In the highlands of Mexico and Central America, where it is believed to be indigenous, the white sapote ranks among the principal cultivated fruits. Outside of this region it is not well known, although it has, in recent years, attracted attention in California and Florida.
The Aztecs of ancient Mexico used the term tzapotl to designate soft sweet fruits such as the sapodilla and its allies. The lack of acidity and the heavy sweetness of these fruits makes them less acceptable to palates accustomed to apples and peaches than the mangosteen and certain other tropical fruits. They are, however, liked by many northerners, and natives of tropical regions consider them perfect.
Fig. 60. The white sapote (Casimiroa edulis), a common fruit of the Mexican and Central American highlands, is now grown in California and Florida. (X 1/2)
The white sapote is a medium-sized erect or spreading tree, having palmately compound leaves, small inconspicuous flowers, and yellowish green fruits the size of an orange. The fruits have a thin membranous skin, yellowish flesh of soft melting texture and sweet or slightly bitter flavor, and one to five large oval or elliptic seeds.
In its native region the white sapote is a fruit of the highlands. Throughout Mexico and Guatemala it is found at elevations of 2000 to 3000 feet, and occasionally as high as 9000 feet. It is not grown in regions subject to heavy rainfall.
It has borne fruit at La Mortola, in southern Italy, and is occasionally seen elsewhere on the Riviera. It is said also to have fruited in the island of Jersey. Although introduced into California from Mexico about 1810, it has not yet become extensively cultivated in that state, and large trees are rare. One of the oldest, believed to have been planted more than a century ago, is growing on De La Guerra Street in Santa Barbara. A number of younger trees, most of them propagated by F. Franceschi and distributed about 1895, are fruiting in various parts of southern California; although some of these produce small bitter fruits, others bear large ones of delicious flavor. In Florida the species has not been cultivated so long as in California, but it has proved quite successful in the southern part of the state.
The Aztec name for this fruit is cochiztzapotl, meaning "sleep-producing sapote." It is commonly known in Mexico at the present day as zapote bianco (white sapote). In Guatemala it is called matasano.
The fruit is usually eaten fresh, but attempts have been made in Central America to prepare a sweet preserve from it on a commercial scale. Some of the early writers considered the white sapote unwholesome, and stated that it would induce sleep if indulged in too freely, but recent experience does not indicate that there are grounds for such beliefs. Francisco Hernandez observed that the seed, if eaten raw, was poisonous to animals and men. An analysis of the fruit made at the University of California shows it to contain: Water 72.64 per cent, ash 0.44, protein 0.64, total sugars 20.64 (invert sugar 8.44, sucrose 12.20), fat 0.46, crude fiber 1.26, and starch and the like 3.92.
In its climatic requirements the tree is distinctively subtropical. It is not altogether successful in Central America below 3000 feet, and it thrives at elevations of 5000 to 6000 feet. It is even found in places which are too high (i.e., too cold) for the avocado. It prefers a well-drained sandy loam, but may be grown on clay if the drainage is good, and in Florida it has done well on shallow sandy soils underlaid with soft limestone. It is drought-resistant, but succeeds much better in dry regions if irrigated like the orange.
While young, the tree should be watered liberally to encourage growth, and when it is about three feet high it should have the terminal bud removed, in order to induce branching; three or four laterals will develop, and these in turn, after they have grown to a length of one or two feet, should have the terminal buds removed. Unless this is done, the tree may grow ten or twelve feet high before it branches.
Seeds should be planted as soon as possible after their removal from the fruit in flats of light porous soil, or singly in three-inch pots, covering them to the depth of an inch. If the weather is warm, or artificial heat is provided, germination will take place within three or four weeks. The young plants should be grown in pots until two or three feet high, when they may be set out in the open ground.
Seedlings do not come into bearing until seven or eight years old, and many produce fruit of inferior quality. For this reason propagation should be effected by some vegetative means. Shield-budding is successfully practiced, the method being essentially the same as with the avocado. Stock plants should be selected from young vigorous seedlings whose stems are about | inch in diameter at the base. Budwood is taken from the ends of the branches, but of fairly well matured wood which has acquired an ash-gray color. The buds are cut about 1 1/2 inches long, leaving any wood that may adhere to them, and are inserted in T-incisions, after which they are bound firmly in place with waxed tape. At the end of two to four weeks, depending on the weather, they may be unwrapped and then rewrapped loosely, leaving the bud exposed so that it may start into growth, at the same time lopping back the stock to a point three or four inches above the bud. In the tropics budding can probably be done at almost any season of the year; in California spring and summer, when the stock plants are in most active growth, are the best times.
Seedling variation results in some trees being very productive, while others bear little fruit. No budded trees have yet come into bearing. The ripening season in Guatemala is April and May; in Florida it is May; in Mexico it extends from May to July; and in California it begins in September and ends in November. Because of its thin skin and delicate texture, the fruit does not ship well, unless picked while still hard and dispatched so as to reach its destination before it has had time to soften.
Several horticultural varieties have been described, but none has been propagated or planted extensively. Harvey and Maechtlen are two which have been offered by the trade in California; Parroquia and Gillespie have been described, but not propagated.