potatoes attain, the heavy crop and the poor quality as judged by the general southern taste. It is rapidly going out of culti- vation except as hog-feed. Aekansas Beauty. — This is a long tapering potato, very smooth and yellowish in color. The roots, which are very uniform in size, are borne in clusters. The skin is pronounced yellow, while the flesh is light yel- low and very delicate looking. The vine growth is good but it is a poor yielder. Big Stem Jersey. — This potato is distinguished by being the most widely cultivated of all varieties for the northern markets. Growers on the eastern shore have long grown this and its near relative, the Little Stem Jersey. The Virginia Truck Experiment Station at Norfolk has given the following ofiicial description of the variety : '' Vines long, heavy, leaves large ; potatoes long, spindle shaped, irregular, often veiny, many very large. Skin bright yellow, flesh creamy to pinkish. Table quality fair, dry. A fairly heavy yielder, especially for early crop. Not adapted to ham- per pack. There are pink-flcshed strains especially good for canning, since the flesh of the potato is of a very attractive color for this purpose. The table qual- Varieties 123 ity of these strains is also superior." ^ In addition to the above description, it might be added that the vines are long, slender and creeping. The leaves are small, green on both sides and entire. The potatoes are late in season to mature. This variety is a heavy yielder and can be grown farther North with better success than the moist-fleshed varieties. (See Plate IV.) Black Spanish. — This variety is identical with the Nigger Killer, or Negro Choker, described below. Braziliaist. — The roots of the Brazilian are large, smooth, roundish and uniform in shape. The skin is light yellow; the flesh white. It is a hardy variety and very prolific, with a luxriant vine growth. Ceeola. — This is a heavy yielding variety, very valuable for stock-food. The foliage is characterized as follows: " Stem single, rather thin, white below sur- face, deep ruby red above surface of ground. Leaf somewhat inclined to be triangular. Margins entire. Medium green above and grayish green underneath. Vines light green, rather large. Petioles medium thick, very long, light green color." ^ DooLEY Yam. — One of the best yielders and keepers among the long list of strictly southern grown sweets is the Dooley. This is an old variety and is well known and extensively produced in all of the southern states. The vines are slender but very long, often attaining a length of 15 feet or more. They are dark green and the leaves are entire with three to five tiny marginal points according to the age of the leaf. The dark green vines blend into a greenish-purple color as the i.T. C. Johnson and J. T. Rosa, Jr., Bull. 19, p. 414, Va. Truck Exp. Sta. 2 T. C. Johnson, Va, Truck Exp. Sta., information to author. 124 The Sweet Potato roots come to maturity. The potatoes are fair in size, being short, smooth and spindle-shaped. The flesh is dark yellow to salmon in color, very soft, sweet and juicy when baked. The Dooley is not an early maturer. (See Plate IV.) Delaware. — ■ This is one of the dry mealy types or- iginating from the original Nansemond, or Jersey Sweet, of Maryland and Virginia. ruLLEKTo«sr Yellow Yam. — The potatoes are very long in proportion to their diameter. They are borne in clusters and are very prolific. The skin is light yellow; the flesh white spotted with yellow, and sweet and sugary in nature. Florida Yam. — In a series of variety tests conducted by C. E. Brehm, of the Tennessee Station, the Florida yam gro\\Ti under identical conditions with a number of other kinds, was only equalled in yield by the Nancy Hall. Brehm says : " Although seedmen differentiate between the varieties Florida yam and Nancy Hall, I am confident that there is no difference. The only difference that I can see is that when shipments are made North they call sweet potatoes of this variety Nancy Hall and when shipped South they call them Florida yams. From the standpoint of appearance and yield they are identical." General Grant. — This variety has been noticed to produce very few small potatoes. The roots are either of good size or they are strings. The large potatoes are smooth and well-shaped. The strings are worthless. The skin is very light yellow and the flesh pure white. The vine growth is prolific but the yield of potatoes is small. Gold Skin. — This variety belongs to the Nansemond Varieties 125 class together with the Yellow and Tied jSTanscmond, the Delaware, Big and Small Stem Jersey and the Red Nose. The name " Gold Skin " seems to be more of a trade name for " Jersey Sweets " rather than a term designating a distinct variety with outstanding varietal characteristics. Gold Skins are sold extensively on the northern markets. They have the mealy flesh char- acteristic of the Nansemond potatoes. Geokgia ok Split-Leaf Yam. — This variety is ex- tensively grown for home use throughout the South Atlantic and Gulf states and is known under several local names, such as the Georgia Buck, Split-Leaf and East Texas Yam. The vines grow long and slender; the stems are light green in color; the leaves are the same color and seven-parted, being very deeply cut. Johnson ^ describes the vine growth as follows : " Stem branching, bushy, rather slender, portion below surface of ground is white to pinkish, and that above surface is pinkish to green. Leaf is deeply divided, prominent shoulders; margin entire; color medium green up- per surface, grayish green lower surface; veins heavy, light green; petioles thick, moderate length, light brownish color." This variety is a good yielder and is adapted to gr'owing for home use and for markets de- manding a sweet, very moist potato. Hayman oe Southern Queen. — The Hayman and Southern Queen are identical, having whitish skin and creamy flesh. This variety and the Nancy Hall are the only " yam " kinds grown in the eastern shore produc- tion section. The Hayman has long been well known in that section but years ago it was taken up by B. K. Bliss, then a leading seedman in New York City, and 1 T, C. Johnson, Va. Truck Exp. Sta., information to author. 126 The Sweet Potato sent out as a new potato under the name of Southern Queen. It is now known in manj sections by the latter name. It is very earlj, unusually productive and is considered one of the earliest varieties to keep in storage. It is much improved in eating quality by storage and though not a very choice eating potato in fall and early winter, it becomes very good indeed in late winter and spring. It is of a very light color outside, presenting a grayish-white rather than yellow appearance. The flesh is pale yellow. The vine growth is heavy. The tubers are inclined to become over-large in rich soil, unless early digging is practiced. (Plate IV.) Jewel Yam. — This is a yellow potato very like the dry Nansemond but with the sweet soft flesh of the yams. It was formerly grown to a limited extent through the Carolinas. It is a heavy yielder with prom- inent veins and is almost identical in appearance and quality with the Yellow Barbadoes. Key West Yam. — This is one of the sweet juicy potatoes similar to the Porto Rico. It is a good yielder and sells well on the southwestern markets. It is largely grown in the Manhattan sweet potato section of Kansas and perhaps equally extensively in other parts of the Southwest. It is also well known on the eastern coast. Because of the heavy yield, it is largely used as stock food. '' Stems branching and bushy, quite thick ; color below ground pink, above ground deep ruby red ; leaf auriculate, sharply pointed, mostly shouldered ; mar- gins very finely serrated ; dark green upper surface, light green under surface; veins prominent, purplish color; petioles long, thick, with green purplish tinge." ^ 1 T. C. Johnson, Va. Truck Exp. Sta., information to author. Plate V. — Diseases of sweet potatoes, a, A section through a sweet potato showing the blackened ring just below the surface caused by the stem-rot fungus, h, A sweet potato plant showing the characteristic symptoms of stem-rot. c. Sweet potato black-rot. Small sweet potato plant showing the characteristic blackening of the underground part of the stem. d. Soft-rot. A sweet potato showing the moldy growth of the fungus causing soft-rot. e. Soil-splotch. Varieties 127 LiTTXE Stem Jersey. — The Little and Big Stem Jerseys are extensively grown for the northern markets by all farmers in the eastern shore sweet po- tato district, where the Eastern Shore of Vir- ginia ProduceExehange has done much to stand- ardize the production. Bulletin 19 of the Vir- ginia Truck Experi- ment Station gives the following' description of the variety : " Vines long, slender, leaves small ; potatoes uni- formly medium sized, regular, rounded to spindle shaped; bright yellow skin, creamy flesh, a moderate yielder; table quality good, dry. This variety is espe- cially adapted for shipping in the hamper pack to north- ern markets." The" vine growth is similar to that of the Big Stem Jersey except that it is more slender. The potatoes are smaller, more uniform, smoother and less veiny than the Big Stem Jer- sey, according to Miller.^ 1 Fred E. Miller, Farmers' Bull. 999, p. 28. Figure 12. — A hill of healthy- Little Stem Jerseys having more than five potatoes of marketable size. Fifty hills of such po- tatoes will give a barrel of mar- ketable potatoes and some culls. Such healthy high-yielding hills of uniform potatoes are especi- ally good for seed. Figure 13.— A hill of healthy Little Stem Jerseys with potatoes of good shape, but not lai'ge enough to mar- ket as primes. This photo- graph is the same magnifi- cation as Fig. 12. 1S8 The Sweet Potato Plate IV shows two types of Little Stem Jerseys (listed Yellow Jerseys) generally grown. One represents the long spindle type, and the other a short chunky strain. (See Figs. 12 and 13.) Meyebs Early. — This is a sweet, rich, yellow- fleshed sort resembling in character and quality the Nancy Hall. It is a selected strain of the Nancy Hall and is almost identical with it. It is known throughout Georgia, but is not widely distributed in other states. The vine's have short nodes rather close together, and with medium to small " entire " leaves. The Meyers Early is said to grow a little longer than the Nancy Hall and the veins on the roots are more pronounced. In fact, the description of a well-grown Nancy Hall potato will fit the Meyers Early very well. Nancy Haljl. — This is the most popular of all the yellow " yam " varieties. When cooked, the flesh re- sembles closely that of the Pumpkin yam of Georgia and the Norton yam of Norfh Carolina. It does not resemble these before cooking, however. This variety naturally grows short and chunky and the skin is pale yellow with stray streaks of pale pink. The flesh is deep pumpkin yellow when cooked. The Nancy Hall, under field conditions, is outstanding in producing a greater amount of No. 1 bakers with fewer jumbos and culls. The potatoes are of good shape, rather prolific and are very early maturers. The vine growth is luxu- riant. The vines are medium long (3 to 5 feet) and green except for a purple stain at the junction of the blade and petioles. The leaves are entire. (See Plate Nansemond or Jers.ey Sweet. — The original Nan- Varieties 139 semond, or the old yellow sweet potato of Maryland and Virginia, is a dry yellow potato popular in the northern markets. This potato, renamed in New Jersey, has given rise to the Delaware and the Ked Nose varieties and to the various other strains of the Jersey potatoes. NiGGEK Killer. — The Nigger Killer, or Nigger Choker, has a purplish red skin and the whitest flesh of any potato. It is very dry but really sweeter than the dry yellow varieties. The vines are very long, vigorous and dark purple in color. The potatoes are long, cylin- drical and crooked. The quality is poor, the variety being grown mostly for stock-food. Norton Yam. — This variety belongs to the pumpkin colored yams, and is largely grown and sold through- out North Carolina. It has a yellow skin and the flesh is dark pumpkin colored when cooked. Old Fashioned Yellow Yam. — " Stem is medium thick, white below soil surface and purplish above. Leaf is very deeply divided, with three lobes and two shoulders; margin entire, light green above and gray green under surface; veins moderately heavy, light green in color; petioles are thin, rather short, light purplish in color." ^ Peabody. — This potato grows to an immense size, has yellow flesh, red skin, and is very dry and tasteless. It is often sold on the Raleigh, North Carolina, market, when about one-fourth gi*own, as there are usually no good potatoes on the market at that time. When fully grown, it will not sell for table use in the South but is frequently used as food for hogs, the animals being turned on the fields to gather the roots as desired. 1 T. C. Johnson, Va. Truck Exp. Sta. 130 The Sweet Potato PiEESON. — This kind resembles quite closely the Red Bermuda described below. The roots are light yellow, well shaped, but often very much crooked and rough, with light yellow flesh. The Pierson comes early and finds some sale on the extra early markets. It is not a heavy yielder. Johnson describes the vine growth as follows : " Stem single, long, branching rather thick, white below surface, bright reddish to purplish above surface of ground. Leaf auriculate, very sharply pointed; margins entire; upper surface of leaf is dull green with purplish pink near edge ; lower surface gTay green; veins prominent, medium size; petioles slender, rather long, light green, with purplish tints." PoLO'. — This is medium to large in size, very smooth, the roots rather round and the skin and flesh white. The vine growth is luxuriant. Porto Rico. — Growers throughout southern Georgia, Alabama and Mississippi and in northeast Texas have in recent years become enthusiastic over the possibilities of the Porto Rico potato. It is said al- ways to give a good yield on almost any soil, although some growers claim it does not thrive on new ground. It not only yields well but is a fair keeper, ships well and is good as soon as dug. This variety, though not as widely known as the Nancy Hall and the Nanse- mond, is very rapidly becoming popular on the big markets. The Porto Rico, however, seems to be very susceptible to attacks from the sweet potato root-borer or sweet potato weevil. The potatoes are medium large, rounded, regular, deep salmon skin, very rich salmon flesh, sweet and juicy and in the South are considered very choice for baking. ( See Plate IV. ) Varieties 131 Pride op Kansas. — This variety is ^rown to a limited extent in certain parts of Kansas where it originated. It is not a standard variety and is not known and demanded on the markets outside of the purely local trade in the sections where it is grown. Pumpkin Yam. — This is a yellow or pumpkin- colored sort similar in color of roots to the N'ancy Hall. The vines are long and the leaves entire. The stems are green and hairy and the leaves are green on both sides. The roots are medium sized, -smooth and well formed with prominent bright-yellow veins. The flesh is mottled yellow and white with yellow predominating. The potatoes are formed unusually deep in the ground and for this reason are not so readily attacked by the sweet potato weevil, though the roots seem quite sus- ceptible to fungous diseases. This variety is very sweet, very moist and soft in texture. (See Plate IV.) PuKPLE Yam. — This potato grows very long in pro- portion to its diameter. The skin is purple; the flesh white. It is a very poor yielder. The roots are borne near the surface of the ground, making the soil crack open more than is customary with heavier yielding varieties. The vines are large in size but the stems are spaced far apart with few leaves. Eed Bermuda. — This is especially adapted for use as stock-food. It is a very heavy yielder, the vine growth is vigorous and the potatoes seem unusually hardy and free from disease. This variety belongs to the " yam " group but it not so sweet and juicy as the Porto Kico. The roots are rose red and the flesh light yellow. This potato will thrive farther north than most of the so-called yams. 133 The Sweet Potato Red Brazil. — " Stems single, thin, light pink below surface of ground, deep ruby red above surface. Leaves long and sharply pointed; margins finely ser- rated; leaves are light green to purplish above and grayish green on under surface; veins are prominent, purplish in color; petioles thin, medium length, with purplish color." ^ Eed Caeolina. — The variety is nothing more than the Red Jersey sold under a name indicating its place of production. Red Jersey or Red E'ansemond. — This variety was a bud sport from the Yellow I^ansemond. The vines are identical in appearance and the taste of the flesh is quite similar. This variety is popular on markets which show preference for a red-skinned potato. It is a heavy yielder and finds more sales on home markets than in shipping. (See Plate IV.) Red Nose. — Among the offsprings of the old original jSTansemond, or Jersey Sweet, is the Red Xose. This is a yellow-fleshed yellow-skinned sort with brown- ish-red blotches around the neck. Shanghai. — The vine growth is very luxuriant, the stems growing large and vigorously. The roots resemble those of the I^igger Killer in shape, grow- ing very long and cylindrical, but in color they are almost white. The meat is yellowish-white but turns a rich creamy yellow on cooking. It looks better than it tastes, as the flavor is rather poor and it is somewhat dry and mealy. It is a good yielder and is used to a limited extent in the Gulf coastal regions of Alabama, Mississippi, Georgia and Florida for stock-food. iT. C. Johnson, Va. Truck Exp. Sta. Varieties 133 Shanghor Yam. — Keitt describes this potato as be- ing " A somewhat irregularly shaped, white fleshed variety, skin slightly yellow. Much larger percentage of large to small tubers than that of White Spanish. Seems entirely free from disease. The potato is not what is usually called a yam, for it analyzed high in starch and low in sugar. It is not prolific." ^ Tennessee I^otciileaf. — This potato is described by Keitt as : " Eather small, somewhat stringy pota- toes, which are borne in large clusters. It is a yellow fleshed variety. Was attacked by a white rot before gathering. Very prolific, but makes very little growth of vines." ToLMAN Variety of Old Spanish. — The Spanish potatoes constitute a distinct class characterized by the slim narrow crooked potatoes with white skin inclined to pinkish shades and with grayish- white flesh. The Tolman strain is very similar to its close relative, the White Barbadoes. Triumph. — The Triumph is the earliest potato on the market and being white and mealy sells well in the North. It is not so good for the southern trade and does not sell so well after the early season demand is over. The Triumph is not a good keeper. It is a heavy yielder and is noted for the prominence of the veins and the large size of the roots when left in the ground until mature. The vines are bushy in nature and the leaves deeply cut. Because of the bushy nature of the vines, they are very easy to cultivate. The vine growth has been described as follows : " Leaf auriculate, pointed, double shoulders; margin irregular 1 T. E. Keitt, S. C. Exp. Sta., Bull. 146, 1908. 134 The Sweet Potato and serrated ; color, upper surface deep green ; lower surface, light green ; veins, heavy, deep red ; size, medium to rather small; petioles, thick, long, green and purplish." ' (See Plate IV.) ViNELEss Bunch Yams. — The Vineless seems to be a sport from the ]S[orton Yam, as bunch sorts frequently appear among the ISTortons. The roots in appearance and quality are identical with the Nortons. This variety is described as follows : ^ — " Long, tapering, uniform ; but rather small tubers ; having a yellow skin, and white and light yellow mottled with white flesh, with some deeper yellow spots. Not much vine growth and a shy bearer." (See Plate IV.) White Bakbadoes. — This is another of the Spanish potatoes and is almost identical, if not quite so, with the Tolman variety of Old Spanish. Both the white and yellow Barbadoes are thicker in shape than the Old Spanish. The White Barbadoes is pale whitish in flesh, and yellow outside. White Spanish. — This is described by Keitt as follows : " Very irregularly shaped, a few being large, smooth and roundish ; but the majority being long and stringy. They have a perfectly white flesh and white skin. They are not prolific, but make a heavy growth of vines." ^ White Yam ok White Belmont. — This variety is very hardy, is a big yielder, is unusually sweet for a white potato, and is largely used for stock-food. The vine growth has been described as follows : " Stem branching, rather bushy and very thick; light green iT. C. Johnson, Va. Truck Exp. Sta. 2 S. C. Exp. Sta., Bull. 14G. ST. E. Koitt, 8. C. Exp. Sta., Bull. 14G, p. C. Varieties 135 below surface and dull deep red above surface of ground. Leaves heart shaped, pointed ; margins entire ; deep green upper surface, gray green lower surface; veins prominent, green color, medium size; petioles short, dull green." ^ Yellow Baebadoes. — This potato has sweet soft flesh very much like the Jewel yam. The roots are noticeable by their very prominent veins. The roots are yellow inside and out, differing in this respect from the Wliite Barbadoes which, although possessing a yel- low skin, has whitish flesh. Yellow Belmont. — This potato, which has been illustrated in various publications as a distinct variety, seems very closely allied if not identical with the Yellow Nansemond or Yellow Jersey. It is yellow inside and out and has a rather dry mealy texture. The tubers resemble the Small Stem Jersey more closely than the Big Stem, being smooth and less veiny than the latter. For all practical purposes, the Yellow Belmont may be considered a short chunky strain of the Yellow Jersey. (See Plate IV.) Yellow N"ansemond. — The Nansemond class has many subdivisions, among which is the Yellow Nanse- mond. It is a long, smooth, tapering unifonn yellow potato with almost white flesh. The roots, which are small, are borne in clusters prolifically. The vines and leaves are small. Yellow Steasburg. — This is a heavy-yielding variety used largely for stock-food. It is not widely grown and is not known on the markets, iT. C. Johnson, Va. Truck Exp. Sta. 136 The Sweet Potato Of all the varieties of sweet potatoes given above (and there are perhaps a hundred more subspecies), only about a dozen are important from the market standpoint. The Jersey type is generally preferred on the northern markets, though some of the moist fleshed kinds, especially the Nancy Hall, are being rapidly introduced into markets where heretofore a prejudice existed against southern potatoes. The southern markets demand the moist fleshed variety or the so-called yam kinds. The Nancy Hall and the Porto Rico are the most popular and widely grown for the middle and late markets, while the Triumph (a medium dry variety) is most popular for the extra early market. When grown for stock-food only, the heaviest yield- ing varieties such as the Yellow Strasburg, Red Ber- muda, White Belmont and Hayman, should be used. The contention of some growers that the high sugar- content of some of the lesser yielding kinds will offset the advantage of big yields in fattening stock has not been found to hold true in practice. CHAPTER VII INSECTS AFFECTING SWEET POTATOES It is commouly thought that the sweet potato is not aifected seriously by insect pests. The home garden or small patch many seasons is practically free from in- sect injury, but the commercial grower will have to fight several insect enemies, some of which do millions of dollars' worth of damage annually to the sweet potato crop. The different sections of the country have their specific insect enemies, the southern states possessing by far the greater number and suffering much more material damage than the eastern and middle western states. Insects that affect the sweet potato plant are divided into two general classes, the biting or chewing insects, and the sucking insects. The first class destroy parts of the plant or the tubers by gnawing or eating, and leave visible signs. The sucking insects obtain their substance by sticking a small thread-like bill into the plant and drawing the juices out without leaving visible sig-ns to the natural eye. The first class, or biting in- sects, usually do much more damage than the sucking insects. THE SWEET POTATO FLEA-BETBTLE {Chcetocnema conflnis) As soon as the sweet potato plants are set in the field, they are often attacked by millions of small brownish- 'l37 138 The Sweet Potato black flea-beetles. The leaves are affected by having channels eaten out in both surfaces, the work being characteristic of this particular species and quite dif- ferent from other flea-beetle injury. As a result of these attacks, many of the loaves of the newly set plants are killed outright; some turn brown and partially de- cay. ISTew leaves usually put out from the stalk and thus prevent the plant from dying, but this injury checks the growth of the plants to a considerable extent, and in some cases kills them. Some seasons this injury is more serious than others, and some authorities claim that it is worse on low land. It is most serious on lands that were planted the previous year to potatoes, and the first injury is usually near hedge-rows, old fences, or other rubbish, where the beetles have hibernated during the winter. This beetle is about Mg inch long, thick- set, of a brownish color, and the wing-covers when seen under the microscope are distinctly furrowed. The beetles hibernate over winter in rubbish under logs, leaves, or other vegetation, and emerge in the spring, usually about May. They mate as soon as they have fed, and after doing damage to the young plants that are set in the fields they usually disappear about the middle of June. Very little is known about the early stages of the insect, and they have never been found on sweet potato plants. The larva most probabl^y feeds on the refuse of bindweed and morning-glories ; it is a slender white grub about Ys inch long. The beetles appear in August, but do not as a rule feed on the tough sweet potato plants at this season. Many of the beetles will be killed, if. when the plants are taken from the draw-bed, they are dipped in a solu- tion of arsenate of lead 1 pound to 10 gallons of water. Insects Affecting Sweet Potatoes 139 By combining this solution with bordeaux mixture at the ra«te of 4-4-50, it will also serve as a repellant and probably will be more effective than the plain arsenical dip. All plants should be allowed to dry partially before setting out. Dipping the plants is preferable to spraying as it saves much time and they can be more thoroughly and evenly covered by this method, and it is also less expensive. Late planted sweet potatoes are less seriously injured than early set ones. Sturdy plants will withstand the attack and recover from the injury much better than weak plants. TORTOISE BEETLES One of the commonest pests of sweet potatoes is the tortoise beetle. There are several species belonging to the Chrys'omelida?, which are commonly known as gold- bugS or leaf -eaters. They attack the leaves- of the plants in both the lai*val and adult stages. The tortoise beetles hibernate over winter in rubbish and trash of any kind that affords them protection from the cold. In the early spring they feed on the morn- ing-glory, which is probably their original host-plant. As soon as the plants are set in the fi'eld, the beetles begin to eat large round holes in the leaves and so com- pletely riddle them that many plants have to be re-set. Rarely are new shoots seriously eaten or the eggs de- posited on them. The larvse hatch during the first half of June in Maryland ; probably earlier in the South, and somewhat later in the northern and north- central states. The larvse are very ugly and each is provided with a tail-like fork about as long as the body. Upon this fork is heaped the excrement and cast skins of the larva, and they are often overlooked or taken 140 The Sweet Potato for a bit of mud sticking to a leaf. This bulk borne on the fork has given them the name of peddlers. When fully grown, the larva fastens itself to a leaf, its skin splits along the back, and the pupa is held to the leaf by its fork. About a week or ten days later, the adult beetle emerges, eats for a time and then disappears from the sweet potato patch until the following spring, Tt doubtless feeds on its wild food plants until cooler weather drives it into hibernation. The two-striped sweet potato beetle (Cassida bivittata). This species is usually the most common of the tor- toise beetles attacking sweet potatoes. The beetle is pale or yellow-brown, striped with black. The larva is yellowish-white with a longtitudinal band along the back, on either side of which is a much lighter band. The blach-legged tortoise beetle {Cassida nigripes). This species very closely resembles the golden tor- toise beetle, but is not so brilliant in color, is larger, has black legs and three black stripes on each wing- cover, and is larger and more readily seen than the golden species. The larva is a bright straw-yellow with two black marks just back of the head, and with the body-spines tipped with black. As with the adult, the larva is much larger than that of the golden beetle. This larva causes more injury to the plants, although possibly it is not as common as the striped beetle. The eggs of the other species are laid singly, while those of the black-legged tortoise beetle are more or less bunched, usually placed in rows of about three dozen. As soon as the larvffi hatch, all being on one plant or leaf, their Insects Affecting Street Potatoes 141 injury is very noticeable, certain plants being de- voured and others not injured at all. The golden tortoise beetle (Coptocycla bicolor) (Fig. 14). This is one of the commonest species and is found on morning-glory and bindweed during practically the whole summer. The beetles on first emerging are dull orange with three prominent black dots on each wing- FiGUEE 14. — The golden tortoise beetle: a, adult; b, larva; c, faecifork; d, pupa (enlarged). cover, but a little later they assume a metallic color, shining like the most brilliant colored tinsel, and the black spots are not so conspicuous. All the tortoise beetles, and particularly this species, have the habit of dropping quickly to the ground and feigning death when the plant is shaken or when they are disturbed. The eggs of this beetle differ from those of other species in having three spinal prongs projecting from the posterior margin. The larva is easily distinguished 142 The Sweet Potato by being nearly concealed under the heavy load of ex- crement which it supports on its spine. Usually it is of a dark brown color, being browner around the edges and a lighter shade along the middle. The pupa re- sembles the larva. The mottled tortoise beetle (Coptocycla signifera). This beetle is strikingly different from the other species in being black marked with golden spots and usually with a band of black extending across the shoulders to the edge of the transparent margin of the wing-covers. The larva is a pale smooth yellow during its early stages, but after the last molt the color changes to green, and after the excrement is removed from the fork it is very difficult to recognize on a green leaf. The larva does not feed during this last stage. The pupa is also green, but probably brighter than the larva, and marked by a few black bands around the first abdominal spiracles. The argus tortoise beetle. (Chelymorpha argus). This is the largest of the tortoise beetles, although it is not as common as the preceding species. It is also injurious to several other plants, among these being raspberry, horse-radish and milkweed. The adults are usually brick-red in color with six black dots on the pro- thorax and six on each wing-cover which is variable in size and color. The extension of the wing-covers present in the other tortoise beetles is lacking in this species. The eggs are laid in a bunch supported by a long stalk. When the larva hatch, they remain close together and very quickly defoliate the plant. When Insects Affecting Sweet Potatoes 143 full grown the larvae average about /^ inch. They are slightly convex, of a pale yellowish color, marked with mnnerous dark brown tubercles and prominent lateral spines. The pupa is of a yellowish color, marked with dark brown which in time becomes almost black. Control of tortoise heetles. From the similarity of life -history and habits of these closely related species, their control may l)e the same. The adult beetles do the bulk, of the injury just after the plants are set. It is advised that they be dip- ped in arsenate of lead before setting, as for the flea- beetle. If the beetles become serious in the field, plants should be sprayed with arsenate of lead, 4 pounds to 50 gallons of water. All places of hibernation, such as fence-rows, hedge-rows, woodlands and trash, should be destroyed during the winter, as this will kill many of the adults in hibernation. SAW-FLIES. (Fig 15) Probably the first injury from saw-flies was reported from Ocean Springs, Mississippi, in 1886, by C. V. Kiley,^ the larva practically ruining an entire crop of sweet potatoes. This pest is very injurious in certain seasons, the most damage probably being in the southern states. Saw-flies have since been found on sweet pota- toes and morning-glories in Nebraska, Iowa, Illinois, and several other central and eastern states. The in- jury from these flies cannot be said to be serious, and the outbreaks are more or less sporadic and local. The writer, in 1919, found about a 50 per cent defoliage 1 C. V. Rile}', formerly of Bureau of Entomology. 144 lite Sweet I'utato FiGXJRE 15. — The smaller sweet potato saw-fly (Schizocerus ebenits) : a, h, larva; c, d, segments of larva showing spines; e, eggs deposited under leaf; /, male saw-fly; g, antenna of female saw-fly. All mucli enlarged; c, d, greatly enlarged. near Ocean Springs, Mississippi. Two species have been identified on sweet potatoes, Schizocerus ebenus and Schizocerus privahis. These insects usually com- mit their depredations in the middle of the summer, probably the first appearance being, in July. The eggs are deposited on the leaves and the larva? hatching from them eat the leaves to a honey-comb, the damage last- ing from two to four weeks. These larva? are pale green in color with rows of small dots or tubercles run- ning longitudinally along the body. When seen through the microscope, small fine hairs are readily noticed. When saw-flies become serious in a field, an Insects Affecting Sweet Potatoes 145 arsenate spray is advised, using 4 or 5 pounds arsenate of lead to 50 gallons of water. To make the spray stick better 1 pound of fish-oil soap may be used. This should be applied as soon as the young larvpe are noticed. Eiley succeeded in bringing out a number of para- sites from the larva?; this is probably one reason why the insect does no more damage. Tt is thought that the parasites, especially in the southern states where the winters are mild, will partially if not completely con- trol this pest. SWEET POTATO WEEVIL (FigS. 16-23) Cylas formicarius Within the last decade, by far the most serious in- sect pest of sweet potatoes has proven to be the sweet potato weevil. While this insect has been present in the United States since about 1879 and its ravages have been noticed locally in Texas, Louisiana and Florida, yet it was not until the beginning of the War when the whole world was looking to the United States for its food sup- ply that the seriousness of this pest was recognized. In 1917 the Bureau of Entomology started investiga- tions with the idea of control and in some instances eradication. This insect was found in Texas, Louisi- ana, Mississippi, Alabama, Florida and Georgia, and also our insular possessions. It is estimated that Texas in 1917 raised $9,000,000 worth of sweet potatoes and suffered a loss of 20 per cent, or $1,800,000. Louisi- ana, with a crop valued at $5,000,000 lost 12 per cent, or $600,000, and Florida with a $4,000,000 crop lost $400,000 worth. Thus it will be seen that the loss in the southern states is about $3,000,000 or $4,000,- 146 The Sweet Potato 000. Fortunately, this insect is confined to the six southern states just named; in Texas about seventy counties in the southeastern section are infested ; in Louisiana most of the parishes south of Vernon Parish; in Mississippi, Hancock County, Harrison County, Jackson County and part of Pearl River County ; in Georgia, Charlton County ; and in Florida a great number of counties down both the east and west coast. In all of these sections the weevil is found breeding the year round on potatoes in the field, the tubers in storage and also on certain species of sea-side morning-glories and some species of bindweed. Infestation in the spring usually takes place through the over-wintered weevil. Weevils may pass the winter in three ways: First, in storage; second, in roots left in the ground from volunteers; third, in those left through poor har- vesting. Weevils in all stages may be found in buried sweet potatoes along the Coast during the winter. In nearly all instances, infestation can be traced to me- chanical means of transportation. By this is meant the selling and giving away of seed potatoes, plants, draws or vines, or in carelessly shipping potatoes for commercial purposes. All sweet potato gTowers or dealers and the transportation companies should be warned against this danger. Sweet potatoes or plants for propagation purposes should be carefully examined before being shipped, and no such material should be accepted from a weevil-infested area. To meet such conditions, state quarantine regulations should be placed in effect that will compel the small grower either to take care of his own crop or to permit it to be destroyed in case of severe infestation of weevil. Insects Affecting Sweet Potatoes u: While it is not known definitely how much cold this insect can withstand, it is reasonahle to suppose that if it should be transported to the northern states it would be protected from the cold winters by being- housed with the potatoes. It is a prevailing opinion that while the insects would probably freeze out in the fields, the protection given to potatoes in storage will also protect the weevils and perpetuate them from year to year. Description. The adult of the sweet potato weevil is a snout beetle of an ant-like appearance, about Vi inch long, with metallic blue wing-cov- ers, the thorax brick red, head dark blue, and the legs brick red. The antenna are long and have clubs at the end. The male bears the longer larger club, thus distinguishing him from the female. The eggs are pale yellow, partially oval, and somewhat narrowed at the end which is at- tached to the potato. The surface is not shining or polished, but is gi*anu- lated. The length is about Mo of an inch. The larva when full grown is cylindrical and robust ; the segments are permanent and rounded, color practically pure Figure 16. — The sweet potato weevil : Adult, greatly enlarged. 148 The Sweet Potato white ; head pale brown ; mouth-parts a brownish shade ; a few delicate hairs can be seen under the micro- scope. The larva is legless, although very thick leg pads are apparent (see Fig. 17). The length when grown is about % of an inch. Tho pupa is at first the same color as the larva, but before trans- formation to the adult be- comes considerably darker. The wing pads are short and narrow, folded, over the un- der side of the body; the head and back fold down upon the breast ; on the head are several small tubercles, e'ach one bearing a slender spine; it is about % of an inch long. The pupa is not active, not partaking of food. The lower half of the body is mobile, enabling the p^ipa to turn about in its burrow or pupa case. b Figure 17. — Tlie sweet potato weevil: a, larva; ft, dorsal and ventral views of pupa. Enlarged. Life history. While it is thought that the sweet potato weevil passes through a part of the winter in hibernation, it is active throughout the entire year in the Gulf states. Eggs, larva^, pupa? and adults may be found throughout the winter over its entire range. ^^ ^ Insects Affecting Sweet Potatoes 149 Figure 18. — Present known distribution of the sweet potato weevil in tlie southern United States. From observations made by authorities, very little egg-laying takes place during the winter, but the adults are active on warm days and are frequently found crawling about and feeding on stored potatoes. In the spring and in the field the beetles become much PiGURE 19. — ■ Sweet potato, nearly fresh, showing exit holes and feeding punctures of sweet potato weevil toward stem. Note outer end scarcely attacked. Sample from Louisiana. 150 The Sweet Potato more active. Frequently potatoes in storage that have been little affected during the winter may be entirely riddled in the two spring months. In the field or draw- bed, the beetles first feed on leaves and the stems of Figure 20. — Sweet potato badly infested by sweet potato M'eevil, decidedly dry, but sliowiiifr break at middle where living larvae, pupae, and adults were found. Somewhat reduced. the young plants, eating or gnawing irregular holes and excavations in them. After the plants reach a sufficient size to become woody, the eggs are deposited on the stem near the surface of the ground. If the ground is loose or cracked from the baking sun, the female will follow the vine down as far as possible and deposit her eggs there. If the tubers themselves are exposed to the surface, eggs are usually deposited on them. The young larva eats into the potato, leaving an irregular tunnel or furrow filled with excrement. They burrow and feed throughout the winter until their full growth is reached, when they form an oval cavity or pupal cell, usually near the surface of the potato, in which they pupate. In cases in which the eggs are deposited on the vines in the -field, the larvse bore down the stem until they reach the potato and Insects Affecting Sweet Potatoes 151 enter it. In this way the upper portion or the end attached to the vine is always attacked first. After the beetles emerge from pupation, thej break irregular £^r ^ ^»l ^^ n%;t^Rnl^^^^l^ ^^v SI^^^S'^Ff^K^^sl V gi)^BW.«jgjWBtwfa^ 1 H 1^ Figure 38. — Showing universal fold- ing crate before bottom is placed and standing on end after placing bottom in position. at home and used for shipping sweets. It is, however, little known on the markets, and only in special cases where lumber is cheap would it be profitable. By refer- ence to Table XIII it will be seen that it is absolutely impossible to make a crate that will hold a bushel of po- Preparation for Marl-et 231 tatoes by weight. The Bu- reau of Markets favors the establishment of a standard bushel crate by volume to the one adopted by the Jackson- ville meeting in 1018. If this crate is rather small, one containing one-half bushel by volume could also be used. On some of the markets, such as Denver, Colorado, 100- pound crates are sometimes seen, but in the eastern mar- kets barrels are commonly employed when a container is desired holding more than one bushel. More standard- ization of the containers in shipping sweet potatoes is needed, and such standardization can only be brought about on a volume basis. Figure 39. — Octagonal shipping crate for sweet potatoes. PROPER PRODUCTION When the individual has determined to his own satis- faction the best varieties or variety to grow, the season of the year in which the potatoes will net the biggest return and the kind of container which seems best suited to his individual needs, he has found out the actual requirements of his market. In other words, he has discovered the technique of the marketing business. ]\Iarketing really begins with production. Unless the producer can put into his stock the desirable quality; unless he grows a quantity sufficient to enable him effi- ciently to utilize his labor and equipment, and to supply his market demands; unless his potatoes are properly 222 The Sweet Potato harvested, handled to prevent bruising, and graded or culled according to trade requirements, he has not solved his marketing problems. The grower must know how to produce the finished article in the most profitable manner possible if he is to reap the rewards of a well- rounded marketing system. Quality. All trade admires superior quality. The actual " velvet " received on a transaction involving a large shipment of sweet pota-toes is often realized entirely on the degree of superiority which the shipment in ques- tion possesses over the average market quality. Qual- ity includes every factor which makes the goods more attractive and desirable because of uniformity, grade, or edible characteristics. The Eastern Shore of Virginia Produce Exchange has built up for itself a very enviable reputation for the quality of its " Star Brand " Irish potatoes, and this same Association is doing much for the sweet potato industry in that section. Individuals and cooperative associations need to set for themselves a certain standard of excellence and always live up to this standard. This is the only way to gain a reputation for honesty, fair dealing and superior quality. Many of the New Jersey and Delaware growers take great pride in cultivating this special fancy trade, and the same may be said of individuals throughout the South and Central West. The quality of a sweet potato is materially influenced by the type of soil on which it is grown, the rainfall, the variety, fertilization, cultivation, harvesting, curing, subsequent handling and grading. All of these sub- Preparation for Marhet 223 jects have been fully discussed in other parts of this work except the handling and grading, which will be treated in the following pages. Grading. (See Fig. 40.) The sweet potato root which brings the highest price on the markets is of medium size, smooth and uniform and spindle-shaped, that is, long, and tapering from the middle towards both ends. The roots of varieties should never be mixed. For all practical purposes the average farmer will use only two grades roughly classed, (1) those to be marketed, and (2) those used at home. When sold to a canning factory, the potatoes are usually taken " field run " and do not require grading. Sweet potatoes for the general market should not be less than 1^ nor more than 4 inches in diameter, and not more than 7 inches long. The following grades on sweet potatoes which were temporarily adopted by the State Department at Austin, Texas, August 16, 1918, have furnished the basis of all attempts for standard grades made since that time: " No. 1. This grade shall consist of sound sweet pota- toes of similar varietal characteristics which are prac- tically free from dirt or other foreign matter, frost- injury, bruises, cuts, scars, cracks and damage caused by diseases, insects or mechanical means. The diameter shall not be less than one and three-fourths inches nor more than three and one-half inches. " Five percentum by weight of any lot may be below the least or above the greatest diameter prescribed, and, in addition, five percentum by weight of such lot may be below the remaining requirements of the grade. 324 The Sweet Potato " 'No. 2. This grade shall consist of sound sweet pota- toes of similar varietal characteristics not meeting all the requirements of grade No. 1 which are free from serious damage caused by dirt or other foreign matter, frost-injury, heat decay, bruises, cuts, scars, dry rot or other diseases, insects (including weevils) or mechanical means. The diameter shall not be less than one and one-half inches. "Five percentum by weight of any lot may be less than the diameter prescribed, and in addition, five per- centum by weight of such lot may be below the remain- ing requirements of this grade. " ' Sweet Potatoes ' include yams. " ' Practically free ' means that the appearance shall not be injured to an extent readily apparent upon casual examination of the lot and that any damage from the causes mentioned can be removed by the ordinary processes of paring without appreciable increase in waste over that which would occur if the sweet potatoes were perfect. " ' Diameter ' means the greatest dimension at right angles to any portion of a central line running through the sweet potato from stem end to root end. " ^ Free from serious damage ' means that the appear- ance shall not be injured to the extent of more than 20 percentum of the surface, and that any damage from the causes mentioned can be removed by the ordinary process of paring without increase in waste of more than ten percentum by weight over that which would occur if the sweet potato were perfect." A number of attempts have been made to design a practical sweet potato grader, but thus far all efforts Preparation for Marl-et 225 Figure 40. — An easily con- structed potato grader. have been futile and the best means of grading now known is with the hands. A me- chanical grader is rendered difficult of design because of the oblong rather than round shape of the sweet potato, and the ease with which these roots are bruised by handling. The construction of a rather ingenious grader to be oper- ated by means of a sieve of braided belts was at one time undertaken by an employee of the Unite'd States Bu- reau of Markets, but for some reason was never com- pleted. Quantity. A consideration which must enter into the calcula- tions in formulating a well-balanced marketing system through the production end is the question of quantity. A farmer should never grow more potatoes than he can efficiently handle or his available market will absorb. At the same time, he must grow enough to supply his profitable trade and keep his labor, team and capital busy in such a way that the cost of providing a bushel will be reduced to a minimum. If all of the potatoes are to be marketed when dug, the amount to grow will depend almost entirely on the harvesting period, the absorption power of the market at that time, and the labor which will be available when harvest time arrives. If adequate sto-rage facilities are available, the potatoes can be handled much faster, in greater quantities and 226 The Sweet Potato with less danger of loss from growing more than can be marketed immediately than when such facilities are absent. The distance to the railroad, the possibility of securing cooperation from neighbors, available team, condition of the roads, distance from loading point to destination and expense will all be vitally influencing items in properly regulating the quantity production side of the business. Storage. Inasmuch as storage often enables one to receive double the price for sweet potatoes, it constitutes a very important phase of profitable marketing. It is also common knowledge that well-cured sweets are superior in eating quality to those which are not kiln-dried. The buying public recognizes this fact and such stock is given preference by the big markets. Storage-houses often render handling more econom- ical and profitable because of the ease with which potatoes may be placed in storage and then packed and shipped out at some later date when farm labor is not so much needed in routine crop hai*vesting operations. PACKING OPEKATIONS The proper time to grade sweet potatoes is in the field at digging time. If to be kiln-dried, grading may be facilitated by storing in crates which may be taken directly to the field and the various grades placed in separate crates and hauled to storage without further handling. Even when handled in this way, the potatoes should be resorted before shipping out the following winter or spring. This should be done by placing the roots directly into the containers in which they are Preparation for Marl-et 227 fe^^^ i#i ..J^^ayM./ /y/^ shipped, as they are taken from the storage crates. Every care must be used to prevent bruising in all hand- ling operations, as such blemishes give an opportunity for bread mold, or soft-rot to set in. Containers must be chosen for their carrying quality and economy in the sense of properly protecting the potatoes from injury. In packing barrels, no espe- cial care in filling is neces- sary as in the case of apples or other fruit, but the rock- ing should be done about three times during the pro- cess of filling to insure a good pack and full measure (Fig. 41). As the process of fill- ing progresses, the barrel is gently rocked back and forth to settle the roots well down as closely together as possible. This process is started by placing the barrel on a plank about two inches less in width than the diameter of the barrel, instead of using a follower to hold down the potatoes and inserting a head, or as is sometimes done with Irish potatoes and frequently in packing various fniits, the barrel is slightly hooped, or as is known in fruit-packing bilged. The burlap cover is usually secured by having it covered by the top loop. If the barrel has been properly packed and rocked, 1 to II/2 inches bilge will insure a full barrel on arrival at destination. If the bilge is too much, the top layer of potatoes will be so badly bruised in transit that they will decay rapidly when opened. Figure 41. — Sweet potato barrels and device for press- ing the heads into place. 228 The Sweet Potato Growers who are workinc; np fancy trade sometimes use paper lining around the inside of the barrel, with corru- gated paper caps on the ends. These caps are sup- posed to prevent bruising. Lace circles of paper are often placed on top to make the barrel more attractive when exposed for sale. These frills are, however, un- called for and with sweet potatoes more than any other fai-m crop superb quality of the product with neat and substantial packing will in the end prove most profitable. In packing hampers or crates, there is less tempta- tion to bruise the potatoes by dropping into the contain- ers than is true of barrels. Sweet potatoes should be lifted from one container and placed as carefully in another as in handling eggs. It is remarkable the speed that can be acquired with a little practice and at the same time handle the roots in such a manner that they will not be bruised. Hampers or bushel crates should be packed tightly with about •'^-inch bilge. A full bushel hamper or crate holding 2150 cubic inches will hold 50 to 52 pounds of No. 1 sweet potatoes after they have been cured, if tightly packed. Most growers try to put 51 pounds into a package of this kind, calcu- lating that it will contain about 50 pounds net when it reaches the consumer. The appearance of packs can be greatly enhanced if careful facing is done. By facing is meant the special placing of the top layer of potatoes to insure a smooth, even and attractive sur- face. Facing is not a means of defrauding the buyer by placing potatoes of one grade on top and inferior grades on the bottom and selling the whole on the basis of the top quality, but consists in the systematic arrange- ment of the top layer of potatoes so that the appefirance will be pleasing. Proper facing not only assists in Preparation for MarVei 229 selling but prevents undue bruising of potatoes that might otherwise be projecting above the average level of the pack. Crates or hampers which hold a bushel are quite con- venient to handle and make attractive packages. The objection sometimes heard to the crate is that if there is a small or off-grade potato in the package it will be more readily seen than with the hamper. This is no doubt true but should not be a serious objection, as it enables the buyer to see exactly what he is getting and encourages the strictest honesty and careful grading on the part of the shipper. The very defect provides an advantage in giving better ventilation. PKOPER TRANSIT After the requirements of the market have been care- fully determined and after all the attendant troubles of production have been effectually overcome, the pota- toes safely stored until the prices are attractive, and then perfectly packed in the most secure and attractive manner possible, the business will be a failure if the product is not gotten to market in salable form. The difference between profit and loss is often incurred in forty-eight hours from injuries in transit that have been avoided for months on the farm and in the storage- house. Often these injuries represent losses that could have been avoided had proper attention been paid to: (1) selecting the type of car best suited for the ship- ment at season in which it was made and for the specific distance which the car was to cover before reaching destination; (2) correctly packing the car with the special containers used; (3) proper regula- tion of ventilators in transit. The goods must reach the 330 The Sweet Potato cousumer in usable condition if profit is to result. Even when goods are sold f. o. b. the track, the seller owes it to his customer to take every possible precaution to insure him a safe delivery. Sweet potatoes are ex- tremely perishable and intelligence is essential in pro- viding proper accommodations in transit. Further- more, the way in which a car is packed has much to do with the commission merchants' possibility of dis- posing of it profitably at the other end of the line. Choice of car. Four types of freigbt cars may be used for shipping sweet potatoes to market: (1) the common freight car; (2) the air-ventilated cars; (3) the refrigerator cars; and (4) the heated cars. The common freight cars are the ones in which ordi- nary merchandise is usually shipped. This type is not well adapted to the shipment of sweet potatoes even for short hauls. They are employed only when a few crates or barrels are shipped along with other merchandise on short freight hauls that can be made in one or two days. Occasionally the common freight is provided with a false bottom and used for shipping sweets to canning factories in bulk, but even in such cases the air-ventil- ated cars arc preferable. Such cars should never be used for shipping car-lot potatoes over long distances, for they are provided with no means of regulating ven- tilation, and in long hauls, especially with new potatoes, heating is almost sure to occur with disastrous results. Air-ventilated cars represent tlie type best suited for handling sweet potatoes in all regions where special in- sulation is not necessary to prevent freezing. Such cars Preparation for Marl-et 231 can usually be secured as easily as an unventilatod box- car, and they should always be used in preference. These cars are provided with two ventilators at either end wall which can be opened or closed as desired. These vent openings have iron rods or heavy iron cloth to prevent stealing when the doors are open. Though not regularly furnished with a false bottom, such a floor should always be installed when shipping long distances and for short shipments when the potatoes are bulked. A false bottom can be constructed of rough lumber for about 1 cent a bushel capacity of the car, and is very cheap insurance. In installing such false floors, care should be taken to have the runners placed lengthwise the car with floor strips crossways, and to see that the under air passage formed is not obstructed in any man- ner, else the object of the false floor will be defeated (see Fig. 42). The railroads will supply refrigerator cars for per- ishable or semi-perishable shipments to the extent of their ability, preferably for longer runs. These cars should always be used in shipping sweet potatoes to the northern markets, as the special insulation prevents freezing and the top ventilators in each end provide ample circluation of air as long as the car is in motion. A certain percentage of these cars belonging to the various roads is already equipped with false floors, or floor racks. It is contemplated eventually to equip all of the cars in this way. When not so equipped when secured, the shipper will always find it profitable to put in these floors at his own expense rather than ship long distances with the bottom ventilation that would be provided. During the war period, the United 233 The Sweet Potato States Railroad Administration issued an order in which they stated that " The railroads will reimburse shippers for the value of floor racks so placed to the amount of Preparation for Marl-et 233 fifty (50) cents per linear foot of the total inside length of car " ^ but in normal times the shippers would have to hear this expense. No ice is used in refrigerator cars for sweet potatoes. An average of about 630 hampers can be put in a car, 30,000 pounds being considered a safe load. Thorough ventilation is an absolute essential in making successful shipments of sweet potatoes in any type car. Stock cars are occasionally used for short shipments in warm regions. Paching in car. There is an unwarranted tendency toward careless- ness in loading sweet potatoes. Often avoidable breakage occurs in cars care- fully packed. In ad- dition to ample ven- tilation, the car should be so loaded as to avoid shifting ^ ^„ . . ^. , ^, p Figure 43. — A variation of the 01 the load m transit standard load. Loading 100-pound and breakage of the ^^^ks so as to secure a heavy-weight ^ shipment with the greatest amount of containers by contact ventilation. with each other. BaiTels. — Both the double-headed ventilated barrel and the cloth-top barrel should be loaded on end rather than on their bilge, as investigation shows that much less breakage results.^ The main objection to loading on end is that when very tightly packed, owing to jolting 1 Circ. CS-43, U. S. R. R. Adm., W. G. McAdoo, Nov. 15, 1918. 2 Farmers' Bull. Xo. 1030, p. !>. 234 The Sweet Potato in transit, the barrels may appear to be of slack measure when they arrive at the market. This fault can be largely eliminated by proper rocking of the barrel while tilling (page 227). When circumstances justify loading on the bilge, headlines should be used. When loaded on end, five barrels placed across the end of the car will give a snug fit. A 36-foot car will carry 105 barrels in each such layer. When the first layer has been distributed throughout the car, strips of wood should be put on top of these barrels and the second Figure 44. — Barrels loaded on their bilge crosswise of the car. Note that the barrels on the fourth layer should have been against the wall on the right. Figure 45. — Double-headed ventilated barrels loaded on end. Strips should have been placed between the layers in this load. layer placed directly on top of the first row, taking care throughout the car to keep the barrels tight against each Preparation for Market 235 Figure 4fi. — Sacked sweet potatoes being shipped in stock car. Plenty of ventilation, but dangerous on ac- count of changes in temperature. other. With cloth-top barrels, less briiisina; will per- haps result if the top layer is loaded on bilge. When loaded in this man- ner the cloth-tops should be placed to- ward the inside, par- ticularly in the door- way. In old-sized cars it is sometimes necessary to load all barrels on bilge which are in the doorway to insure a tight fit. In all cases the doorways should be stripped up with lumber an inch or more thick, from the inside to prevent bilging of the doors or falling out of doorways (se'e Figs. 43-4-5). Sacks. — As stated, sacks are unsatisfactory as con- tainers but are still sometimes used. Sacks holding more than 100 pounds should never be tolerated, 90- pound bags being most commonly used. Loading sacks in any car without provision for ventilation throughout the load is inviting loss. Figs. 46-48 show correct and incorrect ways of loading sacks. Hampers should never be loaded on their sides. The practice sometimes followed cannot be too severely condemned (Figs. 49-50). Hampers should always be Figure 47. — This car was not loaded properly and did not carry safely. 236 The Sweet Potato loaded on end with alternate baskets inverted. Every pos- sible care should be taken to make the load tight with no slack space either at ends or across the car. Some grow- ers prefer to brace the load by nailing strips across the car every three or four tiers of hampers. Frequently no hampers are placed in the door, but each end of the car is braced separately, leaving the door space vacant for ventilation. Crates may ordinarily be packed tightly in the car Figure 48. — Correct way of loading sacked sweet po- tatoes. Figure 49. Breakage and damage in a car of hampers loaded on their sides. and at the same time be sufficiently ventilated by plac- ing strips an inch thick between layers of crates. The crates should be held in place with car strips and no slack space be left under any circumstances without suitable bracing. Especial care is necessary to have the crates securely tiffht from end to end of the car. Preparation for Marl-et 237 From 600 to 700 crates constitute an average good load. Temperature in transit. — The effect of various methods of ventila- tion in transit and the relative influence of varying tempera- tures on the carrying quality of sweet po- tatoes are at this time under investiga- tion by specialists of the Bureau of Mar- kets. It is known that ventilation is essential, that over- heating is as disastrous, or more so than freezing, and that temperatures between these two extremes may con- siderably influence the susceptibility of the potatoes to disease attacks and decay. Of the technical details of these things, however, little is yet knovm. P^ B|M| '^ ^-\^ f "HS^ShHI X^wq lpffll ^w w^M% Figure 50. — Do your sweet potatoes arrive at market like this? CHAPTER XII COMMERCIAL DISPOSAL OF THE SWEET POTATO The sweet potato is now going throngh the process of standardization and introduction into the world mar- kets. This fact will be appreciated when it is noted that out of the eighteen states growing sweet potatoes, those which produce less than one-tenth of the total crop of the United States make more than one-half the total car-lot shipments. Nevertheless, marketing has made remarkable strides within the last few years. It is only in recent years that the general sweet potato grower has taken any interest in the selling of his surplus beyond the limits of his immediate markets. These markets have usually consisted in the many small towns where the potatoes were occasionally peddled out on the streets or in a few local sales in small quantities to neighbors less abundantly supplied. Conditions have changed very rapidly within recent years and sweet potatoes are now known and called for in many markets which until lately have been in ignor- ance of this southern delicacy. All regular market re- ports now quote sweet potatoes in season, along with other leading fruits and vegetables. The standardiza- tion of market conditions and the fact that new mar- kets are continually being opened up and old markets are capable of development by controlling seasonal dis- 238 ' Commercial Disposal of the Siveet Potato 239 tribiition and carefully catering to the desires of the best trade, make it imperative that the present day grower know something of the available marketing agencies and familiarize himself with the best methods of manipulating his crop through the various chambers of commerce. The present tendency is for the grower to take an active interest in the disposition of his pota- toes and in many instances do the actual selling him- self. This calls for good business judgment in: (1) choosing the best markets and properly developing them ; (2) cultivating sales in various markets; (3) properly weighing the importance of various sales factors which influence market conditions each season; and (4) deal- ing with the different selling instrumentalities which commerce will always make legitimate and necessary. The grower must also know something of the terms and methods which may be employed in transacting sales, if his operations are to be placed on a business At the present time, only two channels of trade are opened to the producer. They consist of the " home market " and foreign markets. The latter term is not used to designate markets outside of the United States, but refers to all markets outside of the state where grown. This usually means shipping to the eastern, northern, or middle-western fruit- and vegetable-con- suming cities, as New York, Philadelphia, Cincinnati, Chicago or Omaha. At present, local canning factories handle a large part of the home market trade. These canneries are now located in practically every state where sweet potatoes are of any considerable importance, and are playing an important part in consuming much of the crop during the harvest months. Many enthus- 240 The Sweet Potato iastically predict the development of an important ex- port trade in sweets as scientific storage-houses become more widely used. MARKETS The markets to be patronized will influence to an im- portant extent all of the pre-marketing operations of the grower. The requirements of different markets should be studied and the advantages and disadvantages of each carefully compared. This will necessarily have to be learned largely by experience. Most growers believe with. good reason that they can dispose of their crop more satisfactorily in territory within their reach by wagon, provided the quantity is not so great as to flood the market. Many things favor the home market. In practically all parts of the South it has been the main dependence as an outlet and even so has not been over-supplied when marketing was distributed over the entire year rather than a few months at digging time. There is nearly always a scarcity of sweet potatoes, even in the principal production areas, during the spring months. Many growers, however, do not yet have proper storage facilities, the capital or the inclination to hold their potatoes for advanced prices, and when the home markets are already abundantly supplied or when the price is low in local centers which are over- supplied, the growers must turn to the larger cities. It must be remembered that over one-half the total pop- ulation of the United States is within a radius of 500 miles of Xew York City. Consequently this area has a consuming power equal to all the remainder of the United States combined. The location of a suitable market is of first im- Commercial Disposal of the Sweet Potato 241 portance. Sometimes growers may contract to produce potatoes for a canning factory at a fixed price, or the latter may guarantee to handle the growers' output at prevailing prices at digging time. The grower who is near a city may often build up a fancy trade among certain families, restaurants, hotels, or fancy stores. Such a trade is often very profitable and satisfactory. When good home markets are not available, the grower may sometimes become acquainted with some individual in other regions who is able to handle his crop. Many times a grower, because of the superiority of his product, the neat appearance of his packages, or his care in grading, will attract the attention of some reliable broker, wholesale grocer or commission-man in some city, and gain his confidence to the extent that each year he will look to this particular producer for his best stock. The grower will often find it well worth while to make an occasional trip to market and become per- sonally acquainted with the men who buy his products. When the shipper does not personally know some buyer on the market, names of reliable dealers may be secured from the marketing department of his state agricultural college. The day of the unscrupulous dealer in town is almost over. Any standard firm or brokerage that advertises regularly in the leading trade journals may be dealt with without fear of fraud. The grower will, of course, have to use his own judgment in the way he sells in any one instance. Home marhets. Home markets offer a better medium through which to sell than foreign ones. When potatoes are shipped to some distant city, a commission has to be paid to 342 The Sweet Potato some one for handling them. Any possible commission is eliminated, however, when the grower sells directly to the consumer on a home market. In addition to this, many growers prefer the home markets because they are given an opjwrtunity to put into their sales their own individuality. They meet and know their buyer personally, become acquainted with their desires, and are better able to meet trade requirements. Such per- sonal contact is also conducive to improvement and de- velopment in selling. The grower thereby learns the value of what would perhaps otherwise seem unimpor- tant details of efficient salesmanship. It enables him to grow with the increasing demands of his business. Frequently when it is not convenient or desirable to sell direct to the consumer, it may be possible to sell to small grocery stores, canning factories, storage plants, or local buyers who assume the risk of shipping. Although the gross price received from such sales is always less than from a private retail trade, it is some- times more than the net returns would be when the ad- ditional time and expense involved in the more direct small sales are figured. Because of better organized and more efficient means of selling, a grocer can some- times pay the grower a better net price than the latter could secure by personally peddling his potatoes. This is not always, or even frequently, the case, however, as dealers who buy usually allow enough margin to insure a good profit on such perishable goods. This is especially true of local buyers who purchase with an idea of shipping. Such men are usually well posted on market conditions and certainly keep on the safe side of purchasing prices. Commercial storage companies and local canning factories furnish one of the most sat- Commercial Disposal of the Sweet Potato 243 isfactory means of marketing locally. Sncli institutions when owned and operated by progressive men can often be the means of remarkably developing the sweet potato industry in a very short time. When sold to such con- cerns, the grower can usually sell in as large quantities as he desires, he assumes no risk, and does not have to wait for his money. However, when all of these advantages have been thought over, there is a dangerous tendency to yield to the most convenient method at the expense of profit. The grower should keep well posted on prevailing mar- ket conditions all over the country and after carefully calculating the relative cost, trouble and risk of selling on various markets, dispose of his goods through that channel which will probably give the greatest net return. A farmer will sometimes continue selling on one market regardless of price because of habit and his more inti- mate knowledge of the specific conditions there. Foreign markets. When sweet potatoes are marketed beyond the terri- torial range possible of personal attention by the grower, some third party must be entrusted with the responsi- bility of their satisfactory disposal. The transporta- tion lines are responsible to a certain extent for safe de- livery at destination. This, however, covers only such incidents as can be charged directly to the negligence of the transportation company, and does not relieve the shipper of errors in selection of car type and proper packing. When foreigTi markets are patronized, the potatoes are usually handled through a commission agency of some kind which takes its pro-rata toll for the service rendered. This commission medium may 244 The Sweet Potato be the regular vegetable broker in the city or a cooper- ative shipping association, owned by the growers them- selves. Snch organizations have overhead expense that must be met by requiring a certain percentage of the gross sales. When owned by growers, any tendency towards economy of sale will be in their favor, which is not true of privately operated selling mediums which must not only meet actual expenses but must make at least a living wage in profit besides. Occasionally it is possible for a producer to cater to a private trade when his reputation for honesty, quality and fair dealing has been sufficiently established, even on the more distant markets. In developing a trade of this kind, agreements have to be made, often months in advance of delivery, with the manager of hotels, res- taurants, resorts, clubs, or private houses, to use a certain quantity of a specified grade delivered at such time as may be agreed on between buyer and seller. Regions in which sweet potatoes of the best quality are not well known offer the best territories in which to work up such private trades. Thousands of individual growers all over the South have established such private trades in distant cities- by sending an acquaintance in the territory samples of his most select roots, requesting the receiver to give them to his friends. Sometimes the grower will have printed on a neat wrapper his name and address and a few words concerning his potatoes. Each potato may be wrapped separately in these papers. It is nearly always necessary to send samples of the potatoes to be sold in working up private trades. With the advance of the new scientifically constructed storage-house, the possibility of putting sweet potatoes in storage in the cities is destined to open up one of the Commercial Disposal of the Sweet Potato 245 most important systems of marketing. If a company of progressive growers could be organized that would build a chain of commercial curing-plants in the large markets, with managers to receive the stock, store it and later sell to the jobbers and retail trade when the price was sufficiently high, a most efficient commercial storage and marketing system could be developed. In fact, if such a corporation had sufficient capital and support of the growers over the country, there is no reason why in time it could not almost control the entire sweet potato industry of this country. Without doubt the very near future will witness the growth of just such a corporation, controlled and managed as are the big corporations which now import tropical fruits. Some factors in foreign marketing coincide with those of local marketing, and there are also many differences. It is instructing to compare these two methods of sell- ing. The commissions, freight, and additional expense of packing make it necessary to receive a much larger price than can be obtained at home. ISTet prices on home markets, other things being equal, are more often greater than the net returns from foreign shipments. Competition is also greater on the big markets because the goods must measure up to the highest standards of all other sections of the country. The best of every- thing is shipped. The sweets must not only be' the best of their variety, but the variety itself must be of the kind in popular favor. Most of the larger markets give preference to certain standard varieties, which, al- though perhaps not so good as some other kinds, are most popular because of prestige gained through years of continued appearance. To change such varietal market demands is a problem of judicious advertising 246 The Sweet Potato requiring years of faithful and patient cultivation. The g-rowers of the South are now making united efforts to gain for their more juicy " yam " varieties prestige in the northern and western markets over the dry- fleshed Nansemond kinds, which at the present rank first in commercial demand. In shipping to foreign markets, considerable skill is necessary in making ar- rangements for the loading and handling of cars, and if sold personally by the shipper on the city markets, the necessary trackage and warehouse space must be pro- vided when large shipments are involved. When ex- tensive shipments are being made, the services of a specialist who has made a study of these conditions may be necessary. Growers are often unfair in their ex- pectations of the home markets. They frequently ask the grocer as much for' their potatoes as they would expect directly from the consumer. If there is any sur- plus to be shipped, it usually consists of the best and the net retvirns are often less than received on the home market for goods of inferior quality. Home markets everywhere are, generally speaking, capable of being de- veloped materially above their present status. Advertising. Although having no effect on seasonal distribution, advertising does have, and with sweet potatoes will con- tinue to have an ever-increasing influence on territorial distribution. There is a large field of consumption yet to be opened up in new territories where the best quality of sweet potatoes is now unknown. This will only be accomplished by advertising in one way or another. " Sunkist " oranges have been made famous by advertis- ing, as well as scores of other articles too numerous .to Commercial Disposal of the Siveet Potato 247 mention. Advertising is sure to play a very prominent part in the future development of our sweet potato marketing system. An attractive trade label is one of the most efficient and convenient advertising mediums at hand with the sweet potato grower. These can be printed on paper and pasted on the market container, or they may be stenciled or printed directly on the container itself. Many growers have found small printed circulars, which were placed in each package, to be highly profitable. These usually tell what variety is represented, how, where, and by whom the potatoes were grown, and they may contain some new or desirable cooking re'cipes.. Advertising is sometimes inserted in the standard fruit and vegetable journals or papers. SELI.ING AGEiNCIES Sweet potatoes may be sold on local markets as already discussed ; through the medium of a commission house ; cooperative marketing association ; or by direct personal sale to individuals or firms in distant markets. Commission house. Doubtless the oldest and best known method of selling sweet potatoes in the United States is through the medium of the commission-man. Long before cooperative marketing was given any serious thought by southern farmers, the commission-man was at hand to sell their produce for a specified toll out of thee gross receipts. ]\Iany of the larger commission firms have sent out traveling agents who made it their business tO' locate centers of produc- tion and endeavor to get growers to ship to their 248 The Sweet Potato firm. The policy of these men has been to solicit ship- ments direct to the house on the basis of prevailing markets at time of arrival rather than to quote anj price in advance. Commission-men have been severely criticized at times as unnecessary middle-men. In former years much of this criticism was brought on by unscrupulous dealers who did not give their cus- tomers honest service. Public opinion and sounder business principles have done much to discourage dis- honest practice, however, and the commission-man has greatly simplified the farmers' marketing problem and no good way has yet been found to eliminate him from the selling program. In selling through commission firms, the first step is to learn the names of reliable houses in the nearest markets. It would be well to write the firm several weeks before shipping season aaid find out how many potatoes they can use a day or a week, and their terms. It would be wise to get in touch with several firms in the respective big markets in this way. Daily Market Report sheets, which give the prevailing prices in each leading market for that day, may be obtained free of charge from the nearest office of the Bureau of Markets. These should be watched each day. Though they do not tell what a given carload of potatoes will bring a pound or a bushel, they report prices on the actual sales which took place during the day and thus give a very clear indication of the tendency of prices in the various city markets. One or two days before the grower is ready to load his car, he should wire one of the commission- men with whom he has been corresponding, who lives in the particular city where prevailing prices seem to be best as indicated by his Market Report Sheet at the Commercial Disposal of the Sweet Potato 249 time he is ready to ship. In the telegram the grower will ask whether the commission-man can handle a cer- tain number of cars of a particular variety, packed in .a given container, loaded at a certain point on a" given day. The commission-man will investigate his order for that time, caleuhite the time it will take the potatoes loaded at the given point to reach him and will advise the shipper whether or not he can handle them, at that time. It may happen that he is already expecting the arrival of several cars from other points at that time and cannot handle the potatoes then, bnt would like to have them a few days later. When he advises the grower to this effect (by telegraph), the latter may be afraid to wait until that time for fear prices will fall or for some other reason. In this event he immediately tries another firm in the same manner. The Market Report sheets always indicate the demand and rate of movement in the various cities and if these reports are promptly acted on, there will never be any difficulty in finding some firm in the strongest market who can han- dle the shipment. It may, however, happen that some one house is over-supplied at that time. An example of the information contained in the Market Report sheets is as follows : UNITED STATES DEPARTMENT OF AGRICULTURE Bureau of Markets Daily Market Report Memphis, Tenn. Rooms 601-03 Exchange Bldg. Feb. 15, 1919. Telephone — Main 796 No. 128 SWEET POTATOES Reports by direct leased wire from important markets. This morning's sales unless otherwise reported. Chicago: 32° Snowing. 1 Tenn. arrived. 2 cars on track 350 The Sweet Potato including broken. Demand and movement good, little change in price. Sales to jobbers, Tenn. bushel hampers, Nancy Halls, quality and condition generally good, 2.50- 2.65, mostly 2.65. St. Louis: 28° Snowing. 4 Tenn., 1 Ga., 1 Fla. arrived; 7 ears on track, demand and movement slow, prices sliglitly lower, quality and condition good, few decayed. Sales to jobbers, Tenn. bushel hampers, Nancy Halls, repacked, mostly 2.45-2.55. Georgias, bushel crates red varieties, quality and condition ordinary, slightly decayed, 1.75-2.10. Florida cloth top stave-barrels, yellow varieties, wide range in quality and condition, 5.00-5.75. Cincinnati: 23° Snowing. 2 Ala. 4 Va. arrived. 9 cars on tracks including broken. Supplies heavy, movement drag- ging, little change in price. Sales to jobbers, quality and condition generally good. North Carolinas, barrel crates, Nancy Halls, and Southern Queens, 5.75-6.2*5. Seed: Virginia cloth top stave barrels, Big Stem Jersey 7.00. Delawares, bushel hampers, Big Stem Jersey, 2.75, few 3.00. Alabama bushel crates 2.40-2.65. Some growers prefer to have government inspection when the car arrives at destination, which can be secured for $2.50 a car on request. The report of the govern- ment inspector stands as conchisive evidence in any court of the United States should a suit arise concerning the condition of the potatoes on arrival. The inspector makes four copies of his report ; one is kept on file ; the shipper and receiver are each supplied with one; and one copy is sent to Washington to be kept on file there. From 5 to 10 per cent of the gross sales is usually the commission charged. After being sold, the commission is deducted from the gross sales, the freight and drayago is then subtracted, and a check for the balance is sent the grower. Receipts for freight and all other money paid out by the commission-man on the producer's goods Commercial Disposal of the Sweet Potato 351 should be sent the latter with the check for his net returns. As has been said, the grower should never lose an opportunity to become personally acquainted with the commission-man who handles his goods. Personal ac- quaintance will be mutually profitable. The ]!^ational League of Commission Merchants will give information concerning the reliability of any leading commission- Cooperative shipping. Intensification of state cooperative extension work from the land grant colleges has done much to stimulate cooperation in all lines of farming and especially cooperative shipping of perishable truck crops. Local agricultural agents in each county to notify the farm- ers of the day designated, with a state marketing specialist to place the cars, have greatly facilitated cooperative shipping of sweet potatoes throughout the southern states, where the sweet potato industry as a commercial enterprise is comparatively young, and where many of the farmers know nothing of marketing principles. The only way in which an organized coopera- tive association can be formed successfully among farmers is for a specific and urgent need to exist for cooperative effort in order that some one thing of com- mon interest may be accomplished. The need must be immediate. Frequently when some outside agency has helped a number of growers to get together to ship a car of potatoes cooperatively, the need for an organiza- tion will be recognized. Much has been said and writ- ten about cooperation within the last few years, some 252 The Sweet Potato of which has been practical and some more or less imag- inary. Cooperation through the Eastern Shore of Vir- ginia Produce Exchange has made New Jersey, Dela- ware and Virginia famous for their superior Nanse- mond, or Jersey Sweets. Cooperation, through the efforts of the Georgia Sweet Potato Growers Associa- tion, has made Tennessee Nancy Halls known and de- manded throughout this country. The good work of similar organizations could be cited in other states. The method of forming a cooperative shipping associa- tion will depend entirely on local conditions, ability of the leaders, and the amount of sweet potatoes to be marketed. A good leader with experience and well formed plans who possesses the personality and execu- tive ability to carry them out is an essential constituent of the association that succeeds. Cooperative shipping associations are non-profit-sharing in character, and usu- ally meet their current operating expenses by levying a certain tax on each package or bushel of potatoes sold. SELLING METHODS The individual method of keeping in touch with mar- kets and selling through commission firms, just now discussed, treats in general the methods used by any selling agency. Exchanges or large cooperative ship- ping associations may do sufficient business to justify them in keeping a salaried salesman in the big markets during the shipping season. This is supposed to be de- sirable in some instances, because regular salaried agents of the association call on the trade from time to time and solicit their business for the particular kind of brand of potatoes which the organization has for sale and is trying to establish on the market. The ad- Commei'cial Disposal of the Sweet Potato 253 vantages of such work are obvious. As sweet potato shipping associations become more numerous and better organized, the commission house will be less used. The employment of a special salesman is, however, a heavy expense which the greater number of small associations cannot afford to bear, and different substitutes for such a representative have been tried. Theoretically, if a large number of separate associations had their special salesmen on the markets, they would eventually be com- peting against each other and thus defeat the original principles of cooperation. This condition wouhl be likely to occur more quickly with an association handling only one commodity. Instead of employing salaried salesmen, some associations have merely agreed with some standard selling agency in the market to handle all of their output. Such an agency might, of course, make similar agreements with any number of other associations. It is possible that as the sweet potato industry grows, centralized distributing associations will eventually be established in the big cities which will handle the business of a large number of associa- tions and exchanges all over the country. At present the exchanges either handle their sales direct or sell them to various firms already on the market. Track and f. o. b. sales. — Perhaps the most satis- factory method of selling sweet potatoes is to contract them to a reliable firm for a specified price delivered free on board the cars. This relieves the grower of any further responsibility, does not require him to wait for his money, and when a sufficient shipment is being made to attract the buyer to the loading point, better net returns are frequently received. A track sale means selling the potatoes at the car on the track nearest the 254 The Siveet Potato point of production. An f. o. b. sale may specify that the potatoes are to be delivered free on board at any point that may be agreed on. The terms are, however, very closely related and are often used interchangeably. Open consignment. — When a commission firm is well known, the usual method of selling is merely to bill the car to the firai in question on open account. Buyers frequently claim that they can handle goods to better ad- vantage when shipped in this way. The original re- ceivers in the big markets usually resell to jobbers. Jobbing houses have been referred to as the food banks of the country. They buy from the original receivers or commission merchants and resell to the retail stores of the country, who in turn pass the goods on to the con- sumers. Commission merchants prefer having sweet potatoes shipped to them on open account because it requires less immediate outlay of capital, and at the same time gives them all the privileges of complete ownership in selling to the jobbers or other buyers. If the reliability of the person to whom the grower orig- inally consigns the goods is not known, however, it is best to have some kind of a check on his actions. Bill of lading attached. — The shipment of sweet potatoes bill of lading attached is the method followed by a large number of small associations that have been remarkably successful in the collection of all their accounts. The car of potatoes is billed direct tO' a buyer. A sight draft covering the price of the contents of the car is attached to the bill of lading and goes with it. A copy of this bill is at the same time sent to the bank which handles the buyer's business. The railroad then protects the seller by requiring the buyer to go to his bank and take up the attached bill, which automati- Commercial Disposal of the Sweet Potato 255 callj becomes a sight draft, and after being paid becomes a receipted bill. The buyer then presents his receipted bill to the railroad company, which turns over his car- load of potatoes. No credit is extended, no room is left for fraud, and the seller receives his money immediately. When business is done in this way, the seller must play the game fairly and stand squarely behind his goods and his selling price. If the goods do not measure up to what they were bought for, he should make the deficiency good. Miscellaneous metliods. — Sweet potatoes are fre- quently sold to a considerable extent by direct sale to consumers in different parts of the country. This is a favorite way of selling seed stock. Usually adver- tisements are run in the classified columns of numerous farm journals and the goods are shipped by express or freight direct to the buyer. To avoid handling a large number of small accounts, the seller usually requires the order to be accompanied by the purchase price. A mode of selling sweet potatoes which has recently come into use on the markets, but with which the grower has no connection, is through the fruit auction companies. Carload lots of specified grade, variety and character are sold to highest bidders. These auction companies are usually profit-sharing corporations. Growers never consign cars directly to an auction company, they are always sent to some agent, who may turn them over to the auction company if the shipper so desires. If the car is a cooperative shipment, a manifest of the contents of the car, giving the name of each contributor and the quality, variety and grade which it contained, is made in duplicate, one copy being sent to the agent and the other to the auction company. The manifest should be sent 256 The Sweet Potato to arrive the day before the car, so it may be properly catalogued. Sweet potatoes sold at auction are usually inspected in the car, rather than sold from samples as with many fruits. INDEX Aceto-arsenite of copper, 171 Acid phosphate, 102 Acreage in United States, 13 Advertising, 88, 246 Agnes, sweet potato a la, 50 Air-ventilated cars, 230 Ajes, 5 Albvgo ipomo'CE-pandurancB, 164 Alcohol manufacture, 41 Amates, 5 Ammonia, 100 Analysis of feeding stuffs, 27 of tubers and vines, 20 of vines, 33 Anguilla, 122 Argus tortoise beetle, 142 Arkansas Beauty, 122 Arsenate of lead, 170 Arsenite of lime, 171 Ashes, hardwood, 103, 111 Baked sweet potato custard, 50 sweet potatoes, 47 Banking, 203 Barrel pumps, 174 Barrels for shipping, 215 packing of, 233 Barrett, J. H., and Son, quoted, 45 Batatas, 5 edulis, 5 Beattie, cited, 31 Beattie, J. H., cited, 121 Bedding, 73 Beds for planting, 62 Bejuco de puerco, 6 Big Stem Jersey, 122 Bill of lading sales. 254 Biscuit, sweet potato, 48 Black-leaf -40, 172 Black-legged tortoise beetle, 140 Black-rot, 160 Java, 166 Black-shank, 160 Black Spanish, 123 Blanca, 120 Blue-stem, 156 Boiled sweet potatoes, 51 Bordeaux mixture, 173 Botanical classification, 5 Brazilian, 123 Bread, sweet potato, 48 Brehm, C. E., quoted, 124 Bretschneider, quoted, 1 Browned sweet potatoes, 47 Bunch, 134 Camote, 5 Camotes, 5 Candied sweet potatoes, 48 Canned sweet potatoes, 45 Carbon bisulfid, 173 Cars for shipping, 230 Carver, G. W., cited, 30, 39, 83 Cassida bivittata, 140 nifjripes, 140 Chaetocnema confinis, 137 Charcoal-rot, 167 Chelymorpha argus, 142 Chips, 39 Chittenden, F. H., quoted, 116 Chlorids, 102 Classification, 5 Climatic requirements, 16 Clusius, cited, 2, 5 Coldframes, 65 Collins, quoted, 6 Commercial disposal, 238 fertilizers, 103 plant business, 85 258 Index Commission house, 247 -man. 247 Composition of Irish potato, 22 of sweet potato, 21 Compressed air sprayers, 174 Containers, 212 Convoliithis Batatas, 5 Cook, quoted, 6 Cookies, sweet potato drop, 51 Cookinfi of sweet potatoes, 46 Cooperative shipping, 251 Coptocycia hicolor, 141 sif/nifera, 142 Cotton-seed meal, 100, 101 Crates for shipping, 218 packing of, 236 Creola, 123 Cultivation, 93 Curing-houses, commercial, 202 Custard, baked sweet potato, 50 Cylas formicarius, 145 DeCandolle, cited, 2, 5 Dehydrated sweet potatoes, 34 Delaware, 124 Description, 3 Desiccated sweet potatoes, 34 Devil's food, sweet potato, 50 Diaporthe batatatis, 166 Dioscorea, 6 Diplodia tnhericola, 166 Disease, selection of seed for, 57 treatment of seed-bed for, 79 Diseases, 155 influence of rotation on, 115 Distribution, 10 Domestic animals, food for, 25 cooking, 46 Dooley Yam, 123 Drawing tlie plants, 80 Draws, ])ropagation by, 54, 80 Dried blood, 100 sweet potatoes, 35 Drop cookies, sweet potato, 51 Dry-rot, 160 Dusters, 175 East Texas Yam, 125 Excretions from roots, 114 Facing, 228 Feeding stuffs, analysis of, 27 Fertilizers, 96 Fish scrap, 100 Fitz, Jas., cited, 84 Flea-beetle, 137 Florida Yam, 124 Flour, sweet potato, 38, 51 Flowers, description of, 4 F. o. b. sales, 253 Food for domestic animals, 25 for man, 21 value, 21 Foot-rot, 158 Foreign markets, 243 Fried sweet potatoes, 47 Fullerton Yellow Yam, 124 Fungicides, 170 Fii sarin m batatatis, 156 hyperoxysporum, 156 General Grant, 124 Georgia Buck, 125 Yam, 125 Gold -bugs, 139 Gold dust, 172 Golden tortoise beetle, 141 Gold Skin, 124 Grading, 223 Green-manures, 109 Hampers for shipping, 217 packing of, 235 Hardenin'g-off, 79 Hardwood ashes, 103, HI Harvesting, 177 Hayman, 125 Henry, cited, 27 and Morrison, cited, 114 High, M. M., cited, 151 Home markets, 241 -mixing fertilizers, 105 Hotbed, Ihie-lieated, 69 manure-lieated, 67 pi])e-heatod, 71 House, (juoted, 5 Humboldt, cited, 5 Humus, 108 Index 259 Insecticides, 170 Insects, 137 influence of rotation on, 115 Ipomrra Batatas, 5 fastiffiata. G Irish potato, composition of, 22 Irrigation, 96 Java black-rot, 1G6 Jersey mark, 102 Sweet, 12S Jewel Yam, 12fi Johnson, T. C. quoted, 7fi, 122, 123, 125, 126, 129, 130, 132, 134, 135 IMineral phosphates, 101 Mottled tortoise beetle, 142 Muck, HI Muffins, sweet potato, 49 Murates, 102 Nancy Hall, 128 Nansemond, 128 Nicotine sulfate, 172 Nigger Choker, 12fl Killer, 129 Nitrate of ammonia, 101 Nitrates, 101 Nitrogen, 100 Norton Yam, 129 Kainit, 103 Keeping, 180 Keitt, T. E., cited, 20, 27, 32, 40, 133, 134 Key West Yam, 126 Knapsack pumps, 174 Old Fashioned Yellow Yam, 129 Old Spanish variety, 133 Open beds, 64 consignment, 254 Organic nitrogen, 100 Ozonium omnivorum, 159 Lang^vorthy, C. F., quoted, 24 Laundry soap, 172 Leaf-blight, 163 -eaters, 139 -mold. 111. 164 -spot, 103 Legal wei->ht, 213 Lime, llT Little Stem Jersey, 127 ]\Tameyita, 120 Mameyona, 120 Man, food for. 21 Manufactured products, 33 Manure, 110 Marketing, 207, 238 Market preparation, 207 Report Sheet, 249 requirements, 207 Markets, 240 foreign, 243 liome, 241 Meyers Early, 128 Miller, E. A., quoted. 84 Miller. Fred E., quoted, 71, 90, 106, 116, 118, 127 Packages, 213 Packing, 226 Paris green, 171 Peabody, 129 Peanut croquettes, sweet po- tato. 49 Peat, 111 Phosphates, 101 Phosphorus. 101 Phyllnstirta batatas, 163 Pie product, 38 Pierso)). 130 Plant-bed, 02 Plant business, commercial, 85 Planting, 91 preparation for, 90 Plowdomvs destruens, 158 Poison bran mash, 172 Polo, 130 Porto Rico. 130 Potash, 102 Poultry manure. 111 Power outfits, 175 Preparation for market, 207 for planting, 90 Price, J. C. C, quoted, 69 260 Index Pride of Kansas. 131 Production in Unitod States, 11 of seed potatoes, GO Propajration, 54 iPumpkin Yam, 131 Purple Yam, 130 Quality of product, 222 Quantity to produce, 225 Raisins and marshmallows, sweet potatoes with, 50 Recipes for cooking, 47 Red Bermuda, 131 Brazil, 132 Carolina, 132 Jersey, 132 Nansemond, 132 Nose, 132 Refrifrerator cars, 230 Requirements for market, 207 Rhizopus nigricans, 165 Riced sweet potatoes, 51 Riley, C. v., cited, U3 Ring-rot, leS^.^f*-' . Root excreti'6nst"ll4 Root-r^^rlSO ; Rosts,' as food .ff)r animals, 30 Rosa, J.. T.. quoted, 76, 122 RotfitJori, 112 Rots, control of, 167 Ruktaln, 6 Rust, 162 Sacks for shipping, 214 packing of, 235 Salad, sweet potato, 49 Saw-flies, 143 Schisocervs cbenus, 144 privatus, 144 Sclerotium hataticfola, 167 Scott, J. M., quoted, 29 Scurf, 162 Seed-beds, covering for, 75 Seed, description of, 4 potatoes, production of, 60 selection of, 56 Selecting seed, 56 Selling, 238 agencies, 247 methods, 252 Septoria bataticola, 163 Setting plants, 92 Shanghai, 132 Shanghor Yam, 133 Silage, 28 Simpson, Cornelia, cited, 46 Sirup from sweet potatoes, 42 Sliced and baked sweet pota- toes, 51 Soft-rot, 165 Soil-splotch, 162 stain, 102 types, 16 Southern Queen, 125 SpJiacronema fimhriatum, 160 Split-Leaf Yam, 125 Spray machinery, 174 Stable-manure, 110 Starch manufacture, 39 sweet potato, 53 Stem-rot, 156 Storage, 179 Storage-house, advantage over bank, 185 construction of, 189 operation of, 198 outbuildings for, 201 Storage rots, control of, 167 Sugar, 39 Sulfates, 102 Superphosphates, 102 Sylvinit, 103 Tankage. 100 Temperature of plant-bed, 77 Tennessee Notchleaf, 133 Texas root-rot, 159 Thompson, quoted, 203 Tillage, 90 Tobacco decoction, 172 Tolman, 133 Tortoise beetles, 139 Track sales, 253 Transit, 229 Transportation, 229 Triumph, 133 Index 261 Tubers and vines, analysis of, 20 description of, 4 Turpin, cited, 2 Two-striped sweet potato beetle, 140 Utilization, 20 Value in United States Varieties, 120 Vine-cuttings, S2 Vineless Bunch Yams, 134 Vines, analysis of, 33 for hay, 32 Watering of plant-bed, 78 11 Weeds, influence of rotation 115 Weevil, 145 Weight, legal, 213 White Barbadoes, 134 Belmont, 134 -rust, 164 Spanish, 134 Yam, 134 Wilt, 156 Yam. origin of word, 6 Yellow Barbadoes, 135 Belmont. 135 iSTansemond. 135 Strasburg. 135 Yield to the acre, 9 PRINTKD IN THE TTNITKD STATES OT AMERICA