of The College of A £ V \ UNIVERSITY C A L I F O RfcN I A LIVE PRODUCTION IN CALIFORNIA H. T. HARTMANN CALIFORNIA AGRICULTURAL Experiment Station Extension Service MAI^AL 7 LIVE PRODUCTION IN CALIFORNIA H. T. HARTMANN UNIVERSITY OF CALIFORNIA COLLEGE OF AGRICULTURE Agricultural Experiment Station and Extension Service THIS MANUAL is one of a series published by the University of California College of Agri- culture and sold for a charge which is based on returning only a portion of the production cost. By this means it is possible to make available publications which, due to relatively high cost of production, or limited audience, would otherwise be beyond the scope of the College publishing program. CONTENTS SECTION 1 1 The Economic Background ... a short history of olive produc- tion . . . importance of the crop . . . the major varieties. SECTION 2 12 Getting Started . . . choosing a site . . . preparing the land . . . planting and caring for young trees. SECTION 3 15 Propagation, Training, and Pruning . . . information about olive trees that the grower can profitably use. SECTION 4 33 Setting a Satisfactory Crop . . . the effects of controllable and non- controllable influences on fruit set. SECTION 5 39 Production of the Crop . . . the cultural practices that will con- tribute to satisfactory yield through the years. SECTION 6 50 Pests and Diseases . . . how to identify them . . . some recom- mended controls. Distribution of olive acreage in California. Each dot represents 100 acres. Data from California Crop and Livestock Reporting Service. Tulare County leads with 9,019 acres, followed by Butte County with 5,041 acres, and Tehama County with 3,392 acres. THE AUTHOR: H. T. Hartmann is Assistant Professor of Pomology and Assistant Pomologist in the Experiment Station, Davis. OLIVE PRODUCTION in California H. T. HARTMANN l.The Economic Background ... a short history of olive production . • impor- tance of the crop . • the major varieties. lives are among the important tree fruits produced commercially in Califor- nia. Crop values of olives for a five-year period ending in 1950 held ninth place in the list of California tree fruits — above plums and cherries, but below almonds and apricots. The olive crops showed an average annual valuation of $9,763,000. In bearing acreage, olives ranked tenth in 1950, above apples, plums, and avoca- dos, and just below figs and pears. Commercial olive orchards in Califor- nia are located mostly in the Sacramento and San Joaquin valleys. With their rela- tively cold winters and warm summers free of fog, they are more suitable for olive production than the coastal re- gions or southern California. Yields are heavier and more regular, and insect control is less difficult than along the coast. Although many olive plantings were made along the coast in the past, there are few new plantings in this area. However, the olive will grow in all Cali- fornia counties except where winter tem- peratures are low enough to kill the trees. How did olive production start in California? Commercial olive production is gen- erally found in two belts around the world, one between 30° and 45° N. lati- tude, the other between 30° and 45° S. latitude. At higher latitudes the olive can- not be cultivated because of low winter temperatures. Olive trees will not survive temperatures below 10°F. (-12.2°C), most varieties being injured at 15° F. (-9.4°C). Olives will grow vegetatively nearer the equator than 30° N. or S. lati- tude, but with few exceptions are un- fruitful. This is due probably to insuf- ficient winter chilling for proper flower formation. There is evidence that olives were first grown on the island of Crete in the Medi- terranean Sea about 3500 B.C., although some historians state that they originally spread from a range in Syria westward along the southern coast of Turkey to- ward Greece. They were not planted in California, however, until 1769, when olive seeds were brought to Mission San Diego from Mexico by Father Junipero Serra and Don Jose de Galvez. The variety resulting from this early planting was named the Mission and is, perhaps, a seedling of the Spanish vari- ety, Cornicabra, which it resembles. The Mission today comprises about half of the bearing acreage of olives in California. Other commercial varieties currently grown here were introduced about 1875 from Spain and Italy, where they existed as standard pickling varieties. Numerous varieties were introduced [i] wo a| t- CO oqiqcopiqpoqt- r| O O H tfi r] O IT t> o o fed© g« «> P5 N O H «J 00 r- CO O W CO CO rH cs CN c d : d <2 o§ ft tH Cft 00 CO G) CO CO T- r- tH n nh • o m *-" §5 sg J? o b S b 3 o ®r cd oq to ^ q p to (D ^ 00 IO ri 6 IO © t- • o «o «o Tj< ; CO IC9 iH CJ c lO o • o -* : d : c * ►— ft tH co «tf co T-t t- t4 I— in p p *** ' ° g ■^ rH rH rH (A (CHN^NNOIM t- rl © t» OS H r CN CN rH O O O O o ^OMoinddi- t-* oo cc c 1- IT p p iq co o co e4 d d o 3 IHMH >»** Tt iH CO CO ^ T- r- O. tH CD O CO ** rH CO iH iH ■d yw ' M © CO Q. ^?3 O O fc~ ^ ^ t - CJS 'tt* t" c^ CO -<* ^ n d t« t> «* lO -^ •* rH 0C ■<* > "* 0) to © to c «o« to **s (O^Otf CO "^ IC c c O © p CC % o p C5 a (N O C p 35 cr o T* 8S t- CD CS CO CO rH h oS d « a- (N t> C5 (> CJ oc 1- i-i CO « u: c tfi ^ d d c o in 0) ©°§ 3 d ^C O) w oc cc oo cr "<* r- r-T CC <> r- 00 N t c c- Cn H 00 N « lO" N H r > cc rH u: l« __ * T^ M c d oo" d p t- lO t- CO i-l rH 's ' ^ CN rH r- ' 00 " oc * CO~ rt " TJ " C4" rH~ r- 1- r- * s A XJ--' •g 1 3 "O V d Q. a "O o C s t» u A 1 CO 1. (4 < o O o • 1 1 o fc 02 sa i c co .1 o £ "3 1 o .1 1 Eh g a S c c b < •c 1 V A CO "8 1 1 p hi < rJ •s I Ph el t < o s a 4 32 si wQ * -♦- 1 between 1850 and 1900 from the Medi- terranean countries, and much effort was given to testing them, chiefly for oil pro- duction. By 1875 the industry showed promise of becoming important in Cali- fornia agriculture, with about 11,500 trees in bearing. In 1910 trees of bearing age numbered 958,000, but the emphasis was shifting from oil to table varieties, with many orchards grafted to the more profitable pickling types. A peak in bear- ing acreage was reached in 1928, but by 1950 it had declined from 29,000 to 26,826 acres. During the past 4 or 5 years, however, many new olive plantings have been made in California. The nonbearing acreage in 1950 was 4,193 as compared with 620 in 1940. The present industry in California California produces more than 99 per cent of the olives grown in the United States. Arizona is the only other state having a commercial acreage, with a pro- duction of 100 to 600 tons per year. Olive production in the United States averages about 47,000 tons per year, or almost 1 per cent of the total world production. The California output of olive oil sup- plied only 14 per cent of the total needs of the United States during the years 1945- 50, the remainder being imported, mostly from Spain, Italy, Tunisia, and France. Imports of olive oil into the United States are increasing, 10,419,000 gallons having been imported in 1950 — the larg- est amount entering this country in 20 years. Spanish-green olive production in Cali- fornia accounted for only about 12 per cent of this product consumed in the United States during the years 1945-50, the remainder being imported, mostly from Spain. This type of olive was not processed commercially in California until 1935, and the output has not in- creased since 1940 chiefly because of com- petition from the imported product. It is apparent from the data on page 4 that the olive industry of California is based on the production of canned ripe olives (black-ripe and green-ripe), with the output increasing from 2,300 tons in 1919 to 20,400 tons in 1949. The production, utilization, and aver- age returns to California olive growers for the postwar years 1945-50 are given on page 6. It may be seen from this table that production of olives for can- ning is usually the most profitable outlet for the grower. During the war years, however, when foreign shipments of olive oil were cut off, the sale of olives for oil manufacture was as profitable as for can- ning. A limited market exists for the ship- ment to eastern cities of fresh, uncured olives that are bought by persons of Mediterranean descent for processing at home. The yield per acre for olives varies considerably throughout the state, de- pending upon the district, age of trees, variety, and cultural care. For the 10- year period ending in 1950 the average bearing acreage of all varieties of olives Acreage, yields, and returns to growers for California olives from 1922 to 1950. Sharp drop in acreage in 1933 was due to freeze from which trees made a rapid recovery. Data in the graph from Calif. Crop and Livestock Reporting Service. [3] in the state was 24,946, and the average marketable crop was 46,727 tons, giving an average yield per acre for the state of 1.87 tons. Heaviest yields are obtained with all varieties in the Tulare County district, with the Manzanillo tending to outyield other commercial varieties in all districts. Olive trees generally start bearing in California during the fourth or fifth year and gradually reach full production by the twelfth to twentieth year. It has been the experience of many California olive growers that older trees, 40 to 50 years old, start declining in productivity, espe- cially if planted too close together. Close- ness of planting, which affects the ulti- mate size of the tree, is an important fac- tor treated under the section on Establish- ing Your Orchard. Marketing your olives Processor-canners, of whom there are about 30 in California, handle the mar- keting of olives. Their output is chiefly the canned ripe olive, although most also pack Spanish-green, chopped olives, and other types; some also manufacture olive oil. A few grower-owned cooperatives market a considerable quantity of the Comparisons between California production and imports of olive oil, Spanish-green olives, and canned ripe olives. 1930-1940 1940-1945 1945-1950 Olive Oil Average annual California production Average annual U.S. imports Per cent of U.S. consumption of olive oil supplied by California (1945-1950) . . . 428,000 gal. 7,328,000 gal. 1,200,000 gal. 779,000 gal. 680,000 gal. 4,221,000 gal. 13.9 Spanish green olives Average annual California production Average annual U.S. imports Per cent of U.S. consump- tion of Spanish-green olives supplied by Cali- fornia (1945-1950) 588,000 gal. (1935-1939) 6,188,000 gal. 1,738,000 gal. 7,687,000 gal. 1,251,000 gal. 9,437,000 gal. 11.7 Canned ripe olives (Black ripe, green ripe) Average annual California production Average annual U.S. imports Per cent of U.S. consump- tion of canned ripe olives supplied by California .... 3,349,000 gal.* (9,210 tons) none 5,330,900 gal.* (14,660 tons) none 6,878,545 gal.* (18,916 tons) none 100 * A gallon is approximately equal to 5.5 pounds of olives. Data from: California Olive Association; Calif. Agr. Exp. Sta. Bui. 678. Production of Spanish-type green olives; Calif. Agr. Exp. Sta. Cir. 370. California olives, Situation and Outlook, 1947. [4] olives produced. About 80 olive-oil plants operate in California, although some do not run every year. Processing olives and olive oil requires considerable capital as well as technical knowledge. The California Olive Association, with headquarters in San Francisco, was or- ganized in 1920 to promote the interests of the ripe olive industry, largely through collecting and pooling information. It is a trade association of ripe-olive canners but does no marketing of olive products. Under the California Marketing Act of 1937 an order was issued entitled, "Mar- keting Order for California Canned Olives and California Green Olives." This was made effective in February, 1948. Its principal objectives are: (1) to carry out advertising and sales promotion activities for California canned olives; (2) to establish certain minimum-quality requirements for canned olives and Cali- Bearing and nonbearing acreage of olives most important districts as of in California in the 1950. County Bearing acreage Non-bearing acreage Total Sacramento valley Butte 4,473 704 1,813 760 2,839 377 727 568 129 11 10 553 39 5,041 Glenn 833 Sacramento 1,824 Shasta 770 Tehama 3,392 Yolo 416 Yuba 727 Total 11,693 1,265 380 344 494 353 7,075 9,911 1,066 1,133 471 1,062 1,310 192 81 150 85 1,944 13,003 San Joaquin valley Fresno 1,457 Kern 461 Kings 344 Madera San Joaquin 644 438 Tulare 9,019 Total 2,452 41 79 136 8 12,363 Southern California Los Angeles 1,107 Riverside San Bernardino 1,212 607 San Diego 1,070 Total All others 3,732 1,490 264 167 3,996 1,657 State total 26,826 4,193 31,019 Data from California Crop and Livestock Reporting Service. [5] • - d e> ^ o w o n (O t- lO T)i fl) M CM O © ■£ *-> N W H rl H N cs •43 T3 (► £ 4) 6* 69 1 3 M o o o o o © © o o o © o CO o o H d o o o o o o o i- in H d oo d oo » n CO ^ ^ *o CO ^ ©5 7 111 ©■£ n OS CO CT> 00 OS © 00 O » fj H ^ tN ^ r-i *4 rH lH CO s • O > * 03 o h o > © o> 69- 69 o d 5 O oi © © © © O © o o © o o © CO 00 1 o d o » H M N rH •a "£ r-i d k cfl "rj" M- 9 23 3 u © - d O « 00 Tj< (35 O ■<* © t> t- t> © 4> v> €0 01 44 o e o W u O o o o o o o 00 CO § CD D\ C- CO ft. CO d o S © > H 0> ^ 05 CO C^ CT> ua H H CO rH H boo J. © TJ 2 £ c Sag si 2 H O «fi ^ 00 U5 OIO00CN IOO 00 d © csta *d C4-S # N CO ^ tH tN CN CO CN *8 a 4) 2 > © a) 69- 69 *2 «■* J3 g <2 to — I © *£ to O O O O O O O O O O O O CO rH 3 d if) UJ t- IO Tf OJ 09 «£: o » W.rt s H CO t> CO CO O «tf « «i3 53 -a C rl N H H (N N rH # 35 ► * ^2 3 ^w ft. d a 11 a 4) •Ho ^^ ©r? O. 8 o !•§ IO CS l> CO O) O a. a ■ ? l •^ TjH -^ "<* ^ Ifi a, CJS <3> CTS CJ> CT> OS > rH tH rH T-i rH rH < fornia green olives; and (3) to establish certain minimum-size requirements for canned, whole, or pitted olives. An Olive Advisory Board of seven olive producers and seven processors was established to make recommendations and assist the Director of Agriculture, California State Department of Agricul- ture, in the administration of the Market- ing Order. To carry out the objectives of the Order a compulsory fee not to exceed $12.00 per ton is assessed on all olives received by processors for canning or preservation. One-half this assessment is paid by the processor and one-half by the producer. It is generally believed that the nation- wide advertising campaign carried out under this marketing order has stimu- lated the demand and sale for California ripe olives. A second olive Marketing Order en- titled, "Marketing Order for Canned Olive Stabilization," was placed in effect in March, 1952. The principal objectives of this Marketing Order are: (1) to pro- vide reasonable correlation between the supply of canned olives and the consumer demand, and (2) to establish more stable marketing conditions in the canned olive industry. Under this Marketing Order an Olive Stabilization Advisory Board was established consisting of nine members, each a processor of canned olives. This marketing order affects the olive grower indirectly, inasmuch as the me- chanics of the order apply only to proces- sors. Should this Marketing Order suc- cessfully attain its stated objectives, how- ever, olive growers will benefit through the increased stability brought to the in- dustry. Five varieties are commercially important The Mission variety is grown on about 52 per cent of the bearing acreage in Cali- fornia (13,846 acres in 1950). Next in order are the Manzanillo, Sevillano, Asco- lano, and Barouni. In nonbearing acres [6] Fruits and pits of the most commonly grown olive varieties in California. Top to bottom: Redding Picholine; Nevadillo; Mission; Manzanillo; Barouni; Ascolano; Sevillano. The sample fru/ts, half- fruits, and pits shown are about nine-tenths actual size. [7 in 1950 Manzanillo led with 2,229 acres (or about 53 per cent of the total) fol- lowed by Sevillano, Mission, Ascolano, and Barouni. The value per ton of olives increases considerably as the size of the fruit in- creases. Therefore varieties producing large fruits, such as the Sevillano and Ascolano, should be considered in making any new plantings. If these large-fruited varieties were available to processors in considerably greater quantities, however, price differentials between size grades might not be so large. In the Tehama County district, Se- villano and, to a lesser extent, Manzanillo are preferred for new plantings and for top-working other varieties. In Butte County, Mission is chiefly grown, the packers in that area favoring this variety. There are small acreages of all the other varieties, with Manzanillo increasing. In Tulare County, Manzanillo is considered the most suitable, with Sevillano and As- colano recommended for more limited plantings. Mission is not advised for new orchards in the Tulare district. All the olive varieties grown commer- cially in California are table olives for pickling. No orchards are planted for the express purpose of producing olive oil, as experience has shown that California is unable to produce it as cheaply as the Mediterranean countries. Olive oil pro- duction in California is largely a salvage operation, usually for small, cull, or frozen fruits. Each of the five commercial varieties will be treated briefly below. You may find a fuller discussion of varieties in California Agr. Exp. Station Bulletin 720, Olive Varieties in California.* Mission. The fruit of this variety is easy to process and its high oil content provides an alternative market for the grower in years when olive-oil prices are satisfactory. Furthermore, this variety is most resistant to cold of any commer- * Out of print, but may be obtained in many libraries. cial variety grown in California, some old trees surviving temperatures as low as 8° F. in the 1932 freeze. Its disadvantages, however, tend to outweigh its advantages. The fruit is relatively small, with the low- est flesh-pit ratio of any commercial vari- ety. Since the demand is for the larger fruits, this must be met with other vari- eties. Missions of "Mammoth" or larger size are rare. The fruit matures for pickling rather late in the season, during late October or November, when there is danger of freezing injury. If this occurs, the fruit shrivels and is no longer suit- able for pickling but is useful only for oil extraction. This variety tends toward alternate- bearing, in which a large crop of small fruit is produced during the "on" year and a small crop of relatively large fruit in the "off" year. Some Mission orchards, however, especially in the Butte County section, bear quite regularly and have been profitable. Mission trees tend to grow tall and unless kept pruned become difficult to harvest. While resistant to attacks of olive knot, Mission is quite susceptible to infections of peacock spot. It is believed that there are several dis- tinct strains of Mission. Manzanillo. According to data of the California Livestock and Crop Reporting Service, this is consistently the highest- yielding of the four leading commercial varieties, averaging about 75 per cent higher than Mission. The trees are rela- tively low and spreading and easy to har- vest. Fruits of this variety process easily, are generally larger than those of the Mission, and have a much higher flesh- pit ratio. The oil content is sufficiently high to justify use of the crop for oil ex- traction, if this becomes necessary. Bear- ing is fairly regular, not fluctuating in yield as much as some of the other vari- eties. The fruit matures early enough so that it is rarely injured by early frosts, but trees of this variety are considered to be quite susceptible to low-temperature injury. Manzanillo is not likely to be- [81 n bo M O 5 * © o » © u *E V. "5 u c > # > "o o X *• c o 4) (A c o "Z a E o v £ o Q ° II CM ° o'S, V u c$ O 1- 45 05 *3 to 0. ? © 05 ._ §>.B.a2 2 to w ho 11-1 00 rH o lO ~ (N t- 25 - £ 5 42 *> S3 b a a> d pq H H t- - g O) ® oS *2 £ ,2 ^ M H H o o o *. a3 O « ft I 1 o & o S ® ►». 0) O i fl 4J (« fa « M t» ft ft CD 1 OCOCO«OCOCOC>Ot> o w o o w H t- -* OS t* CO N N H 5 » W M q o q q o» ri eg io h h 6 d 6 6 t?i i^ i>* h n oi H N N tN CD -f- ^®5 So.3 w o glss » » W H 13 CO b CO rt » h£ ft t- ^ OJ t- CO CO tN N rl qoqio^o>eooqo5H 6 d 6 n od t> n «d ^ t»' i-H (N r-l i-H rH O N 00 CO If) t> 00 fl> H CO ■a e ||1 1 3 © W O 3 ^3Sh w ^ T3 co 02 02 S.S5 2! en ft ss -c CO . CD 3! °o 9 a^ c »-l» CD^ CD >>"3 J CD M «3 " fl d • lis S 2 2 £ s 2 •\«f2P8fes l ><> Top— Enlarged views of olive flowers at full bloom: A, staminate (male) flower; B, perfect (male and female) flower; P, pistil. Center— Photomicrographs of olive pistils (female part that develops into fruit) shortly before bloom; C, aborted pistil in staminate flower; D, developed pistil in perfect flower. Bottom— Inflorescences (flower clusters) shortly before and during bloom. (A and B after Brooks.) [16] in the floral tube. Its color is a light green in the bud, becoming a deep green at full bloom. In the staminate flower, the pistil is rudimentary, barely raised above the floor of the floral tube, while the style is small and either brown, greenish-white, or white. The stigma is not large and plu- mose as it is with functioning pistils. Occasionally, pistils reach an almost nor- mal size before aborting. The reason for the abortion of the pistil in staminate flowers is not known, but it is possibly some nutritive or hormone relationship. The normal pistil in the olive flower has two carpels originally, each contain- ing two mature normal ovules capable of fertilization and development. However, in the subsequent fruit only one carpel is found, usually having only one seed. The olive fruit is considered a drupe (like the peach, apricot, and plum). It consists entirely of carpel tissue, the wall of the ovary having both fleshy and dry portions, the skin being the exocarp, the flesh the mesocarp, and the stone or pit, the endocarp. The seed is within the endo- carp. The mature seed is made up of a thin seed coat, enclosing the starch-filled endo- sperm, which surrounds the tapering, flat, leaflike cotyledons and short radicle (root) and plumule (stem). The first evidence of flower formation in olive buds is found about 8 weeks be- fore bloom, with a subsequent rapid de- velopment of floral parts. Full bloom in California occurs from about May 1 to June 1, depending upon the variety, sea- son, and location. The blooming period is generally one to two weeks earlier in the southern than in the northern sections. Propagation The olive, like other fruit species, fails to produce the true variety from seed, hence must be propagated by budding or grafting the desired variety onto seed- lings, or by some other vegetative method such as cuttings or suckers. A full dis- cussion of propagation will be found in California Agr. Exp. Sta. Cir. 96, Propa- gation of Fruit Plants. Nursery stock. Of the methods for starting olive trees used in olive-produc- ing countries, the first three in the list below are the most important. 1) Grafting or budding seedlings in the nursery or volunteer trees in orchards or forests. 2 ) Removing suckers from the base of old trees and starting them in the nursery or orchard. 3) Making cuttings of wood several years old, 1 to 3 inches in diameter. 4) Making cuttings of year-old growth with leaves attached. 5) Removing and planting knobby-type growth (ovuli) from trunk and roots of old trees. 6) Layering suckers from old trees by mounding soil around the base of trees. 7) Planting truncheons (large pieces of wood horizontally just under the soil) . 8) Layering the shoots arising from trun- cheons. 9) Bench-grafting (whip-grafting of scions onto whole or piece roots). All the above methods have been used to some extent in California, but the most satisfactory are : propagation by cuttings, both hardwood and softwood, use of de- tached suckers from old trees, and graft- ing or budding onto seedlings. Propagation by hardwood cut- tings. If properly done this is probably the best method, as it requires no special equipment. It has the disadvantage of using relatively large branches ; therefore if you want a considerable quantity of cuttings it involves removal of much fruit- ing wood from trees. If you can find an orchard that is being pruned heavily, you can use pruning wood gathering imme- diately after cutting. Take care in all types of propagation not to use wood infected with Olive Knot, or the new trees will have this disease. Do not try to start Sevillano trees from cuttings, as they root with difficulty. The use of hormones is beneficial. The figure [17] \ i Mission olive nursery stock after 2 years in nursery propagated in 3 ways: left— suckers with piece of old root attached; center— hardwood cuttings; right— softwood cuttings. on page 20 shows trees propagated by this method after one year in the nursery. Directions, Prepare cuttings in late January or early February from wood 3 One-year-old cuttings: left, no treatment; right, soaked 24 hours in indoleacetic acid and callused in moist sawdust 30 days at 65° F. to 4 years old, and from 1 to 3 inches in diameter. Cut into 1-foot lengths and re- move all leaves. Soak the basal few inches of the cut- tings for 24 hours in a fresh solution of indoleacetic acid or indolebutyric acid at a strength of about 13 p. p.m. (% gram in 1 gallon water).* Dissolve the chemi- cal in a small amount of alcohol before adding to the water. Bury the cuttings in moist (not wet) sawdust for about 30 days for callusing, preferably in a building where the tem- perature will be from 60° to 70°F. The callusing treatment is essential for this method. Hormone treatments without cal- lusing are of no value. After callusing, it has been recom- mended that the cuttings be soaked in a Vitamin B x solution for another 24 hours before planting. Results of tests conducted by the California Agricultural Experi- ment Station showed no benefit from this. Plant cuttings in a well-prepared nurs- ery soil, with about % of the cutting above ground. Frequent irrigations dur- ing the summer are essential. * Most druggists will weigh these small amounts. [18] Indoleacetic acid and indolebutyric acid, referred to on this page and else- where, are available from the Eastman Kodak Co., Organic Chemicals Division, Rochester 4, N.Y.; or from Thompson Horticultural Chemicals Co., 3600 Monon St., Los Angeles 27, Calif. Propagation by softwood cut- tings. With this method many cuttings can be prepared without the removal of an excessive amount of fruiting wood from trees. It has the disadvantage of requiring glass-covered beds or green- house facilities and, preferably, provision for maintaining bottom heat. While the cuttings of most varieties will root even- tually without any hormone treatment, the response is so marked that it is well worth while to use it. This type of cut- ting, even after having rooted, must be handled under almost greenhouse condi- tions, or the losses will be heavy. How- ever, if cuttings are properly hardened off they can be lined out in the nursery row. Some nurserymen prefer to transplant rooted cuttings into gallon cans and grow them in the cans until they are large enough to plant in the orchard. Rooted softwood cuttings are shown on page 20. Directions. Take cutting wood in Sep- tember from wood of the previous sum- mer's growth, using fairly vigorous water- sprout type of wood. If greenhouse facili- ties are not available, the cuttings should be started soon enough so that they will be rooted before cold weather. Prepare the cuttings as indicated above, avoiding the use of the succu- lent terminal portions of the shoots. They should be about 4 or 5 inches long, with the basal cut just below a node. Retain two leaves at the top of the cutting. Keep cutting-wood and cuttings damp at all times. Dip the basal ends of the cuttings for The use of hormones, callusing treatment, and Vitamin B* in the propagation of olives by hardwood cuttings. Cuttings started in nursery on April 6, 1951. Mission variety, Davis, California. Treatment Per cent of cuttings rooted Av. no. of roots per cutting Av. shoot length per cutting Check (no treatment) cm. 4 Callused in moist sawdust for 30 days 15 2 30 Callused in moist sawdust for 30 days. Soaked in hor- mone for 24 hours before callusing and Vitamin B , for 24 hours after callusing. 1 Indoleacetic acid (13 p.p.m.f) Indolebutyric acid (13 p.p.m.) Water check 50 95 35 8 22 4 52 124 70 Callused in moist sawdust for 30 days. Soaked in hor- mone for 24 hours before callusing but not in Vitamin Indoleacetic acid (13 p.p.m.) Water check 65 50 13 4 131 32 * Several Vitamin Bi preparations are available' for use on plants. The one used in this test was "Vita- Flor," containing 0.1 per cent thiamin chloride, used at 8 drops per gallon. t Parts per million. [19] Softwood cuttings after 7 weeks in the rooting medium: left to right, dipped for 1 second in indolebutyric acid at 4,000 p. p.m.; leaves retained but not treated; leaves removed but treated with IBA; leaves removed and not treated. 1 second in a 50 per cent alcohol solu- tion of indolebutyric acid (see above) at about 4,000 p.p.m. (Add an equal amount of water to 95 per cent alcohol to obtain approximately a 50 per cent alco- hol solution. Dissolve % gram of indole- butyric acid in % pint of the 50 per cent alcohol solution. This will be enough to treat several thousand cuttings. Rubbing alcohol may be used.) Place the cuttings in beds of clean sand, or sand and peat moss, or sand and coarse (insulation grade) vermiculite, or coarse vermiculite alone. Keep the cuttings cov- ered with glass at all times and water them frequently, but not excessively, to main- tain a high humidity. Protect them from the full sun. Some provision for bottom heat under the cuttings, such as electric soil cables or a one- or two-foot layer of fresh manure, is desirable but not essential. The cuttings will usually root in 10 to 15 weeks, when you can remove them and transfer them to pots or gallon cans. Keep them under conditions of high hu- midity for a time after this to prevent losses. After being well-established in the soil, they can be moved to the nurs- ery or, if in gallon cans, left until large enough to set out in the orchard. Propagation by the use of de- tached suckers. This very simple method of starting new trees is highly successful, requiring no special equip- ment. The suckers are'sometimes planted directly in the orchard, but it is prefer- able to grow them a year in the nursery. All that is necessary is a source of large trees which produce an abundance of suckers from the base. One disadvantage of this method is that the suckers may be of an unknown or an unwanted variety, in which case they must later be budded or grafted to the variety desired. Directions. In February remove the suckers from the old tree, using an ax or sharpened heavy shovel to take a piece of the old root with the sucker. Cut back to about 18 inches and remove all leaves. Plant immediately in the nursery with the root piece about 6 inches deep. Irrigate when necessary through the summer. After one year in the nursery, trees are [20] usually large enough to set out in the orchard. Propagation by grafting or bud- ding seedlings. There are some claims that olive trees on seedling roots are longer-lived and less likely to blow over in heavy winds than trees started from cuttings. However, no experimental evi- dence exists to support this belief. In California very fine orchards have been propagated by both methods. Starting trees from seedlings is generally slower than using cuttings, but where a very large number of trees is needed and time is not important this is probably the best method. It is almost necessary to use it for propagating the Sevillano variety, which is difficult to root from cuttings, even with the use of root-promoting hor- mones. Directions, Germination of seeds. It is advisable to secure seeds in November from black fruits of the Redding Picho- line or some other variety such as the Chemlali, in which a high percentage of the seeds germinate. The seeds are planted in rows in a nursery and grown until they are large enough to bud or graft, which usually requires two years. To facilitate germination, gently crack the pits or clip off the tip end. Germina- tion can also be hastened by soaking the pits in concentrated sulfuric acid, which causes partial disintegration of the pit and allows the seedling to emerge more readily. Pits of the Redding Picholine variety were soaked in acid for 26 hours, then washed thoroughly in running water for 2 hours and planted. The seedlings germinated in about 6 weeks, whereas un- treated seed required 5 to 6 months to germinate. The acid-soaking period may be different for different varieties. Some nurserymen have as sources of seedlings large Redding Picholine, Mis- EXTREME CAUTION should be taken when using concentrated sulfuric acid to avoid contact with the skin or eyes. sion, or Manzanillo trees, under which volunteer seedlings can be pulled up each year after rainy periods during the win- ter, thus saving the trouble of germinat- ing seeds. Such seedlings are usually grown another year in the nursery before grafting or budding. Grafting or budding the seedlings. The seedlings may be grafted in the nursery, using preferably the side graft shown on page 22, in late February or early March. Cut back the tops above the graft about a month after grafting. Some nur- sery trees are started in California by whip-grafting scions onto seedlings or to short pieces of olive roots dug up from mature trees. After a callusing period in moist sawdust, they are planted in nur- sery rows in March. The seedlings may be budded (see lower picture, page 22) in late February or early March, using the "T" or shield- bud method. It is essential to cut back the seedling to the bud 2 to 3 weeks after budding. If the soil is somewhat dry, an irrigation shortly before budding is help- ful in getting the buds to "take." The grafted or budded seedlings are usually grown in the nursery row for one or two years before the trees are large enough to set out in the orchard. Top-grafting. In many cases it is desired to change the variety of a tree or orchard. This can easily be done by grafting. Directions. Do the work in spring — any time from early March to late April. Select 3 to 5 well-spaced scaffold branches, cutting them off as low as pos- sible but leaving a smooth place to graft. Cutting the branches low will eliminate considerable water-sprout growth and will start the tree at a desirably low height. With large branches it is neces- sary to use enough scions (spaced 3 or 4 inches apart around the trunk) to obtain satisfactory healing of the stub. One branch, preferably on the south or south- west, should be retained as a "nurse" or "safety" branch to be removed the follow- [21] Left— "Side graft": (A) method of making cuts in stock and scion; (B) graft union tied with plastic tape; (C) graft after 1 year's growth; (D) section cut through graft union. Right— "Whip grafting": scion is about 4 inches long with 4 to 6 buds. Union is tied with string and waxed, or it may be wrapped with tape. SOME POINTERS ON GRAFTING Satisfactory method of making bark graft for top-working olives: (A) side of scion that rests against the wood of the stock; (B) side view of scion; (C) opposite side from A. Right— Scions in place, held firmly by 2 flat-headed wire nails driven through scion (% inch, 20-gauge nails will serve). After grafting, all cut surfaces are thoroughly covered with grafting wax. B C [22] /^i XI "Twig-bud" method of budding olives, using the T, or shield bud technique: A— bud stick with desirable "twig-bud"; B— "twig-bud" removed; C— stock cut and prepared for insertion of bud piece; D— bud in place and tied with budding rubber. Ordinary dormant buds may be used satis- factorily rather than "twig-buds." ing year. The other branches can be re- moved at the trunk, either at the time of grafting or a year later. Graft the stubs not more than 3 or 4 hours after the limbs are cut back, using the bark-graft method with 2 to 4 scions in each stub unless the branches are quite large, in which case more scions would be necessary. Use scion wood of the de- sired variety taken at the time of graft- ing from trees with good fruit and bear- ing characteristics. It should be % to % inch in diameter, obtained from wood one or two years old. Remove the leaves im- mediately and keep the scion sticks con- stantly moist and cool in damp burlap. Scions ready for insertion should be 5 or 6 inches long, with 2 nodes (4 buds) Mature tree top-worked to another variety by bark-graft method; branches white-washed to prevent sunburn. "Nurse branch" will be re- moved when grafts can sustain tree. above the stub, as shown above. Some- times a longer, slanting cut can be made on the scion, and it can be inserted between the bark and the wood of the stub without slitting the bark. Above— Mature olive trees shortly after being transplanted to a new location. Below— Tree cut back and ready to be replanted. Photographs courtesy B. E. Glick & Sons, Corning. In a test conducted in 1946 by the Cali- fornia Agricultural Experiment Station, a comparison was made between the bark- graft and the cleft-graft methods for top- working olives. Of 152 scions inserted by the bark-graft method, 55 per cent grew vigorously, 30 per cent were weak, and 15 per cent failed to grow. With the cleft-graft method, using 70 scions, 26 per cent were vigorous, 41 per cent were weak, and 33 per cent died. Immediately after grafting it is very important that all the exposed cut sur- faces be thoroughly covered with grafting wax, either hot wax or one of the commer- cial asphalt-emulsion grafting prepara- tions. The latter type will wash off if rains occur before it dries. The wax often cracks; when this happens the graft unions should be rewaxed once about a week after grafting. After waxing, whitewash the scions, branches, and trunk of each tree. This facilitates healing of the graft union by reducing the temperature and prevents death of the exposed wood due to sun- burning. If the grafts become very vigorous and top-heavy by midsummer, especially in areas where strong winds may occur, tie them to stakes or prune them back to pre- vent their breaking off. A vigorous sucker and water sprout growth is usually ex- perienced following top-working. These should be removed around the scions but can be left on the trunk for a time during the summer to nourish the tree and to pro- tect the bark from the sun. Head them back, however, to prevent excessive growth. Withhold nitrogenous fertilizers from newly grafted trees for 2 or 3 years, but continue irrigation, although the water requirements are, in many cases, considerably less because of the reduction in leaf area. During the next year or two after graft- ing, remove the nurse branch and prune the grafts lightly and judiciously to select the branches that are to be retained per- manently, while cutting back the other [24] grafts gradually until the stub heals over. At this time the excess grafts should be completely removed. The grafted branches will usually be in bearing the third season after grafting. Moving large trees If the trees have been planted too close together (e.g. 20 x 20), orchards are benefited by the removal of some of them. In such cases, the trees can be pulled out, moved to a new location, and replanted, and will be in bearing again by 3 or 4 years. For such an operation to be a suc- cess all the primary scaffold branches should be cut back to the trunk and the digging and moving done during the cool, wet winter months. After replanting, the trees should be thoroughly watered and frequent irrigations continued through the summer. Training and pruning olive trees The purposes of pruning olives are the same as those outlined by W. P. Tufts in California Ext. Cir. 112, Pruning De- ciduous Fruit Trees: (1) to produce a vigorous, mechanically strong, healthy tree, free from sunburn, and capable of producing heavy crops over a long period of years; (2) to secure a tree well-shaped for convenience and economy in orchard management; (3) to distribute the fruit- ing area well over the tree; (4) to insure a succession of profitable crops; and (5) to secure desired size and quality of fruit. Young trees. Olive nursery stock in gallon cans or balled and burlaped can be planted with no pruning other than removal of suckers or badly placed branches. Bare-rooted trees should be cut back to 24-30 inches from the ground. After the first growing season, 3 to 5 laterals, well distributed around the tree and spaced as widely apart along the trunk as possible, should be selected and the remaining branches, especially suck- ers from the base, removed. By giving the young orchard several summer prunings much can be done at little expense in cre- ating a desirable framework and elimi- nating unwanted branches before they develop. The first pruning should be in May or early June with another in August. It is i %.<:. Left tree— trained to 3 scaffold branches by two summer prunings for two years and one the third. Total pruning time 5 minutes; little or no further pruning needed until tree comes into full bearing. Right— no pruning. Both trees started bearing in their fourth year. [25] The natural fruit-bearing area of olives is a hemispherical shell. If this is kept in a healthy growing condition production is better than if tree is opened at top to try to promote fruit pro- duction inside the tree. important that the branches be removed while they are small. Delaying the time of pruning until the unwanted branches attain a considerable size will result in the removal of so much wood that the growth of the tree will be retarded. During the second, third, and fourth growing seasons the pruning should con- sist of removal of suckers from the base of the tree, any broken branches, or those crossing over in unwanted positions. Fre- quently in olives there will be a number of vigorous water sprouts rising verti- cally up through the other branches. It is advisable to remove these while they are still small. Keep the pruning at a mini- mum, but at the same time try to develop a satisfactory system of scaffold branches. Excessive cutting will delay the age at which young olive trees come into bear- ing. However, it is not wise to eliminate pruning altogether, as this will necessitate a heavy pruning and the removal of large branches after the tree comes into bear- ing, with no provision for selecting a strong framework of branches. Bearing trees. In the olive the fruits are usually borne laterally along shoots of the previous season's growth. The bear- ing area is a more or less hemispherical shell 2 to 3 feet in depth surrounding the tree. Very few fruits are borne inside this shell. To get maximum crops the pruning should be designed to keep a continuing supply of new fruiting wood and to keep this entire bearing region in a vigorous condition with a maximum leaf area. This is impossible if the trees are planted too close together, in which case excessive shading will reduce the bearing surface to the top, the south half, and perhaps the upper sides of the east and west halves of the tree. This of course results in a reduction in yields. Cutting out the top in order to let light into the north half of the tree will not solve the problem, as this merely eliminates fruit- ing wood from one portion in an attempt to produce it in another. Closely planted orchards should have some trees removed. Moderate annual pruning is necessary in mature, bearing olive trees for the following reasons: (1) The stimulation of pruning is necessary to maintain the growth of new fruiting shoots of moder- ate vigor. (2) There is a continuing pro- duction of dead or dying unfruitful twigs caused by shading out in the fruit-bearing "shell." These should be thinned out to admit more light, facilitate harvesting and spraying, and reduce the chance for infestation by insects and diseases. (3) After the tree occupies all the space that can be allotted to it, with allowance for good light conditions on all sides, a mod- erate pruning is necessary to hold it to the desired size. Continuing unchecked growth, espe- cially where trees are planted fairly close together, will gradually result in the shad- ing out and death of fruiting wood on the sides, confining the bearing suface to the tops. This condition is accompanied by a marked reduction in yields. With ex- tremely close planting, such as 20 x 20 feet, little can be done by pruning to obtain satisfactory yields. Some program of partial tree removal should be consid- ered. Sometimes a more severe type of prun- ing is justified. Occasionally the trees show numerous large scaffold branches [26] with, at the top of each one, a small tuft of fruiting wood. A gradual removal, over a period of several years, of a number of these large branches will finally result in a better distribution of fruiting wood. Older trees, especially of the Mission vari- ety, sometimes grow to such great heights that it is impossible to harvest the fruit in the tops. In such cases a severe heading back of the upright branches is justified, followed by an annual cutting back of the branches tending to grow out of reach. Neglected orchards, having had little or no pruning for many years, sometimes require severe cutting to remove dead wood and broken or crossing branches. When heavy cutting is practiced, nitrogen fertilizers should be withheld for a year or two to avoid excessive sucker and water-sprout growth. If much bark area is opened to direct sunlight in pruning, whitewash should be applied to avoid sunburning and death of the tissues. Once a well-spaced system of scaffold branches has been established and all un- necessary branches eliminated, avoid any type of excessive or severe pruning. This results only in the removal of fruiting wood with a consequent reduction in yields. Encourage instead a maximum fruit-bearing "shell," reaching almost to the ground around the entire tree. All experimental evidence in California has consistently shown that, under irrigated conditions, continued severe pruning of olive trees reduces yields markedly with- out a sufficient increase in fruit size to offset the reduced yields. Many of the Mediterranean olive orchards grown un- der nonirrigated conditions are severely pruned, however, in order to reduce the leaf surface so as to reduce water loss and the development of shrivelled fruits. When "Olive Knot" is present in an orchard, the pruning should be done in the summer if possible to guard against spreading the disease. If the pruning must be done in the winter, the tools should be sterilized frequently. A satisfactory solution for sterilizing pruning tools con- Tree above too severely pruned— most lower fruiting branches removed; tuft of fruiting wood at end of each scaffold branch is hard to har- vest. Tree below had moderate annual pruning for 5 years; vigorous, well-developed bearing surface has low branches easy to harvest. Such pruning results in heaviest yields. sists of 1 ounce of corrosive sublimate (mercuric chloride) , 3% gallons distilled water, and y% gallon glycerine. This so- lution is very poisonous. In years of excessive fruit set summer pruning may be done about July 1 to thin the crop. Most growers, however, prune during late winter or early spring when labor is more plentiful and working con- ditions are favorable. The brush from pruning should be shredded or hauled out of the orchard. [27] Brush burning in the orchard injures the trees and should be avoided whenever possible. Fruit growth The growth of the olive fruit exhibits a cyclic pattern, the first stage being one of very rapid growth followed by a second stage in August and September when increase in size is slower. The third stage, occurring in October, is again one of rapid growth and comes just be- fore the normal harvest period. There seems to be a further gradual increase in size if the fruit is allowed to remain on the tree, due perhaps to the increased accumulation of oil. This latter stage may not be evident if the fruits are shrivelled by winter freezes. Inasmuch as the value of olive fruits increases markedly with size, it would be very much to the grower's benefit to delay the harvest of canning olives as long as possible to take advantage of the rapid increase in fruit 40 a MISSION OLIVE o^ 30 DAVIS 1947 FRUIT STARTING ~T0 COLOR 1 <— FRESH WEIGHT • s • / U — MOISTURE / ^/ 10 / o ^ J '•/ . DRY MATTER OTHER THAN OIL •/■ l// • ^^^ •^OIL . r 1 JUNE JULY AUG SEPT. OCT. NOV DEC. JAN. Graph showing growth curve of olive fruits. Fruit growth # I Vegetative growth 100 90 BRANCH GROWTH BAR0UNI VARIETY*^ ACCUMULATED HOURS OVER 70" BRANCH GROWTH MISSION VARIETY ""^ 1000 < o 500 > -I e> Q. H >" o Z CD or or >- UJ 2 Z> 5 o o: I-: >' d 3 O o UJ < UJ < Q. < 3 o o -> < O z Q ~3 u. i < 2 ~3 <