CALIFORNIA AGRICULTURAL EXTENSION DIVISION CIRCULAR 51 December, 1930 APRICOT GROWING IN CALIFORNIA A. H. HENDRICKSON Cooperative Extension work in Agriculture and Home Economics, College of Agriculture, University of California, and United States Department of Agriculture cooperating. Distributed in furtherance of the Acts of Congress of May 8 and June 30, 1914. B. H. Crocheron, Director, California Agricultural Extension Service. THE COLLEGE OF AGRICULTURE UNIVERSITY OF CALIFORNIA BERKELEY, CALIFORNIA Digitized by the Internet Archive in 2011 with funding from University of California, Davis Libraries http://www.archive.org/details/apricotgrowingin51hend APRICOT GROWING IN CALIFORNIA A. H. HENDRICKSONi DISTRICTS IN WHICH APRICOTS ARE GROWN The commercial production of apricots in California is largely confined to the great interior valley, the central coast section, and certain parts of southern California. Generally speaking, these are the sections to which this fruit has proved itself to be best adapted, but dooryard trees or small home orchards of apricot trees may be found in many places where the production of this fruit is not followed on a commercial scale. The chief reasons for this restriction in areas suitable for commer- cial plantings seem to be climatic conditions and the prevalence of certain diseases. Although the tree is hardy enough to withstand winter temperatures comparable to those found in many eastern fruit sections, its habit of early blossoming makes it particularly subject to injury by spring frosts. Ordinarily, this fruit is not grown above elevations of about 1,200 feet in the northern part of the state and 2,000 feet in the southern. In some districts the prevalence of spring rains makes the control of fungus diseases difficult. One phase of the apricot industry is the production of early fruit for the eastern markets. Among the important places where the fruit ripens early are certain areas in the Winters, Vacaville, and Arbuckle districts. The bulk of the early shipments to eastern markets are pro- duced in these districts. Other sections which also contribute to the early shipments are rather small areas in the southern San Joaquin Valley and southern California. During recent years, shipments to various fresh fruit markets have also been made from some of the foothill areas in the Santa Clara Valley. It is a peculiar fact that, although at least one early variety of this fruit originated in the Newcastle district of Placer County, that county produces no apricots for shipment to early markets. The prevalence of certain diseases in that section may be responsible for the fact that apricots are no longer grown there extensively. During the past seven years, from 60 per cent to 75 per cent of the apricot crop of the entire state was dried; from 15 per cent to 35 1 Associate Pomologist in the Experiment Station. 4 California Agricultural Extension Service [C^k- 51 per cent canned; and usually less than 10 per cent shipped or con- sumed locally as fresh fruit. Apricots^ grown in the central coast region ripen late in June or early in July and are utilized principally for canning. The remainder are dried or used to supply the local fresh fruit markets. In the interior valleys the bulk of the crop is dried, but in some years when the fruit is free from blemishes a con- siderable portion is canned. In southern California the crop usually ripens during the first tw^o weeks of July and is mostly dried. The remainder is canned or sold as fresh fruit. In general, the trees in the interior portions of the state are sub- ject to gummosis and shot-hole fungus, while those nearer the coast are sometimes seriously troubled with brown rot. These diseases, which in some years are serious, necessitate special treatments which will be discussed in a later section. PLANTING THE ORCHARD Apricots are usually planted on the square system, 20 to 30 feet apart. The average spacing distance is from 24 to 26 feet.^ The apri- cot on deep, fertile soil makes a large tree, so that it is probably best to plant the trees about 30 feet apart. In areas where the soil is shallow or irrigation is impractical and the trees are known to gi'ow slowly, 20 or 22 feet would probably make a satisfactory planting distance. By the hexagonal system of planting, in which each tree is equidistant from the trees surrounding it, approximately 15 per cent more trees can be planted on an acre than by the square system. On rolling land where irrigation is practiced, the trees may be planted on contours, with the trees approximately as far apart on the contours as they would be in the square system of planting.* If the orchard to be planted is of considerable size, the wisest plan would probably be to have a surveyor stake it out or at least establish the base lines. After stakes have been set for each row, it is com- paratively simple to set the remaining stakes by sighting them in place or by measuring with a steel tape or wire which has been marked to indicate the correct spacing between the rows. Usually each orchard 2 For detailed information on the distribution of the apricot acreage see : Well- man, H. R. Apricots (Series on California crops and prices). California Agr. Exp. Sta. Bui. 423:1-42. 1927. 3 For detailed discussion of spacing and thinning see: Allen, F. W. Planting and thinning distances for deciduous fruit trees. California Agr. Exp. Sta. Bui. 414:1-29. 1926. 4 For details of contour planting see: Huberty, M. E., and J. B. Brown. Irrigation of orchards by contour furrows. California Agr. Ext. Div. Cir. 16:1-16. 1928. 1930] Apricot Growing in California 5 district affords men who have had experience in staking orchards and who may be relied upon to do accurate work. After staking, it is a good practice to sight along each row to see if all the stakes are in their proper places. Planting is done as soon as the trees can be secured from the nursery, which is usually in January or February, and should not be delayed until March or April if it can possibly be done earlier. After the trees are dug from, the nursery row or received from the com- mercial nurserymen, the roots should not be allowed to become dry. The young trees should be heeled in until planting time, and roots should be covered with canvas or wet burlap while being moved from one place to another. Trees showing the characteristic warty knots of crown gall should be discarded. In planting, the bruised or broken roots are first cut off. Then, if the remaining roots are so close together that it would be difficult to tamp the soil around them, a few are removed to facilitate working the soil in firmly around those which remain. The hole is dug large enough and deep enough to hold the roots conveniently, and the tree is planted at approximately the same depth at which it grew in the nursery. The soil is worked between the roots and then firmly tamped so that the tree cannot be removed by a strong man pulling on it. As a rule, deep planting should be avoided, except possibly in some very light soils where there is danger of the wind blowing the soil away from the roots. After planting, the tree is pruned, as will be discussed under the section on pruning. A coat of whitewash or a tree protector applied soon after planting is a valuable protection against sunburn. A convenient method of planting trees to secure straight rows is by means of a planting board, which is simply a piece of scantling about 5 feet long and 4 inches wide. Notches 2 inches deep are cut in the middle of one side and in the middle of each of the ends. The apexes of these notches then lie in a straight line bisecting the board from end to end. The field is staked, a stake being placed for each tree to be planted. The planting board is then placed with the notch in the side held snugly against the tree stake. A second and a third stake are next driven in the ground in the apex of each end notch, care being taken to set each one firmly so that there can be no move- ment of the board between them. The board is then removed, the tree stake pulled up, and the hole dug. In planting, the board is replaced between the end stakes, and the trunk of the tree is held in the notch formerly occupied by the tree stake. With the roots in the proper place, the tree is planted and the board removed. The tree is 6 California Agricultural Extension Service l^'^^- ^l thus planted in the position formerly occupied by the tree stake and consequently in line with every other tree. Apricot trees one year from the bud are used for planting. This means that the root is approximately two years and the top one year old when planted in the orchard. Although apricot trees are easily grown from seed and later budded to the desired variety, growers usually prefer to buy trees from a nurseryman rather than to grow them.^ ROOTSTOCKS FOR APRICOTS The principal rootstocks used for apricots are apricot, peach, and myrobalan. The apricot and peach are more generally used than the myrobalan. The apricot cannot be relied upon to make a strong union with the myrobalan, for, although the trees often grow wtII for a number of years, they are apt to break at the graft union under stress of heavy loads or strong winds. The apricot root is resistant to the attacks of nematodes and the Pacific peach tree borers, and for this reason is valuable in districts where these pests are known to exist. All three principal rootstocks used for apricots are more or less susceptible to crown gall. The myrobalan is thought by some growers to be more resistant to oak fungus than either the apricot or peach, and is therefore used to some extent as a rootstock for the apricot. A questionnaire submitted to the nurserymen of California by the Division of Pomolog}^ showed that the percentage of apricot trees propagated on apricot stock in the years 1923 to 1928 inclusive varied from 30 per cent to 56 per cent. The percentage on peach stock varied to approximately the same extent. The percentage of apricots on apricot stock was greater than on peach stock four years out of the six for which records were obtained. The proportion of apricots on myrobalan decreased from 22.5 per cent in 1923 to about 12 per cent in 1928. A few apricots on Davidiana stock were also propagated during this period. In 1929 approximately 46 per cent of the apricot trees propagated were on apricot root, 16 per cent on myrobalan, and 38 per cent on peach. The almond is not used as a rootstock for apricots. POLLINATION OF APRICOTS All of the commercial varieties of apricots now grown in California are self -fertile or able to set fruit with their own pollen, and no pro- vision for using pollinizers is necessary in laying out an orchard of this fruit. 5 For further information regarding propagation and grafting see: Stahl, J. L. Propagation of deciduous fruits. California Agr. Exp. Sta. Cir. 294:1-24. 1925. 1930] Apricot Growing in California NTERCROPS Intercrops may be grown between the young trees. Spinach, lettuce, string beans, potatoes, tomatoes, nursery stock, strawberries, or raspberries are often used as intercrops during the first two or three years after planting the orchard. In some districts a disease known as verticilliosis or black heart is common on young apricots where some vegetable crops, particularly tomatoes, had previously been used as an intercrop. In these districts it is probably best not to use tomatoes as an intercrop in young apricot orchards. This disease will be discussed more fully in the section on diseases. The apricot tree makes a spreading, vigorous growth, so that ordinarily intercropping is not practiced after the second or third year. PRUNING YOUNG TREES One-year-old apricot trees, as received from the nursery, are characterized by numerous lateral branches, differing from pear, apple, cherry, and prune trees, which are usually straight whips. These lateral branches, if properly spaced, may be utilized to form the head of the tree, but if unsuitable must be removed. In the latter case the head of the tree is formed from branches produced during the first season in the orchard instead of from those produced by the tree while still in the nursery row. If these lateral branches are removed at planting time, care should be taken to leave a short stub at the base. Most apricot trees in California are grown with a relatively short trunk, with the lowest main branches at a height above the ground suitable for cultural operations that may be necessary from time to time. The nursery tree is cut off at a height of 24 to 30 inches above the ground. If lateral branches produced in the nursery are left, the spacing should be in accordance with the suggestions given in a later paragraph on pruning one-year-old trees. After planting and the removal of unsuitable lateral branches, the trunk of the tree should be protected against sunburn by means of a tree protector or a coat of whitewash. Ordinarily, young apricot trees produce many lateral branches, most of which are cut off at the first dormant pruning. If those branches which clearly cannot be utilized later as main scaffolds are pinched back from time to time during the spring and summer, begin- ning when the new growths are 3 or 4 inches long, the remaining branches will be benefited. Much may be accomplished toward shaping the young tree during the first summer if this work is done carefully. California Agricultural Extension Service [^^- ^i Fig. 1. — Apricot tree after one season's growth in orchard. FIRST DORMANT PRUNING The pruning at the end of the first growing season is extremely important from the standpoint of securing a well-balanced head of strong scaffold branches. The branches chosen at this time to make up the foundation for the framework ordinarily remain during the life of the tree. Consideration should be given to their position relative to one another, to their height above the ground, and also to the kind of crotches they form with the trunk. 1930] Apricot Growing in California Three main scaffold branches, separated 6 to 8 inches from one another along the trunk and spaced approximately 120 degrees apart, when viewed from above, make an ideal tree. Some growers prefer four or five branches ; but when these numbers are used, one or more may be crowded and must be removed later. Two main branches forming an evenly divided crotch usually do not make a satisfactory Fig. 2. — Same tree as in figure 1 after pruning. The branches left will form the main framework for the top of the tree. tree, because of danger of splitting. At the first pruning the three branches chosen to form the head are left, and the remainder are cut off close to the trunk. The three main scaffold branches are then headed back to the height at which it is desired to have the secondary scaffold branches grow (figs. 1 and 2). The height at which this heading is done varies considerably; but if it is done so that the cut ends are about breast high, the secondary scaffolds will grow in approximately the desired 10 California Agricultural Extension Service [Cir- ^l position. Generally speaking, the main scaffold branches should not be cut to the same length, because of the tendency of the lower branches to grow faster than the upper ones and crowd out the latter. If the uppermost branch is left considerably longer than the lower ones, this difficulty may usually be avoided (fig. 2). Furthermore, in this system the lower branches tend to make strong crotches Avhere they unite with the trunk. Figure 3 shows how a relatively weak Fig. 3. — Eelatively weak central branch that is being crowded out by the large branches below. central branch is often crowded out by the more vigorous branches below. Sometimes vigorous young apricot trees produce whorls of small laterals at certain places on the main branches. On older trees these whorls are useful in producing fruit. On one-year-oid trees, however, it is best to remove them unless they are situated where it is desired to have the secondary framework branches. In the latter case about two laterals may be left on each main scaffold. 1930] Apricot Growing in California 11 Fig. 4. — Two-year-old apricot tree before pruning. 12 California Agricultural Extension Service [Cir. 51 PRUNING TWO-YEAR-OLD TREES By the end of the second growing season, the apricot tree has usually produced a large number of laterals, not only on the scaffold branches but even well down on the trunk of the tree. All of these laterals, except a few short growths 3 to 5 inches long on the trunk and main branches, should be removed up to the height where the secondary framework branches should be formed. The number of secondary branches left at this pruning will depend upon their posi- tion and size. Ordinarily, 5 to 7 secondary scaffolds breast high will be found to be sufficient (figs. 4 and 5). The remainder are removed. PRUNING THREE AND FOUR-YEAR-OLD TREES Pruning at the ends of the third and fourth seasons and thereafter is essentially a thinning process to remove branches which are crossing or crowding one another (figs. 6 and 7). The trees should be thinned sufficiently to permit full development of the remaining branches and to admit light to the centers of the trees to encourage the growth of fruit spurs on the larger branches. At this age apricots grow vigor- ously, often producing new growth 6 feet or more in length. On these new growths there are one and sometimes two whorls of laterals. At pruning time these whorls should be thinned out by removing from one-half to two-thirds of the laterals. This necessity for heavy thin- ning usually disappears when the trees are older and the growth is more upright. In many places the apricot tree tends to be a spreading grower, and some branches which seem to be high enough must be removed because they later tend to droop so low as to interfere with cultural operations. During this period of training, many growers head back the branches of the previous summer's growth from one-fourth to one- third, to induce a somewhat more upright growth. In some sections where the trees grow rapidly, fruit is set on the extremities of rather long and slender branches. The weight of the fruit tends to aggravate the drooping tendency, and for this reason light heading back to laterals is often practiced. PRUNING OLD APRICOT TREES The apricot bears most of its fruit on comparatively short-lived spurs, which seldom live more than four or five years. A small portion of the crop is sometimes produced laterally on vigorous new shoots. 1930] Apricot Growing in California 13 Fig. 5. — Same tree as in figure 4 after pruning, showing main and secondary scaffold branches. 14 California Agricultural Extension Service [Cir- 51 The pruning systems followed with old trees- aim, for the most part, to secure the production of new spurs to replace those broken off in picking the crop, those lost through disease, or those past their fruitful period. An understanding of the growth habits of the apricot tree will aid in determining the kind and amount of pruning neces>sary. If we start with a vigorous one-year-old branch, we find that during the second season fruit will be produced from some of the buds, other Fig. 6. — Five-year-old apricot tree before pruning. buds will grow into short branches known as fruit spurs, and the bud nearest the apex will produce a branch nearly as long as the one from which it grew. Disregarding strong lateral branches for the time being, we shall then have a branch the basal half of which is two years old and the upper half one year old. On the basal half there will be a number of fruit spurs, and on the upper half a number of buds, some of which will produce fruit, and others, fruit spurs. At the end of the third season, the basal third has spurs which have produced one crop of fruit, the middle third has spurs which will produce their first crop the following season, and the upper third has either fruit-buds or leaf-buds. Instead of all the lateral leaf-buds producing fruit spurs, a few of them grow into strong lateral branches, which in turn behave like the branch just described. 1930] Apricot Growing in California 15 The pruning- should be of such a nature as to provide for the maximum crop consistent with the production of new fruit spurs to replace those which die or lose their usefulness. Ordinarily, this result may be accomplished by light to moderate thinning of branches and by the shortening of new wood back to laterals. As the trees grow older, the length of the new branches produced each year be- comes less. In mature trees the new growth should be from 15 to 30 inches each year. If the new growth is less than this amount, >^ -_.^, ^ Fig. 7. — Same tree as in figure 6 after being thinned. more severe cutting should be practiced. The pruning of apricots often varies somewhat with the district, particularly with regard to the shape of the tree ; but in general all growers realize the necessity of maintaining an approximate equilibrium between the crop and the amount of new growth produced under the soil and climatic conditions of the particular section. CULTIVATION OF APRICOT ORCHARDS Apricot orchards are not cultivated so frequently now as formerly. The usual practice is to plow or disk the covercrop in the spring, harrow once or twice, and then cease cultivating unless many weeds appear, when another harrowing may be necessary. If a covercrop is 16 California Agricultural Extension Service [Cm. 51 sown in the fall, it may be necessary to prepare the seed bed to insure even germination of the seed. In the unirrigated orchards, cultivation is given only to control weeds vi^hich may appear, and as only a few weed seeds germinate after the surface of the soil is dry, little if any tillage is necessary after the first few cultivations in the spring. In irrigated orchards, however, weeds generally grow luxuriantly after each irrigation. Cultivation in these cases is necessary to remove them and also to provide loose soil for constructing levees or furrows for the next irri- gation. If irrigations are frequent and if the weeds do not use too much of the water applied, the furrows or basins may be used more than once before they are broken down by cultivation. In the fall, cultivation is unnecessary after the last irrigation vmless the furrows or basins would interfere with the spraying or pruning operations during the winter. In a few cases, it may be desirable to cultivate and leave the surface rough after the last irrigation to aid the penetration of the first rains. Thus, the general purposes of cultivation are to remove competition for water by weeds, to incorporate the covercrop or manure in the soil, to prepare land for subsequent irrigations, to facilitate certain orchard operations such as spraying, harvesting, pruning, and planting a covercrop, and, in some cases where the soil has been compacted, to aid in penetration of rain which might other- wise be lost by surface run-off. COVERCROPS Covercrops are used in some orchards, while in others the native vegetation is deemed sufficient. Covercrops serve several useful pur- poses. They add organic matter to the soil, making it more friable, they aid in improving the environmental conditions for beneficial soil organisms, and, if a legume is used, they add nitrogen to the soil. Because of these beneficial effects on the soil, the use of covercrops in orchards is a desirable practice. The legumes most commonly used for covercrops in deciduous orchards are vetch and Melilotus indica. Other legumes such as Hubam clover, horse beans, fenugreek, cowpeas, soy beans, and alfalfa have also been used. In other districts the common bur clover and lupine grow as volunteer crops. Sometimes a nonlegume, such as barley or rye, is planted in combination with vetch. The various cover- crops are seeded at approximately the following rates per acre : vetch, 60 pounds; bur clover, 20 pounds; field peas, 80 pounds; Melilotus, 20-30 pounds; barley, 50 pounds; rye, 50 pounds; barley and vetch, 20 and 40 pounds respectively. 1930] Apricot Growing in California 17 The general practice with winter covercrops is to sow in September or early October and turn under in March. Difficulty is experienced in securing a satisfactory stand, if the fall rains are late ; and for this reason most covercrops are started in conjunction with a fall irriga- tion. Crops such as vetch are ordinarily drilled in or harrowed in after broadcasting as soon as the soil can be worked following an irrigation. Small-seeded crops, such as Melilotus, are often broadcast while the soil is still very wet or even before the water has disappeared from the surface. When the soil is dry enough the levees are worked down and seeded to Melilotus or vetch, the rest of the basin being left undisturbed. The seeding on the levees is done by hand sowing. Covercrops started at this season will usually grow to be 3 or 4 inches high before cold weather and will then make rapid growth early in the spring. IRRIGATION OF APRICOT ORCHARDS Apricot orchards are irrigated by the basin (fig. 8), furrow, or contour method, according to the topography of the land, the texture of the soil, the amount of water available in a unit length of time, the facilities for handling the irrigation stream, such as ditches, pipelines, and hydrants, and the custom generally prevailing in the district. The ideal irrigation layout is one which permits wetting the soil in the entire orchard to a uniform depth with a minimum amount of hand labor. In general, where the land is not too steep, the basin method is used chiefly. This method consists of square or rectangular basins enclosing one or more trees. The water is allowed to fill one basin to the desired depth; then it is diverted into the next basin and the first one is closed. The lowest basin in the row is usually filled first, then the next, and so on until the basin next to the pipeline or ditch is filled, then the water is started in the next row of basins. Another method now used rather extensively is the contour-basin method. In this system, the levees follow contour lines instead of the straight lines between tree rows. The number of trees enclosed by the levees in this system varies from 5 to 20 or more trees. The position of these contours is determined by surveyors, w^ho indicate by colored marks on the trees where the levees are to be built. This system has proved to be economical as far as labor is concerned, but the tendency to include too many trees in each basin results in an uneven wetting of the soil. The furrow system consists of several furrows between and parallel to the tree rows. It is used by some growers who have well-graded orchards and facilities for distributing small streams of water down 18 California Agricultural Extension Service [Cm. 51 a number of furrows at once. This system requires comparatively little labor but often has the disadvantage of using too much water at the upper ends of the furrows and not enough at the lower, when the furrows are too long. Another method of applying irrigation water, but one not used extensively in apricot orchards, is by contour furrows, in which the rows of trees are planted on contours according to grades established by a surveyor.*^ Pig. 8. — Many apricot oicliaids are irrigated by tlie basin method. Wherever irrigation water is available, apricot orchards are usually irrigated several times during the growing season. In some of the rolling foothill areas, however, Avhere water is either unavailable or too costly, the trees are grown without irrigation. In the latter dis- tricts a fair crop of fruit is usually produced, but the trees do not grow so large as they do in the irrigated sections, and the yields are smaller. Because the apricot ripens its fruit comparatively early in the season, the orchards are seldom irrigated more than once or twice before the crop is picked. On some fine-textured soils which hold a relatively large amount of readily available moisture, no irrigation may be necessary until after harvest. On sandy soils, on the other hand, it may be necessary to irrigate two or three times before picking. 6 Huberty, M. E., and J. B. Brown. Irrigation of orchards by contour fur- rows. California Agr. Ext. Div. Cir. 16:1-16. 1928. 1930] Apricot Growing in California 19 In some districts the winter rainfall may not be sufficient to wet the soil containing- a majority of roots. In this case the trees in these districts enter the growing season with some of the roots in dry soil. This fact must be considered in planning the irrigation schedule for the year. Likewise, an allowance should be made for the water used by covercrops, if the latter are allowed to grow late in the spring. A certain proportion of the total amount of moisture in the soil is readily available to trees. As this proportion is the same for all fruit trees, apricot trees can use as much as others, but no more. The normal processes of growth of tree and ripening of fruit are main- tained when the tree is not allowed to exhaust this readily available moisture and to remain dry for any considerable period. If the readily available moisture is exhausted, the leaves droop and the growth of the fruit is retarded. The wilted condition of the trees is noticeable in many apricot orchards during the summer and fall after the crop is picked. This neglect probably results from the mistaken belief that the tree's principal work is finished when the crop is picked. The soil-moisture conditions in an orchard,^ when the readily avail- able moisture is thought to be nearly exhausted, may be approximately determined by observing the behavior of some of the common weeds, such as pigweed. These plants send their roots deep into the soil, and when they show signs of drooping the grower may be certain that the trees also will droop in a few days. A few of these weeds in various parts of the orchard are valuable as indicators of the soil-moisture conditions. Examination of the soil with an auger to the depth containing most of the roots is also helpful. The soil auger is useful in ascertaining the depth of penetration of irrigation water. The average irrigation does not penetrate so deep as most growers suppose. Each irrigation should wet the soil con- taining a majority of the roots. This depth will vary, but in most cases it can probably be safely assumed that most of the roots are contained in the upper 5 or 6 feet of soil. If this depth is wetted at each irrigation, the number of applications necessary is less than where only relatively shallow penetration is secured each time. THINNING Thinning is practiced with apricots for shipping fresh, for can- ning, and to some extent for drying. The apricot, unless injured by frost, fungus diseases, or unseasonable climatic conditions, tends to set heavily, and must be thinned in order to produce fruit of market- Tor full discussion see: Veihmeyer, F. J., and A. H. Hendrickson. The essentials of irrigation and cultivation of orchards. California Agr. Ext. -Div. Cir, 50;l-24. 1930. 20 California Agricultural Extension Service l^^^- ^l able size. This work is usually done when the fruit has attained the size of large marbles. The usual practice with fruit intended for shipping or canning is to thin the fruit so that on the long branches the fruits are about 1% to 3 inches apart. In case of a heavy set the maximum distance of 3 inches is probably preferable, because with such a set many fruits are borne outside of the usual bearing zone ; but if the set is comparatively light, the fruits may safely be left approximately 1% inches apart. Heavy thinning may reduce the yields without proportionately increasing the size of the individual fruits. On the spurs the bunches of closely set fruit are broken, two or three fruits being left on a spur. Fruit which is sometimes set on the extremities of long twigs is usually injured by sunburn. In some coastal regions where the ripening fruit is attacked by brown rot, it is advisable to thin so the fruits will not touch one another when ripe. In this way the danger of the disease spreading from one fruit to another is reduced. PROTECTION FROM FROST The apricot, being one of the earliest fruit trees to blossom, is often injured by frost. In certain areas, otherwise admirably adapted to growing apricots, the frost hazard is one of the principal problems with which the grower must contend during the early spring months. The practice of heating orchards or smudging is well established in some of the best apricot sections of the state. As long as the tree is perfectly dormant, the twigs and buds are able to withstand any temperature ordinarily encountered in the fruit- gi'owing sections of California. The open flowers and young fruits are, however, very tender and are easily injured by temperatures slightly below freezing. The period during which the young fruits or flowers of the apricot may be injured by frost extends from the blossoming time in February or early March to about the first week in May, after which time there is little danger of frost. During the early part of the growing period the fruit becomes progressively more tender as the season advances. Thus, the buds when beginning to show color are more hardy than the fully opened flowers, which, in turn, are able to stand a lower temperature than the small green fruits. The buds, when beginning to show color, will endure a temperature of 25° Fahrenheit for 30 minutes or less without serious injury to the crop, while the open flowers and the young green fruits will endure only 28° F and 31° F, respectively, for the same length of time.^ 8 Schoonover, Warren E., Eobert W. Hodgson, and Floyd D. Young. Frost protection in California orchards. California Agr. Ext. Div. Cir. 40:1-73. 1930. 1930] Apricot Growing in California 21 '& ^ r - ^-- Fig. 9. — One orchard heater is usually placed in the square formed by four trees. 22 California Agricultural Extension Service [Cm- 51 With the minimum temperatures that may ordinarily be expected in most apricot districts, it is perfectly feasible to heat the orchard and save the crop. The operation is, however, a rather expensive one, and probably adapted for use only with those deciduous fruits which, like the apricot, either command relatively high prices or produce exceptionally large yields. The equipment used by apricot growers for orchard heating usually consists of approximately 100 open lard-pail type heaters per acre (fig. 9), several tested thermometers, an electric frost alarm, lighting torches, a storage tank, and a tank wagon for distributing the fuel. On small places several old oil drums are sometimes used both for storage and for distribution of oil. These can be obtained cheaply and are usually satisfactory except during prolonged cold periods when the central supply stations may run out of fuel oil. One-gallon can- nery tins, two or three being used in a place, make fairly satisfactory substitutes for the standard manufactured heater. The heaters are usually placed one in the center of each square formed by four trees, with a double row on the windward side of the orchard. Once filled, they are covered to keep out the rain. The use of many small fires uniformly distributed in the area to be heated usually gives the best results in deciduous orchards. In most apricot sections where heating is necessary, the temperatures do not fall much below the freezing point. Equipment that will raise the temperature 4 or 5 degrees is usually all that is necessary. Furthermore, the length of time necessary to burn the heaters is relatively shorter than that in certain citrus orchards where heating is necessary. Dangerous tem- peratures during cold periods are usually reached at about 3 or 4 o'clock in the morning, but occasionally it is necessary to light the heaters as early as midnight. Whenever the heaters are started, the grower should be able to keep them burning until after sunrise, as the coldest time is shortly before daylight. The open lard-pail heater burns for 3 to 3% hours before refilling is necessary. The frost alarm is set to ring a bell when the temperature reaches 33° F or 34° F. At first about one-half of the heaters are started. By watching the thermometers in various parts of the orchard, especially those in the cold places, the grower is able to decide whether he should light all of the heaters or ma}^ extinguish some of them with safety. Close observation of local weather conditions, such as direction and velocity of air currents, formation of clouds, and temperature during the preceding afternoon will often serve as a basis for economical use of heaters, avoiding unnecessary use of fuel before the danger point is reached. 1930] Apricot Growing in California 23 While some growers heat their orchards economically and success- fully, others fail. Some of the chief causes of failure are: use of untested thermometers ; failure to connect up frost alarm ; insufficient storage capacity to permit refilling heaters each morning after firing, through protracted cold periods; and use of insufficient numbers of heaters to maintain temperatures above the danger point during the last hour before sunrise. Beginners sometimes try to maintain tem- peratures higher than necessary, seeming to take pride in heating the orchard to 35° F or 36° F, when 32° F or 32i/2° F would give just as good results. Frost injury on young apricots may usually be detected during the forenoon following the night when freezing temperatures occurred. The first indication of frost injury is color on the skin of the kernel in the pit. If this shows any brown color, even though the spot is no larger than a pinhead, the fruit will drop before maturity. After a few days, frost injury can also readily be detected by small, light- colored dots on the surface of the fruit. About a week after a frost, severely injured fruits are usually stunted in size and beginning to turn yellow in color. Fruit less severely injured may remain on the trees until about two weeks before picking time. SPRAYING APRICOTS Apricots are subject to attacks by a number of diseases and insect pests, some of which are difficult to control. Some of these diseases and insects are widespread and occur in nearly all of the apricot- growing sections, while others are more restricted in distribution and occur chiefly in rather well-defined areas. Shot-hole fungus is more prevalent and difficult to control in the interior valleys than near the coast. Brown rot, green rot, and brown apricot scale give more trouble in the coastal regions than in the interior. Oak fungus, crown gall, bacterial gummosis, sour sap and other troubles may occur wher- ever apricots are planted. Some of these troubles are most effectively controlled by spraying, while others must be handled by other means as described in the following sections. The usual spraying program for the diseases and insects ordinarily found in the interior sections consists of an application of bordeaux mixture early in December, followed by one or more sprays during various stages of blossoming. Nicotine sulfate or an arsenical is some- times added to the spring sprays for the control of certain insects. In the coastal regions, the December spray may sometimes be omitted, but care must be exercised to see that the trees are sprayed at the right time in the early spring to control brown rot. Scale insects are best 24 California Agricultural Extension Service [^^- ^l controlled by the application of an oil spray, usually early in January. Experience has shown that lime-sulfur spray should not be used on apricots. COMMON DISEASES OF THE APRICOT Shot-Hole Fungus. — The presence of this disease is manifested by several unmistakable symptoms. During the winter the buds are blackened and killed ; in the spring, spots in the leaves fall out, leaving small round holes, from which the disease tal^es its common name. The fruit may also show small red spots and, in case of severe infection, may be deformed. The control for this disease consists of a spray of 5-5-50 bordeaux applied between November 15 and December 15 to prevent the killing of the buds. Another spray of 5-5-50 bordeaux is applied in the spring when the buds are showing innk. In badly infested orchards a third spray of 2-3-50 bordeaux to prevent spotting of fruit is some- times applied immediately after the 'jackets' are shed from the young fruit. Brown Rot. — This disease is often serious in many apricot sections, particularly in the coastal region. It affects both the fruiting wood and the fruit itself. Probably the most serious damage, if the fungus is uncontrolled, is the killing of the fruit-bearing wood, curtailing the crops for several years. The disease works rapidly on the young wood and spurs, but seldom kills branches over two years old. It is characterized by a browning and dying of the twigs shortly after blossoming. At the base of the infected twigs there is also formed an exudation of gum. Unless removed, these dead twigs form a source of infection from which the disease spreads the following spring. The fungus gains entrance through the blossom. It may enter through a blossom near the end of the branch and spread downward, or it may enter through a blossom near the middle of the branch and spread both ways. In this way a branch involving dozens of blossoms may be killed because of one infection. The disease is usually most severe when rains, heavy dews, or fogs occur during the blossoming period. On the fruit, the disease is not severe during ordinary seasons. The fungus attacks the fruit when it is nearly ripe and spreads rapidly, especially when the fruit is in thick clusters. The organism causes a soft brown spot which rapidly spreads and covers the entire fruit. Masses of gray spores are produced on the rotting fruits, spread, and infect other fruits, which later dry and shrivel to form mummies. These mummies remain on the trees unless picked off, and constitute sources of infection for the following year. 1930] Apricot Growing in California 25 The control for the disease affecting the blossoms in the spring consists in cutting out the diseased branches at pruning time and spraying with bordeaux in the spring. If the orchard is not seriously diseased or is situated in a district where the disease is not severe, a satisfactory control is usually a spray of 8-8-50 bordeaux applied at the red-bud stage or a little later. A somewhat weaker spray such as 5-5-50 or 6-6-50 bordeaux will frequently give satisfactory results under these conditions. If the orchard is known to be badly diseased, several successive sprays should be applied, the first at the red-bud stage and the last when the trees are in full bloom. For the disease on the growing fruit 4-5-50 bordeaux may be used up to within about two months before ripening; but it should not be used later because spray-stained fruit is not acceptable for canning. Green Rot. — Green rot is a disease closely related to brown rot. It occurs on the young fruit up to the time the young fruits are about % inch in diameter, while the jackets are still on the fruit. The disease does not seem to occur regularly. Shaking the trees vigorously to make the jackets fall, seems to reduce the amount of disease in some cases. Oak Fungus. — The apricot, like many other fruit trees, is suscep- tible to oak fungus. This disease kills the roots of the trees. It spreads underground from tree to tree until a large area is infected. The diseased trees die at any time during the year (fig. 10). As a rule the fungus will send up a large clump of toadstools near the trunk of the tree immediately after the first heavy fall rains. So far no effective control is known. Trenching or building barriers of various materials extending from the depth of cultivation down 5 or 6 feet around the infected area have been used in some places. Infected areas may be replanted with California black walnuts, figs, or pears on French root, as these species seem to be resistant to the disease. In some districts this fungus seems to spread with great rapidity, while in others it spreads very slowly. Apricots topworked on vigorous myrobalan seedlings, when four or five years of age, seem to be somev/hat resistant to this disease. Crown Gall. — Another disease which affects the underground por- tion of the tree is known as crown gall. This disease is caused by a bacterium which is present in most soils in California. It produces roughened swellings on the roots and sometimes on the trunk. These swellings eventually have the effect of girdling the root or the entire tree. As a rule the disease works rather slowly, and many trees live for years after it is well established in them. Diseased trees are usually characterized by stunted growth and a tendency to overbear. 26 California Agricultural Extension Service [Cir. 51 No effective remedy is known. If the galls are near the surface of the ground, they can be readily uncovered ; and if they do not com- pletely girdle the roots upon which they are growing, they may be chiseled off and the diseased tissue removed down to healthy Avood. The wounds are then painted with a disinfectant and covered with a protective paint like bordeaux paste or asphaltum. Trees having large galls near the surface of the ground may also be infested with borers. Fig. 10. — Apricot tree killed by oak fungus. The tree started to grow in the spring but died before midsummer. In this case it is probably best, unless the tree is vigorous and still producing satisfactory crops, to remove it and thus get rid of two pests at one time. Nursery trees showing evidence of galls on the roots should not be planted. Black Heart. — This peculiar disease is also known as verticilliosis. It attacks other stone fruits as well as a large number of woody and herbaceous plants. The symptoms, in the case of apricots, are often very striking. One or more branches on an apparently healthy tree wither and dry up during the growing season, usually about the middle of June (fig. 11). Upon examination, the xylem (wood) of these branches is found to be of a dark color, from which the disease 1930] Apricot Growing in California 27 takes its common name, black heart. Fortunately, the tree usually recovers. The disease seems to be most severe on trees up to five or six years of ag'e, and practically never appears on older trees. The trouble was formerly thought to be associated with frequent irrigation during the latter part of the growing season, but experiments have shown that this disease is common on tomatoes, and that where tomatoes are used as an intercrop in young apricot orchards, the young trees are often infected. The disease apparently enters the tree through its roots. rig. 11. — Api icot tree having several branches infectcMJ with black heart. The withered leaves remain on the diseased branches until fall. No remedy is known for diseased trees, but the trouble can be avoided by not using tomatoes, potatoes, eggplant, okra, or raspberries as an intercrop. The diseased branches that do not recover are removed at pruning time. Bacterial Gummosis. — This is a bacterial disease, characterized by cankers which usually p^roduce gum abundantly on the trunk and main branches. The cankers live from year to year, killing the branches that they girdle and forming a source of infection from which the disease spreads. Foliage on diseased branches is yellowish in color and later turns brown and dies if the branch is girdled. 28 California Agricultural Extension Service [Cm. 51 The best known methods of control consist in removing the badly diseased branches and scarifying and disinfecting the small cankers with a mixture of mercuric chloride and mercuric cyanide, 1 part each to 500 parts of water. This work should be done in the fall before the first rains and should be followed by a thorough inspection in the spring to find any cankers overlooked the previous autumn. Sour Sap. — The cause of this trouble is not fully known. The usual symptoms are failure to leaf out in the spring or sudden death of leaves and branches after the leaves have unfolded. When cut, the bark from trees having this trouble has a characteristic odor, from which the disease takes its common name. Cankers of various sizes may be found on diseased trees, but as a rule they are inconspicuous and produce no gum. In many cases the disease seems to stop at the surface of the ground, and suckers grow up from the apparently healthy roots below. No satisfactory control measures are known. INSECTS OF THE APRICOT Brown Apricot Scale and Black Scale. — These two somewhat simi- lar scale insects may both be found on apricot trees. When mature they are nearly hemispherical and are sometimes found clustered in great numbers on the twigs and small branches. They exude a honey- dew, on which grows a black smut that discolors the fruit. Effective control can readily be secured by the use of an oil emulsion spray applied between December and early February. Ordinarily one appli- cation every two or three years is sufficient. Branch and Ttvig Borer. — This insect is a small beetle which bores clean round holes at the bases of buds, fruit spurs, and crotches of small branches. Old prunings should be removed and burned to destroy breeding places. Peach Twig Borer. — Both the young tender tips of twigs and the fruit of the apricot are injured by this small brown caterpillar. The first-brood worms bore down the center of the new growth in early spring, causing it to wither and die back a distance of 4 or 5 inches. Later broods hatch about the time the fruit is beginning to ripen and enter, causing wormy fruit. The insect hibernates as minute caterpillars in the crotches of the branches and may be killed with a spray applied in the spring as the buds begin to break and when the caterpillars are leaving their bur- rows. As lime-sulfur is not a safe spray for apricots, a combination of 8-8-50 bordeaux and basic arsenate of lead, 3 pounds to 100 gal- lons, seems to be best. Through the use of this combination, the twig 1930] Apricot Growing in California 29 borer, brown rot, and shot-hole fung^us may be controlled in one spray- ing. If fungus diseases are not troublesome, nicotine sulfate, % pint to 100 gallons of water, with 3 pounds of soap as a spreader, may also be used to control the twig borer. For control of worms in the fruit a spray of basic lead arsenate at the rate of 3 pounds to 100 gallons of water with % pound of casein spreader may be used. This spray should not be used within two to three weeks of picking time. Pacific Peach Tree Borer. — This borer works in the trunk of the tree at or near the surface of the ground and does not attack the aerial portions as does the insect discussed in the preceding paragraph. The young borers enter the bark of the tree sometime between June and September and grow rapidly to a length of about one inch. The presence of this borer can first be detected by the gum and frass (a sawdust-like material which passes through the body of the insect) that is usually found on the trunk just above the surface of the ground. The insects live on the soft new tissue under the old bark, and often cause severe injury to old trees and death to young ones. They should be removed or killed before they girdle the trees. This work was formerly done by digging out the borers with a knife or hooked wire. Paradichlorobenzine, generally known as PDB, is a soil fumigant that has proved to be very satisfactory for this purpose. The soil around the tree is first smoothed, and then a ring of para- dichlorobenzine 2 to 3 inches wide is sprinkled around the base of tree with the inner edge of the ring 2 or 3 inches from the bark. Soil is then mounded up around the tree to a depth of 6 or 8 inches, and the mound is slightly compacted with the back of the shovel. Care should be taken to see that this material does not actually come into contact with the tree. For mature apricot trees, from 1^/2 to 2 ounces is the usual dose ; for younger trees, a smaller amount should be used. The most effective control is usually secured when this method is applied from about the middle of September to the middle of October. The soil should be fairly dry when the application is made, as experi- ments have shown that poor results are obtained on wet soils. As a rule only one treatment a year is necessary. Other Insects. — Other insects, such as cankerworms (measuring worms), fruit tree leaf rollers, red humped caterpillars, and brown day moths, are occasionally troublesome. Some of these insects can be controlled by spraying with powdered basic lead arsenate, 3 pounds to 100 gallons of water, or by burning or cutting off those which collect in colonies. The apricot, unlike other stone fruits, seems to be but little injured by red spiders. 30 California Agricultural Extension Service [Cir- 51 MISCELLANEOUS TROUBLES Fog Spot. — Near the coast a spotting of the fruit, similar to that produced by shot-hole fungus, sometimes occurs. It evidently results from climatic conditions and does not seem to be caused by a specific organism. Sunhurn. — Exposed fruit, particularly that on the ends of branches, is sunburned if daytime temperatures remain high for a period of several days or more, especially if these high temperatures occur immediately after a rain or fog. The affected spot shows cracks in the skin, shrivels, and dries unless it is entered by one of the com- mon fruit rots which commonly work on ripe or partly ripe fruit. Pit Scald. — Apricots in the interior sections are subject to a trouble which is thought to be caused by a period of exceptionally hot weather occurring between the time w^hen the fruit begins to lose its grass- green color and the time when it is ripe enough for shipping or can- ning. The first evidence is a softening of the flesh around the pit as if the pit had been heated and had thus caused the flesh in the interior to ripen faster than on the exterior, while the outside part of the fruit remains firm. The soft area turns brown in a few days, but no evidence of the trouble is visible at the surface. Fruit in the late stages of this trouble when cut often shows the presence of one or more of the rots which will attack ripe fruit. Evidence of this con- dition can be most readily seen by cutting the fruit at right angles to the suture. Such fruit cannot be used for shipping or canning but may be utilized for drying, if actual decay has not started. HARVESTING OF APRICOTS The stage of maturity at which apricots are picked depends largely upon what the fruit is to be used for. For drying, the fruit is picked riper than for canning; fruits for eastern shipment are picked while still hard and firm but showing some yellow color. The exact stage of maturity of apricots for each of these three uses can probably best be learned from growers or shipping companies who have had extensive experience in handling apricots. Picking for Eastern Shipments. — Apricots for eastern shipment are picked when they have attained a size that will malve a desirable 'pack' and show the undercolor to be turning yellow or straw color. If picked earlier, the fruit presents a poor appearance when it reaches the market. Experience indicates that trees bearing comparatively light crops mature their fruit a few days earlier and more evenly than do trees with a heavy crop. 1930] Apricot Growing in California 31 The California Fruit, Nut, and Vegetable Standardization Act of 1927 as amended in 1929^ gives the sizes of packages that may be used for shipping, makes certain specifications concerning the quality of the fruit that may be shipped, and provides for the manner in which the container shall be marked. This law also provides for the total amount of all defects that may be allowed in the package and for the tolerance for any one defect. It also makes provisions concerning the numerical count of the fruits in the container to prevent placing the largest and most attractive fruits on top. The usual container for eastern shipment is the four-basket crate, in which the fruit is regu- larly arranged. For local shipment and to some extent for shipment to more distant markets, lug boxes are also used. The standardization act defines the sizes of these containers, but also provides that other containers may be used if they are properly marked. Containers that fulfill the requirements of this act are usually obtained from the various growers' organizations or shipping companies. Picking for the Cannery. — Apricots for canning are picked w^hen the fruit is yellow over the entire surface but still firm. The fruit may or may not be blushed, depending upon its position on the tree. Representatives of the various canning companies are usually present in the field during the harvest season to help the growler in determin- ing when to pick the crop. In most cases the entire crop, if sold to the cannery, may be harvested in tw^o or three pickings. Picking for Drying. — Apricots for drying are picked when thor- oughly mature and in prime condition for eating 'out of hand. Fruit which is allowed to become overripe, however, does not made a high- grade product because of the difficulty in making a clean cut to remove the pit, and the tendency of the fruit to flatten out on the trays. Green fruit gives a product inferior in appearance and flavor to that allowed to mature fully on the trees. The orchard is .usually gone over three or four times to gather the ripe fruit. Most of the apricots for drying are picked by hand, but in certain districts the practice is to harvest the fruit by knocking it off, by shaking the trees and allowing the fruit to fall to the ground. In the latter case, in spite of precautions such as making the soil as free from lumps as possible, or spreading canvas sheets under the trees, the fruit is often severely bruised. Furthermore, small pieces of gravel or bits of soil are frequently imbedded in the flesh. An additional dis- advantage in drying fruit shaken to the ground arises from the fact that invariably a certain number of green, immature fruits fall to 9 Copies of this act may be obtained from the State Department of Agricul- ture, Sacramento, California. 32 California Agricultural Extension Service [Cir- ^l the ground with the ripe ones. When dried, these green fruits malve a smaller and less attractive product than the ripe ones. The cost of picking is reduced by shaking, but this practice may prove to be poor economy in the end, because of the inferior quality of the dried product delivered to the packing house. The practice of shaking apricots to the ground is strongly condemned by the various organiza- tions selling this fruit. Fig. 12. — After sulfuring, the trays are placed on the ground in the dry-yard for a day or two. The drying is completed in the stacks. DRYING APRICOTSio Dried apricots are almost always cured in the sun (fig. 12). They ripen early in the summer when there is abundant sunshine and little or no danger of rain. Sun-drying also tends to produce a uniform grade of fruit as far as color and appearance are concerned. In other words, some individual fruits when placed on the trays are less mature than others ; but when the drying process is completed, this difference largely disappears. In the case of dehydrated apricots, the fruit comes out of the dehydrator showing nearly the same color it had when it went in. An entirely acceptable product may, however, be obtained if the fruit is partially dried in the sun and finished in the dehydrator. 10 For full discussion see: Nichols, P. F., and A. W. Christie. Drying out fruits. California Agr. Exp. Sta. Bui. 485:1-46. 1930. 1930] ■ Apricot Growing in California 33 The apricot is cut in half by running a sharp knife entirely around the fruit at the suture. 'Slipping"' the pits, or forcing the stone through the fruit without cutting all the way around produces dried fruit with a ragged appearance. The halves are placed cut side up on the trays as close together as possible. Internal defects caused by worms or bruises are trimmed out or the fruit discarded. The pits are saved and dried. Fig. 13. — A convenient arrangement of sulfur houses and cutting shed for a small orchard. The trays are loaded on small cars as fast as they are filled ; the ends of the trays are staggered in stacking; and, when a sufficient number are ready, they are taken to the sulfur house (fig. 13). The house is then closed and the fruit exposed to the fumes of burning sulfur for a period of about 3 or 4 hours. The Dried Fruit Associa- tion of California states that exposure to dense sulfur fumes for 2 hours is sufficient for apricots. The sulfur is usually burned in a small pit under the trays and near the door. The amount of sulfur necessary varies somewhat according to the amount of leakage occur- ring from cracks or around the door ; but 3 to 4 pounds of sulfur, if used in a tight house, is sufficient for 1 ton of green fruit. The cutting and sulf uring should preferably be so arranged that the sulf ured fruit is not placed in the dry yard in the evening or late afternoon. As a rule, the fruit is dried in the sun 3 or 4 hours in the interior valleys and 1 or 2 days in the coast sections ; then the trays are stacked in a staggered pile with the open ends toward the prevailing winds. 34 California Agricultural Extension Service l^^- ^i After several days in the stack, the fruit is ready to be placed in the storage bin for sweating. During removal from trays, the 'slabs' and discolored pieces are picked out. Slabs are half-fruits which flatten out on the trays and do not show clean-cut edges when dry. They are not necessarily inferior in quality, but do not present a commercially attractive appearance. Apricots when properly dried should be firm but pliable, and the skin should not separate from the flesh when rubbed. On the other hand, they should not be dry enough to rattle on the trays. Individual pieces should practically resume their orig- inal shape when the pressure is released after squeezing a handful together. The 3 ft. X 6 ft. trays hold about 36 pounds of cut fruit, 55 to 60 trays being needed for a ton of fruit. With the 3 ft. X 8 ft. size, 40 to 45 trays, each holding about 48 pounds of cut fruit, are required. Each tray may be used three or four times each season, according to the length of the harvesting period. Because the crop ripens over a considerable period it is unnecessary to have enough trays to hold the entire crop at one time. The supply of trays necessary during the course of the season may be estimated by allowing 10 to 15 of the 3 ft. X 6 ft. trays and 8 to 11 trays of the 3 ft. X 8 ft. size for each expected ton of fresh fruit. The average dry yard space necessary is 1 acre of dry yard for each 20 acres of mature orchard. For a crop of 100 fresh tons of fruit in a season from 300 to 350 50-pound lug boxes are ordinarily required. The number of 3 ft. X 8 ft. trays to handle this size of crop varies from 800 to 1,100, depending upon how many times each tray can be used. The trays cost about $0.90 to $1.00 each, and the lug boxes cost $0.20 to $0.25 each. Other pieces of equipment necessary are 6 to 8 tray cars, 1 transfer car, 6 sulfur houses, sufficient tracks to move the trays from the cutting shed to the dry yard, shed space for cutting, and storage room for sweating the fruit. In some districts where grapes for drying are grown on the same farm with apricots, the small grape trays, approximately 2 ft. X 3 ft., are used. When necessary these small trays can be handled by one man, instead of two as required for the larger trays. Officials charged with enforcing the Federal Food and Drugs Act have made certain stipulations applying to the interstate shipment of dried fruit with special reference to the presence of dirty, decayed, or insect-infested fruit in the shipment. They suggest that the grower exercise every effort to dry only fruit free from dirt, decay, and insects. The location of the dry yard with reference to the dust from 1930] Apricot Growing in California 35 roads or near-by fields is important from the standpoint of keeping the fruit free from dust and grit. Washing the trays at intervals (fig. 14), whenever necessary during the drying season, and storing the dried fruit in clean, dry bins are helpful in producing a product which complies with this act. Details concerning the arrangement of dry yards, cutting sheds, and sulfur houses, and the care of utensils used in the drying process are given in bulletin 485 of this Station and may also be obtained from the field representatives of the various companies handling dried fruits. Fig. 14. — Washing trays with water under high pressure from a spraying outfit. VARIETIES OF APRICOTS Three varieties, the Royal, the Blenheim, and the Tilton, make up the bulk of the commercial apricot planting in California. Many other varieties, formerly extensively grown, are gradually being re- placed by the three given above. Several other varieties that combine earliness with other good qualities are being planted in limited num- bers in the early shipping sections. Observation of the blossoming season for several years at Davis indicated that Hemskirke and Moorpark reached full bloom first. These were followed in a few days by Blenheim, Derby, Newcastle, and Royal. Tilton was usually the last variety to reach full bloom. 36 California Agricultural Extension Service [Cir. 51 In ripening, Newcastle and Derby were first, followed in a few days by a group containing* the Blenheim and Royal. Then came Hems- kirke and Moorpark, with Tilton last. Royal. — This variety is supposed to have been originally intro- duced from Europe. The tree is vigorous and productive. Fruit, when thinned, is of good size, ripens evenly, and is used for canning, drying, and shipping. The fruit is large, roundish-oval, slightly com- pressed, with a shallow suture; skin is dull yellow, tinged with red in some districts; the flesh is yellow, firm, juicy, with a rich flavor when fully ripe. It is grown extensively in the warm interior valleys. Blenheim. — This variety is said to have been originated by a Miss Shipley of England. The tree is vigorous and productive. The fruit is medium to large in size ; oval in shape, and compressed ; the suture distinct and sometimes deep at the cavity; the color golden orange with red cheek in well-colored specimens. The flesh is deep yellow, fine grained, sweet and rich when ripe. The stone is free to partly clinging. Originally the Royal and the Blenheim were considered separate varieties. Of recent years nurserymen have propagated and sold them indiscriminately, so that it is now impossible to be certain of the varieties. Several strains of each have also been propagated, tending to increase the confusion. Tilton. — The Tilton is reported by Wickson to have originated on the place of J. E. Tilton of Kings County about 1885. The tree is a strong grower and bears well in some interior sections, but is not regular in production in some of the coastal counties. In certain interior valley sections, this variety sometimes drops a large portion of its fruit buds shortly before they open. The fruit is large, oval in shape, and distinctly compressed, having a flat appearance. The skin is light yellow in color, often with a pink to reddish blush. The flesh is somewhat lighter in color than either the Royal or Blenheim. Moorpark. — The Moorpark is an old variet}^ named about 1672 for the country home of Sir William Temple. It is of excellent flavor and quality, but is gradually being replaced because of its uncertain bearing and tendency to ripen its fruit unevenly. The fruit is large to very large, roundish ovate, and compressed with a distinct suture and halves often unequal. The flesh is bright orange, juicy, with a rich, luscious flavor. It is a fine variety for the home garden. Heniskirke. — This variety is also said to have originated in Eng- land. It is no longer being planted extensively in California. The fruit is large, and roundish, the halves are equal, the skin orange- colored. The flesh is very juicy and thought by some to be more 1930] Apricot Growing in California 37 sprightly than that of the Moorpark. It is said to drop before it is fully ripe. It is excellent for home use. Derby. — The Derby is a shipping apricot grown principally in the Winters district, where it is valued for its early ripening and shipping qualities. It is said to have originated on the old Derby place near Winters about 1900. The fruit resembles the Royal but ripens 4 to 7 days earlier. It is roundish ovate, slightly compressed in shape, with halves equal and apex slightly flattened. The color is somewhat lighter than the Royal when ripe, and the pit is a partial clingstone. Newcastle. — Originated with C. M. Silva and Son of Newcastle about 1881. It was formerly a favorite shipping variety, but seems to have lost favor among growers, possibly because of poor shipping quality. It is described as a roundish fruit, highly colored, with a nearly spherical pit. The tree was reported to be moderately vigorous and regular in production. This variety is reported to have ripened, in some seasons, as much as 25 days before the Royal. COST OF GROWING APRICOTS The cost of producing apricots varies considerably from year to year and from district to district. Generally speaking, large crops may be produced at a smaller cost per ton than small ones, because the costs of many of the necessary orchard operations, such as culti- vation, irrigation, spraying, and pruning, are not materially changed by the size of the crop being produced. The cost of other operations, such as thinning, picking, and drying, increases for each acre but not necessarily for each ton, when the crop is large. In some sections additional expenses are incurred because of the necessity of heating the orchard during frosty nights, or because of the presence of certain diseases that require an unusual number of sprayings for their control. No unusual or costly equipment is necessary for groAving apricots. In addition to the ordinary orchard machinery, a supply of trays and lug boxes, an inexpensive cutting shed, and a number of sulfur houses, according to the size of the orchard, are about all that is needed. The approximate numbers of trays and boxes required for a crop of certain size have been given in a preceding paragraph. The University of California Agricultural Extension Service has studied the costs of growing apricots in one of the counties that pro- duces this fruit on a large scale. While the results obtained in this one section may not necessarily apply exactly in all apricot centers, they will give an approximation of the costs of many of the operations involved in producing this fruit. 38 California Agricultural Extension Service [C^ir- ^l Under the conditions given, the costs of pruning, harvesting, and drying constituted a major portion of the cash expenses during the year. During a three-year period, the average cost of pruning mature trees and burning brush in fourteen orchards was approximately $18.00 an acre or about $4.50 per ton of fresh fruit; in individual orchards the costs varied from $11.00 to $29.00 an acre. The average time of pruning each tree was % hour. These costs are probably representative of those in other apricot districts. Harvesting the fruit constituted a considerable item in the total cost of operation. The average for three years was about $50.00 an acre or $11.00 a ton. In individual orchards, the cost of picking varied from about $6.00 to $14.00 a ton. Drying costs varied from $66.00 to $81.00, the average being about $73.00 an acre. The combined costs of harvesting and drying aver- aged $17.78 per ton of fresh fruit. On a dry-ton basis, the drying ratio being approximately 5 to 1, the cost was $88.80, which is in agreement with costs estimated by growers in other parts of the state. The cost of producing a covercrop varied from $1.83 to $9.51 an acre or from $0.42 to $1.47 per ton of fruit. Presumably in years of low prices or poor yields less money was spent on this item than in years when returns were better. The cost of spraying averaged $8.97 an acre or about $2.04 a ton. This figure is fairly low and probably means that the growers in this district were able to produce clean fruit with a minimum of spraying. In years favorable to fungus diseases, this cost would probably be much higher than it was during the years when this study was made. The cost of irrigation is given as about $8.50 an acre or $2.00 a ton. The region in which this study was made is supplied with rela- tively cheap gravity water. If it were necessary to pump water from deep wells, the cost of irrigation would be greater. The average cost of cultivating the orchards was found to be nearly the same as that of irrigating them. The cost of this operation in different orchards, however, varied widely; e.g., one orchard was culti- vated at a cost of $2.00 an acre, and another at $22.50. The tendency seems to be to do less cultivating than in former years. Thinning is not practiced in all apricot orchards ; but, where it is practiced, it often constitutes a considerable item of expense. The average cost as reported in these studies was $6.65 an acre, or $0.66 a ton. Extreme variation was found in different orchards, the cost varying from $1.75 to $25.34 an acre. Thinning is evidently one oper- 1930] Apricot Growing in California 39 ation that must be watched carefully in order to have the work done economically and effectively. Contrary to what might be expected, the cost of protecting the orchards from frost by heating did not prove to be exorbitant. The costs for labor and material in 1929 in the heated orchards were $17.50 an acre or about $1.57 a ton. In other years, when frost is frequent, this cost would of course be increased; and in years of little or no frost, it would be reduced. Ordinarily the operating costs of lard pail heaters may be assumed to be about $1.15 an acre for each hour the heaters are burning. To the foregoing items must be added the costs of propping the trees when necessary, of hauling fruit, or repairs on tools, ladders, trays, and boxes, and of the inevitable miscellaneous jobs which are hard to foresee. In addition there must be considered taxes, interest on land, interest and depreciation on trees, improvements, equipment, and buildings. Records secured in three counties by the Division of Agricultural Extension in 1926 and 1927 showed that the total average cost of producing apricots including all of the items in the preceding paragraphs varied from $180.31 to $187.30 an acre, or $39.02 to $53.04 a ton. agricultural extension service circulars No. 3. 5. 7. 8. 10. 11. 12. 13. 14. 15. 16. 17. 21. 22. 23. 24. 25. 26. 28. Feeding Beef Cattle in California. Lettuce: Series on California Crops and Prices. Suggestions on Grapefruit Culture in Imperial Valley. Diseases and Parasites of Poultry in California. Rabbit Raising. The Home Preparation of Fruit Candy. Cauliflower Production. Wool Production in California. The Manufacture of Monterey Cheese. Selection and Care of Electrical Equip- ment Used in Dairy Manufacturing. Pork Production in California. Irrigation of Orchards by Contour Fur- rows. Liver Fluke and Stomach Worm of Sheep. 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. Brooding and Pullet Management. No. 29. Control of Pocket Gophers and Moles in California. 30. Elements of Grape Growing in Cali- fornia. 31. Powdery Mildew of the Grape and Its Control in California. 32. What to do About Bovine Tuberculosis. 33. Rearing Dairy Heifers Free from Tuber- culosis and Abortion Disease. 34. Plum Growing in California. 35. Alfalfa Production. 36. Beekeeping for the Beginner in Cali- fornia. 3 7. Home and Farm Preparation of Pickles. 38. Alfalfa Varieties and Seed Supply. 40. Frost Protection in California Orchards. 41. Prune Culture in California. 42. Peach Culture in California. 43. The California Avocado Industry. 44. Bang's Disease (Infectious Abortion). 45. Zinc Chloride Treatment for Pear Blight Cankers. 46. Cherry Culture in California. 47. Equipment for the Bulk Handling of Grain. 48. The Manufacture of Cottage Cheese. 16m-l,'31