For the preparation of sherbets and other refreshing drinks, the soursop is unrivaled. Those who have visited Habana and there sipped the delectable champola de guandbana will agree with Cubans that it is one of the finest beverages in the world. Soursop sherbet is equal to that prepared from the best of the temperate zone fruits, if not superior to all other ices.
Plate VIII. Upper, the cherimoya at its best; lower, the soursop and other fruits.
The tree is more strictly tropical in its requirements than the cherimoya or the sugar-apple. It withstands very little frost, and succeeds best in the tropical lowlands. Though widely disseminated, it is nowhere grown on an extensive scale. This is due, most probably, to the scanty productiveness which characterizes the species in general. There is an opportunity here for an excellent piece of work; by obtaining a productive variety and propagating it by budding, or by increasing the productiveness of the species through improved cultural methods, the soursop could be made profitable and of considerable commercial importance. In the large cities of tropical America there is a good demand for the fruits at all times of the year, a demand which is not adequately met at present.
The soursop is a small tree, usually slender in habit and rarely more than 20 feet high. The leaves are obovate to elliptic in form, commonly 3 to 6 inches long, acute, leathery in texture, glossy above and glabrous beneath. The flowers are large, the three exterior petals ovate-acute, valvate, and fleshy, the interior ones smaller and thinner, rounded, with the edges overlapping. The fruit is the largest of the annonas; specimens 5 pounds in weight are not uncommon and much larger ones have been reported. It is ovoid, heart-shaped, or oblong-conical in form, deep green in color, with numerous short fleshy spines on the surface. The skin has a rank, bitter flavor. The flesh is white, somewhat cottony in texture, juicy, and highly aromatic. Numerous brown seeds, much like those of the cherimoya, are embedded in it. The flavor suggests that of the pineapple and the mango.
Alphonse DeCandolle says that the soursop "is wild in the West Indies; at least its existence has been proved in the islands of Cuba, Santo Domingo, Jamaica, and several of the smaller islands."Safford states that it is of tropical American origin. The historian Gonzalo Hernandez de Oviedo, in his "Natural History of the Indies," written in 1526, describes the soursop at some length, and he mentions having seen it growing abundantly in the West Indies as well as on the mainland of South America. At the present day it is perhaps more popular in Cuba than in any other part of the tropics. In Mexico it occurs in many places, and the fruit is often seen in the markets. It is also grown in the tropical portions of South America. H. F.
Macmillan says that it thrives in Ceylon up to elevations of 2000 feet. It is cultivated in India, in Cochin-China, and in many parts of Polynesia. Vaughan MacCaughey states that it is the commonest species of Annona in the markets of Honolulu. Paul Hubert notes that it is cultivated in Reunion and on the west coast of Africa.
It will be observed that its distribution is limited to tropical regions. In the United States it can only be grown in southern Florida, where with slight protection it succeeds at Miami and even as far north as Palm Beach. Exceptionally cold winters, however, may kill the trees to the ground. In California it is not successful.
The name soursop is of West Indian origin, and is the one commonly used in English-speaking countries. In Mexico the fruit is known as zapote agrio, and more commonly as guanabana (sometimes abbreviated to guanaba), which is the name most extensively used in Spanish-speaking countries. Guanabana is considered to have come originally from the island of Santo Domingo. In the French colonies the common name is corossol or cachiman epineux. Yule and Burnell say : "Grainger identifies the soursop with the suirsack of the Dutch. But in this, at least as regards use in the East Indies, there is some mistake. The latter term, in old Dutch writers on the East, seems always to apply to the common jackfruit, the 'sourjack,' in fact, as distinguished from the superior kinds, especially the champada of the Malay Archipelago." In Mexican publications the soursop is sometimes confused with the soncoya (A. purpurea), though it actually differs widely from the latter both in foliage and fruit.
The soursop is more tolerant of moisture than the sugar-apple, and can be grown in moist tropical regions with greater success. Temperatures below the freezing point are likely to injure it, although mature trees may withstand 29° or 30° above zero without serious harm.
The soil best suited to this species is probably a loose, fairly rich, deep loam. It has done well, however, on shallow sandy soils in south Florida. F. S. Earle has found in Cuba that liberal applications of fertilizer will increase greatly the amount of fruit produced. The formula used is the same as that recommended for the sugar-apple. Little attention has yet been given to the cultural requirements of the plant.
The soursop, grown from seed, comes into bearing when three to five years old. The season of ripening in Mexico and the West Indies is June to September; in Florida it is about the same.
Mature trees rarely bear more than a dozen good fruits in a season. . Oftentimes there are produced numerous small, malformed, abortive fruits which are of no value. These are due to insufficient pollination, only a few of the carpels developing normally, the remainder being unable to do so because they are not pollinated. The same phenomenon often occurs in the cherimoya, and, less commonly, in the sugar-apple and bullock's-heart.
Seedling trees differ in the amount of fruit they yield. Only the most productive should be selected for propagation. It may be possible still further to increase their productiveness by attention to pollination, and it has been shown that proper manuring is a great aid. Since the fruits are commonly of large size, it cannot be expected that so small a tree will produce many; still, the average seedling does not bear more than a small proportion of the crop it could safely carry to maturity, and the object of future investigations should be to obtain varieties which will be more productive.
In various parts of the world the tree is attacked by several scale insects, and the fruits by some of the fruit-flies, notably the Mediterranean fruit-fly.
Propagation of the soursop is usually effected in the tropics by seed. Choice varieties which originate as chance seedlings, however, can only be perpetuated by some vegetative means.
P. J. Wester has found that the species can be budded in the same manner as the cherimoya. He recommends as stock-plants the bullock's-heart and the pond-apple, both described below. Seeds are germinated in the same manner as those of the cherimoya.