CALIFORNIA AGRICULTURAL EXTENSION SERVICE CIRCULAR 34 October, 1929 PLUM GROWING IN CALIFORNIA F. W. ALLEN PUBLISHED BY THE COLLEGE OF AGRICULTURE UNIVERSITY OF CALIFORNIA Cooperative Extension work in Agriculture and Home Economics, College of Agriculture, University of California, and United States Department of Agriculture cooperating. Dis- tributed in furtherance of the Acts of Congress of May 8 and June 30, 1914. B. H. Crocheron, Director, California Agricultural Extension Service. UNIVERSITY OF CALIFORNIA PRINTING OFFICE BERKELEY, CALIFORNIA 1929 71 03 PLUM GROWING IN CALIFORNIA F. W. ALLENi Plums are grown in California for three distinct purposes: for shipping as fresh fruit, for canning, and for drying. In a large measure the fruit grown for shipping purposes is produced in different localities from that grown for drying. Moreover, growers shipping their crop as fresh fruit or selling to a cannery are designated as plum growers, while those producing the drying varieties are known as prune growers. Although the different orchard operations and the production of shipping plums and prunes are in some respects similar, the harvesting and handling are different, and the two classes of growers have diverse interests and different problems. As a. previous publication has been issued on prune growing, 2 this circular will consider only plum growing in the strict sense of the term. Even with the subject limited in this manner, it is impossible to discuss all phases of production and handling in any great detail. However, in connection with many of the topics considered, references are given to other available bulletins ; and it is hoped that those who are interested in more complete information regarding any single phase of plum growing will secure these references to supplement the material given in the following pages. GENERAL DISTRIBUTION AND IMPORTANCE With many species and varieties differing greatly in their habits and climatic requirements, plums have an exceedingly wide distribu- tion. For home use, they are recognized as being suitable for most orchards throughout the temperate zone. Commercially, their produc- tion is much more restricted. Varieties of the American species (Primus americana) although hardy, productive, and easily grown, produce fruit of relatively small size and of too soft texture for best shipping quality. They have been produced therefore, almost entirely for home use or local trade. Most of the European (Prunus domestica) and Japanese (Primus salicina) types, on the other hand, being i Associate Pomologist in the Experiment Station. 2 Hendrickson, A. H. Prune growing in California. California Agr. Exp. Sta. Bui. 328:1-38. 1923. California Agricultural Extension Service [Cm. 34 susceptible to diseases and insect pests, or having- an early blooming habit, are adapted commercially only to the milder climates and to places where the more serious plum diseases are not prevalent. On account of these disadvantages, their planting in the United States has never been so extensive as that of apples, peaches, or pears. Extensive commercial production of plums is largely confined to those sections of the Pacific states where the European and Japanese types can be grown most successfully. Rather limited areas produc- ing fruit for local and nearby markets are to be found in Texas and the states south and east of the Great Lakes. The average total ship- TABLE 1 Estimated Becking Acreage and Production op Plums in California, 1920-30- ' Year Acreage Cars 1920 17,300 19,715 22,434 23,800 25,398 29,055 30,668 33,458 34,875 37,600 38,800 2,564 1921 3,113 1922 3,498 1923 5,247 1924 2,882 1925 . . 3,709 1926. .. . 5,221 1927 4,117 1928 (est.).. 4,678 1929 (est.) 1930 (est.) merits from all of these states for the past five years is approximately only one-tenth of the average annual shipment from California. In the three northwest states of Oregon, Washington, and Idaho, plant- ings estimated at 1770 acres, are perhaps 90 per cent of the Italian and French prune, although approximately 80 per cent of the crop is shipped as fresh fruit. Rauchenstein reports these states as having shipped 3068 cars in 1927 as compared with 4085 cars shipped from California. Since 1895, the trend of shipments from California has shown an annual average increase of 6.6 per cent. 4 The acreage of bearing plum trees in California has doubled since 1920, and as 6676 acres of trees are still classed as being of non-bearing age, a somewhat greater bearing acreage is in prospect by 1930. Past and present, as well as future, estimates of bearing acreage are shown in table 1. 3 California Crop Report, 1927. California Dept. Agr. Spec. Pub. 86:34-40. 1928. * Rauchenstein, Emil. Economic aspects of the fresh plum industry. Cali- fornia Agr. Exp. Sta. Bui. 459:7, 12, 14. 1928. 1929] Plum Growing in California As production increases, the value of the crop might be expected to decline. Rauchenstein's figures show this not to be true with plums. In individual years, however, the unit value of the crop is influenced to some extend by the quantity produced. Reducing the production to a tonnage basis, the Crop Reporting Service gives the values shown in table 2. TABLE 2 Production and Value of Plums, 1923-19285 Production Unit Year (tons) value Total 1923 69,000 $30.00 $2,070,000 1924 39,000 45.00 1,755,000 1925 51,000 40.00 2,040,000 1926 71,000 25.00 1,775,000 1927 57,000 45.00 2,565,000 1928 66,000 37.00 2,442,000 PRESENT CONDITION AND PROFITABLENESS OF THE SHIPPING- PLUM INDUSTRY Although production of shipping plums is still somewhat below the record crop of 1926, and although the general trend of prices has for the past few years remained practically on a level, the quantity of fruit now being raised seems sufficient to meet the present demands. The profitableness of plum growing to any individual, while influenced by numerous factors, has depended very largely upon the variety, size, season of ripening, and general quality of the fruit shipped. Leading districts are now eliminating many of the older varieties and are replacing them with more recent introductions that more nearly meet the market demand. With more attention being given to a relatively few sorts and to the shipping of these in larger lots, a distinct improve-, ment is being effected in marketing. Much emphasis is also being placed on the production of larger-sized fruit and on handling and shipping it in the most careful manner. The erection and operation of a larger number of community packing houses is doing much to improve and standardize grades. Their operation also makes possible the shipment of carlot quantities under a brand or trademark which is or soon becomes known to the trade. Recent export shipments of plums offer some possibility for new markets, but as yet it is difficult to predict just how important these may become. 5 California Crop Report, 1927. California Dept. Agr. Spec. Pub. 86:32. 1928. Also Mimeo. Summary, 1928. January 2, 1928. 6 California Agricultural Extension Service [Cra. 34 Yields. — As a working basis for estimating yields, a previous pub- lication 6 gives the figures following, based on an estimate of 80 crates per ton: Crates Tons Average yield per acre 250 3 A safe estimate for business purposes 350 4% A good yield which a competent man may secure 450' 6% Yields not infrequently secured under favorable conditions .... 650 8 Possible but extraordinary yields 850 10% From a recent survey of the different plum districts, a 4 to 5 ton yield was found to be the most common throughout the San Joaquin Valley, although a few growers who give their orchards exceptional care secure 8 and 10 tons. One grower in the Santa Clara Valley reported occasional yields from old trees of 12 tons per acre. Yields secured by Placer County growers average approximately 2 1 / 4 crates per tree or 3V2 to 4 tons per acre. 7 TABLE 3 Eeturns: Early Pool of Beauty and Santa Rosa Plums, 1927 Variety Price Size Variety Price Beauty Beauty Beauty Beauty $1.66 1.41 1.16 .98 4x5 5x5 5x6 6x6 Santa Rosa Santa Rosa Santa Rosa Santa Rosa $2.23 1.98 1.68 1.50 Returns. — Rauchenstein 8 gives detailed returns for the more impor- tant varieties of plums sold on the New York auction market between 1917 and 1927. Some of these data clearly show that prices early in the season are usually higher than later when larger quantities are being shipped and plums come more into competition with peaches and other fruits. Late varieties likewise generally bring more satisfactory prices than those ripening in midseason. The relation between size of fruit and price is indicated in table 3, which shows the gross sale price received by a large association in the San Joaquin Valley. e Hunt, Thomas Forsyth, et al. California Exp. Sta. Cir. 210:3. 1919. " Estimating 150-175 trees per acre. s Rauchenstein, Emil. Economic aspects of the fresh plum industry. Cali- fornia Agr. Exp. Sta. Bui. 459:18-26. 1928. 1929] Plum Growing in California Table 4 gives average returns for different varieties secured by one of the large fruit shipping houses of Placer County during the years 1923-1926 inclusive. The seasons of 1923 and 1926 were years of heavy crops and low prices. In 1924 the crop was reduced by frost and returns were relatively high, while 1925 represented what might be considered a normal year with average prices. TABLE 4 Shipments and Gross Sale; Price of Plums by Varieties, 1923 to 1926, iNCLTTSrVEP Variety President Apex Gros Prune* Hungarian* Beauty Tragedy Mazal Formosa Kelsey Duarte Sugar Prune Wickson Prize Satsuma Assorted Bradshaw Gaviota Crates 36,915 4,956 1,245 6,173 47,936 10,707 60 29,548 52,587 11,920 502 74,363 741 4,093 1,061 31,743 Gross sale $1.96 1 74 1 74 1.72 1.66 1.65 1 64 1.61 1 58 1.56 Variety Climax 76,501 50,023 43,423 1,534 38,293 92,178 742 4,898 7,675 Standard 890 80,406 Shiro 960 1,554 5,799 Miscellaneous Plum 9,999 . Total Average sale price 727,859 Crates Gross sale $1.57 * Generally recognized as the same variety. In connection with these and similar figures which might be given for other producing districts, it should be emphasized that they are averages and that prices received in any single year may vary widely. Likewise, prices received by two growers having the same variety may be much more variable than the average differences shown for the different varieties. The quantity of fruit on the market on any given day, and the quality of the product offered for sale are the primary factors in determining the sales price. In comparison with these returns for packed fruit, some of that raised in the San Joaquin Valley is either sold in the orchard or marketed loose in lugs, the returns varying from 2 cents to as much as 6 cents per pound. The latter price, however, is usually secured only by a few growers who give special attention to size and quality. 9 Planting Recommendations and Four-yen r Averages — Loomis Fruit Grower's Association. 8 California Agricultural Extension Service [ Ctr - 34 Cost of Production and Net Profits. — All production and market- ing" costs must be deducted from figures showing gross sales price before the grower can determine his net profit. As yet few growers have kept detailed cost records of their expenditures for the different orchard operations. From those who have these facts available it is apparent, however that such costs, vary widely, the tonnage or size of the crop being the most important factor. With a yield of slightly over 200 crates, or 2% tons per acre, one grower's expense up to the time of harvesting was 60 cents a crate or $48.00 a ton. In another district and with very favorable conditions for high yields, 6000 to 7000 crates or 8 tons an acre, the cost was as low as 32 cents a crate or $25.00 a ton. Between these two figures, the latter being very low, $40.00 to $45.00 a ton or approximately 50 cents a crate is perhaps the^ most general expense of growers producing average yields. The chief items of expense entering into this cost are shown in the latter part of this publication on the form sheets for keeping cost accounts. Harvesting cost may likewise vary, depending on the number of pickings necessary. Packing, shipping, and marketing costs are, how- ever, usually less variable. The total cost at present for these various operations is slightly in excess of $1.00 per crate. The items and amounts as determined by numerous averages in one of the shipping- sections are : Picking and hauling to shed $0.04 Packing 07 Shook, nails, shims, labels, baskets, paper, making boxes, lidding .20 Overhead, including depreciation, insurance, supervision, etc .03 Hauling to railroad 03 Loading '. 03 Freight $1.60 per hundred to New York (average crate, 26 pounds) 41 Refrigeration 10 Commission, 7 per cent of gross on auction sales 12 $1.03 Exclusive of the price of the land, estimated costs of bringing a young orchard up to bearing age range from $50.00 to $150.00 or even $175.00 per acre. In sections where the trees are planted close and where cultivation, spraying, and other orchard operations are high on account of the topography of the land, the latter figure may apply. 1929 ] Plum Growing in California LOCATION OF THE PLUM ORCHARD Climate. — As many varieties of plums, especially those of the Japanese type, have an early blooming habit, the location selected should be as free as possible from late spring frosts. With shipping- plums, early districts possess a distinct advantage over those where the fruit ripens later. Later sections may in some cases, however, pro- duce a sufficiently heavier yield to offset the usual decline in prices when shipments are moving in greatest quantity. Such sections may also secure good returns from the late varieties. With the European varieties grown for canning purposes, earliness is of secondary impor- tance to that of yields. Since the cannery also prefers green or yellow varieties to those of high color, most of the cannery stock is produced in the coastal valleys. Soils. — Plums make their best growth and produce the highest yields when grown on rather deep, well-drained loam or clay loam soils. However, because of the earliness of the district, good irrigation, and transportation facilities, the largest single center of production is in the Sierra foothills where the soil is relatively shallow. Trees on such soils are of necessity shallow rooted and are of small size. Close planting and frequent irrigation are necessary in order to attain a satisfactory tonnage of high quality fruit. Some growers have found that the application of commercial fertilizers has also resulted in some- what larger yields. Irrigation Facilities. — Irrigation is necessary in most districts and highly desirable in all plum sections of the state. Where dependent entirely upon the winter rainfall, the grower may experience difficulty in producing fruit of good size ; and except in years of a very light crop, it is generally difficult to sell small fruit at a profit. The avail- ability of water when most needed is therefore one of the most important factors in choosing a location for a commercial orchard. The more shallow the soil or the more sand or gravel it contains, the greater the need for frequent application of water. Transportation and Marketing Facilities. — The perishable nature of shipping plums demands that they be marketed without unneces- sary delay. With the relatively large number of shipping organiza- tions and with daily refrigerator car service, all the main production centers are well supplied with transportation and marketing facilities. Much of the fruit produced in the southern part of the state is trans- ported to the Los Angeles market by motor truck. With main high- ways paved, or well graded and oiled, motor trucks have solved the problem of local transportation. 10 California Agricultural Extension Service [Cm. 34 PRODUCTION CENTERS Figure 1 shows the different counties of the state having 500 acres or more of plum trees. Although plums are produced to a limited extent in most counties of the state, Placer County in the Sierra foot- hills, Sacramento, Solano, Yolo, and San Joaquin counties in the central part of the state, and Tulare and Fresno counties in the San Joaquin Valley are the three heaviest producing regions. ACREAGE OF PLUMS IN CALIFORNIA EacK dot = 300 acres Lcadir^ Ccajiv :i?l b\j Acres Placer 6.626 Tulare 6,217 SoIojvo 5.049 S&cr&merYlo 4,050 Fresivo 3,7 50 Sejv Joaquirv 1,950 Yolo 1,823 . Kerrv 1 ,150 Fig. 1. — Outline map of California, showing- plum acreage of the counties containing a minimum of 500 acres. From California Crop Report 1927. 1929 1 Plum Growing in California 11 Placer County. — Placer County leads the state in total production and has a very large concentrated acreage, extending from an eleva- tion of 400 feet at Loomis to 1500 feet in the vicinity of Auburn. The principal fruit soils of the county are 'the Holland sandy loams which characterize the foothill slopes of the Sierra Nevada mountains. These soils are friable, open, easily tilled, but relatively low in organic matter. They vary in depth from one to six or more feet and are underlaid with disintegrating granite. North and east of Auburn the reddish brown Aikin loams predominate. These likewise vary in depth from only a few inches to over six feet. Their desirability for fruit depends upon their depth, and the character of the subsoil. The general topography of the county is rolling to hilly in character. Low "frost pockets" should be avoided. The trees are of relatively small size, closely planted, and receive frequent irrigation. While the tonnage produced per acre may be somewhat less than that produced in the valleys, the fruit ripens early and is of excellent shipping quality. The district is well supplied with marketing associations, through which the growers have made much progress in standardizing their pack and in improving the quality of product produced. Sacramento County. — Plums are produced in Sacramento County in the Delta and Natomas districts on the bottom lands of the Sacra- mento Kiver, on the uplands adjacent to the American River, and on the higher, more rolling land around Orangevale and Fairoaks. The Sacramento River district between Hood and Walnut Grove, char- acterized by a deep alluvial loam soil, abundantly supplied with irri- gation facilities, is the largest producing section in the county. Both rail and water transportation are available. Production on the uplands is not so extensive, the soil being more shallow and requiring more frequent irrigation. Solano County. — Plum growing in Solano County centers about Fairfield adjacent to Suisun Bay and in the Vacaville-Winters district, The general topography in the former district is relatively level, and the soil is of Solano and Altamont loam to clay loam type. The former is inclined to be sticky and somewhat difficult to work. The district is characterized by rather low summer temperatures and fre- quent winds. The Vacaville and Winters districts further north, pro- tected from the bay influences by hills, are two of the earlier producing sections. General climatic conditions are more like those of the Sacra- mento Valley. The topography of the land varies' from level to rolling 12 California Agricultural Extension Service [Ont. 34 or hilly. The soil, although varying from clay loam to clay, is gen- erally of a more friable type than that in the Fairfield district. Irrigation water is available in some parts of the Winters district. Yolo County. — The Winters area lies both in Solano and Yolo counties and also extends further west to Esparto and into the Cap ay Valley. The general climatic and soil conditions are similar to those mentioned above. San Joaquin County. — The main production areas of San Joaquin County are adjacent to Lodi and Acampo, with some mixed plantings around Farmington. The growth of the trees is materially influenced by the type of soil and the amount of water received. Soil types vary from the deep, very light Hanford, fine sandy loams, to the clay loams. Tulare and Fresno Counties. — Plum orchards in these counties are rather widely separated, and in most instances plum trees form only a part of the orchard. Soil types are very diverse, ranging from the friable sandy loams with good depth, to the heavy-textured loams underlaid with hardpan at depths of from one and one-half to five feet. The orchards naturally show a marked variation in size, vigor, and profitableness of trees. Some localities in these counties produce particularly early fruit, and the average yield is somewhat higher than that in other sections. GROUPS OF PLUMS Somewhat more than two thousand varieties of plums, comprising fifteen different species, are or have been grown in the United States. Of this number, however, only relatively few are of commercial impor- tance to the California grower. All shipping varieties from this state belong to the species Primus domestica (or European plums), to Primus salicina (the Japanese plums), or to hybrids of the latter. European Type. — The European type of plums includes such ship- ping varieties as Giant, Diamond, Grand Duke, Tragedy, and Presi- dent; the French, Sugar, Imperial, and other sorts used for drying; and also the varieties in demand for canning. The importance of this type is therefore readily apparent. The trees are usually characterized as large, strong, vigorous growers with large, thick, leaves, glossy dark green above and pale green with considerable pubescence beneath, edges coarsely notched or sawtoothed. The fruit is borne mostly on spurs, ,-ia variable in size, color, and shape, and either clings to or 1^29] Plum Growing in California 13 separates from the flesh. Because of the rather wide variation in color, shape, and flesh characteristics of the fruit, the following sub-groups of European plums are recognized: (a) Reine Claude group, characterized by fruit more or less round in shape with a very slight suture aud of green, yellow, or slight red color. The flesh is tender, sweet, and juicy. Reine Claude, Washing- ton, and Jefferson are canning varieties belonging to this group. (b) Prune group, including French, Sugar, and all varieties of plums grown for drying. Prunes are usually distinguished from other plums as being those which can be successfully dried without removal of the pit. (c) Yellow Egg group, a comparatively small and relatively unim- portant group, desirable for canning, and is perhaps best known by the Yellow Egg variety. (d) Imperatrice group, a rather large group, including practically all the blue plums. Aside from the color of the fruit, the chief char- acteristics are a heavy bloom, medium size, oval shape, firm flesh, and thick skin. The quality is only fair. Among California varieties per- haps the most important are Diamond, Grand Duke, Tragedy, and President. (e) Lombard group, very similar to the above, except that the fruits are of red color instead of blue, probably of smaller size, and on the average of lower quality. Pond, Lombard, and Bradshaw are representative varieties. Japanese Type. — Since the introduction of the Kelsey in 1870, the Japanese plums or their hybrids have continued to grow in popularity and now comprise the larger number of shipping varieties. Although an early blooming habit renders some of them susceptible to frost, the majority of the varieties are hardy and adapted to a wide range of conditions. The fruit is usually easily distinguished from the other types of plums by its large size, its heart shape, often with a pronounced apex, and its bright yellow or red color. Japanese varieties are never of blue color. The flesh is yellow or red, firm, and juicy; the dessert quality ranges from fair to excellent, depending upon the variety. In character of tree growth there is also considerable variation, some varieties being low and spreading in habit, while with others the growth is straight and upright. In general habit of growth, color, and type of bark they somewhat resemble the peach. The leaves are of medium size and sharp pointed, and lack the pubescence found on the 14 California Agricultural Extension Service [Gib. 34 lower surface of the European sorts. The early and very abundant flowers, produce three to a bud, on new wood as well as on spurs, are also distinguishing characteristics. Other Types. — In addition to these two important types, the fol- lowing may be found in home orchards or are worthy of mention because of their value as rootstocks or for hybridizing. The Myrobalan or Cherry Plum, P. cerasifera, is an old species producing a hardy, vigorous tree, now largely used as a rootstock for other varieties. The fruit of the Myrobalan is small, oval or round, yellow or red in color, and with a rather insipid flesh. Its chief value is for the seed it contains. Simon type, P. simoni, is often called the apricot plum on account of its similarity to the apricot in shape and color. This type is again of little importance for commercial purposes but has been of value for crossing with the Japanese type, giving such varieties as Climax and Wickson. Damson plums, P. insititia, are very hardy, productive, and free from diseases, require little care, and are usually reproduced from seed rather than by budding or grafting. While still found in some of the older home orchards, the small, sour or acid fruit has little value except for limited culinary uses. VARIETIES Although the number of plum varieties grown in this state is still large, plantings are now confined to those which offer the greatest com- mercial returns. The following list is, therefore, limited to those now grown and shipped in largest quantity. Beauty. — The Beauty plum is one of the earliest commercial varie- ties of the Japanese type and has an important place in the early producing districts. The fruit is medium in size and heart-shaped with the crimson skin covered with white dots ; the flesh is amber streaked with scarlet. It is very attractive and a good shipper for an early plum. Trees are vigorous and prolific, so that thinning of the fruit is usually necessary. The variety seems self-fertile. The ship- ping season extends from June 1 to June 15. Burbank. — Burba nk is one of the most popular varieties grown either for commercial or home use. The fruit is almost globular, deep yellow, mostly overlaid with red and dotted with yellow spots; the flesh is golden yellow, juicy, very sweet, and of agreeable but not high 1929] Plum Growing in California 15 flavor. It is an excellent shipping variety. The tree is a vigorous, spreading grower and a precocious bearer. Thinning of the fruit is usually necessary in order to attain desirable size. The season is late June and early July, with a relatively long ripening period. The blossoms are self -sterile. California Blue. — This variety, also known as Vacaville or Vaca- ville Blue, is of less importance than the two varieties above, but is often described as "the first really good blue plum." The fruit is medium to large in size, round, blue in color, and a good shipper. In quality it is only fair. The tree, while usually classed as prolific, tends in some localities toward alternate bearing. In habit of growth it is spreading and open with little tendency toward branching. The blossoms are reported as self -fertile. The season is late June. Climax. — Climax, despite the tendency of the fruit to crack badly under certain conditions, is one of the most popular early shipping varieties from the early sections. The fruit ripens relatively early, is of large size, of deep red color, heart-shaped with pronounced apex, and very attractive. The flesh is yellow, juicy, and of good sub-acid flavor. It ripens rapidly, especially at the apex, and must be handled carefully. The tree, a prolific bearer, is vigorous, thrifty, and inclined to spread like the Burbank. The blossoms are fertile. The fruit ripens the last half of June. Diamond. — The fruit is large, oblong with flattened ends, of a dark purple color with heavy bloom, and with a slightly coarse, dry, tart, yellow flesh. The quality is only fair, but the variety ships well and on account of its attractive appearance is a good market variety. The tree is a strong grower and good producer. In most instances, how- ever, it should be cross-pollinated. Harvesting begins the last half of July and continues into early August. Duarte. — Duarte is a large plum somewhat resembling Satsuma. It is the earliest of the red or ' ' blood ' ' plums to ripen ; its rather dark or dull red skin, thickly covered with large cream or brownish dots, makes it an especially attractive variety. The flesh is dark red when ripe, juicy, and of good flavor. Although one of the newer varieties, it is important in the leading shipping sections. The trees are vigorous and upright in their growth, with numerous fruiting branches. The blossoms, which appear rather late, are self-sterile and require cross- pollination. The season is July 10 to July 25. Formosa. — Formosa may be classed among the best of the large early varieties and when carefully handled is very attractive. The 16 California Agricultural Extension Service [Cir- 34 fruit is large and heart-shaped, with a smooth yellow skin turning to a cherry red as it ripens. The flesh is pale yellow, firm, sweet, and juicy, with a rich aromatic flavor. Though possessing good shipping qualities in general, it shows bruise marks readily. The trees are thrifty but apparently not always productive. Cross-pollination is necessary. The fruit ripens in the middle of June. Gaviota. — One of Burbank's crosses between the Japanese and American types of plums. The fruit is very large and attractive, deep red when fully ripe; the flesh is yellow, firm, sweet, and of good quality. It is a good keeping and shipping variety with a relatively long harvesting season. The trees are usually vigorous and prolific if the blossoms, appearing rather late, are cross-pollinated. The season of ripening comes among the last of the Japanese type, in late July and early August. Giant. — Giant is a cross between the Agen or French prune and the Pond. In size it is intermediate between the two. In shape the fruit is slightly necked ; it is light purplish red in color and covered with a bluish bloom. The flesh is light yellow, coarse, and of very mild or insipid flavor; when ripe it readily separates from the pit. Because of its rather dry flesh it ships well but is of only fair quality. The trees are vigorous and productive. The blossoms are self-fertile. It ripens among the later varieties grown for fresh shipments, during the first half of August. Grand Duke. — On account of its attractive size, color, and good shipping qualities, Grand Duke is one of the more important and most widely grown European varieties. The fruit is large, oval with unequal halves, deep purple in color, and covered with a heavy whitish bloom. The flesh is greenish yellow, firm, sweet, not very juicy, and of only fair dessert quality. The trees are characterized as upright spreading, vigorous, and productive. It blooms late, and the blossoms require cross-pollination. The season is one of the latest of the ship- ping varieties, August 1 to August 20. Kelsey. — Kelsey was probably the first Japanese variety to become known in California. Favorably received from the start, it has con- tinued to grow in popularity. The large, heart-shaped fruit is of excellent dessert quality and having a rather long ripening season is one of the important varieties. In most instances Kelsey is usually known as a green plum. When it colors well, however, it becomes yellow splashed with red. The flesh is yellow, juicy, firm, and of excellent quality. The tree is moderately vigorous and upright in habit of growth and usually bears well when planted with other varieties. The season extends from July 20 to August 10. 1929 ] Plum Growing in California 17 Pond. — Pond is often known as Gros or Hungarian prune. The fruit is of medium to large size, oval with a distinct neck, and of reddish-purple color. While attractive to the eye, and a good shipping variety, it has been described as ''disappointing to the palate." The flesh is firm, dry, and possesses little flavor. A very serious defect of the variety is the tendency to form doubles. One side of the fruit is also often imperfect in shape. In the interior valley the trees are reported as lacking in vigor. The blossoms while partially self-fertile, should be cross pollinated for best results. The season, similar to that of Giant and Grand Duke is August 5 to August 20. President. — President is one of the best late varieties, ripening after almost all others. It is medium to large in size, oval in shape, very dark purple in color, good in texture and flavor, and an excellent shipping plum. The fruit is attractive and of good quality, while the trees are thrifty and with cross-pollination usually bear large and regular crops. The season is August 15 to September 10. Santa Rosa. — During the past few years Santa Rosa has been largely planted and, among those ripening relatively early, is one of the leading shipping varieties. The fruit is large, roundish, purplish- crimson in color, with conspicuous dots and a whitish bloom ; the flesh is yellow to dark red near the skin, rich, juicy, and delicious in flavor. It is a very good shipping variety if picked relatively early. The trees are vigorous, upright, compact growers and usually produce large crops. Thinning the fruit is frequently necessary in order to secure large size. It is an early bloomer, the set of fruit being improved by cross pollination. The season is the last of June and the first half of July. Satsuma. — This variety, while of minor commercial importance, is still grown for home use and local markets. The fruit is usually of medium size, round or slightly flattened, dull red in color, and with red flesh similar to Duarte. The flesh is firm, juicy,, and of good dessert quality. The variety, however, is used primarily for culinary purposes rather than for fresh shipments. The blossoms are self- sterile. The season is late July and early August, : Tragedy. — Tragedy is regarded as the best of the early European varieties and is a favorite in early sections. While only medium in size, the fruit is attractive and possesses high quality. It is oval in shape with a rounding apex and sides often unequal, dark purple in color with yellowish green flesh, firm, sweet, well flavored, and separat- ing. from the pit. . T ha tree is classed as an upright, strong grower. The blossoms are self -sterile, and unless well .pollinated tha. trees .may tend tdward shy^ bVaring. The season is June 10 to June 30. 18 California Agricultural Extension Service [Cm. 34 Wickson. — Among California shipping varieties, Wickson is one of the most important. The fruit is large and heart-shaped like Kelsey, but usually ripens to a yellowish-red or solid red color. The flesh is bright yellow, tender, juicy, aromatic, of excellent flavor and of good carrying quality. The trees are productive, vigorous, upright growers. Cross-pollination should be provided. The season is the middle of July. The following are the principal canning varieties : Jefferson. — The fruit is large, round-oval, with greenish yellow skin, often with a slight red blush; the flesh is orange-yellow, rich, juicy, firm, and sweet. Canners wish approximately 25 per cent of this variety in their total pack. The season is August 1 to August 15. Beine Claude. — Reine Claude, also listed by many nurserymen as Bavay's Green Gage or Bavy's Reine Claude, is an old variety still grown for home use and desired in small quantities by canners. The round, oval, yellowish to yellow fruit possesses juicy, firm, mild, sweet flesh of good dessert quality. The trees are of only moderate vigor but usually productive. The fruit ripens in mid-season. Washington. — Washington is of approximately the same importance for canning as is Jefferson. The fruit of the former is large, roundish, yellowish green in color, faintly marbled, and often with a faint blush. The flesh is yellow tinged with green, firm, sweet, and mild. The trees are vigorous and good producers. The season is identical with or slightly ahead of Jefferson. Yellow Egg. — Canners desire more of this variety than of any other. The fruit is very large, oval, and necked, of a golden yellow color, covered with a white bloom. The flesh is yellow, firm, juicy, and rather acid, but becomes sweet when fully ripe. The season is early August. The trees are large, vigorous, and productive. POLLINATION Experiments extending over a period of fifteen years have amply demonstrated the necessity of cross pollination for the great majority of shipping plums. Climax, Giant, and California Blue set good crops when the flowers are pollinated with their own pollen; a few others set fair crops in favorable seasons; while a much greater number will, with their own pollen, set only very light crops or none at all. Present practice, •therefore, is to have several varieties of similar blooming perioid planted in the same orchard. . 1929] Plum Growing tk California 19 Blooming Dates. — Blooming" dates frequently vary two to three weeks, depending both upon the locality and on the individual season. However, a comparison of different varieties in this respect shows that there is a rather well established sequence of blooming- one year with another and also between different districts. This sequence permits grouping the varieties as early, medium, or late blooming. Table 5 TABLE 5 Comparative: Blooming Dates of Plum Varieties — Full Bloom Placer County* University Farm 1925 1928 1914-21 Early blooming: 2/19 2/20 2/23 3/6 3/7 3/6 3/7 3/8 3/8 3/7 3/8 3/8 3/5 3/18 3/11 3/18 3/20 3/9 3/7 Early to mid-season blooming: 2/25 2/26 2/27 2/27 2/27 2/28 2/28 3/13 3/12 3/16 3/21 3/16 Abundance Mid-season to late blooming: 2/28 . 3/2 3/4 3/7 3/8 3/9 3/18 3/18 3/20 3/21 3/13 3/15 3/17 3/19 3/27 3/17 3/21 Late blooming: Pond(Gros) 3/20 Washington * Observations made by Alexander Butler, Penryn, California. t Tragedy has a relatively long blooming period and is therefore classified in the two mid-season groups. shows a few r comparisons of some of the commercial varieties. Others can easily be added to whichever group they seem to fit best. The grouping is, of course arbitrary, and one variety placed in one group may in some instances readily be placed in another, or it may overlap sufficiently in its blooming period to cross-pollinate with a variety in the adjoining group. This is particularly true with the Tragedy, wdiich has a long blooming period. 20 California Agricultural Extension Service [Cm. 34 Fruitfulness of Varieties. — The fact that two varieties bloom con- currently is not sufficient to insure a satisfactory set of fruit. While the blossoms may be successfully cross-pollinated, two varieties such as Formosa and Gaviota may be intersterile. Tragedy successfully pol- linates the Japanese varieties but is not pollinated by them. Clyman and Grand Duke seem the best pollinizers for the Tragedy (fig. 2). Fig. 2. — Typical branch of Tragedy, showing fruit when cross-pollinated with Grand Duke. Varieties thus vary in their ability to set fruit when either self- or cross-pollinated. Tables 6 and 7 have been compiled largely from the extensive experiments and observations of Hendrickson. 10 ' u » 12 While in some instances results different from those indicated may be secured, this information will generally apply. io Hendrickson, A. H. Plum pollination. California Agr. Exp. Sta. Bui. 310: 1-28. 1919. Further experiments in plum pollination. California Agr. Exp. Sta. Bui. 352:247-266. 1922. 12 . Third report on plum pollination. California Agr. Exp. Sta. Mimeo. leaflet. 1927. 1929] Plum Growing in California 21 o o 3 3 "<; * H fr ► Jq <5 2 CL w J> P ^ w 3 O • P 8s 3; p. «< rr o 2. o o 2 a 3. ** p § 3 3 TO > fc O T1 P p ^D 3 hj > O g 3 o '^ 13. S» «* 33 c< » 3 O < ffl 3> 05 | ■< O ? O o o p- T p ss a go ?§- i 3. m sag 5 ST 3 3 : P : j Los Gatos Methley Prize s 72 El Dorado Flickinger Abundance Amador Apex Beautyt Becky Smith Burbank Climax Combination w o a M04040000 t D ,I f h 10 h i!OD^O ,1 iOO ] Normal Set 1 Crossed with 000404000000000004000 j' Self j o Abundance O O j Amador hj 1 hj hjj j q\ t-jj hj hj ; ; hd 1 hd hd 1 >-d O • Apex nij j O; O; ^O^; ! Oj OOj 4| Beauty hd 1 o 1 ° 1 Becky Smith o c ■aj I j *d ; O O ^ © I ; 1 QOIOi j *i J Burbank Hd j ; o o : i o a *i | O Climax o Combination I i 1 ^ M ; o j j O I ^ ; | Duarte *Tj) | *"d '"d : ^hj^j: O *"d • ^d^d'^ *TJ^d: El Dorado i O ; Flickinger O'-d'-dTJ; j '-dOO- j t j hd *d j *i ►d 1 Formosa O ^Q^'Tdi j ^OC: j O ! hdhdj >=j hd j | Gaviota 1 o *d ; *d *d i 1 hd^)'-d ; | ►■dO'D^O'Td^^d: | Kelsey 3 3 : O O | ; j : Los Gatos *< : ^ ! Methley c Prize O >-d ; •=* I j il'slO; OOi *i •^j f " i Santa Rosa O | ^ ^ ! O : Satsuma o | Upright O "nd j o i oo o *i Q j O Q -d t: Q \ * j j Wickson 3 1 h td I ^ ►tf OS N DO H s g 02 22 California Agricultural Extension Service C Cir - 34 SSg; *o\px o 1 1 to j O uojSuiqs^w ! 1 ! II II II II II i ! II M M II M o j Apag-BJj^ | Mo Mo M |o M Mh |o M uBjpng II 1 1 II 1 1 1 1 1 1 1 II 1 II 1 o 1 JBSng O O : o o M o | M to o | 1 o i o o 1 o i to i l-iimig to o i II 1 1 II II ; II II II ° ° 1 pxBpuBjg to 1111111111111111°! .iopuajdg o | M 1 | | | 1 | | | | | | | | o o | KAng M 1 O 1 1 1 1 i Ph I i -jag ap asoyr M M to j | | Ph 1 j to j 1 ssoqua^D^nQ M M || M M | to Ph M ^uapisajj 1 o 1 1 o || | o M | | o o M | pttoj | O I 1 u< to ; ; i Ph i uosjajjaf 1 Ml to | fBusdmj I'o o|||oMtooo|MM loo UBUBgunjj o i i* j 1 to : a ; 9j{na PUBJQ ; fe O ; iO i | to j rfafeOi i to i }UBI£) O ;ofaO i ; to to i qouajjj o o 1 to a 1 to | M to j liOlOOiOj (UBIP3JI) Sjaquajiatj to M | o \ pUOUIBlQ o I o|Mo||||ooM|o| loll ^sanbuoQ 1 to 81 H S3^0Q to I II 1 ll 1 1 1 1 1 1 1 1 o \ UBUI^JQ 1 O 1 1 II to M M | M M 1 o || 8n I9 ' B ! UJO JH' B la | loo ; looo uo^ang; J Ph ! t'jmy | Ph 1 1 II II 1 1 1 II Ml 1 o o jpg J dHfcOCfePHfe^feOpHfeO^feOP.^f^OOfeOOOOO o c < c i a a J c 1 > ad 5 c 1 o c O C 1 c 3 Fellenberg (Italian) French Giant Hungarian G O -/ 1 Pond Quackenboss Robe de Sergeant Silver Splendor Standard Stuart Sugar Tragedy Washington Yellow Egg 1929 J Plum Growing in CalifoRx\ia 23 Arrangement for Pollination. — In instances where one has a good pollinizer which otherwise is not a particularly profitable variety, one such tree to every nine, placed as the third tree of each third row. will be entirely sufficient. One or more limbs grafted in each tree may also serve equally well. Both of these methods, however, present diffi- culties in harvesting, and with the relatively large number of good pollinizers which are also desirable commercial varieties, the trees may be planted in rows. Two rows of one variety are more easily handled than only a single row, and it is not uncommon to find four and even six rows of a. variety before alternating with the pollinizer. With favorable weather at blooming time and the presence of bees in or near the orchard, such an arrangement is recommended. Desirability of Bees. — DeOng 13 reports that of all the insects that visit the flowers of deciduous fruit trees, honey bees are the best adapted of any to act as carriers of pollen. Their value in this respect has been shown in several previous publications by Hendrickson and others. While perhaps many orchardists dislike having the extra care of bees, their presence during the blossoming season is deemed highly desirable. In some instances growers may rent bees from a professional bee- keeper for this period, or a group of individual orchardists may join and employ a beekeeper to look after their stands. As bees readily fly a distance of half a mile, one group of stards, if centrally located, may serve one or even more small orchards. For best results, one stand is recommended for each acre of trees. ROOTSTOCKS OF PLUMS As with other deciduous fruits which do not reproduce true to type from seed, plum seedlings are allowed to grow only one, or sometimes two seasons, and are then budded or grafted to the particular variety desired. Originally grown only on plum stocks, plums are now also grown on the peach and to a very limited degree also on the apricot and almond. Myrobalan Plum, — Rather than use the seed of the commercial varieties which would be difficult to secure in any quantity, or the seed of the native sorts which produce a tree inclined to throw up suckers from the roots, the wild Myrobalan or cherry plum furnishes isDeOng, E. R. The honev bee as a pollinizer. California Agr. Exp. Sta. Circular 297:17. 1925. 24 California Agricultural Extension Service [da. 34 the most desirable plum stock. The Myrobalan, while not a vigorous grower, is hardy, long-lived, and deep-rooted. It is notably adapted to the deeper and heavier type of soils, especially where the rainfall is heavy or the orchard is given liberal irrigation. It is, however, also reported as giving very satisfactory results on deep, comparatively dry soils. These characteristics have been responsible for its extensive, and until recently, almost universal use as a stock for plums. The Myrobalan seed is now largely produced by local nurserymen, and an effort is being made to eliminate as many variations as possible between the different types. The brown color of the roots usually distinguishes the Myrobalan seedlings from other stocks used for plums. Peach. — While not so well adapted to heavy or wet soil, the peach has during the past few years been gaining in popularity as the most desirable stock for plums in the earlier shipping sections where the soil is comparatively shallow, light, or of a sandy-gravel nature. The roots of the peach are usually regarded as more shallow and of a greater spread than the plum. They are, therefore, inclined to start growth earlier and to be better adapted to the earlier varieties grow- ing under such conditions. Some growers believe that the peach stock may increase the size and earliness of the fruit. Experimental data are, however, not available on these possible influences. Practically all Japanese plums seem to make a satisfactory union with the peach but this is not true with some European varieties. A recent survey of the nurserymen of the state shows, however, that of the different shipping varieties of plums more than half the total are now propagated on peach stocks. 14 Pits of the Lovell or Salwey varieties are mostly used. Trees on peach stock can usually be told by the light yellow color of the young peach roots and the dark red color of the older roots. Apricot. — Plums are propagated on the apricot to a limited extent, this stock being chosen on account of resistance to nematode and per- haps a greater tolerance of alkali. While some growers have reported success, most varieties do not form a satisfactory union, and the stock cannot be generally recommended. Almond. — The almond root is chiefly suited to warm, dry soils. Commercially, very few plums are propagated on this stock. Some varieties seem to unite with it very successfully, while others do not. !*Data collected by M. J. Heppner, formerly Research Assistant, Division of Pomology. 1929] Plum Growing in California 25 NURSERY PRACTICED To produce nursery stock successfully requires much time and patience besides a certain amount of skill obtained only by experience. Fruit growers, therefore, usually purchase their nursery trees from a nurseryman. In some instances, however, individual growers may wish to produce their own trees. Seed and Method of Handling. — Myrobalan plum seed may be pur- chased from large seed companies or nurserymen, or in some cases from individuals having one or more such trees. Peach pits in quantities are secured from dry yards. The usual method of handling such seeds is to keep them in a cool place until early fall, when they are stratified in shallow boxes of soil. Here they are kept damp through the fall and early winter until it is possible to put the nursery soil in loose, friable condition. Planting in the nursery usually takes place in January or February. The rows are laid out four feet apart and the seed dropped in shallow furrows two to four inches apart. While this is closer than it is actually desirable for the seedlings to stand, difficulty is fre- quently experienced in getting over half the seed to germinate. Fre- quent cultivation, including hand hoeing, watering, suckering, and other care, is necessary to produce young seedlings desirable for budding. Budding. — The young seedlings, if properly grown, should be from Vie to % inch in diameter by the last of July or first of August, when they are ready to bud. A week or ten days before the actual operation of budding, all branches and leaves within six inches of the ground should be removed. This allows room for the buclder to work and gives the wounds sufficient time to heal before the buds are inserted. The buds are generally placed low down on the stock, the shield method of insertion being used. Bud sticks previously cut from trees of the desired variety should be protected from drying out during the budding operation. Success in budding depends primarily upon get- ting and holding the new bud in close and direct contact with the growing layer of the stock. Newly set buds should be examined at weekly or ten-day intervals for the first few weeks after they are placed. Within a month they will either have set and will appear green and plump, or will have dried out and become loose. In the latter instance the stocks may be rebudded. The string or material used for holding the bud to the is For detailed description and illustrated methods of budding, grafting, and handling of tree seeds see Stahl, J. L., Propagation of deciduous fruits. Cali- fornia Agr. Exp. Sta. Cir. 294:1-24. 1925. 26 California Agricultural Extension Service [d*- 34 stock should be cut within a few weeks after budding ; otherwise the stock will become girdled. Buds inserted during July or August remain dormant until the following spring. As soon as the seedlings show signs of growth, the tops are removed. Subsequent care consists in keeping the soil in loose, moist condition and in frequently removing all suckers from the stock. Grafting. — In case it is not possible to bud the seedlings during the summer, or in case good results are not secured from budding, the stocks may be grafted during the following winter or spring. Either the seedlings may be dug and bench-grafted indoors, or the tops may be removed and grafted in the nursery row. The latter is the more common method. TOP WORKING Purposes. — Many varieties of plums planted previously have proved unsatisfactory in one or more respects. The trees themselves may have been poor growers or shy bearers. Perhaps a larger number, however, produced fruit of poor dessert or shipping quality and ripened at a time when they met with the greatest competition. The effort of some districts to eliminate many of these undesirable sorts and to change the trees to a relatively few of the leading commercial varieties has resulted in much interest in top grafting. With the orchard trees already established and usually of bearing- age, new tops can be developed more rapidly and brought into fruiting earlier than if new trees were planted. For this reason top working is also a valuable practice if more desirable sorts are needed for cross-pollination purposes or if one wishes to fruit quickly some new or untried variety. In some instances one may even wish to change some of the other stone fruits to some variety of plum. Affinities. — Without actual trials it is impossible to know whether or not a certain variety of plum can be successfully top grafted to an almond, apricot, peach, or even another variety of plum. For- tunately, however, many trials of this nature have been made, and some very valuable information is already available. Many trials and observations show a wide variation in the results secured when grafting one type or variety of plum upon another. Many of the Japanese varieties can successfully be top worked on the European sorts, although the Japanese plums are not suitable as stocks for the Europeans. The California Blue variety, when used as either a stock or scion, has in nearly every case given poor results after a few years. 1929] Plum Growing in California 27 3 3 ' 3 c q ■D CO CO S3 g. s co.O 50 c * I s s to 3 3 2. 3 ° 31 I 3. 8 = ■6 1' 1 G 3 3* 3 3 3 B B 3 ! 3 a- < 3 3 SB T j > 3 ■6 X X § Scion XCOCfiCeCeCOCGCGGGCeCOCC CO CO CO CO CO CO CO d CO 'X x Apex XXXXXXXXXXXX CO CO X X CO X X d CO' ^ X Beauty coco: XXXXQXXX CO x o x x o d X co Burbank d x x x CO CO' CO CO a X d Burton dddi d d i d d d d d d d dddd^X^^^ California Blue co co co ; co co co co co co co' -co co co- yj in ui 'A y, r\ r\ 'f- x Climax d x x ; d d ; x d x x x - co ddco^ddddd Clyman d x x ; c! d j 2° d CO CO CO d CO dd^xddddd Diamond cocococococococococococo CO CO x^xxxdxxx Duarte cococccocococececocccoco 02 CO ><| d CO ddcoxddddd Giant dcoco; dd; codco> R QC X 28 California Agricultural Extension Service Cm. 34 Fig. 3. — Three-year-old Grand Duke top on peach with Clyman plum as an intermediate stock. The Clyman graft, between points indicated, has made an excellent union with both the peach trunk and the Grand Duke top. The tabulated summary giving the results of many growers' trials and the investigations and observations of Heppner and McCallum is herewith reproduced (table 8) with only slight changes from a former experiment station publication. 16 The peach, largely used in nursery practice as stocks for Japanese plums, makes a good union with all Japanese varieties observed except the Climax. Among the European varieties, Giant, Hungarian, Presi- 16 Heppner, Myer J., and Koy D. McCallum. Grafting affinities with special reference to plums. California Agr. Exp. Sta. Bui. 438:1-20. 1927. 1929 Plum Growing in California 29 dent, Tragedy, Quackenboss, and the French prune make good growth when top worked on most peaches. Grand Duke and Burton have also given good results in some cases, although the top generally materially outgrows the stock. This, however, may be overcome by double working, grafting some more congenial variety on to the peach, and then later budding or grafting the desired variety on this inter- mediate stock (fig. 3). The President plum has given poor results on Fig. 4. — Burton graft on Grand Duke, showing a fine union and rapid healing over of the Grand Duke branch. the Lovell peach. Diamond breaks rather badly, California Blue does not seem well adapted to peach stock, and most of the prunes do not make successful unions. On the almond stock, Apex, Duarte, Formosa, Clyman, President, Tragedy, and the French, Hungarian, and Standard prunes make satisfactory growth. California Blue and the Robe de Sergeant prune are not compatible with the almond, while other varieties are still largely question able. 30 California Agricultural Extension Service [Ore. 34 Most attempts to graft plums to apricots have been failures, although some growers are very well pleased with the results from Olyman, Giant, Kelsey, Satsuma, Tragedy, Wickson, Quackenboss ; and Imperial, Standard, French, and Sugar prunes. In practically every case the plum outgrows the apricot. Peaches and almonds fail to grow on plums, and apricots have not proved successful to any extent. I i \ Fig. •>. — Left, four-year-old Gaviota plum, showing one-year-old grafts before pruning. Right, the same tree after pruning. Methods and Care. — Top grafting is done in the winter and early spring before growth starts. The usual method with young trees is to remove the main branches to the desired height and insert in the stub of each two to four short scions, using the cleft, saw kerf or bark method of grafting. Although old trees may be cut back into the main scaffold branches, the stubs of the secondary or smaller branches will heal over more quickly (fig. 4). With a little knowledge of the fundamental principles of graftage and care in performing the operation, a large percentage of the grafts should grow. Ordinarily only one, and not more than two successful 1929 1 Plum Growing in California 31 grafts are left to each limb. Subsequent attention must be given the trees to see that shoots or sprouts from the base of the limb do not choke the growth from the scion, and that the growth of the latter, if very vigorous, is tied to a support in order to avoid being broken off by strong winds. Some training or pinching back may be desirable during the growing season. After the first season 's growth the surplus grafts may be removed and cut back to secure desirable branching (fig. 5). SELECTION AND PURCHASE OF NURSERY STOCK California has a large number of reliable nurserymen, and since this state grows more shipping plums than any other, desirable nursery trees are usually easily obtained. A first-class tree should be well grown, with well matured wood, the bark clean and smooth, and the top well supplied with good buds or branches. It should of course be true to name — both with reference to the top of the tree and also its root system. The two should be well united, as a poor union not only is likely to break a few years later but offers a good place for the entrance of various fungus troubles. Formerly nursery trees were graded only according to their height, but at present the leading nurserymen also consider the diameter of the trunk. One-year-old trees, the age recommended for planting, are usually classified as follows : Grade 1, 6-8 feet high — % inch or over in diameter. Grade 2, 4-6 feet high — %-% inch in diameter. Grade 3, 3-4 feet high — %-% inch in diameter. Grade 4, 2-3 feet high — %-% inch in diameter. The price of trees naturally varies with the size and grade. It is doubtful if the smallest sizes should be purchased when it is possible to secure those which have made a better growth. Upon receipt of the trees they should be removed from the original package and, unless planted immediately, heeled-in at some convenient place, preferably where they will not be exposed to the afternoon sun. PREPARATION FOR PLANTING Preliminary Planning. — The profitableness of an orchard not infre- quently depends upon careful planning before planting. Mistakes difficult or impossible to correct after the trees are planted can often be foreseen by carefully laying out the proposed orchard on paper. The trees should be located and spaced according to scale at the 32 California Agricultural Extension Service 1°™- 34 distances decided upon, different varieties properly arranged for effec- tive cross-pollination, and roadways and possible irrigation ditches shown. Such a map enables one to see how many trees are needed of a given variety, and how they may be spaced to the best advantage. If properly labeled and preserved, it may also serve as a ready refer- ence as to the location of any given tree in the orchard. Of the different systems of planting, the square is the most popular and convenient, except perhaps on very rolling land, where the tri- Fig. 6. — Eight-year-old Santa Rosa plum trees on shallow soil. Trees planted 16 x 16 feet. angular is largely used. This system allows somewhat more room for diagonal cultivation and is popular in Placer County. The quincunx system or double planting is rarely used with plums, as the early bearing of the fruit renders filler trees of no advantage. Planting Distances. — Proper distances of spacing the trees and the necessary provision for cross-pollination can also best be determined from a paper plan of the orchard. Distances for planting vary rather widely, depending upon the soil, the available water supply, and the varieties to be grown. In the shallow soils of the foothill areas, w r here the trees receive a normal supply of irrigation water, plantings are 1929] Plum Growing in California 33 found as close as 16 feet (fig. 6). Although most of these trees are of the Japanese type, naturally smaller than the European varieties, this is very close planting, and ordinarily 18 feet is felt to be more satis- factory. In other sections of deeper soil, where the trees make a larger K Fig. 7. — Twelve-year-old Kelsey plum trees on deep, sandy loam soil, Fresno County. Trees planted 22 x 22 feet. Yields have been as high as 700 pounds to the tree. growth, from 20 to 24 feet is considered necessary for the smaller growing varieties (fig. 7). On the most fertile soils 25 feet is sug- gested as a minimum for the larger European sorts. While a large proportion of the varieties now grown for fresh shipment must be planted relatively close in order to secure maximum returns, yet over- 34 California Agricultural Extension Service [Cir. 34 crowding- not only increases the difficulty of orchard operations but may actually result in slow, weak growth of the trees, a poor set of fruit buds, and fruit of inferior color. 17 Provision for Cross-Pollination. — Suitable varieties should be chosen and interplanted according to the suggestions and information previously given. Fortunately, this provision for cross-pollination is easily met in most plum plantings because a succession of varieties as regards ripening of the fruit is usually desired. Preparation of the Soil. — Proper preparation of the land previous to planting is of great importance in giving the trees a satisfactory start, and their growth the first season often determines their future productivity and profitableness. Deep plowing, followed by a disc or harrow until the soil is in fine, friable condition, furnishes the most favorable conditions for rapid root development. Where the land has formerly been devoted to grain crops, it is especially desirable to plow to a depth several inches greater than previously practiced in order to break up any "plow sole" which is likely to exist. In some instances subsoiling in the tree rows may be desirable. This should always be done in the fall previous to planting. Except on steep slopes, where washing is likely to occur, the land may also be plowed in the fall. Fall-plowed land, left rough, will absorb the maximum amount of moisture during the winter and may be planted earlier in the spring. Most planting in Placer County is preceded by blasting of the holes. Where blasting is felt to be advantageous, it is best done in the fall previous to the spring planting. Aside from proper plowing and putting the soil in the best physical condition, it may be necessary to level it for irrigation purposes, pro- vide drainage for low spots, and give attention to the question of fertility. Irrigation is practiced in the majority of the plum districts, and it is believed that in most instances where the orchards are dependent entirely upon local rainfall for their moisture supply, more satisfac- tory crops would be secured had the land been graded and irrigation facilities provided. Leveling for orchards consists mostly in cutting off the high points and depositing the soil in low places. The grade of the land as a whole is usually changed very little, if at all. Different systems of irrigation can be used to advantage on the tracts having different slopes. 17 Allen, F. W. Planting and thinning distances for deciduous fruit trees California Agr. Exp. Sta. Bui. 414:1-29. 1926. 1929] Plum Growing in California 35 New land is usually well supplied with organic matter, but that which has been long cultivated or for many years devoted to grain crops is likely to be deficient in this respect. It is suggested that such soils receive, the fall previous to planting, an application of barnyard manure, 15 to 20 tons to the acre, or that the land be sown to some green manure crop which can be turned under the following spring. The latter practice is becoming more important because animal manures are becoming more scarce and difficult to obtain. Where the soil is inclined to be heavy and inadequate natural drainage allows free water to remain in the soil for considerable periods, the trees may show unfavorable symptoms. Laying Out the Orchard. — Properly laying out an orchard requires considerable care. A mistake made at this time in locating even one or two trees, those from whieli subsequent measurements are made, may put a great many others out of alignment. Straight rows not only are a source of pride, but are quite desirable from the standpoint of orchard cultivation. The progressive orchardist should therefore thoroughly understand the simpler and more satisfactory methods of staking out the trees before attempting the actual field work. With contour planting, the services of a surveyor are usually advisable in establishing the proper grades and contours. The former vary from one to two feet in each 100 feet, depending upon the type and soil and the amount of cross slope. 18 Laying out for square planting on level land is much more simple, although considerable care is necessary. One of the most simple and practical methods is first to establish a base line with a similar line extending at right angles from one end. The location for these may easily be determined by the formation of a right triangle, the lengths of the sides being 6, 8, and 10 or multiples thereof. Along these two lines, stakes are set at exactly the distance desired for the rows. From the ends of these two lines the third and fourth sides may be obtained by measurement, These are then staked off in the same manner as the first two. In the case of large plantings or on hilly land, additional rows of stakes can be placed along the wire drawn from corresponding stakes on opposite sides of the field. With one or more of these rows of stakes in both directions, the remainder of the field can be staked by alignment. is Huberty, M. B., and J. B. Brown. Irrigation of orchards by contour furrows. California Agr. Ext, Cir. 16:7-14. 1928. 36 California Agricultural Extension Service [d*- 34 PLANTING Before removing the stake, which determines where the tree is to stand, its location should be marked by the use of a planting board, for only in this way can the trees be placed in proper alignment. If the ground has been well prepared previously, digging the holes is not a large task. The removal of a few shovelfuls of dirt, just enough to permit planting the young tree without bending the roots, is sufficient. Setting the tree at the proper depth and compacting the soil well around the roots are important considerations. Nursery trees usually form their roots at a depth most congenial for their development, and the trees, when set in the orchard, should be planted at approximately the same depth as they stood in the nursery. This depth can generally be determined from the appearance of the tree trunk. In order to avoid air pockets, well pulverized soil should be placed next to the tree roots and tramped thoroughly as it is thrown in, or else settled with water. All injured roots had best be removed before setting. In order to facilitate planting, the remaining roots may be shortened back to six or eight inches. Cutting back is considered pre- ferable to bending out of their natural position. Small, fibrous roots, usually dead before the tree is set, may likewise be removed, since these make it more difficult to place the soil in firm contact with the larger roots. It requires some time for the newly transplanted tree to become established, and as it is desirable that new root growth precede that of the branches, trees may profitably be planted as early in the season as mature nursery stock can be had and the soil can be put in good con- dition. When conditions are favorable for planting in late November and in December, trees set at this time should have considerable advan- tage over those not planted until March. As a large part of the feeding roots is cut in digging from the nursery, the top of the tree should be reduced to a corresponding degree. At the time of planting, therefore, the main stem is usually cut back to a height desired for the scaffold branches. Trees already having desirable scaffolds at the time of planting should have these cut back to such lengths as will best develop the young tree. Imme- diately after planting, it is recommended that the trees be protected from sunburn, and incidentally from borers, by a coat of whitewash over the entire trunk. 1929] Plum Growing in California .'*7 CARE OF THE TREES Young trees should grow vigorously. Cultivation and an adequate moisture supply in the soil during the growing season are the most important considerations. Frequent irrigations and subsequent stir- ring of the soil are essential. On some of the deeper soils, perhaps sub-irrigated or located where irrigation water is very abundant, an excess supply of water may produce more rapid growth than is desired. This is the case especially with young trees that have arrived at fruit- ing age. The necessity for encouraging or checking the growth is therefore dependent upon local conditions. Pruning during the first two or three years is for the primary pur- pose of developing a strong, desirably shaped tree — one capable of producing' large crops in subsequent years. In some instances this may necessitate the removal of many excess branches. Later, as the tree comes into production, pruning may be less severe but should not be neglected. The proper balance between vegetative and fruiting wood is of chief importance. Diseases and insects of orchard trees are always potential enemies, and it is highly desirable to discover their presence before they do severe damage. Sunburn, perhaps caused by wrong pruning, borers following sunburn, sour sap, possibly caused by poor drainage or unsuitable soil, gummosis resulting indirectly perhaps from a wound, and other such troubles frequently cause severe injury before being noticed. Attention to miscellaneous practices, such as straightening up blown-over trees, bracing weak limbs or crotches before they break, removing suckers, painting large pruning wounds, or trapping gophers, will in the aggregate amount to much. CULTURE Cultivation. — Cultural practices in orchards include the various methods of cultivating the soil, irrigating the trees, and growing cover crops and intercrops. The time, methods, and frequency of cultivation vary somewhat in different sections with different soils and with the irrigation or non- irrigation of the trees. In most instances, however, the winter cover crop is first turned under with the plow in the spring and the soil sub- 38 California Agricultural Extension Service 1 Cib » 34 sequently pulverized with the disc or spike tooth harrow. The opera- tions of plowing and pulverizing are more or less combined by the use of the double disc. Many soils, particularly those of an adobe structure must be worked at just the right time, as plowing or discing either too wet or too dry results in a hard, lumpy soil which often remains in this condition throughout the season. In non-irrigated orchards it is important that spring plowing be done relatively early, if possible before the last rains, in order that any weed growth or cover crop may have better chance to decay. This will also give opportunity to secure good tilth of the soil before it becomes too dry. Postponement of the spring plowing in order that the cover crop may make a greater growth is likely to result in an excessive loss of soil moisture. Under such conditions a cover crop may prove more detrimental than beneficial. With the soil put in good condition at the beginning of each grow- ing season, the frequency of subsequent cultivations will depend primarily upon weed growth and the frequency of irrigations. In non-irrigated orchards cultivation for the control of weeds, such as morning-glory (Convolvulus arvensis) is of great importance in maintaining moisture in the soil. As long as weeds do not appear, however, little, if any, benefit seems to be derived from frequent or continuous cultivation. 19 This practice is therefore not so universal as formerly. Where orchards are irrigated only two or three times during the growing season, cultivation usually follows each application of water. When the water is applied eight to ten times during the summer, the irrigation furrows or basins frequently stand undisturbed between each two irrigations. After the second or third watering, the surface crust is broken up and the ground releveled. In most orchards of Placer County little or almost no cultivation is practiced between irrigations. Fall plowing, chiseling, or subsoiling is practiced to a limited extent in some sections of the state, in order better to absorb the winter rains. Irrigation. — If bearing trees are to produce from ten to thirty inches of new wood and successfully size a good crop of fruit year after year, they must be well supplied with water. Although in the early districts of Solano and Yolo counties, and in some of the small 19 Veihmeyer, F. J. Some factors affecting the irrigation requirements of deciduous orchards. Hilgardia 2:125-290. 1927. 1929 J Plum Growing in California 39 plantings near the coast, plums are produced without irrigation, apply- ing water would without doubt increase both tonnage and size of the fruit. In the large Sacramento and San Joaquin valley sections, and in the Sierra foothill districts, irrigation is considered essential. Type of soil, topography of the land, the amount of irrigation water available, and its cost will determine the most satisfactory means of application. In the furrow system two, four, or sometimes six large furrows are made between each two rows of trees. In some instances Fig. 8. — Beauty plum trees in Fresno County receiving heavy flooding. such furrows are made with a double moldboard plow combined with a subsoiler which opens up the soil to a depth of two feet or more. This allows for good penetration of the water in shallow soils. In the hilly foothill sections, furrows are most frequently run on the cross slopes. The efficiency of such a system is much greater than when the furrows are run straight down the hill. With shallow soils and on steep grades water tends to move laterally, and one or two furrows may be sufficient for each tree row. In some sections of the Sacramento and San Joaquin valleys where water is plentiful, flood- ing is frequently employed (fig. 8). Flooding is best adopted with large heads of water, on medium to light soil, and on flat grades. Whatever system is used, the chief essential is to secure good penetra- tion and even distribution. 40 California Agricultural Extension Service [Oir. 34 Commercial practice of applying water in furrows in different sections varies from a twenty-four hour period every twelve to four- teen days to a seventy-two hour run only two or three times a season. In one individual orchard in the San Joaquin Valley, where the soil ranged from sandy to a heavy clay loam, length of water runs ranged from three hours to five days. In other orchards, flooding every two or three weeks is practiced. In the Sierra foothills, where flooding is not practical, a small stream of water is allowed to run in the furrows for a period of three to four days. The total quantity of water used during an entire season generally varies from fifteen to thirty acre- inches per acre. 20 Sufficient amounts should be applied to secure thrifty growth and to develop good size in the fruit. Where cover crops are grown it is generally desirable, in the absence of rain after plowing them under, to give the first irrigation soon after this plowing. This will aid in the decay of the cover crop and prevent the surface soil from becoming dried out to the depth at which it was turned. The time and frequency of subsequent irriga- tions are determined by local factors. A supply of available moisture throughout the growing season is the condition desired, and frequent examination of the soil with a soil auger is the most satisfactory method of determining the necessity for and the frequency of supply- ing water. Trees should never be allowed to show signs of the foliage wilting before irrigating. Orchards in alfalfa will require especial attention to see that the trees do not suffer for water. Intercropping. — During the first few years of a young orchard, intercropping may be a profitable practice. When there is a market, or one can readily be established, such cultivated crops as lettuce, potatoes, spinach, beans, squash, melons, peas, or tomatoes are usually preferable. In any system of intercropping, however, such a practice after the first two or three seasons becomes in reality double cropping, in that soil fertility and moisture removed by the intercrop is, in some instances, needed for the best growth of the trees. The fact should not be lost sight of that the trees are the main crop : if they have to com- pete with some other crop for moisture and plant food elements, they cannot make their most rapid or satisfactory development. As a rule, therefore, intercrops are most successful on soils of good fertility and on land where it is possible to irrigate frequently. During the first 20 An " acre-inch' ' is the amount of water required to cover an acre of ground to a depth of an inch. In Placer County the Statute Miner's Inch is still the most common unit of measurement. With one miner's inch to five acres of ground, the amount of water used is from eighteen to twenty acre- inches per 9 ere, depending upon the length of the irrigation season. 1^29] Plum Growing in California 41 year after setting the orchard, crops should not be planted closer to the tree rows than six feet, and this distance should be increased slightly each year until the intercrop is discontinued. Fertilization and Covercrops. — Although many orchards have been grown with little thought given to soil fertility, its importance as related to tree growth and yields is now generally receiving greater attention. Since manures add nitrogen and at the same time improve the physical condition of the soil, they have long been recommended. At the present time, however, their scarcity limits their use to a com- parative few who are situated near large sources of supply. When the cost is not prohibitive, applications of ordinary barnyard manure may be made at the rate of from three to five tons to the acre. Larger quantities may slightly delay the coloring and maturity of early varie- ties. Applications are generally made during the dormant season. In the fertilization of mature trees, it is advisable to scatter the manure well in between the rows rather than immediately adjacent to the tree trunk. With the scarcity of animal manures, the growing and plowing under of some green crop offers the most feasible means of building up the organic matter of the soil. Not only do cover crops add this organic matter, but the legume crops also add nitrogen. Owing to the necessity for an adequate supply of water throughout the summer months, cover crops in California have been confined largely to those grown during the fall and winter months. During recent years, how- ever, numerous orchards in the San Joaquin Valley have, after reach- ing bearing age, been sown to alfalfa as a permanent crop. With adequate irrigation facilities such a practice may prove desirable (%. 9). Among the leading annual legume crops grown in California are the common vetch (Vicia sativa), purple vetch (Vicia atropurpurea) , bitter clover (Melilotus indica), Canada field peas (Pisum arvense), bur clover (Medicago hispida), and horse bean (Vicia faba). For cover crops in orchards, the vetches and clovers are as a rule the most widely grown. Bur clover does well in most parts of the state, and if some of the seed is allowed to mature will usually reseed itself year after year. As a rule, however, it fails to produce as heavy a growth as the vetches or bitter clover. Various other volunteer crops fre- quently come up and make considerable growth, but in most instances they do not produce so much tonnage of green manure as do the crops which are seeded. 42 California Agricultural Extension Service [ Cib - 34 In order that a g v ood growth may be obtained before the end of the growing season, cover crops may be sown in irrigated sections in August. In non-irrigated sections, little if any advantage is gained by seeding the crop before the beginning of the fall rains. Drilling in the seed is to be preferred to broadcasting, as the depth of the plant- ing can be regulated and a more even stand secured. Although they may vary slightly in different sections, the following rates of seeding are recommended: Field peas, per acre, 60-80 pounds; vetch and Fig. 9. — Plum orchard near Bakersfield in which alfalfa has been growing six years. horse beans, 40-50 pounds; Melilotus, 25 pounds, or if scarified, 15 pounds; bur clover and cereals (where planted with legumes), 20 pounds; cereals planted alone, 50-60 pounds. Unless the nodule bac- teria are already present in the soil, inoculation may be necessary for the fixation of nitrogen by legumes. Where irrigation is not available the land should be plowed and worked down in good condition relatively early. This will often per- mit of little spring growth of the cover crop, but delay in this case of even ten days or two weeks may result in a very appreciable loss of moisture from the lighter soils. With a supply of irrigation water, the crop can both be started earlier in the fall and allowed to grow later in the spring. The greater the growth made by the crop and the more nearly it can be allowed to approach maturity, the greater will be the 1929] Plum Growing in California 43 amount of organic matter derived from it. Cover crops should pro- duce from ten to thirty tons of green material per acre. Legume crops may contain from ten to thirteen pounds of nitrogen per ton of mate- rial. Little if any beneficial effects are usually evident from the use of either manures or cover crops until the second season. Chemical fertilizers have in the past not been used extensively, and their value is uncertain. Where trees are not making satisfactory growth, however, growers may be justified in applying such fertilizers on a part of their orchard. With fruit trees generally, the nitrogenous fertilizers, such as nitrate of soda and ammonium sulphate, have given the most marked results. In some instances where the application of these materials has stimulated a marked increase in vegetative growth, the ripening of the fruit appears to have been slightly retarded. In early producing sections this is of course undesirable. When applied, the material is scattered over the surface of the soil, under the branches of the tree, during the dormant season. The usualrate of application is from one to two pounds for trees one to eight years of age, and from two to three pounds for bearing trees. PRUNING Inasmuch as pruning of deciduous fruits has been discussed in detail in two previous publications 21 ' 22 only the more salient points as they apply to plums will be included here. At planting time the top of the young tree should be cut back to a height of twenty to twenty- four inches, for the double purpose of balancing the top with the root system pruned when dug from the nursery, and in order to secure branching. Where the young tree is only a whip when planted, the scaffold branches can of course not be selected until new growth starts. In many instances this selection is not made until the first dormant pruning. Somewhat quicker and better development is secured how- ever if these are chosen in April, when all undesirable growth may be pinched back. If this practice is followed, the shoots previously selected will be the larger, longer branches at the time of the first winter pruning. Three main scaffold branches are usually preferred. These should be placed not only at approximately equal distances from each other 21 Tufts, W. P. Pruning voung deciduous fruit trees. California Agr Exp Sta. Bui. 313:1-44. 1927. Pruning bearing deciduous fruit trees. California Agr. Exp. Sta. Bui. 386:1-48. 1925. 44 California Agricultural Extension Service [ Cir - 34 around the main stem or trunk but to produce the strongest tree, should vary a few inches in height. In instances where all of the branches are in the same plane and the use of three for the main framework seems desirable, it is suggested that the tree be trained according to the delayed open center type by cutting back the center branch less severely than those on either side. In this way a much stronger tree can be secured than if all the branches are headed at the same height. Unless desirable secondary branches have formed during the first season in the orchard, the main scaffolds should be cut the first winter to the height at which such secondary limbs are desired. Formerly this heading has been rather severe, resulting in too many branches close to the ground and in a general dwarfing of the tree. With less severe heading, trees may be brought into good commercial production from one to three years sooner. All growth not needed for the primary or secondary branches of the tree is removed. This first year's prun- ing is most important, in that it determines the general framework and the subsequent form and strength of the tree. Improper pruning at this time can never be corrected. At the second winter pruning, rubbing, crossing, or any surplus branches should be removed. With most varieties that branch rather freely, little if any additional heading is desirable. The Pond variety, however, sends out its new growth from the top of the one-year wood and hence should be headed at the height where additional branching is desired. With some of the more upright growing varieties such as Wickson and Formosa, additional heading may be necessary in order to induce sufficient branching. Where trees are growing under very favorable conditions for rapid growth, it is often desirable to advance a part of this second dormant pruning to the previous April or May. If at this time the new shoots which are to become the secondary branches have made a length growth equal to that which should be left at the second winter pruning, they may be cut at this point. Additional branching is thus secured during the second season. Also, by the removal of surplus growth, the subsequent winter pruning is reduced to a minimum. During the third and fourth seasons the pruning practice differs little from that previously given. It should be remembered that the lighter the pruning the greater will be the development of the tree and the sooner profitable crops will be produced. Up until bearing age, and with some varieties even afterwards, some attention should be given to securing or maintaining satisfactory- 1929] Plum Growing in California 45 shape. Varieties naturally of a very upright habit of growth, such as Santa Rosa and Wickson, should be encouraged to form a more spreading head by cutting to outside laterals. On the other hand, varieties similar to Burbank, with low spreading branches, should have the outer or lower branches shortened or removed. After the first few years, the main function of pruning is to secure and maintain the desired quantity and quality of fruit. To secure this there must be a. so-called "balance" between fruitfulness and vegetative growth. If the crops are smaller than normally expected there may be, on account of heavy pruning, an excess of vegetative growth. In the absence of a sufficient amount of new wood each year, the crop may be exceedingly heavy, but with individual fruits of small size. Much damage may also be done to the tree through breakage. In Japanese plums as a class, young bearing trees should be so handled as to produce from ten to twenty-four inches of new wood growth annually. Older bearing trees should produce at least ten inches. On account of the tendency of most Japanese varieties to overbear, pruning is somewhat heavier than with most European varieties. 23 Judicious pruning of the former will materially reduce the amount of subsequent hand thinning of the fruit. Trees growing on the more shallow, drier soils may require relatively heavy cutting in order to reduce the size of the crop, but increase the size of the fruit, Among the varieties grown in Placer County, which set particularly heavy crops and thus should receive rather heavy pruning, are Beauty, Bur- bank, Climax, California Blue, and in some instances, Wickson and Kelsey. Santa Rosa, Formosa, Duarte, Gaviota, Wickson and Kelsey more often require only moderate cutting. Particular attention should be given to thinning enough wood from the upright growing varieties in order to allow sufficient sunlight to maintain the fruiting spurs in vigorous condition and in order to color the fruit satisfactorily. THINNING24 Even when rather severe pruning is practiced with the definite purpose of reducing the total crop, it is desirable to supplement this by hand thinning. European varieties will usually size better in 23 Varietal growth and fruiting habits are fully discussed and illustrated in: Kinman, C. F. Varietal characteristics of plums in the Pacific States in relation to pruning. U. S. Dept. Agr. Bui. 1477:1-38. 1927. 24 For greater detail see: Tufts, Warren P. Thinning deciduous fruits. California Agr. Exp. Sta. Cir. 258:1-14. 1923. 46 California Agricultural Extension Service [Cm. 34 clusters than the Japanese and are thinned less severely. In years favorable for the production of a heavy crop, many Japanese varieties set such a large number of fruits that they are unable to size properly (%. 10). To secure the large, uniform, well-colored fruit, plums should ordi- narily be from one to three inches apart when mature. Among the different varieties of the Japanese type, Beauty perhaps demands the Fig. 10.— Si r-old Santa Rosa plum tree producing an over most severe thinning of any. Burbank also tends to set very heavy crops. Climax and Santa Rosa tend to thin themselves as the fruit develops, and hand thinning, where practiced, is usually light. The operation of thinning should be delayed until after the so-called " June drop" in April or May. In sections subject to strong winds, thinning may be much lighter than otherwise. Aside from resulting in increased size and more uniformly colored fruit, thinning may be equally important in preventing breakage to the tree, maintaining its general vigor, reducing disease and insect injury, and in decreasing the labor of handling the crop. The value of thinning is, therefore, conceded even though the actual cost to a few growers runs as high as one dollar to the tree. 1929 Plum Growing in California 47 DISEASE AND PEST CONTROL The damage done to plums by disease and insect pests varies in different districts and in different seasons. While many growers are at present able to produce fruit of satisfactory quality without spray- ing, one or two applications of spray material or dust are frequently desirable or even necessary. In Placer County, Kelsey, President, and Wickson plum trees are frequently attacked by the peach twig borer, while the latter variety is also susceptible to shot-hole fungus. In TABLE 9 Suggested Spray Calendar, for the More Common Diseases anb Insect Pests of Plums When to spray Fall. Nov. 15-Dec. 15 During winter As buds are opening and later if necessary As buds are showing white. As buds are showing white to when 1/5 of flowers are open Following full bloom and later if necessary Middle of May In summer when red spiders appear (April to July) In summer when adults ap- pear (May- June) Kind of spray Lime-sulfur 1 to 9, or Bor- deaux 5-5-50 Commercial petroleum oil sprays. 4 to 7 per cent in water Miscible or summer oil plus nicotine sulfate, or re- peated dustings with nicodust Lime-sulfur 1 to 12, or Bor- deaux 5-5-50 plus 3 pounds basic arsenate of lead Bordeaux 8-8-50 Miscible or summer oil plus nicotine sulfate or re- peated dusting with nico- dust Basic arsenate of lead, 3 pounds dry to 100 gallons water* Dust with dry sulfur Nicotine-soap sprayj Remarks For shot-hole fungus (known also as peach blight). Lime-sulfur at this time will also control San Jose scale and help kill red spider eggs (Bryobia). For scale insects of all kinds. If red spider eggs are present, use heavy rather than light oils. For Italian pear scale and caustic soda to kill moss under which scales live. Follow directions of manufacturer for using. For pear thrips. Winter cover crops, if not plowed under too early, help to keep thrips in the ground until after blossoming. For peach twig borer. If this pest is serious and lime-sulfur is used, add 3 pounds basic arsenate of lead to 100 gallons of spray.* This spray will also help control San Jose scale, shot-hole fungus, and brown rot. For brown rot, where serious, plow under all mummies and diseased twigs before bloom- ing. For wheat thrips. Clean cultivation or early plowing under of cover crops may assist in their control. For peach twig borer. Larvae in Wickson, Kel- sey, President, and other late varieties. For adults of red spider (Bryohix and Tetrany- chus). Apply as soon as infestation is not- iced and repeat if nscessary. For mealy plum aphis. Spray before leaves curl. * Lead arsenate is effective but is objectionable in that it may leave undue amounts of arsenic on fruits. This spray should be used only where late infestations of twig borer are serious and after consulting with local authorities. t Summer oils also effective but they remove "bloom" from the fruit. 48 California Agricultural Extension Service [ Cir - 34 other districts a fall application of lime-sulphur is given for shot-hole fungus and as a general clean-up spray against red spider eggs (Bryobia). During the summer one or more applications of dust are also frequently given against thrips and red spider. Considering all districts in which plums are grown, shot-hole fungus or peach blight, peach twig borer, mealy plum aphis, red spider, and thrips are perhaps the more important troubles calling for a spray program. The accompanying spray calendar shows in condensed form sug- gestions for combating the more general diseases and insects affecting plums. As only rarely will all of these more general troubles be present in any single orchard, few growers will find it necessary to follow the spray calendar in its entirety. Other troubles not infrequently found in plum orchards in some parts of the state are cankerworms, red-humped caterpillar, flat-headed apple tree borer, oakroot fungus, crown gall, bacterial gummosis, peach root borer, and cherry fruit sawfly. All of the above pests are dis- cussed in California Agricultural Experiment Station Circular 265, "Plant Disease and Pest Control." Growers who do not find the above control measures effective under their particular conditions may find it profitable to consult with the local county Farm Advisor or Agricultural Commissioner. Methods of control are constantly subject to some change, and those which are now effective in one district may prove more or less unsatisfactory in another. HARVESTING Time of Picking. — Two main factors should be considered in deter- mining at what stage to harvest any plum variety. Within limits, the greener the fruit when harvested, the better will be its carrying quality. On the other hand, the more mature the fruit when harvested, the better will be its dessert quality. Fruit should be delivered to the market and to the retailer in good, firm, attractive condition. The finest flavored fruit cannot be sold at a profit if it is overripe or shows decay when placed on the retail stands. For this reason the wholesale buyers or jobbers desire that the fruit reach them even before it attains its full color. On the other hand, a permanent industry requires fruit of the highest possible dessert quality. Consequently, the questions of plum maturity are : 1929] Plum Growing in California 49 how ripe can the different plum varieties become, prior to harvest, and still be delivered to market in good condition ; and, what is the earliest stage at which these varieties can be harvested, and still ripen with fair to good dessert quality. The answer to the first of these questions will vary largely with the temperatures in transit and the handling conditions to which the fruit is exposed. Within a period of ten days to several weeks before becoming fully ripe, most varieties of plums undergo marked changes in color. These changes, while continuous, are as a matter of practical convenience divided into several more or less distinct stages. In the Japanese varieties the earliest of these changes, often spoken of as "breaking," occurs when the decided green of the skin changes to a light whitish or yellowish green. With most varieties this yellowish green changes to a more decided yellow or straw color, after which the plum grad- ually assumes its characteristic yellow or red. The fruits are thus spoken of commercially as "straw tip," "slight color," "red tip," "three-fourths red," etc, In the blue or purple varieties, the color changes are usually from green, to greenish blue or reddish purple, followed by dark blue or purple. As color changes are especially noticeable, they have been, and are used as the most important single test for maturity. With the increase in color of fruit there is normally, however a softening of the flesh ; and the firmness of the fruit when picked has proven to be most closely associated with the way fruit will hold up under transit con- ditions. After several seasons of investigational work, a combination color and firmness standard has been suggested for a few of the leading varieties. 25 The rapidity of ripening changes is dependent upon the tempera- ture of the fruit after harvesting. Table 10 shows the maturity standards for both non-precooled and precooled fruit. Fruit picked somewhat riper than the condition described in the first section of the above table can be shipped successfully if loaded in the lower half of the car where the temperature is eight to ten degrees lower. Plums moving by truck to ' ' local ' ' markets should be approximately in the condition shown for precooled fruit. The later maturing, firm-fleshed European varieties may be allowed to become more mature than the earlier, more juicy, thin-skinned sorts. Canning varieties of plums are generally harvested according to the directions of the cannery. In most instances canners desire the fruit to be firm, ripe, and with the maximum sugar content. 25 Allen, F. W. The relation of maturity of California plums to shipping and dessert quality. California Agr. Exp. Sta. Bui. 428:1-42. 1927. 50 California Agricultural Extension Service \ ClR - ;u As all the fruit on the tree does not ripen uniformly, two, three, and even four to five pickings may be made of some of the shipping varieties. In commercial practice the general tendency has been to rush the first picking of the early varieties and to allow some of the mid-season varieties to become slightly overripe. The fruit should be picked slightly firmer and with less color as the season advances. Methods of Picking and Handling. — The perishable nature of the fruit necessitates that it be harvested in the most careful manner. Insofar as practical, the stems should remain attached to the fruit TABLE 10 Recommended Picking Conditions for Plums, Based upon Temperatures in Transit in the Upper Half of Refrigerator Cars When shipped standard refrigeration When precooled and shipped Variety Color range Pressure test* range (pounds) Color range Pressure test* range (pounds) Straw tip to trace pink tip 13- 9 13- 9 18-13 18-12 20-14 15-12 15-11 20-15 16-11 16-11 8- 6 8- 6 12- 8 Yi to full light red 12- 9 Burbank Straw tip to full straw with slight 13- 8 x Ato% yellow Full light to medium red Full light to medium blue... Full light red 11- 8 10- 8 14-10 10- 8 10- 7 ! * The figures given in this column refer to the number of pounds pressure required to force a plunger point 7/16-inch in diameter into the flesh of the fruit 5/16-inch in depth. Pressure tester described in California Agricultural Experiment Station Bulletins 428 and 470. and due precautions taken not to break the skin when removing the fruit from the tree or placing it in the picking receptacle. Baskets, if used for this purpose, should have a smooth inner surface, and the fruit should never be dropped into them. The bloom, very con- spicuous on some varieties, should be disturbed as little as possible. Even though the fruit is sorted later by the packers, the picker should endeavor to harvest on any certain day only such fruit as will meet the desired maturity requirements. Plums may be hauled from the orchard to the packing shed either in the picking baskets or buckets, or in lug boxes. In the first instance the fruit receives one less handling — an advantage not to be minimized. Next in importance to handling the fruit carefully is avoiding any unnecessary delay between the time of picking, packing, and loading. 1929] Plum Growing in California 51 After removal from the tree, plums normally soften relatively rapidly until eating ripe. Their shipping quality is therefore governed very largely by the time period between picking and loading. Since the difference of ten degrees in various parts of a refrigerator car results in the fruit at the higher temperatures ripening twice as rapidly as that exposed to the lower temperature, one can more easily realize that delays when the fruit is warm will increase the rate of ripening perhaps from three to six times. Whenever possible, picking for eastern shipment should be done early in the day and the fruit hauled immediately to the packing shed, or picking done in the late afternoon and the fruit allowed to remain in the orchard overnight. When one is harvesting for the cannery, somewhat less care is permissible since the fruit is not packed and is usually worked up within a few days. Lug boxes are usually furnished bv the cannerv. PACKING Ranch vs. Community Packing. — Packing may be done on the ranch by the grower with what help he is able to employ, or the fruit may be hauled to a central packing house. While considerable ranch packing is still in evidence, the community or central packing house has numerous advantages. Such houses are usually equipped for rapid handling of the fruit. Sizing is accomplished by mechanical sizing machines, grading as to blemishes, color, and maturity is done by experienced helpers, and packing by expert packers who follow the trade throughout the season (fig. 11). Above all, each crate is subject to the critical eye of a trained inspector who is responsible- for -the packed product. The fruit of all growers is combined into one, or perhaps two, grades. Individual variation in quality and manner of packing is eliminated, and a standard product is shipped under a single trademark or label. While in some instances growers may take pride in packing their own fruit and in using their personal label, such practice is now discouraged except for those who have sufficient fruit to market throughout the season so that the trade can depend upon a regular supply and will be willing to pay a premium over that for other miscellaneous brands. Sorting. — All plums packed or offered for shipment must conform to the size, maturity, and general quality requirements of the Cali- fornia Fruit, Nut, and Vegetable Act with which all growers and 52 California Agricultural Extension Service [Cir. 34 packers of fruit should be familiar. 26 This act specifies how the fruit shall be graded and packed, and such fruit or packages as do not meet the requirements will not be passed by the State inspectors. The purpose of these legal restrictions, approved by the growers them- selves, is of course only to protect and maintain the standard and quality of California fruit, The restrictions can easily be met by those who give their personal attention to growing or handling the Fig. 11. — Interior view of a large packing house, showing equipment for sizing and other conveniences for packing. crop. In fact One of the largest marketing agencies has for the past several seasons been putting out an extra fancy grade, the standards for which are considerably above the minimum requirements of the standardization Taw. Their returns indicate the value of this extra fancy quality. Containers. — For Eastern shipment plums are packed either in the four-basket crates or in peach boxes. Fruit for the Los Angeles market is sold in open lugs. In order to avoid too many variations in sizes of the above packages, the California Fruit, Nut, and Vegetable Act v .,. 2 .? Oppy -may be obtained from- Bureau, /of i>ui't"*and. Vegetable- Standardize tlbn State ^Department of* Agriculture; Sacramento, California! 1929 Plum Growing in California 53 defines 1 4 standard ' ' sizes of crates, boxes, and lugs. The measurements are shown in table 11. All other sizes used must be marked "irregular container. ' ? TABLE 11 Standard' Containers for Plums Inside dimensions Average weights Container Depth Width Length Gross Net Inches 4-4% 4M-5M Inches 16 ny 2 Inches VIA Pounds 26 30 30 Pounds 22 26 24-26 The crate containing four square, tin-top baskets is the most popular package for plums (fig. 12, center). These baskets must usually contain three layers of fruit, although they may be packed with only two layers provided they contain the same weight of fruit Fig. 12. — Methods and styles of packing plums. Left, unwrapped plums in peach box, size 132. These are a little small for this type of pack. Center, plums in four-basket plum crate. Bight, carton pack of plums in a peach box, designed for a very fancy trade. as the three-layer pack. In the retail trade each basket may be removed and sold as a separate unit. This container, however, has always had its disadvantages. Since the baskets are constructed with sloping sides, and the standardization law requires that the bottom layer of fruit contain a smaller numerical count than the top, 27 it is necessary to "break the pack" or change the arrangement of the 27 For two-layer baskets, present regulations permit the bottom layer to have an equal but not a greater number of plums than the top layer. 54 California Agricultural Extension Service [Ctr, ;u fruits between the first and second layers. Where the top layer extends above the edges of baskets, much damage from rim cuts has also resulted, when lidding (fig. 14). Placing heavy paper collars just inside the top of the baskets is now recommended in order to avoid this damage. These are shown with the four-basket crate (fig. 15). The peach box is frequently used for large-size plums, the fruit being packed in two layers in the same manner as peaches. Whether Fig. 13. — Left, wrapped plums in peach box, size 84. Right, three-basket pack of plums in peach box. the individual specimens are wrapped or not depends largely upon their size 28 (fig. 13). In Placer County a limited quantity of fruit is packed in peach boxes with only the outside layers wrapped. A modification of the above pack and one now being offered to the trade for their approval is the two and three-basket peach box (fig. 12, right and fig. 13, right). The "baskets" are in reality square or oblong open-top paper cartons which fit into the standard peach box. It is an intermediate type of package between the four-basket crate and the regular peach box. The fruit which is of high quality is covered with a sheet of Cellophane, and is designed for a fancy trade. Using three baskets, each carton should contain 36 plums or a total of 108 in the box. 28 Sizes above 100 are usually wrapped. 1920] Plum Growing in California 55 Filling the Package. — Table 12 illustrates the arrangement and the number of fruits in each of the three layers of the 4 basket-erate pack and the arrangement for packing in peach boxes. In each case of the three-layer pack in baskets it is noted that the bottom layer contains fewer fruits and that they are arranged differ- Fig. 14. — Plums injured by the tin top of baskets. Fig. 15. — Four-basket crate with plums protected from rim-cutting by paper collars inside the tin tops. ently from those in the next layer above. This change of arrangement or break in the pack previously mentioned adds to the difficulty of packing. This is, however, largely overcome by the use of cardboard shims between the bottom and middle layer, and also between the middle and top layer if they are different. The shims also have the advantage of preventing the fruit from settling in transit. 56 California Agricultural Extension Service [Cm. 34 When being placed in the baskets, the fruit is packed with the stems down and most varieties "straight up." With oblong varieties such as Tragedy, Giant, and Grand Duke, leaning or tilting the specimens slightly is of some advantage. The packing of plums is much less rapid than is the case with the larger fruits which are wrapped, and considerable experience is neces- sary before one can master the numerous details which determine the difference between a smooth, solid, uniform pack of proper height and TABLE 12 Plum Packs and Sizes Showing Arrangement of Fruits Standard four-basket crates Wrapped in peach boxes Bottom layer Middle layer Top layer Width Length Depth Total 3x4 4x4 4x4 4x5 4x5 5x5 4x4 3-4x5 4x5 4-5x5 5x5 5x6 4x4 3-4x5 4x5 4-5x5 5x5 5x6 3x4 3x4 3x3 3x3 3x3 3^ 7x8 7x7 8x8 8x7 7x7 7x6 2 layers 2 layers 2 layers 2 layers 2 layers 2 layers I If < 105 98 96 90 84 78 Two tiers in standard crates 4x4 XXX 3 4x4 3x4 3x4 3-4x5 one which lacks these desirable characteristics. Being able to dis- tinguish small differences in sizes or shape and knowing just the proper place and arrangement for each size and shape are perhaps the main qualifications of a good packer. Marking. — At the time of lidding, each container is marked in accordance with the state requirements, which call for the name and address of the orchard or packer, the variety, net weight, and approxi- mate number of fruits (within four of the true count) in the con- tainer or sub-container. In lieu of the number of fruits a numerical description of the pack, counting two adjacent sides of the top layer in the container or sub-container, is generally used. Thus the plums illustrated in figure 12, center, would be stamped a 4 x 5 size. Peach boxes are marked according to the number of fruits which they contain. Hauling. — In the case of most ranch packing, hauling to the ship- ping point is necessary. With the present system of good roads and the almost universal use of motor trucks, hauling is much more rapid 1929] Plum Growing in California 57 and less detrimental than formerly. Care should be taken, however, in loading to see that each crate is placed squarely on top of the one beneath it and that there is no possibility of shifting. A light canvas over the top of the load is very desirable to protect from the sun and dust. Where the fruit is not shipped but goes a considerable distance to market by truck the hauling is frequently done at night. In the hot interior valleys and on some of the main highways leading into such a market as Los Angeles, the advantages of such a practice are obvious. Fig. 16. — Interior of refrigerator car, showing manner of loading and lt stripping' ' crates. (From Circular 239.) LOADING, SHIPPING, AND PRECOOLING Loading and Shipping. — All fruit for eastern shipment should be delivered to the shipping point" and placed under refrigeration at the earliest possible moment. When packed in houses on the railroad, the crates are transferred directly to the cars either by hand trucks or conveyers. Figure 15 shows the general method of stacking and brac- ing the crates in the car. With the railroads specifying 26,000 pounds as a minimum car load and crates accepted as 26 pounds gross weight, 1000 crates constitute a minimum load. These are placed in tiers five crates wide, ten crates high, one^hal.f the distance between the end of the car and the dbbr'and nine crates high throughout the center of the 58 California Agricultural. Extension Service [° ir - 34 car. Twenty-one tiers, eleven in one end and ten in the other, con- stitute the load. Loading is done by those who have become very proficient in the rapid handling of the packages. While some cars are loaded with only a single variety, mixed varieties comprise the bulk of the shipments. Not infrequently plnms are shipped in mixed cars with peaches, and the later varieties from the San Joaquin Valley, with grapes. Details of making out the car manifest, shipping orders, and other necessary details are usually left to one or more individuals connected with shipping companies. Precooling. — With a thousand crates of plums to a car and the tem- perature of the fruit at 80° Fahr. when loaded, the fruit in the top of the load cools very slowly. Records secured by the use of electrical thermometers on a car test trip to the eastern markets 29 show that while the actual temperature of the fruit in the bottom of the load reaches about 45° F in 24 hours, that in the top of cars does not reach this temperature until the seventh day, and that the average fruit tem- perature at the top of the load for this period is approximately 5d° F. 30 Where it is possible to cool fruit thoroughly prior to loading or shipment, temperatures in transit will be lower. If the fruit is cooled to 40° F prior to loading, it will, from the start of the period in transit, be carried at the lowest temperature at which the ice in the car will hold it. The fruit in the top layer will warm up to from 46° to 48° F and carry at that temperature while in transit. The top layer temperatures in thoroughly precooled cars should not average above 45° to 46° F. As this rapid cooling results in materially checking the ripening of the fruit in transit, it arrives in much better condition than that not precooled. Also if thus handled, fruit somewhat riper and of better dessert quality can be shipped. Where the amount of fruit shipped and the length of the shipping season justify the expense of erecting and maintaining a precooling or cold storage plant, this method of precooling is most satisfactory. Plums, apricots, and peaches placed in special cooling rooms where a cold blast of air is kept circulating over and around the fruit can be cooled to a temperature of 40° F in from 18 to 20 hours. Fruit tem- peratures in the center of the package should be reduced to this point if precooling is to be most efficient. 29 Refrigeration test trip, 1924. Conducted by the California Fruit Exchange, Sacramento, in the interests of the California Growers and Protective League. 30 Tables and graphs showing car temperature and rate of cooling also in: Allen, F. W., J. E. Magness and M. H. Haller. The relation of maturity of California plums to shipping and dessert quality. . California Aer. Exd *Sta Bui. 428:36-39. 1927. 1929] Plum Growing in California 59 As a substitute for this method of cooling 1 there are on the market two devices for the precooling of cars after loading*. These coolers, which are portable, are placed in the center of the car between the doors, the doors are closed, and by means of strong electric fans, the natural circulation of the air in the car is materially increased. With one of these devices, cold air from the melting ice is drawn to the center of the load, and in the case of the other the warm air from the top of the car is blown to the ends and over the ice. ' In both instances cooling is accomplished by the more rapid melting of the ice. That these machines do actually lower the air temperature of the car very materially within a few hours has been thoroughly demonstrated. Where the fans are run continuously it has also been found that the fruit can be cooled from an initial temperature of 75° to 80° F to 55° or perhaps 50° P in six to eight hours — the maximum period a car can usually be cooled if it is to be shipped the same day as loaded. While this reduction in temperature is decidedly beneficial, the effects are not so marked as where the fruit is cooled to 40° P. While at the present time the majority of the plum shipments are shipped under standard refrigeration, several districts have been pre- cooling according to both of the above methods for several years, and the practice promises to become more general. DISTRIBUTION AND MARKETING Market Demands. — With the large amount of fresh fruit now sup- plied to the eastern markets, buyers are becoming more critical as to its size, general quality, and condition. While it is impossible for the average grower to know the preferences of individual markets for plums of a certain color or shape, or perhaps packed in some special container, he should always keep in mind that the difference between large and small fruit, between poor and good quality, and between careless and careful handling and packing will mean the difference between a profit or a loss on his season's work. For several years the larger fruit-shipping associations have been emphasizing these points, and the undesirability of small, improperly packed fruit has been reflected in the prices which the growers have received. While it is desirable that the plum grower raise a sufficient number of varieties so that his picking period may extend over several weeks, the market prefers a relatively few varieties and likes to receive these in large quantities. Many small shipments of 10 to 20 boxes are dis- tinctly undesirable and are discriminated against by most buyers. It 60 California Agricultural Extension Service [Cib.34 is suggested, therefore, that the future plantings be confined to some six or eight varieties, and that most of the present miscellaneous sorts be eliminated. For canning purposes the canners desire only the large, firm, green or yellow plums such as Yellow Egg, Washington Green Gage, Jeffer- son, and Reine Claude. First grade plums should not be smaller than 12 to a pound, and second grade plums not smaller than 20 to a pound. Both grades are to be free from doubles, worms, scab, frost rings, hail, and various other defects specified in the cannery contract. Shipping Agencies. — With the grower's time fully occupied with his various cultural practices, his distance from the eastern markets, and his lack of market information, shipping agencies are a necessity. Moreover, the problems of marketing are now so intricate and varied that only large growers, who themselves do not usually attend to the cultural practices, can hope to market their own fruit on the general markets. Shipping agencies serve to collect fruit from various growers, assemble it in cars, and forward these cars to the markets where they think it will meet the greatest demand. Many of them also look after the packing of the fruit and in numerous instances advance money to the grower for handling his crop. Such agencies are repre- sented on the eastern market either by a representative of their own organization or by a broker. The fruit may be sold at private sales to an individual, or it may go to public auction. In large organizations this matter is usually determined by the sales manager. While plums are a perishable fruit, they can easily be shipped to all parts of the United States and are widely distributed in the Eastern, Central, and Southern states where the large European or Japanese plums are very little grown. General Marketing Problems. — Both shipping associations and individual growers must recognize that they have to meet several important marketing problems. Perhaps the greatest problem of the shippers today is that of marketing at satisfactory prices the large quantity of fruit which is now being offered. To meet this situation marketing agencies have carried on advertising campaigns and have made personal visits to the eastern markets in order to meet the trade and secure and maintain their good will. Efforts are also being made to secure better distribution of fruit. Not only will new markets out- side of the United States be established, but perhaps a way will be found for supplying many small markets which at the present time do not enjoy California fruit. For several years an effort has been made whereby all shipping agencies may cooperate more fully toward the better distribution of fruit. 1^29] Plum Growing in California 61 In order to secure the most satisfactory prices the grower likewise, must recognize his responsibility. It is impossible, however, for the shipper to increase the demand for fruit unless the grower can supply what the market demands. Small fruit of miscellaneous varieties and of inferior quality will bring a price, but not a profit. The grower had therefore better take a loss on such fruit before shipping it, rather than afterwards. Where fruit is sold locally to California markets, the chief problem of the grower is to make the proper contact either with some shipping organization or with some representative in the market, to determine the demands of this particular market, and then strive to meet the demand with a continuous and regular supply of fruit. The amount of fruit which such markets can readily take is limited. The Los Angeles market, however, absorbs a considerable quantity of the plums produced in the middle and lower San Joaquin Valley. BUSINESS ASPECTS It has previously been emphasized that the successful grower must produce high yields of good fruit economically. Perhaps most growers know in a general way about how much they expend annually upon their orchard. The experience, however, of those interested in collect- ing definite cost figure is that such estimates are indefinite. Moreover the individual who cuts his orchard expenditures to the minimum, thereby thinking he is lowering his cost of production, may in reality be reducing his yields or lowering the quality of the fruit and thereby increasing his cost. The progressive, businesslike orchardist is often able to make various economies here and there without reducing his returns. In some instances on the other hand, a greater expenditure of money for some particular practice might prove a real economy. Whether or not to buy fertilizers, spend more or less money for pruning or thinning, or apply an extra spray, are questions which each individual is forced to decide. Intelligent decisions of this nature can- not well be made unless based upon previous results or upon certain economic facts. Growers are therefore urged not only to study the problems of production but to study them from a business or economic viewpoint. Cost records are essential for this purpose. The principal value of such records is not merely to show total expenditures and receipts but rather to show the expenditures for each orchard opera- tion, thus permitting the grower to compare his expenditures with those of his neighbor or with similar records kept by growers in other 62 California Agricultural Extension Service [ Cir. 34 TABLE 13 Labor, Record Man Horse Tractor Total labor cost Labor cost per acre Labor cost Item Hours Value Hours Value Hours Value per crate or ton Total TABLE 14 Cost 1 of Materials Item Fertilizers Covercrop seed Spray material Irrigation Props or wire bracing.... Picking Packing Miscellaneous supplies Total material Cost per acre Cost per crate or ton Total. localities. They furnish a picture of the entire year's work and enable one to secure a really intelligent comparison between his operations and those of others. Individual records, kept according to some uniform system, col- lected, and summarized for comparison, at once show wide variations. Not infrequently one may see at first glance where more money could have been made by spending less, or in other cases, more, upon a cer- tain orchard operation. High and low costs of different growers can be compared and analyzed, and more effective and economical prac- tices determined upon for another year. The Division of Agricultural Extension, through its local farm advisors, is now actively engaged in assisting growers in keeping simple records and in tabulating the results of individuals for the benefit of all interested. 1929 J Plum Growing in California 63 TABLE 15 Yearly Inventory Item Average invest- ment Interest at 6 per cent Depreci- ation one year Total charge Cost per acre Cost per crate or ton Equipment, tractors, sprayers, wagons, Total TABLE 16 Record of Al,l Costs Total costs Cost per acre Cost per crate or ton Total labor Sub-total General expenses (estimate 5 per cent of material and labor costs) Machinery repairs County taxes Irrigation taxes Compensation insurance Other cash costs Sub-total Interest and depreciation on trees Interest and depreciation on improvements Interest and depreciation on equipment Sub-total Interest on investment in land Total, all costs While records may be kept largely according to one's own pre- ference, the following tables will serve to illustrate the final analyses sheets such as have been found satisfactory by the Extension Division. The various orchard costs may be divided into those of (a) expenses for labor, (b) expenses for materials, and (c) overhead, including one's investment, interest, depreciation, taxes, repair, etc. Table 13 gives a suggested form, embracing all labor costs, while table 14 is a form designed to cover expenses for materials. Table 15 illustrates a summary of inventory from which the over- head expenses are obtained, and table 16 is a record of all costs. 64 California Agricultural Extension Service f ClR - 34 The total cost of production, thus obtained is then compared with the returns, and the net cost determined. Packing house records kept by the shipping associations or those kept by the grower should show the total quantity of different varieties and grades of fruit grown. The yields per acre can thus be computed, and the net cost per acre and per unit of production be determined. Keeping of records necessarily requires a certain amount of time. If, however, one once becomes accustomed to doing the work, the task becomes small and the value derived from them very great. Where one's costs are unusually high in comparison with others, study must be given to a change in management. Perhaps one's orchard is either too small or too large for the most economical operation, there may be too many or too few varieties, or lack of irrigation facilities may be the limiting factor. These and many others are real management prob- lems which cost records will help one to see and understand. FUTURE OUTLOOK OF PLUM GROWING California plums meet little competition from plums grown in other states. Sales managers of marketing organizations report thai early varieties do meet considerable competition with Georgia peaches, while the mid-season and later varieties come into competition with California Bartlett pears and with shipping prunes from the Pacific Northwest. Rauchenstein, 31 however, believes that the prices received from plums are affected more by the quantity of this fruit which is offered for sale rather than by the quantity of any other fruit. Considering the fact that the bearing acreage in California is expected to increase gradually for several years to come and that the present general level of prices for plums is not likely to increase, it would scarcely seem justifiable to recommend any additional plantings except in the early producing districts. On the other hand, except for short periods when the market may be temporarily glutted, it is believed that the better varieties, sizes, and grades of fruit will always find satisfactory sale. Poor quality, immature, small sized, or mis- cellaneous varieties will most likely fail to pay expenses. Little encouragement can be given the grower who is poorly situated with reference to soil and irrigation facilities and whose orchard contains numerous undesirable varieties. 3i Rauchenstein, Emil. Economic aspects of the fresh plum industry. California Agr. Exp. Sta. Bui. 459:4, 23. 1928. 1929] Plum Growing in California 65 Much progress has been made in the past few years toward better grading and packing. Since the trade wishes fewer varieties in large quantities rather than many varieties in mixed assortments, the present attempt to eliminate many of the less profitable sorts should prove beneficial. Early and late varieties give greater promise of satisfac- tory returns than the majority of those ripening in midseason. ACKNOWLEDGMENTS The writer hereby wishes to express his appreciation to numerous growers and farm advisors for their assistance in furnishing certain points of information and in making valuable suggestions regarding the preparation of this circular ; also to the California Fruit Exchange for a number of the illustrations used in connection with harvesting and packing. agricultural extension service circulars No. 1. 9. Series on Califorina Crops and Prices : Peaches. Home Preparation of Jelly and Marma- lade. Feeding Beef Cattle in California. Irrigation by Overhead Sprinkling. Series on California Crops and Prices: Lettuce. Care and Management of the Milk Goat- Suggestions on Grapefruit Culture in Imperial Valley. Diseases and Parasites of Poultry in California. Rabbit Raising. 10. The Home Preparation of Fruit Candy. 11. Cauliflower Production. 13. The Manufacture of Monterey Cheese. 14. Selection and Care of Electrieal Equip- ment Used in Dairy Manufacturing. 15. Pork Production in California. 16. Irrigation of Orchards by Contour Fur- rows. No. 17. 19. 20. 21. 22. 23. 24. 25. 30. 31. 32. 33. 34. 35. Liver Fluke and Stomach Worm of Sheep. Artificial Incubation of Eggs. Pear Blight Control in California. Bovine Tuberculosis. Thinning Sugar Beets. Strawberry Culture in California. Enterprise Efficiency Studies on Cali- fornia Farms. Bush Fruit Culture in California. The Home Vegetable Garden. Control of Pocket Gonhers and Moles in California. Elements of Grape Growing in Cali- fornia. Powderv Mildew of the Grape and Its Control in California. What to Do About Bovine Tuberculosis. Rearing Dairy Heifers free from Tuber- culosis and Abortion Diseases. Plum Growing in California. Alfalfa Production. STATION PUBLICATIONS AVAILABLE FOR FREE DISTRIBUTION BULLETINS No. No. 253. Irrigation and Soil Conditions in the 407. Sierra Nevada Foothills, California. 263. Size Grades for Ripe Olives. 277. Sudan Grass. 408. 279. Irrigation of Rice in California. 409. 283. The Olive Insects of California. 304. A Study of the Effects of Freezes on Citrus in California. 310. Plum Pollination. 410. 313. Pruning Youne Deciduous Fruit Trees. 331. Phylloxera-resistant stocks. 412. 335. Cocoanut Meal as a Feed for Dairy Cows and Other Livestock. 343. Cheese Pests and Their Control. 414. 344. Cold Storage as an Aid to the Market- ing of Plums, a Progress Report. 415. 346. Almond Pollination. 416. 347. The Control of Red Spiders in Decid- uous Orchards. 418. 348. Pruning Young Olive Trees. 349. A Study of Sidedraft and Tractor 419. Hitches. 353. Bovine Infectious Abortion, and Asso- 420. ciated Diseases of Cattle and New- born Calves. 421. 354. Results of Rice Experiments in 1922. 423. 357. A Self-Mixing Dusting Machine for Applying Dry Insecticides and Fun- 425. gicides. 426, 361. Preliminary Yield Tables for Second- 427. Growth Redwood. 362. Dust and the Tractor Engine. 428. 363. The Pruning of Citrus Trees in Cali- fornia. 364. Fungicidal Dusts for the Control of 430. Bunt. 431. 365. Avocado Culture in California. 366. Turkish Tobacco Culture, Curing, and 432. Marketing. 367. Methods of Harvesting and Irrigation 433. in Relation to Moldy Walnuts. 368. Bacterial Decomposition of Olives During Pickling. 434. 369. Comparison of Woods for Butter Boxes. 370. Factors Influencing the Development 435. of Internal Browning of the Yellow Newtown Apple. 371. The Relative Cost of Yarding Small 436. and Large Timber. 373. Pear Pollination. 438. 374. A Survey of Orchard Practices in the Citrus Industry of Southern Cali- 439. fornia. 380. Growth of Eucalyptus in California Plantations. 385. Pollination of the Sweet Cherry. 386. Pruning Bearing Deciduous Fruit 440. Trees. 388. The Principles and Practice of Sun- Drying Fruit 442. 389. Berseem or Egyptian Clover. 444.' 390. Harvesting and Packing Grapes in California. 445. 391. Machines for Coating Seed Wheat with Copper Carbonate Dust. 446. 392. Fruit Juice Concentrates. 447] 393. Crop Sequences at Davis. 394. I. Cereal Hay Production in California. 448. II. Feeding: Trials with Cereal Hays. 395. Bark Diseases of Citrus Trees in Cali- 449. fornia. 396. The Mat Bean, Phaseolus Aconitifolius. 450. 397. Manufacture of Roquefort Type Cheese from Goat's Milk. 398. Orchard Heating in California. 451. 400. The Utilization of Surplus Plums. 405. Citrus Culture in Central California. 406. Stationary Spray Plants in California. 452. Yield, Stand, and Volume Tables for White Fir in the California Pine Region. Alternaria Rot of Lemons. The Digestibility of Certain Fruit By- products as Determined for Rumi- nants. Part I. Dried Orange Pulp and Raisin Pulp. Factors Influencing the Quality of Fresh Asparagus After it is Harvested. A Study of the Relative Value of Cer- tain Root Crops and Salmon Oil as Sources of Vitamin A for Poultry. Planting and Thinning Distances for Deciduous Fruit Trees. The Tractor on California Farms. Culture of the Oriental Persimmon in California. A Study of Various Rations for Fin- ishing Range Calves as Baby Beeves. Economic Aspects of the Cantaloupe Industry. Rice and Rice By-Products as Feeds for Fattening Swine. Beef Cattle Feeding Trials, 1921-24. Apricots (Series on California Crops and Prices). Apple Growing in California. Apple Pollination Studies in California. The Value of Orange Pulp for Milk Production. The Relation of Maturity of California Plums to Shipping and Dessert Quality. Range Grasses in California. Raisin By-Products and Bean Screen- ings as Feeds for Fattening Lambs. Some Economic Problems Involved in the Pooling of Fruit. Power Requirements of Electrically Driven Dairy Manufacturing Equip- ment. Investigations on the Use of Fruits m Ice Cream and Ices. The Problem of Securing Closer Rela- tionship between Agricultural Devel- opment and Irrigation Construction. I. The Kadota Fig. II. The Kadota Fig Products. Grafting Affinities with Special Refer- ence to Plums. The Digestibility of Certain Fruit By- Products as Determined for Rumi- nants. II. Dried Pineapple Pulp, Dried Lemon Pulp, and Dried Olive Pulp. The Feeding Value of Raisins and Dairy By-Products for Growing and Fattening Swine. Laboratory Tests of Orchard Heaters. Series on California Crops and Prices : Beans. Economic Aspects of the Apple In- dustry. The Asparagus Industry in California. A Method of Determining the Clean Weights of Individual Fleeces of Wool. Farmers' Purchase Agreement for Deep Well Pumps. Economic Aspects of the Watermelon Industry. Irrigation Investigations with Field Crops at Davis, and at Delhi, Cali- fornia, 1909-1925. Studies Preliminary to the Establish- ment of a Series of Fertilizer Trials in a Bearing Citrus Grove. Economic Aspects of the Pear Industry BULLETINS — (Continued) No. No. 453. Series on California Crops and Prices: 462. Almonds. 464. 454. Rice Experiments in Sacramento Val- ley, 1922-1927. 465. 455. Reclamation of the Fresno Type of 466. Black-Alkali Soil. 456. Yield. Stand and Volume Tables for 467. Red Fir in California. 468. 458. Factors Influencing Percentage Calf Crop in Range Herds. 469. 459. Economic Aspects of the Fresh Plum 470. Industry. 460. Series on California Crops and Prices: 471. Lemons. 461. Series on California Crops and Prices: 474. Economic Aspects of the Beef Cattle Industry. Prune Supplj and Price Situation. Drainage in the Sacramento Valley Rice Fields. Curly Top Symptoms of the Sugar Beet. The Continuous Can Washer for Dairy Plants. Oat Varieties in California. Sterilization of Dairy Utensils with Humidified Hot Air. The Solar Heater. Maturit- Standards for Harvesting Bartlett Pears for Eastern Shipment. The Use of Sulfur Dioxide in Shipping Grapes. Factors Affecting the Cost of Tractor Logging in the California Pine Region. CIRCULARS No. 115. Grafting Vinifera Vineyards. 117. The Selection and Cost of a Small Pumping Plant. 127. House Fumigation. 129. The Control of Citrus Insects. 164. Small Fruit Culture in California. 166. The County Farm Bureau. 178. The Packing of Apples in California. 203. Peat as a Manure Substitute. 212. Salvaging Rain-Damaged Prunes. 230. Testing Milk, Cream, and Skim Milk for Butterfat 232. Harvesting and Handling California Cherries for Eastern Shipment. 239. Harvesting and Handling Apricots and Plums for Eastern Shipment. 240. Harvesting and Handling California Pears for Eastern Shipment. 241. Harvesting and Handling California Peaches for Eastern Shipment. 243. Marmalade Juice and Jelly Juice from Citrus Fruits. 244. Central Wire Bracing for Fruit Trees. 245. Vine Pruning Systems. 248. Some Common Errors in Vine Pruning and Their Remedies. 249. Replacing Missing Vines. 250. Measurement of Irrigation Water on the Farm. 253. Vineyard Plans. 255. Leguminous Plants as Organic Ferti- lizers in California Agriculture. 257. The Small-Seeded Horse Bean (Vicia faba var. minor). 258. Thinning Deciduous Fruits. 259. Pear By-Products. 261. Sewing Grain Sacks. 262. Cabbage Production in California. 263. Tomato Production in California. 265. Plant Disease and Pest Control. 266. Analyzing the Citrus Orchard by Means of Simple Tree Records. No. 269. 270. 276. 277. 278. 279 282. 284. 287. 288. 289. 290. 292. 294. 295. 296. 298. 300. 301. 302. 304. 305. 307. 308. 309. 310. 311. 312. 313, 314. 315. An Orchard Brush Burner. A Farm Septic Tank. Home Canning. Head, Cane, and Cordon Pruning of Vines. Olive Pickling in Mediterranean Countries. The Preparation and Refining of Olive Oil in Southern Europe. Prevention of Insect Attack on Stored Grain. The Almond in California. Potato Production in California. Phylloxera Resistant Vineyards. Oak Fungus in Orchard Trees. The Tangier Pea. Alkali Soils. Propagation of Deciduous Fruits. Growing Head Lettuce in California. Control of the California Ground Squirrel. Possibilities and Limitations of Coop- erative Marketing. Coccidiosis of Chickens. Buckeye Poisoning of the Honey Bee. The Sugar Beet in California. Drainage on the Farm. Liming the Soil. American Foulbrood and Its Control. Cantaloupe Production in California. Fruit Tree and Orchard Judging. The Operation of the Bacteriological Laboratory for Dairy Plants. The Improvement of Quality in Figs. Principles Governing the Choice, Oper- ation and Care of Small Irrigation Pumping Plants. Fruit Juices and Fruit Juice Beverages. Termites and Termite Damage. The Mediterranean and Other Fruit Flies. 15m-ll,'29