OLIVE GROWING IJ THE SOUTH. . . I..ITED STATES ^5y~ C. F. Kinman Farmers 1 Bulletin 1249 S. D. A. FARMERS' BULLETIN 1249 UNITED STATES DEPARTMENT OF AGRICULTURE _:. .- ., -. IN THE. SOUTHWEST U N IT ED STAT El THE INTRODUCTION of olives into southern California took place 150 years ago, when the Franciscan Fathers made the first plantings near the San Diego Mission. Since then olive growing has become widely disseminated in many parts of California, in Arizona, and to a very limited extent in a few other sections, although it is only within the past 30 or 35 years that the olive industry has assumed a .place of importance in the commercial fruit industry of the United States. The olive can be grown successfully only in a com- paratively mild climate. A temperature of 10 to 14 F. above zero is likely to prove disastrous to the tree, and the fruit will usually be injured by a drop below 28 F. Furthermore, there are other limita- tions. Although the tree thrives fairly well in the humid regions of the South, where the temperature conditions are favorable, fruit production there is not sufficiently dependable to justify the planting of trees. The dry atmospheric conditions of Califor- nia and the arid Southwest, where the temperature range is favorable and where irrigation supplies the necessary soil moisture, appear to meet the require- ments of the olive. Though few fruit trees withstand the limited soil moisture that the olive can endure, it likewise re- sponds, as do other trees, to favorable soil condi- tions; in fact, it is only under such conditions that regularly successful results can be expected. Contribution from the Bureau of Plant Industry WM. A. TAYLOR, Chief Washington, D. C. February, 1922 36T OLIVE GROWING IN THE SOUTHWESTERN UNITED STATES. C. F. KINMAN, Pomologist, Horticultural and Pomological Investigations. CONTENTS. Olive growing in the United States Cultural distribution Choosing a locality and site for olive planting Varieties Propagation Transplanting Cultivation and irrigation Page. 3 5 10 13 16 20 Fertilization Pruning Harvesting the fruit Grading and processing the fruit Insects and diseases Farmers' Bulletins relating to fruits and closely allied subjects Page. 30 30 34 36 39 44 OLIVE GROWING IN THE UNITED STATES. NEARLY a century and a half ago the Franciscan Fathers brought to this country some olives and planted them at the San Diego Mission, situated near the site of the present city of San Diego, Calif. This first planting, whether in the form FIG. 1. Trees of the original planting of Mission olives at the San Diego Mission near San Diego, Calif. (Photographed in May, 1920.) of cuttings, seeds, or otherwise, was the source of what is now known as the Mission variety. From here, during the next few years, the 3 23311O Farmers' Bulletin 1249. trees were distributed to a number of missions in southern and central California. Some of the original trees, also those planted at the other missions, are still thrifty and productive (figs. 1 and 2). The olive was for many years the most prominent fruit in Cali- fornia; in fact, aside from the grape and the fig, which were intro- duced by the Mission Fathers about the same time as the olive and to each of which has been given the name "Mission," there were no other fruits of importance in Cali- fornia. On account of the sparse popu- lation, only small plantings of olives were made, and the culture of these was often neglected until nearly a century later, when interest in olive growing re- ceived a new impetus and a few men planted good-sized orchards. From that time plantings have continued to increase, until to- day olive culture is a prominent factor in fruit production in California and is of some importance in Arizona. Statis- tics show that 503 olive trees were growing in Califor- nia in 1855 ; J in 1876 2 there were 5,603 trees of bear- ing age; in 1901 the number was 539,568; and in 1919 3 there was a total of 37,412 acres of olives in California, with 24,285 acres in bear- 1 Thomas, Daniel J. On agricultural statistics of the State. In Trans. Calif. State Agr. Soc., 1859, p. 343. 1860. 2 Table of statistics . . . 1876, as reported to the surveyor general by the several county assessors, embracing the entire State. In Trans. Calif. State Agr. Soc., 1876, p. 125. 1877. 8 California Olive Association survey. FIG. 2. A tree of the original olive planting at the San Fernando Mission, Calif. The tree as here shown was cut back several years ago to render the harvesting less expensive. The present top consists of sprouts from the stump. (Photographed in May, 1920.) Olive Growing in the Southwestern States. of the this in uig. In 1917 there were 608 acres in olives in Arizona. The produc- tion of olives in California * in 1918 was 13,801 tons. No accurate data on the production in Arizona exists, but the yield for 1918 has been estimated at approximately 100 tons. The importation of olives from foreign countries in 1919 amounted to more than 3,950,000 gallons ; also about 8,300,000 gallons of edible oil and 287,000 gallons for mechanical or manufacturing purposes. Until 1900 almost the entire production of olives in this country was utilized for oil, although for a number of years small quantities of green-olive pickles were made, and during a few years previous to this considerable interest was given to experiments in the processing of ripe-olive pickles, the article which is now the basis olive-growing industry country. As there is great interest in olive planting and a vast area of land suitable for olive culture is lying within regions of congenial tem- peratures in California and Ari- zona, there are prospects for a continued growth of this industry, the profitable marketing of the crop perhaps being the primary limiting factor. Natural conditions have never given the olive industry any seri- ous setback, but serious handicap has been experienced through the adulteration of the oil or the sale of other oil as olive oil, when the making of the latter was gaining rapidly in importance during the last years of the past century, and also through the faulty sterilization of ripe pickles, which recently resulted in reducing temporarily the con- sumption of this commodity. CULTURAL DISTRIBUTION. The region in which the olive may be successfully grown for the commercial production of fruit in the United States is not as great as for most frost-hardy fruits and has been confined to portions of California and Arizona, although the trees will live and bear some fruit in portions of all of the southern tier of States of this country. *Hecke, G. H. California crop distribution and estimates, 1918 ... In Calif. State Com. Hort. Mo. Bui., v. 8, no. 4, p. 164. 1919. In cooperation with U. S. Dept. Agr., Bur. Crop Estimates. FIG. 3. Outline map of California, showing by means of dots the principal sections where olives are grown. Farmers' Bulletin 1249. Figures 3 and 4 show the regions in California and Arizona where olive growing is now a commercial industry. As with all other fruit crops in the comparatively warm, dry regions of the southwestern United States, the development of the olive industry has been, to a large degree, centered in a number of rather widely separated but extensive sections. Olives are found scattered throughout all the warm valleys where rainfall or irrigation is sufficient for the needs of the crop and where the range of temperature is favorable. The olive is now grown commercially in at least 36 of the 58 coun- ties of California and in a few counties of Arizona. The industry extends from near the border of Mexico to and including Shasta County, which lies next to the most northern county of California. This northern limit reaches nearly to the forty-first degree of north latitude. For convenience, the region of commercial olive production is here divided into five natural sections: (1) The Sacramento Valley, (2) the San Joaquin Valley, (3) the central California coast (the San Francisco Bay) section, (4) southern Califor- nia, and (5) southwestern Arizona. THE SACRAMENTO VALLEY. The olive is grown to a consider- FIG. 4. outline map of Arizona, showing a bi e extent through the central por- by means of dots in the general vi- . . ., TT n i cinity of Phoenix the location of the toon of the hacramento Valley and principal olive-growing section in that the rolling foothill district to the east and north, with centers of most importance near Oroville, in Butte County ; at Fairoaks, which lies northeast of the city of Sacramento, in Sacramento County ; and at Corning, in Tehema County. More than 14,000 acres of olives are growing in the entire valley, of which over 8,000 acres are of bearing age. Little attention is given this crop in the southwestern portion of the valley, which is swept by cold, moist winds throughout most of the summer. THE SAN JOAQUIN VALLEY. The San Joaquin Valley joins the Sacramento Valley and lies to the south of it. Although the most extensive olive plantings have been made in the southeastern portion, olive trees may be found scat- tered throughout the valley (fig. 5). There are nearly 11,000 acres Olive Growing in the Southwestern States. 'of olive orchards in this section, of which 5,500 acres are in bearing. Nearly half of both bearing and young trees are in Tulare County, Lindsay and Exeter being the principal centers. Plantings in each of three counties, Madera, Kern, and Fresno, cover more than 1,000 acres, of which little over one-half are in bearing. The nonbearing acreage (trees not of bearing age) in this and in the Sacramento Valley, indicates the keen interest taken in this crop during the past few years. The deep, heavy, fertile soils of several types sandy loams and gravelly, dry adobe which characterize the southeastern portion of the valley where olives are planted are conducive to a more vigorous tree growth than are the conditions in localities farther north in this valley or in most places in the Sacramento Valley. Olive acreage in California in 1919 l and in Arizona in 1917, by counties. CALIFORNIA. Section and counties. Bear- ing. Non- bear- ing. Total. Section and counties. Bear- ing. Non bear- ing. Total. Sacramento Valley: Butte Acres. 3 229 A cres . 1.981 Acres. 5,210 Central California coast (San Francisco Bay): Acres. A cres . A cres Tehama 2,006 1,034 3,040 Sonoma 650 650 Sacramento. . 1 026 971 1,997 Santa Clara 1 . 230 230 Shasta 519 593 1,112 Napa 202 202 Yuba 586 533 1,119 Other counties 212 15 227 Glen n 355 590 945 Placer 343 70 413 Total 1,294 15 1 309 196 125 321 Sonthprn Pal'fnrt 'a' Total 8 260 5 897 14, 157 Los Angeles 2 717 330 3 047 1 822 638 San Joaquin Valley: San Diego 1 521 245 1 766 Tulare. 2 567 2,729 5 269 San Bernardino 901 502 1 403 Madera 558 575 1,133 Ventura 1,234 1 234 Kern 111 721 1 165 Santa Barbara 492 63 555 Fresno 629 469 1,098 Orange 362 362 San Joaquin 538 287 825 Imperial 108 84 192 301 159 460 Stanislaus . . 202 203 405 Total 9 157 1 862 11 019- 100 2io 310 Mariposa 235 235 Total for State. . 24,285 13, 128 37, 412 Total 5,574 5,353 10,927 ARIZONA. Counties. Acres. Counties. Acres. Yavapai 12 Santa Cruz. 31 Maricopa 499 Cochise 5 Final 61 Total for State. . . 608 1 California Olive Association survey. 5 Calif. State Com. Hort. Mo. Bui., vol. 8, No. 4, p. 164. THE CENTRAL CALIFORNIA COAST (SAN FRANCISCO BAY) SECTION. Soon after olive culture had become a factor in fruit growing in California, that portion of the State which includes the counties lying adjacent to or near San Francisco Bay was looked upon as 8 Farmers' Bulletin offering promising conditions for its culture, but owing to the cool, moist sea breezes which prevail during the summer months over most of the section the returns have not warranted continued plant- ing. Aside from the fruit not reaching a satisfactory size, the ravages of the black scale are general and severe. In some instances olive trees in this section have been removed to make way for the planting of more profitable crops. In places not swept by the cool winds and where climatic conditions are more like those of the in- terior valleys, the olive gives satisfactory returns. In 1919 a little more than 1,300 acres of olives were growing in this locality, and almost the entire area was in bearing. FIG. 5. An orchard of olives of the Mission variety in the San Joaquin Valley, Calif. (Photographed in August, 1920.) SOUTHERN CALIFORNIA. During the early years of the olive industry it was in the section comprising the southern third of California, from Santa Barbara County southward, that most of the olive trees were planted. The acreage in this fruit has continued to increase, although not as rapidly during very recent years as in the interior valleys farther north. In 1919 more than 9,166 acres were in bearing, which is a greater area than in any of the other sections mentioned, and the total planting was 11,019 acres, which is about the same as in the San Joaquin Valley and considerably less than in the Sacramento Valley. The counties in this section in which olive culture has reached greatest importance are Los Angeles, Riverside, Ventura, and San Bernardino, although orchards are found in all the warm valleys where irrigation water is available. Plantings have recently Olive Growing in the Southwestern States. 9 been made in the Imperial Valley, where considerable interest has been aroused in this fruit. As in the northern valleys, plantings are for the most part confined to the slightly elevated places through the valleys and on approaches to and over the low rolling foothills where irrigation water is available and where frost injury to the fruit is least common. ARIZONA. Olives are grown commercially in a few counties of Arizona. The only important center of the industry (and, therefore, the only one considered here) is located near the city of Phoenix. In this section FIG. tJ. An orchard of olives of the Mauzanillo variety near Phoenix. Ariz. (Photo- graphed April 27, 1920.) the scattered orchards total about 500 acres. Plantings in the re- mainder of the State aggregate about 100 acres. Most of the or- chards in this locality were planted near the beginning of the present century, although some were set out a number of years earlier. The earlier plantings were for the most part for the purpose of oil production. During the past few years olive planting has stopped almost entirely, as the interest in fruits has been diverted to farm crops, of which cotton is the most important. Both tree growth and fruit production in parts of this district where water for irrigation is available indicate that the soil is fertile and that natural conditions are satisfactory for olive culture (fig. 6). Climatic conditions here are similar to those of the principal 67366 22 2 10 Farmers' Bulletin 12b9. olive-growing districts of the interior valleys of California, except that the summers are somewhat hotter and the annual rainfall less. In these sections, as in other olive-growing districts, there is dan- ger of injury to the fruit by early freezes if the crop is excessive and therefore late in ripening or if the varieties planted are naturally late in maturing. The Mission and Manzanillo varieties are the principal ones grown for pickling, while a few old orchards are still maintained for oil production. CHOOSING A LOCALITY AND SITE FOR OLIVE PLANTING. In selecting a locality for establishing an olive orchard, the ques- tions of most importance to be considered are for the most part the same as for other fruits. They include climatic conditions, the mois- ture requirements of the trees, soils, good roads, and the distance between the market or processing plant and the immediate orchard site. LOCALITY FACTORS. CLIMATIC CONDITIONS. The most satisfactory climatic conditions for the olive are mild winters, where killing frost does not occur until late in the fall, and hot dry summers. A temperature below 28 F. above zero will usually injure the fruit and 10 above zero will prove detrimental to the trees. Cold, moist, or hot dry winds are not conducive to the setting or maturing of the fruit. Cold dry winds are especially damaging to the partially ripened fruit, causing it to shrivel. Such fruit can be used for oil only and is of second grade even for this purpose. If warm weather follows and there is sufficient moisture in the soil, the fruit will usually regain its natural plumpness. The olive does not blossom until after the danger of spring frosts is over, but it ripens its fruit very late in the fall when in most locali- ties in the olive-growing regions of California and Arizona there is danger of injury to the fruit by light freezes. MOISTURE REQUIREMENTS. As it thrives best in a hot dry climate and the trees will live where protracted droughts are frequent, it was believed for some time after the olive was introduced into cultivation in the United States that irrigation was not necessary even where the close planting of the trees was practiced and where no intensive dry-farming systems were employed. This belief resulted in unprofitable returns from many orchards. At the present time it is recognized that, for satis- factory production, the olive is as dependent as are other fruits Olive Growing in the Southwestern States. 11 upon an adequate water supply. Owing to its requirements, of a hot dry region where the black scale is not destructive and of an elevated site on rolling or sloping land for assurance against frost, irrigation is almost imperative for the regular production of abun- dant crops of large fruit. Dry rolling land where irrigation is neces- sary and water for it is available is therefore favorable, if not requi- site, to the profitable production of olives for ripe pickles. For these reasons olives are not being planted to any extent for com- mercial orchards in localities where irrigation water is not avail- able or where rains are not sufficient to provide for a good tree growth; for even with a good setting of fruit in such sections the crop is likely to prove unprofitable because of insect pests and be- cause of the effect of other attending conditions which are adverse. Probably 85 per cent of the olive orchards of California and almost the entire olive acreage of Arizona are under irrigation. SOILS. Olives are found growing on many types of soil, but they prefer those which are well drained and fertile. Loams, sandy or gravelly loams or clay loams, which have not too high a percentage of humus or nitrogen are most satisfactory, although adobe land, if watered and given good surface cultivation to prevent the drying out and cracking of the surface, has given good results. The belief that the olive would make a good growth and produce profitable crops where nothing could be expected of other fruits has caused many failures, and at present only soils which are considered suitable for other fruit crops are used. Olive plantings for the most part have been made on reddish, brownish, or grayish sandy or gravelly loams belonging to the resid- ual or old valley-filling material groups, which are friable and well drained and darkened by a desirable quantity of humus. Although these types have proved to be satisfactory, their selection by olive planters resulted as much, probably, from a choice of climatic condi- tions as of soil, as they are the types on the lower rolling foothills, where the air drainage is good and detrimental frosts are not com- mon during the ripening season. Profitable orchards are found also scattered through the broad valley bottoms on fertile, well-drained, friable soil areas where sites of slight elevation are found, although the predominating soil type of these regions is characterized by a layer of heavy red-clay subsoil and of hardpan which prevents the penetration of tree roots and water. Trees should not be planted where there is near the surface a stratum of hardpan or other material which is impervious to water. 12 Farmers' Bulletin 1249. In such places the tree grows very slowly and produces small crops, if any, and sometimes is affected with die-back or exanthema. Where trees have been planted in such soil, breaking up the subsoil by blast- ing if the stratum is beyond the reach of the subsoil plow, so that water may penetrate it readily, is considered advisable. Where the stratum of heavy subsoil or hardpan is a few feet below the surface olive trees seem to do well if good culture is given, as they are naturally shallow rooted and do not require the depth of soil demanded by some trees. FIG. 7. An olive orchard near El Cajcn, Calif. (Photographed in 1918.) Soils very rich in humus and nitrogen are inclined to result in excessive wood growth, in only moderate crops, and in delayed ripen- ing of the fruit. This necessitates considerable pruning and expen- sive harvesting and involves occasional severe losses by the freezing of the fruit before it is ripe enough to harvest. Olive trees will live in soils where the humus and nitrogen content is very low, although in such places they usually make but little growth and bear unprofit- able crops. SITE FACTORS. Points of the most importance in the selection of an olive orchard site are (1) air currents, (2) soil drainage, (3) a contour suitable for irrigation, and (4), as with all other commercial fruits, areas where cultivation, harvesting, and marketing may be economically accomplished. As the fruit will be injured by freezing and will not Olive Growing in the Southwestern States. 13 ripen after it is harvested, the selection of a site free from low tem- peratures during the fall and early winter is of first importance. Low flat lands, the lower portions of ravines, and high flat table- lands should therefore be avoided ; sloping stretches and rolling areas with the exception of the lower portions should be chosen, the eleva- tion above sea level being of far less importance than the elevation above the valley or depression immediately adjoining (fig. 7). The air drainage in a depression of but a few feet below a frost-free area may be so poor that temperatures sufficiently low to render fruit unsuitable for pickling will occur. The same is true of the lower portions of ravines through which the heavy cold air flows to lower levels. Surface water drainage is usually satisfactory where the slope is sufficient to insure air drainage, but care must be taken to avoid places where the subsoils are retentive of water. Places ex- posed to prevailing strong or dry winds should be avoided, on account of the danger of damage to the blossoms, the very young fruit, or the fruit nearing maturity. On the other hand, moderate night breezes are desirable during the ripening season, on account of their tendency to prevent damaging frosts. VARIETIES. The Mission variety, which is the one generally accepted as the best for planting in sections of the United States where olive grow- ing is an industry and of late years has been most extensively planted, was also the first to be introduced. As it was for many years the only variety available, it was planted in most of our present olive-growing regions. During the last 30 or 40 years of the nineteenth century 80 or more varieties were introduced, mainly from Spain, Italy, and France, and grown in California. Most of this work was done in the southern portion of the State. Practically all of these varieties were imported for the purpose of manufacturing oil. When the oil in- dustry was displaced by the more profitable pickling of the large ripe olives, the demand for most of the small-fruited sorts which had been grown for their oil disappeared. As in the importation of varieties of other fruits, a large percentage of the varieties of olives proved to be unsuitable for commercial planting in this country, and most of them have been discarded. A few of these varieties, on account of ripening their fruit early in the fall or owing to their extra large size, are still being planted by those who are partial to these qualities. Only a few orchards of the oil-bearing olives remain, the others hav- ing been removed or grafted to large- fruited varieties. The most important varieties at present, aside from the Mission, are the Manzanillo, Ascolano, and Sevillano. Plantings of a few others) including Nevadillo (Nevadillo Blanco*), Redding (Redding 14 Farmers' Bulletin Picholine), Columella, Rubra, Uvaria, Pendulina, and Oblonga, may still be found, but nurserymen claim that there is little demand for trees of these sorts for planting. The few really important varieties have been grown for a number of years under a wide range of condi- tions, and their performance in a locality has established their com- parative merits and the advisability of their continued planting in that section. MISSION. The Mission variety was disseminated from the Mission plantings in California, where it was grown from importations from Mexico and is now the most important variety. It is grown in all important olive-growing sections. Its popularity results from the satisfactory growth of the tree and the production and high quality of its fruit for both ripe pickles and oil. The fruit is medium to large in size, although varying considerably in this respect, depending upon the size of the crop and the cultural conditions. The fruit is usually large if the crop is light or the cultural conditions good and is smaller when the crop is excessive or when unfavorable growing conditions prevail. In shape it is oblique-ovate, with a more or less decided point at the apex, deep purple in color, turning to a shiny jet black when fully ripe. The meat is firm and separates from the seed readily when pickled. The Mission variety is superior for oil making, as well as for pickles. The tree is a vigorous, handsome, upright grower, suitable for borders, avenues, or windbreaks, as well as for general orchard planting. The strong tendency of the trees to make a vigorous upright growth rather than to spread requires that special atten- tion be given to pruning where this variety is planted under condi- tions favorable for wood growth. It is one of the most resistant of all varieties to the olive-knot disease. In some orchards, or with individual trees, much of the fruit varies in form from the normal to a more regular broad-ovate, with but little indication of the point at the apex. These variations in the shape of fruit are peculiar to the Mission variety. They are considered by many to represent distinct strains, while some con- tend that these characteristics are the result of local environment. Both forms of olives may be found on the same tree and even on the same fruit stem, although the predominating shape of the fruit on a given tree is decidedly of one form or the other. An effort to establish by bud selection or otherwise a strain of this variety which will regularly produce the better broad-ovate type of fruit is highly desirable. Olive Growing in the Southwestern States. 15 MANZANILLO. The Manzanillo variety was brought to this country from Spain and bears the Spanish name, meaning "little apple," probably so because the rather broad depression at the base resembles the base of an apple. The fruit is a little larger than the Mission variety and ripens somewhat earlier. For this reason it is a suitable sort for planting in zones where ripe olives may be harvested before the occur- rence of fall frosts, which would injure the fruit of the later ripen- ing Mission variety. The fruit is not as firm as that of the Mission and therefore requires more careful handling when picking and processing it. It is also considered inferior to the Mission for oil making. The flavor of the ripe fruit when pickled is, however, of very high quality and is claimed by some to be unsurpassed. The fruit is of a regular rounded or broad-ovate shape and its color is a rich dark purple, changing to deep bluish black when fully ripe. The tree is a vigorous grower and inclined to be broad and spread- ing, a shape which is always desired. ASCOLANO. The Ascolano olive was brought from Italy. It is one of the largest fruited varieties grown in this country, being a little larger than the Sevillano. On account of its large size it has been used mainly for pickling. The fruit is very tender and requires special care in handling. When ripe it is a deep wine color rather than black. In shape it is a broad oval except for an inconspicuous point at the apex. SEVILLANO. The Sevillano variety is grown to some extent in a number of localities on account of its large fruit. It is claimed to be the large olive imported from Spain and known here as the " Queen." When properly grown its fruit is one of the largest produced in this coun- try and is said to reach a greater size than when grown in Spain. It is of a rather long oblique-oval shape, resembling the Mission, is attractive as a green pickle, and makes a ripe pickle of fair quality, although if allowed to get ripe on the tree it is tender and easily bruised and so soft after processing that it must be harvested when only a thin blush of red is present in the skin. It is usually pickled when a yellow or straw color has developed and before a blush of red appears, and sometimes while green in color, even before signs of maturity are present. The Sevillano is one of the most frost-tender varieties in common cultivation, so far as injury to the fruit is concerned. The tree is vigorous and is considered a good bearer. Like the Ascolano, its 16 Farmers' Bulletin greatest point of recommendation for commercial planting is the large size of the fruit. The demand for large fruit in the eastern markets of the United States has resulted in stimulating the planting of the Ascolano and Sevillano varieties, so that these trees have of late years been very much in demand. REDDING. The Eedding (Redding Picholine} variety was introduced from France and widely planted for the production of oil under the mis- taken belief that it was the true Picholine of that country (California Ex. Sta. Kpt, 1898-1901, p. 271). It is still cultivated where the old orchards have not been grafted to other varieties or grubbed out, but no new plantings are made except to produce rootstocks for other varieties. The trees are vigorous growers and succeed under a wide range of conditions. It is an easy variety to graft. The fruit is very small, oval in shape, and of a deep bluish black color when ripe. Though the variety is exceedingly prolific, the fruit is too small for pickling and is used entirely for oil. NEVADILLO. The fruit of the Nevadillo (Nevadillo Blanco) variety is a little smaller than the Mission. Its shape is oval and regular except that it is somewhat blunt at both ends. When ripe it is a deep shiny black with a thin bloom. The ripe pickles are of good quality and flavor, and the fresh fruit returns a high quality of oil. It is too small to be considered first class for pickles. This is one of the first varieties to be injured by cold, and it is not being planted to any consider- able extent at present. PROPAGATION. THE USE OF SEEDS AND CUTTINGS. The olive may be propagated by seeds and cuttings or by budding or grafting. As seedlings do not come true to the variety and therefore do not produce a uniform type of fruit, they are grown only for stocks on which to bud or graft. By far the greatest por- tion of the olive orchards in the southwestern United States have been grown from cuttings, and this method of propagation is still in use by most orchardists and nurserymen. The reasons given for preferring this method are that but little skill is required in making the cuttings and that the trees are more quickly and cheaply grown, at least to p. size suitable for setting in the orchard, than budded trees. It is claimed by some that by budding or grafting a seedling stock, a tree superior to one grown from a cutting may be produced. Olive Growing in the Southwestern States. 17 The great number of orchards which have given satisfaction when O trees grown from cuttings were planted allay the doubts of most planters, however, regarding the success of such trees. For making cuttings, soft tender tips of branches or older hard- wood are used. Nurserymen \vho require a large quantity of olive trees for their trade and propagate them by cuttings often use the branch tips, as it is difficult and expensive to secure hardwood cut- tings of suitable size in sufficient number. They are also usual>y equipped with the necessary lath houses or other suitable means for furnishing the shade and protection from wind required by the young cuttingo cmv^ lor keeping in proper condition the beds of sand in which the cuttings are placed. About 4 inches is the usual length for making softwood cuttings. The tips selected should be those that have completed their length growth and are becoming firm but are not too hard. The condition of the growth, therefore, rather than any particular period of time, determines when the cuttings should be made. When preparing a cutting for planting the cut is made just below the node (the region where a leaf occurs), the same as for other plants. The two lower leaves are then removed and the others cut back about one-half their length. The cuttings are then placed in the sand bed rather close together, where they remain until roots have started, which under favorable conditions is but a few weeks. They are then transplanted to nursery rows or beds, where they are left until they are ready for planting in the orchard. It is claimed by some that trees thus grown have a better root system than those grown from large cuttings. For making hardwood cuttings, branches three-fourths of an inch to 1-J inches in diameter are usually chosen, although smaller or con- siderably larger ones may be used. Such cuttings are generally made 14 to 16 inches in length. As with most other trees, the best time for making hardwood cut- tings is when the wood is most dormant, which is during January and February. After the cuttings are made they are commonly tied in bundles, then placed in a trench, and covered with moist soil or other material to encourage callusing. When the soil becomes warm in the spring, they are placed a few inches apart in the nursery row, being planted 10 or 12 inches deep, so that only one or two buds project above the surface of the ground. Rooting takes place readily under favorable conditions. The sprouts which grow during the first season are allowed to remain during that season. Then the best one for developing a tree is selected, and all the others are cut off. Growth in the nursery row during the second season follows. 67366 22 3 18 Farmers' Bulletin 1249. TOP GRAFTING. Top grafting is possible on olive trees of any age, and may be done at almost any time of the year with considerable success, although the best time to graft is just as growth starts in the spring. This method of changing an orchard from one variety to another was practiced in many cases in California during the transition period when the demand for fruit suitable for pickles was superseding that for the manufacture of oil and small-fruited varieties were replaced by large-fruited ones (fig. 8). Both grafting into the stumps of large branches ard budding into new shoots, which are allowed to grow for a year or so atter the FIG. 8. An olive orchard, originally of the Nevadillo variety, planted about 1890 near San Fernando, Calif. The trees, as they appear here, consist of 6-year-old Ascolano grafts, the original trees having been top-worked to the latter variety. (Photo- graphed in May, 1920.) tree is cut back, are common practices (figs. 9 and 10). In prepar- ing the tree for grafting, the limbs to be replaced by the new variety are cut off at any desired height by making a smooth, slightly slanting cut which will heal over quickly and not permit water to stand on the cut surface. The usual custom is to cut back only a portion of the top at one time, for fear of giving too great a shock to the tree, __ and the remaining branches are cut back the following year. If branches are to be left at the time those to be grafted are cut back, they should be selected so as to give as much shade as pos- sible to the remainder of the tree (fig. 11). A coat of whitewash should be applied immediately to, the trunk and stumps of branches to be grafted as a protection against sunburn (fig. 12). Olive Growing in the Southwestern States. 19 The cutting back of the branches is usually done in late winter: and the grafting, when the trees start growth in the spring. As large wounds on the olive are inclined to heal over quickly and with- out leaving a permanent weak place in the branch at the point of grafting, larger branches may be removed than could be safely done with many kinds of fruit trees. This makes it possible to establish the new head low, which is always desirable with the olive, as the expense of harvest- ing the fruit is there- by lessened. Where a large branch is removed, two or three scions are grafted in, spaced equally distant around the stump, to insure rapid healing over the stump and to furnish a more satisfactory number of branches for form- ing the new head than if one scion were used. This also insures to some ex- tent against a total loss by the wind breaking the young branches. Both cleft and bark grafting are practiced success- fully. Scions of about one-fourth of an inch in diameter and bearing two to four buds are considered most satisfactory. These should be placed so that the upper edge of the beveled surface of the scion fits firmly to the upper edge of the stump, and the union is tightly bound with cord or tape and protected from water with a coat of grafting wax. Support should be given the new growing branch to prevent it from being broken off by the wind. This may be done by placing a long stick beside the scion and tying it firmly to the old stump and the new branch. FIG. 9. One-year-old olive scions in a 30-year-old stump. (Photographed May 12, 1920.) 20 Farmers' Bulletin TRANSPLANTING As the olive is an evergreen tree and is grown in sections where only light freezes occur, transplanting may be successfully done at almost any time of year, although the time accepted as the most satisfactory for transplanting this tree is after the soil has become FIG. 10. Scions that have made a growth of three seasons in an old olive tree near tsa.i Fernando, Calif. (1'hotographed in May, 1920.) thoroughly warmed in the spring, or during the period from about March 1 to May 15. If the earth is cold, the trees may fail to start growth for a considerable time, and some of the weaker ones may die. Only trees which have been well grown and have good root systems should be planted. Good-si.^ed holes should be made in soil that has been thoroughly prepared to a good depth and the tree Olive Growing in the Southwestern States. 21 FIG. 11. Olive trees 30 years old near San Fernando, Calif., being grafted over to an- other variety. The view shows the trees during the first season after the grafting was begun. Another year, when the scions have become well established, the remaining limb will be cut off and grafted. One main limb is left in order to maintain the vigor of the tree while the scions are becoming established. After they are established they will maintain the tree, so that the limb which now remains can be safely cut off for grafting the following year. (Photographed in May, 1920.) 67366 22 4 Farmers' Bulletin placed a couple of inches deeper than it grew in the nursery. Well- pulverized moist earth should then be filled in around the roots. Olive roots dry out quickly when exposed to the sun or wind, so it is important that they be kept moist and covered until ready to be placed in the hole. As soon as the trees are planted they should be well watered, and the trunks which have been well shaded in the nursery by surrounding trees will now need artificial protection from the sun. A heavy coat of whitewash is valuable, but the tree pro- FIG. 12. Recently grafted olive stumps whitewashed to prevent injury from sunburn. (Photographed in May, 1920.) tector manufactured for this purpose is more satisfactory. If thrifty trees are selected and the work of planting well done, the growth should start within a short time. DISTANCE TO PLANT. The distance for planting olive trees varies considerably in differ- ent localities and with individual orchardists, although the common distance is about 25 feet each way. Where conditions are conducive to a heavy wood growth, 30 or 33 feet, and in extreme cases even 40 feet, has proved to be not too far, for where the branch and leaf Olive Growing in the Southwestern States. 23 growth is very heavy much of the lower portion of the tree is de- prived of sufficient light if too close planting is practiced (fig. 13). FIG. 13. Old olive trees of the Mission variety which were planted too close together. As a result the tops have become very high, thus making the harvesting of the fruit difficult and expensive. (Photographed in May, 1920.) Where olive trees are used for windbreaks, 18 to 20 feet is a good distance (fig. 14). For borders or avenues (fig. 15), for which pur- poses they are very ornamental and under good culture are produc- 24 Farmers' Bulletin tive, the local conditions and the effect desired must determine the distance of planting. Where too close planting has been practiced, growers have in some instances removed alternate trees with good effect, but planting an orchard with this end in mind is not desirable (fig. 16). The olive comes into profitable bearing rather late, especially on soils where the tree makes a heavy wood growth, so when planted at normal distances one would secure only a few harvests before the trees would have to be removed, and those remaining would have been crowded into an unsatisfactory upright growth. The transplanting of large olive trees removed from orchards in order to increase the distance between trees has resulted in an excel- FIG. 14. A row of unpruncd olive trees near Exeter, Calif., which serve as a windbreak and dust screen. (Photographed in March, 1920.) lent stand and a satisfactory growth of transplanted trees (figs. 17 and 18). This result has followed even where the limbs and roots of the removed trees have been cut back to short stumps (fig. 19). INTERPLANTING. Interplanting olive trees with deciduous fruits, grapes, and annual crops is a common practice while the trees are young and where the soil is fertile and there is an abundance of water (fig. 20). Peaches, apricots, and plums are among the most satisfactory fruit trees for interplanting, as they come into heavy bearing early and will with- stand heavy pruning and can therefore be retained for a number of years without causing an unsatisfactory development of the olive tree. Annual crops may also be used, but the planting of them as well as Olive Growing in the Southwestern States. 25 of other fruits should be done with caution, so as to avoid undue com- petition for soil moisture and plant food between the olive trees and the interplanted crop. Interplantings should therefore be used only where moisture and plant food are plentiful, or, in case of an annual crop, where the planting is restricted to narrow strips between the olive rows (fig. 21). CULTIVATION AND IRRIGATION. In the warm dry regions, where most olive plantings have been made, cultivation is very necessary for the conservation of soil mois- FIG. 15. A roadside planting of olive trees of the Mission variety near Phoenix, Ariz. (Photographed in April. 1920.) ture, for maintaining a surface mulch, and for keeping the land free from weeds. Since the soil in which olives are grown is, for the most part, loamy and friable, a satisfactory tilth is not difficult to maintain. The system of cultivation generally followed in a commercial olive orchard is to plow once during the winter or early spring and give only shallow stirrings thereafter. The plowing should be at a mod- erate depth and finished a few weeks before the blossoms appear. Subsequent surface stirrings should then be given with a cultivator or disk harrow in crdsr to maintain a soil mulch and destroy weeds which would rob the trees of the surface moisture. In this way the subsoil is well protected against drying out and the upper soil kept 26 Farmers' Bulletin 1249. in good mechanical condition for new feeding roots, which will grow upward into it in the early spring. While a high humus content is not desirable in the olive orchard, a moderate supply is needed to preserve a good physical condition of the soil for root growth and to maintain moisture. To secure this it is the common practice to encourage a cover crop of wild vegetation during the winter or, occasionally, to sow in the fall one of the legumes commonly used for cover crops and allow it to grow until time for plowing in the spring. It is claimed that bitter clover (Melilotus indica) and common vetch (Vicia sativa) have given the FIG. 16. An olive orchard near Fontana, Calif., which was originally planted too close. This view shows the orchard five years after alternate rows of trees had been removed to relieve the crowded condition. The tree development and the production are now good. (Photographed in May, 1920.) best satisfaction for this purpose. It is important that this crop be not left in the spring until it has robbed the soil of too much moisture, as the period before blossoming is considered the most critical so far as setting a good crop of fruit is concerned. On the return of warm days in the spring, when evaporation of the soil moisture is consider- able, the combined effect of the roots o.f the cover crop and of the olive trees, the roots of which are inclined to be superficial, dries the surface soil quickly. This will result in difficulty in plowing, and the plowed soil .will be left in a rough, cloddy condition if plowing is delayed. The frequency with which irrigations are made and the quantity of water used differ, depending upon the texture and depth of the soil Olive Growing in the Southwestern States. 27 and on weather conditions. In the well-drained sandy loams, where water filtration is good and considerable water, as well as plant food. FIG. 17. A 12-year-old olive tree of the Mission variety which was transplanted in 1912. At that time the tree was cut back to the height indicated by the stubs at the level of the man's hand. The tree as here shown has grown for eight seasons since it was transplanted. may be lost by seepage, frequent light or moderate waterings are preferable to infrequent heavy ones. The vigor of the twig growth 28 Farmers' Bulletin of the current season determines to a large degree the quantity of fruit which will be produced the next year, and a heavier and more thrifty twig growth results where frequent waterings are given rather than where the soil is soaked and later permitted to dry out. In the moderately deep and fairly well drained soils, where by far the most olive orchards are found, every 30 days is considered by many successful orchardists to be sufficient, but by some every three weeks is thought not too frequent for the economical watering of bearing olive orchards. Where water is scarce and applications can not be made at regular intervals it Avill be best (where possible to do so) to irrigate two or three weeks before the blossoms appear, again FIG. 18. Aii olive orchard of the Mission variety near Strathmore, Calif. The trees were transplanted in 1912 and are now 20 years old. (Photographed in March, 1920.) when the fruit is one-third to one-half grown, and again when it is nearly full grown, or during the first part of September. At least, the first and last of these irrigations should not be neglected, as they are considered to be most critical periods with respect to both the current crop and the development of the tree for the following one. When fall and early winter rains are light, an irrigation should be given during this period, as the olive is an evergreen and therefore functions throughout the year. As evaporation is slow during the winter, one early irrigation will usually be sufficient for an entire dry winter if the soil is in good tilth. As with other fruits, care must be taken that water drains out of the lower soil strata and also from all low areas ; otherwise seepage water will collect in such places and cause serious injury to the roots. Olive Growing in the Southwestern States. 29 It is advisable, however, to leave implanted the depressions where water and air drainage are faulty. irrigations that are too frequent or too heavy often prove detri- mental where soils are underlain with hardpan or a stratum of poorly drained material which prevents the downward movement of water. FIG. 19. An old stump of a Mission olive tree near Oroville, Calif., showing sprouts grown during three years since it was transplanted. (Photographed in April, 1920.) as olive roots are sensitive to excessive moisture. Thorough cultiva- tion to maintain a surface soil mulch for the purpose of conserving moisture and the infrequent and light irrigations should prove profit- able on such land. Olives are, as a rule, planted on friable soils where irrigation water moves downward rather rapidly and the feeding roots of the trees 30 Farmers' Bulletin 12b9. \ are inclined to be near the surface; hence, the use of a number of irrigation ditches between the rows, through which the water may be passed and the entire surface soil wet within a short time, is generally more satisfactory than where fewer ditches necessitate many hours for the percolation of the water through the soil (fig. 22). The use of only one or two ditches to the row often results in leaving broad areas with insufficient moisture between the rows, causing an excess of water to collect in low places and in subsoils which are naturally retentive of moisture. KIG. 20. A live-year-old olive orchard of the Manzanillo variety interplanted with Sul- tanina (Thompson Seedless) grapevines near Phoenix, Ariz. (Photographed April 30, 1920.) FERTILIZATION. Most soils on which olives have been planted in the region under consideration are thought by many to be sufficiently supplied with plant food for satisfactory olive production. Among olive growers, however, there is a general belief that fertilizers are needed, and the few who have consistently applied them over a term of years claim to have been well repaid with increased crops. The elements most needed, the quantity required, the time of application, etc., are, how- ever, unsettled questions, as systematic tests to determine the need for the elements commonly used in fertilization have never been carried on or even undertaken in olive orchards in this country. Such tests would be of great value to the olive industry. PRUNING. The objects to be kept in mind in pruning the young trees are (1) to establish the form of tree which can be most conveniently culti- vated ; (2) to provide for a broad, low bearing surface from which Olive Growing in the Southwestern States. 31 fruit can be economically harvested; (3) to favor new growth on all parts of the tree and admit light for its development; (4) to re- move interfering or cross branches; and (5) to maintain shade for the protection of the large limbs against sunburn. Although the growing of many varieties on a large number of soil types and over a broad range of climatic conditions has resulted in considerable divergence of opinion as to the most profitable methods to follow in pruning, primers should keep the above ideals before them and let the severity of the pruning be determined by the needs of the individual tree. Before the nursery tree is set in the orchard it should be headed back severely, leaving but 3 or 4 inches of each of the main branches. It is well also to remove at this time all branches which will not be required for forming a desirably shaped tree. For the branches .KiG. 21. A catch crop hi a young olive orchard of the Mission variety near Lindsay, Calif. (Photographed in August, 1920.) which are to form the top of the tree only strong upright ones should be selected, and these should be spaced a few inches apart along the trunk of the tree and distributed at distances as nearly equal as pos- sible around it. When the tree as planted consists of a single stem it should be cut back to the point where one wishes the main branches to develop, which with most growers is 20 to 24 inches above the ground. Branching in many orchards has been encouraged at but a few inches above the crown, but this is not considered wise, as culti- vation is made more difficult thereby. Before planting, the roots should also be shortened to a length permitting them to be placed in the hole without bending or twisting, and roots injured in digging should be removed at the point of injury. This will be about all the 32 Farmers' Bulletin pruning necessary if the four or five main limbs branch as desired during the next few seasons, but in places where the upright growth of these limbs is very vigorous and they branch but little, they should be cut back during each of the next two or three winters to the point desired for the next branching. For the method of pruning to be followed in succeeding seasons much will depend upon local conditions. On light or shallow soils, where wood growth is slow, little, if any, heading back would bf done; severe cutting back will usually result in seriously stunting the growth of the tree. Pruning under these conditions should consist for the most part in the removal of interfering branches and in thinning out where small branches are too numerous to permit a FIG. 22. A 7-year-old olive orchard of the Mission variety, near Phoenix, Ariz., showing good growth ; also showing the main irrigation ditch and the head ditch, with small outlets for the water into the orchard rows. (Photographed in April, 1920.) thrifty development of new growth. This method will apply more especially to varieties which are naturally inclined to be low and spreading in their habits of growth. In very fertile soil where the central or main branches make an excessive upright growth and are not inclined to form strong satis- factorily spaced lateral branches, the cutting back of these central branches each winter for a few years, to induce the growth of a greater number of framework branches, is desirable. In a few locali- ties the conditions for wood growth are so favorable that the upright growth of a few main branches, which develop where little or no pruning is practiced after the first year, continues year after year at the expense of the lower lateral branches until within a few years the main portion of the crop must be harvested from tall ladders Olive Growing in the Southwestern States. 33 and at an excessive cost. Also, the shading of the interior part of the tree prevents growth there and leaves the main body but barren poles. The developing of a broad, low fruit-bearing surface by severely cutting back the rank interior branches for two, three, or four successive winters, to induce branching, has resulted success- fully, although the trees have probably been delayed in coming into bearing. Conditions are such that in by far the greater number of olive orchards the growth of the tree will come well between these two extremes of too little and of excessive upright growth, and each grower must decide as to the severity and regularity of pruning necessary to develop a strong, broad tree frame and maintain the other conditions already mentioned. Where the growth of the young tree is so slow that no pruning is necessary to secure the open top and spreading shape, the crop will usually be too light to be profitable, and orchard management along lines of cultivation, fertilization, irrigation, or drainage should be employed or adjusted to induce a more vigorous growth. In all pruning of the bearing tree it must be remembered that the fruit is borne on the previous year's growth only, and the crop will be unsatisfactory if this wood does not make a thrifty, vigorous development. When no thinning out of small twigs has been prac- ticed, thick brushes of slender drooping growth with but a very few inches of new wood often result. These masses should be thinned out to admit light to the remaining wood. This is more especially true where the tree is making poor or only fair growth. Where, owing to exceptionally favorable natural conditions or extra care, the trees are very thrifty and vigorous and are making considerable annual growth, the small branches do not droop to a very objection- able extent, the smallest, weakest twigs are crowded out, and little, if any, thinning is necessary. The olive tree is naturally very long lived and reaches a large size, and its period of profitable production should continue over many years. Therefore, the foundation branches should be so developed and the tree tops so kept within bounds by regular thinning that heavy crops may be borne and economically harvested. Of the two principal varieties, the Mission and the Manzanillo, the former is much more inclined to make a tall, slender growth ; it therefore requires considerably more attention at pruning time than the latter. Trees in many orchards where conditions for wood growth are favorable have reached a height where the harvesting of the fruit is so expensive that the orchard can not be maintained at a satis- factory profit, and heavy cutting back of the tree tops has been prac- 34 Farmers' Bulletin 12W. ticed to establish the bearing surface nearer the ground. Such prun- ing should be done with caution, as the production of the trees will be held back a few years by this practice. When the top branches are severely and uniformly cut back a very rapid upright growth of new branches will follow, and usually at the expense of fruit production. By removing some of the large branches and cutting others back to laterals, but not too severely, a more moderate growth of new wood is encouraged. This also develops the low branches by admitting light and secures a larger bearing surface. The latter practice is generally looked upon as the more satisfactory method of the two. The reheading of large, thrifty trees should in all cases be followed by the frequent thinning of some of the vigorous upright-growing branches which follow the pruning and by the shortening of others, to keep the new head within bounds. The open-headed tree, often termed goblet or vase shaped, is the form favored by some growers. This form is secured by cutting out all central branches after the main limbs have become well estab- lished and allowing a heavy growth of lateral branches to develop on the main branches, which grow from the tree trunk at an angle, but not permitting them to fill the center of the tree. While the yield of such trees will probably not be as heavy under all condi- tions as if some of the central branches were allowed to remain, the loss from the injury caused by the black scale will be far less, owing to the admission of an abundance of noonday sunshine. In sections where this insect is troublesome this method of pruning is often practiced advantageously. PROTECTION OF LARGE LIMBS FROM THE SUN. Where large branches are removed in pruning or cut back for top grafting, thereby exposing the bark of the remaining large branches to the sun, such exposed places should be immediately covered with a coat of whitewash to prevent sunburn. The new growth which will appear all along the branches within a short time will soon fur- nish sufficient shelter from the sun. EXPERIMENTS IN PRUNING NEEDED. There is an urgent need for systematic experimental work in the pruning of olive trees. Such work has not as yet been carried on in this country, although there is no subject connected with olive production about which the grower is more keenly interested. HARVESTING THE FRUIT. As a rule, the ripening season extends from two or three to several weeks, depending for the most part upon the size of the crop, but Olive Growing in the Southwestern States. 35 also upon the locality and the variety. Where the crop is light it may sometimes be harvested all at one time. In the foothill sections of the warm interior valleys of northern California some fruit of the early-ripening varieties is sometimes ready for harvest early in October; but in some sections near the coast, where it is cool and often cloudy during the summer months, the picking season is often not over until some time in February. Three or four pickings are usually necessary where the crop is heavy, especially if the orchard lies within the range of the cool sea breezes, where ripening of the fruit progresses slowly. As it is preferable from the standpoint of the processor to gather all the fruit at the same stage of maturity, as there is usually fear of the fruit being injured by freezing, and also as the orchardist wishes to keep his laborers employed after the harvest opens, har- vests are made whenever there is sufficient fruit to justify them. Where a number of pickings are necessary, the harvest becomes very expensive, as the fruit ripens unevenly on all parts of the tree and the entire tree must be gone over at each picking, and except where trees are small much of the fruit must be gathered from ladders. To obtain a uniformly good quality of ripe pickles, well-matured fruit is necessary. The most practical guide for the picker is the color of the fruit. Some canners of ripe olives, whose product is looked upon by many as the standard of excellence, insist upon hav- ing only deeply colored fruit for processing. However, as the fruit on the lower, shaded portions of the tree does not color as rapidly as it does over the outside branches, no color standard for picking can be strictly adhered to, and the picker must be guided also by experi- ence. With modern methods of pickling olives the dark color may be developed even if the fruit is immature, but immaturity is always betrayed by the quality of the product, as the meat, instead of sepa- rating easily from the pit and being smooth and of a rich flavor, is hard and brittle, adheres to the pit, and is lacking in richness. While immature fruit is not satisfactory for making ripe pickles, overripe fruit is also unsuited for this purpose, as it is soft and becomes bruised during picking and processing. Some large-fruited varieties become very tender upon ripening and must be harvested before they are fully ripe, to avoid serious loss by bruising during picking and processing. They are not allowed to remain on the tree after the first blush of reddish color appears. A maturity standard based on the oil content has been suggested as follows: A minimum oil content of 17 per cent in the flesh is offered as a tentative standard of maturity for Mission olives and other common varieties except the Manzanillo, Ascolano, and Sevillano. A minimum oil content of 15 per cent is recommended as a tentative standard for Manzanillo olives. No standards for 36 Farmers' Bulletin maturity are recommended for the large-fruited olives, Ascolano and Sevillano, which must be gathered when relatively immature. These olives, however, should not be sold under the designation " ripe." Because of the great variations noted in the composition of olives of the same variety grown in different localities, it probably will never be practicable to set definite and hard-fixed minima for oil in mature olives, and the proposed stand- ards must be applied with caution. 8 For making ripe pickles, careful handling of the fruit during harvest has been recognized for many years as of first importance. Badly bruised or punctured fruit can not be used for pickles and must be utilized for oil. The fruit is therefore gathered by hand and placed carefully in picking baskets or buckets and transferred to lug boxes for hauling to the pickling plant. Further to insure against bruises, some packers place some water in the picking buck- ets to serve as a cushion for the falling fruit. Stripping fruit from the branches with rakes and allowing it to fall on canvas spread under the tree is practiced occasionally by a few, but a low per- centage of first-class products is expected from such methods. While somewhat less care is taken in harvesting fruit which is to be utilized for oil making, it is recognized that only sound, well-ma- tured fruit will render first-quality oil. For making green pickles, which is a minor industry in this coun- try, large fruits only are used, and these are gathered as soon as they are full sized or when a light-yellow color indicating approaching maturity appears, but before the pink blush develops in the skin. When the processing plant may be reached in a day or so after picking, the fruit is shipped in lug boxes, but when several days are required for transportation, barrels are used and the fruit covered with salt water to prevent bruising and spoiling in transit. GRADING AND PROCESSING THE FRUIT. When the fruit reaches the pickling plant it is first run through a sizing machine and separated into different sizes. During the pick- ling process each size is treated separately, as olives of uniform size can be pickled more uniformly than fruits of different sizes handled together, and the pickles are more attractive when sized. Fruit of different varieties is kept separate throughout the pickling process. This is necessary, not only for marketing but also because the fruit of different varieties is different in texture and quality. Canners of olives do not have a uniform size standard into which they grade their fruit, although It appears that this would be very desirable. The difference in size between grades with most packers is one-eighth of an inch in the narrowest diameter of the fruit. All 6 Hilts, R. W., and Hollingshead, R. S. A chemical study of the ripening and pickling of California olives. U. S. Dept. Agr. Bui. 803, p. 24, 1920. Olive Growing in the Southwestern States. 37 small fruit, which is usually considered to be that below nine- sixteenths of an inch in diameter, is utilized for oil, and the fruit above that size is graded into a number of sizes. Many types of machines devised for sizing olives are in use. Some have screens adapted for separating the fruit of different sizes; others have rollers spaced at the desired distances, over which the fruit is passed, while another type has diverging rollers, but all adjustable for delivering the fruit sized according to the required diameter. Handling the fruit in this operation must be carefully done, and the sizing machine, whatever the type, must be adjusted to prevent bruising the fruit. FIG. 23. An olive pickling room, showing concrete processing vats. From the sizer the fruit is conveyed to vats, where the pickling process starts. Wooden or concrete vats of many sizes are in use, although in the newer plants concrete vats are used almost exclu- sively (fig. 23). These vats are about 3 feet wide, 2 feet deep, and 8 to 9 feet long, a convenient size in which to give the fruit uniform treatment and to handle it easily with the least injury. Here the bitterness which is in the fruit when it comes from the tree is destroyed by soaking in a lye solution, and after the olives have been darkened by aeration and the lye removed by washing in fresh water the fruit is soaked for a few days in salt water. It is then removed from the vats, graded as to color, and canned with salt water after the bruised fruit is removed. The cans are now heated in a water bath or in retorts under pressure at a temperature somewhat above that of boiling water. 23311O 38 Farmers' Bulletin 1249. The California State Board of Health has recently decided to require that all ripe olives, before being offered for sale in that State, be held at a temperature of 240 F. for 40 minutes to avoid all possibility of bacterial contamination. Some variation of the above method, which has been in use since the pickling of ripe olives was first practiced in California, is em- ployed by most olive canners. Though the details of the method, as outlined, are not carried out in the same way in all plants and though some claim secret variations or additions to the customary treat- ment, the fundamental principles of the commercial method are well known. FIG. 24. Olives curing in salt in concrete vats. Ripe olives are cured also by soaking them in strong brine or mixing them with partially ground rock salt processes in which no lye is used (fig. 24). In very recent years a considerable quantity of olives has been treated in this way in California. For these processes only very well ripened fruit is used, and from four to six weeks are usually required to render the fruit palatable. The prod- uct, which is somewhat shriveled in appearance and acrid in taste, is prized by peoples from the Mediterranean countries. It has not been adopted to any extent as a food by Americans. Olives intended for green pickles must be taken from the tree earlier than those for ripe pickles and must not be aerated during the pickling process, as this would result in darkening the color of the fruit. Aside from these variations and a fermentation process to which the fruit is subjected to develop the flavor characteristic Olive Growing in the Southwestern States. 39 of green pickles, the method for making the green pickles is not different, except in a few respects, from that for making ripe pickles. Those interested in the details of olive pickling and oil making may obtain inf orma- tion on the subject from Bulletin No. 803 of the United States Department of Agriculture, en- titled "A Chemical Study of the Ripen- ing and Pickling of California Olives." INSECTS AND DISEASES. Insect pests and diseases which cause serious loss in com- mercial olive or- chards in the United States are few in comparison with those which attack most other cultivated fruits. Among the insects that attack the olive tree in this country the black scale is the only one of importance, and among the diseases the olive knot is the most destructive, although others of minor importance are more or less common. INSECTS. Saissetia oleae Bern., or the black scale, as it is commonly known in olive-growing regions of the southwestern United States, causes greater destruction to the olive in this country than any other insect and is responsible for seriously curtailing the output of fruit in some localities. It does not confine its attacks to the olive, but feeds on a great number of both deciduous and evergreen plants which are widely distributed, making it exceedingly difficult to eradicate, and FIG. 25. Branches of the Nevadillo olive showing olive knots. (Photographed in June, 1920.) 40 Farmers' Bulletin 1249. it must therefore be considered when olive plantings are contem- plated. Fortunately, it does not thrive in sections where the sum- * LW&' FIG. 26. A thrifty olive tree for comparison with the one affected with die-back shown In figure 27. (Photographed April 3. 1920.) mers are hot and dry, such as is the case in practically all of the olive-growing sections which are not cooled and moistened by sea breezes, and in such places spraying is seldom necessary for its con- Olive Growing in the Southwestern States. 41 trol. In the damper regions along the coast, however, the black scale and the black smut which accompanies it cause serious loss where preventive measures are not used. FIG. 27. A 4-year-old olive tree affected witn die-back. Compare this with the thrifty tree shown in figure 26. (Photographed April 3, 1920.) DISEASES. KNOT (BACTERIUM SAVASTANOI). The disease which has caused the most serious loss in olive orchards is the olive knot (fig. 25), which is produced by a bacterium (Bacterium, savastanoi). This bacterium attacks all parts of the tree, including the leaf and fruit stems, but is most harmful on small growing twigs and young vigorous trees. Its destructiveness 42 Farmers' Bulletin is most marked in localities where it is warm and moist and condi- tions are favorable for a rapid tree growth. The best preventive measure known is cutting out the infected portions and disinfecting the resulting cuts, much as is done in pear-blight. As the bacteria come from the knots and are carried to other parts of the tree in wet weather only, their spread may be best prevented by pruning out infected branches before the winter rains occur. The variety most seriously damaged by this disease is the Manza- nillo, although the knot is common on a number of the small- fruited varieties grown for their oil. It is not, as a rule, a serious menace FIG. 28. Olive twigs affected with die-back (at the left). The branch at the right is in a normal healthy condition. to the Mission, Ascolano, Sevillano, and other large-fruited varie- ties, the Mission being almost immune to it. DIE-BACK. OR EXANTHEMA." The die-back of olive trees, which has recently come into more or less prominence in a number of localities, causes the dying back of the twigs and branches. The growing tips of leading branches usually die first, and new growth starts from nodes below, and these, in turn, become stunted and die (figs. 26 to 28). Affected trees fail to bear fruit, and loss of a large portion of the tree, if not the entire Home, W. T. Diseases of the olive. In Pac. Rural Press, v. 88, no. 3, p. 54. Some diseases of the olive in California. In Olive Jour., v. 1, no. 9, p. 4, 1917. 1914. Olive Growing in the Southwestern States. 43 tree, follows within a few years. The trouble is most common where subsoil drainage is faulty. Blasting, subsoiling, or other- wise opening the subsoil to permit a free circulation of moisture and air through it is thought to be the most practicable remedy. DRY-ROT. 7 Attacks of dry-rot result in the shriveling and browning of spots in the flesh of the fruit, and in some seasons it causes considerable trouble. The diseased spots take lye during the pickling process more readily than the surrounding healthy tissue, and great care must be taken during processing if the affected fruit is to be used for ripe pickles. Olive growers should be constantly on the lookout for destructive insect pests and diseases which cause preventable loss either to the tree or fruit. Both insect and disease problems should be referred without delay to either a State agricultural experiment station or to the United States Department of Agriculture for advice. The timely use of preventive or control measures may prevent serious loss. 7 The Olive Journal, vol. 1, No. 5, October, 1916, p. 7. WASHINGTON : GOVERNMENT FEINTING OFFICE : 1922 UNIVERSITY OF CALIFORNIA AT LOS ANGELES THE UNIVERSITY LIBRARY This book is DUE on the last date stamped below DISCHARGE-URL MAR 1 S 1981 Form L-9-15m-3,'34 3 1158 00669 4763