AVOCADO 



AVOCADO 



437 



fruit and comniprcial cultivation on a sound and 

 profitable basis was not possible. The choicest varieties 

 are now propagated by budding and are grown on a 

 large scale. 



The diverse climatic conditions under which the 

 avocado is found enable varieties to be obtained which 

 are suited to regions with cool climates as well as those 

 which are strictly tropical. In Mexico the fruit has been 

 grown for centuries at altitudes of 6,000 or 7,000 feet, 

 where severe frosts are experienced each winter; varie- 

 ties from such regions, as opposed to those from hot 

 and humid lowlands, are suitable for cultivation in 

 those parts of California and Florida in which slight 

 frosts are the usual winter occurrence. When mature, 

 some types will stand temperatures as low as 20° F. 

 without injury, if in proper condition at the time of the 

 freeze; others will not withstand lower than 27° or 28° 

 without serious damage. 



The subject of races or types has not been given 

 systematic attention outside of the United States, and 

 no attempt at classification has been made, other than 

 brief descriptions of types found in limited areas in 

 Mexico and Central America. In California two very 

 distinct types are grown, commonly referred to as the 

 Mexican and the Guatemalan; the former {Fersea 

 drymifolia of some botanists) is ordinarily a small fruit, 

 four to eight ounces in weight, oval or pyriform, and 

 thin-skinned. It is one of the hardiest types in cultiva- 

 tion and very productive, as a rule. The Guatemalan 

 tj'pe is characterized by its thick, woody skin, fre- 

 quently rough or tuberculate on the exterior; the fruits 

 are medium-sized. It is considered one of the best for 

 commercial use, as it can be shipped without difficulty. 

 The type grown in F^lorida is usually referred to 

 as the West Indian-South American. It has a skin 

 sometimes as thick as the Guatemalan, but of softer 

 texture; some varieties are of large size and attrac- 

 tive appearance, but the type is rather susceptible to 

 frost. 



The avocado has been subjected to systematic culti- 

 vation for so brief a period that a large number of 

 named varieties has not been established. In Florida 

 the Trapp is the most widely planted and is, in fact, 

 the standard commercial variety, Pollock occupying the 

 place of next importance. Several others are grown to a 

 limited extent, including Family, Rico, Blackman, and 

 Wester. In California some of the most promising 

 varieties are Taft, Lyon, Meserve and Murrieta; a num- 

 ber of others have been disseminated. Several named 

 varieties have been established in Hawaii. 



For commercial cultivation, winter-fruiting varieties 

 have been found to be the most valuable, since north- 

 em markets are almost destitute of fresh fruit during 

 that season. It is desirable, however, to have a supply, 

 for local consumption at least, during other seasons of 

 the year. Fortunately varieties are obtainable which 

 ripen at widely different times, — in California fruit is 

 in the markets fully ten out of the twelve months, 

 although the season in Florida, at the present time, is 

 not so long. A variety running uniformly about a 

 pound in weight appears to be the most desirable, 

 and if the fruit is round or 6val, it can be more advan- 

 tageously packed and shipped than if pear-shaped or 

 "bottle-necked." The skin should be sufficiently thick 

 and tough to withstand shipment without undue care 

 in packing, and the seed should be as small as possible. 

 It is also important that the seed be tight in its cavity, 

 for in the loose-seeded varieties, the flesh is often seri- 

 ously damaged by the seed shaking around while the 

 fruit is in transit. Flavor and quality must of course be 

 up to the standard, there being a wide difTercnce among 

 the varieties in the.se re-spects. 



Large seedling trees of the small-fruited Mexican 

 type sometimes produce as many a-s 2,000 or 3,000 

 fruits in a season, while a large-fruited variety may not 

 produce more than a few dozen. Two or three hundred 



fruits may be considered a good crop for a tree of a 

 medium-sized variety. 



In F'lorida, budded trees are planted in orchard form 

 20 feet apart; in California the distance is increased to 

 24 or 25 feet. Seedlings must be given more room, — 30 

 feet at least. A well-drained, sandy loam is the soil 

 best suited to the avocado, drainage being the most 

 important requirement. For this reason it is best, where 

 possible, to select a sloping piece of ground as a site for 

 the orchard. Heavy soils, such as clay and adobe, will 

 grow the tree successfully if the drainage is good. 



Transplanting is best done in early spring, after 

 danger of frost is over, but before the tree has started 

 into new growth. In climates such as those of Cali- 

 fornia and Florida, the tree is in a semi-dormant state 

 after the cool weather of winter, and can be moved 

 with little difficulty. A ball of soil should be taken with 

 the roots, and the top pruneil moderately. In light 

 soils which cannot be balled, the trees should be trans- 

 ferred to pots or boxes and allowed to establish them- 

 selves, after which they may be set out in the orchard 

 without disturbing the roots. When the budded trees 

 have been grown in pots, the possibility of injuring the 

 delicate roots is eliminated. 



The cultural requirements of the avocado are similar 

 to those of the citrous fruits. In dry climates the trees 

 must be irrigated regularly and frequently, particu- 

 larly during the first two or three years. For bearing 

 trees a fertilizer containing 3 per cent nitrogen, .5 per 

 cent phosphoric acid, and 12 per cent potash has been 

 recommended, the quantity required each season vary- 

 ing from three to ten pounds per tree, according to the 

 character of the soil. This should be applied in several 

 doses during the growing season. The growth of young 

 trees is greatly encouraged by organic nitrogen. 

 Leguminous cover-crops are very desirable, for the 

 humus they will furnish as well as the nitrogen. 



Often there is a tendency, especially in seedlings, to 

 shoot upward and not spread out; this must be 

 checked by heading back. All weak or unshapely 

 growths should be trimmed out, and all wounds made 

 when pruning should be covered with grafting wax 

 or paint to prevent the entrance of any fungus into 

 the wood. It is well to keep the trees headed low to 

 prevent damage from winds as much as possible; this 

 also brings the fruit within easy reach for picking. 



In regions subject to severe frosts, the trees should 

 be protected during the first two or three winters 

 with a shelter of palm leaves, corn stalks, burlap, 

 or some such material. Where irrigation is practised, 

 it is well to harden the trees by withholding water in 

 late fall. 



In Florida the avocado is attacked by the wither-tip 

 fungus (Colletoirichum glcosporioides) , which can be 

 controlled with bordeaux mixture. Two or three scale 

 insects have been noted on trees in California, but up 

 to the present time they are not of serious importance, 

 with the exception of the black scale {Saisselia ole.r), 

 which sometimes requires combative measures. The 

 avocado mealy bug (Pseudococcus niipse) is troublesome 

 in Hawaii. 



For market purposes, the fruit should be graded 

 according to size, color and form, and carefully packed; 

 it is essential, if the fruit is to be shipped any distance, 

 to select varieties having good carrying qualities. Light 

 wooden crates are used for shipping, containing one 

 layer of fruits, and provided with good ventilation. 

 The fruits must be separately wrapped in pieces of 

 strong paper, and packed clo.sely together to prevent 

 their shaking about and becoming bruised. If they are 

 to be shipped long distances, refrigeration is essential, 

 experiments having shown that the temperature should 

 be 40° to 4.5° I<\ Prolonged storage in temperature 

 lower than 40° results in decomposition of the flesh. 



Seedlings do not usually bear as early as budded 

 trees, and on account of the variation which they are 



