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Page 229 Cherimoya Universally regarded as a premium fruit, the cherimoya (Annona cherimola) has been called the “pearl of the Andes,” and the “queen of subtropical fruits.” Mark Twain declared it to be “deliciousness itself!” In the past, cherimoya (usually pronounced chair-i-moy-a in English) could only be eaten in South America or Spain. The easily bruised, soft fruits could not be transported any distance. But a combination of new selections, advanced horticulture, and modern transportation methods has removed the limitations. Cushioned by foam plastic, chilled to precise temperatures, and protected by special cartons, cherimoyas are now being shipped thousands of kilometers. They are even entering international trade. Already, they can be found in supermarkets in many parts of the United States, Japan, and Europe (mainly France, England, Portugal, and Spain). Native to the Ecuadorian Andes, the cherimoya is an important backyard crop throughout much of Ecuador, Colombia, Venezuela, Bolivia, and Peru. Chileans consider the cherimoya to be their “national fruit” and produce it (notably in the Aconcagua Basin) on a considerable commercial scale. In some cooler regions of Central America and Mexico, the plant is naturalized and the fruit is common in several locales. In the United States, the plant produces well along small sections of the Southern California coast where commercial production has begun. Outside the New World, a scattering of cherimoya trees can be found in South Africa, South Asia, Australasia, and around the Mediterranean. However, only in Spain and Portugal is there sizable production. In fruit markets there, cherimoyas are sometimes piled as high as apples and oranges. A good cherimoya certainly has few equals. Cutting this large, green, heart-shaped fruit in half reveals white flesh with black seeds. The flesh has a soft, creamy texture. Chilled, it is like a tropical sherbet—indeed, cherimoya has often been described as “ice-cream fruit.” In Chile, it is a favorite filling for ice-cream wafers and cookies. In Peru, it is popular in ice cream and yogurt.

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Page 230 World demand is strong. In North America and Japan, people pay more for cherimoya than for almost any other fruit on the market. At present, premium cherimoyas (which can weigh up to 1 kg each) are selling for up to $20 per kg in the United States and more than $40 per kg in Japan. Despite such enormous prices, sales are expanding. In four years, the main U.S. supplier's weekly sales have increased from less than 50 kg a week to more than 5,000 kg a week. Today, the crop is far from reaching its potential peak. Modern research is only now being applied—and in only a few places, principally Chile, Argentina, Spain, the Canary Islands, and California. Nonetheless, even limited research has produced a handful of improved cultivars that produce fruit of good market size (300–600 g), smooth skin, round shape, good flavor, juiciness, low seed ratio, resistance to bruising, and good storage qualities. With these attributes, larger future production and expanded trade seem inevitable. But growing cherimoyas for commercial consumption is a daunting horticultural challenge. In order to produce large, uniform fruit with an unbroken skin and a large proportion of pulp, the grower must attend his trees constantly from planting to harvest; each tree must be pruned, propped, and—at least in some countries—each flower must be pollinated by hand. Nevertheless, the expanding markets made possible by new cultivars and greater world interest in exotic produce now justify the work necessary to produce quality cherimoya fruits on a large scale. Eventually, production could become a fair-sized industry in several dozen countries. PROSPECTS The Andes. Although cherimoyas are found in markets throughout the Andean region, there has been little organized evaluation of the different types, the horticultural methods used, or the problems growers encounter. Given such attention, as well as improved quality control, the cherimoya could become a much bigger cash crop for rural villages. With suitable packaging increasingly available, a large and lucrative trade with even distant cities seems likely. Moreover, increased production will allow processed products—such as cherimoya concentrate for flavoring ice cream—to be produced both for local consumption and for export. Other Developing Areas. Everywhere these fruits are grown, they are immediately accepted as delicacies. Thus, the cherimoya promises to become a major commercial crop for many subtropical

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Page 231 ~ enlarge ~ Cherimoya has been grown for centuries in the highlands of Peru and Ecuador, where it was highly prized by the Incas. Today, this subtropical delight is gaining an excellent reputation in premium markets in the United States, Europe, Japan, and elsewhere. (T. Brown) areas. For example, it is likely to become valuable to Brazil and its neighbors in South America's “southern cone,” to the highlands of Central America and Mexico, as well as to North Africa, southern and eastern Africa, and subtropical areas of Asia. Industrialized Regions. The climatic conditions required by the cherimoya are found in pockets of southern Europe (for example, Spain and Italy), the eastern Mediterranean (Israel), the western United States, coastal Australia, and northern New Zealand. In these areas,

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Page 232 the fruit could become a valuable crop. In Australia and South Africa, the cherimoya hybrid known as atemoya is already commonly cultivated (see sidebar). The cherimoya could have an impact on international fruit markets. The United Kingdom is already a substantial importer, and, as superior cultivars and improved packing become commonplace, cherimoyas could become as familiar as bananas. USES The cherimoya is essentially a dessert fruit. It is most often broken or cut open, held in the hand, and the flesh scooped out with a spoon. It can also be pureed and used in sauces to be poured over ice creams, mousses, and custards. In Chile, cherimoya ice cream is said to be the most profitable use. It is also processed into nectars and fruit salad mixes, and the juice makes a delicious wine. NUTRITION Cherimoya is basically a sweet fruit: sugar content is high; acids, low. It has moderate amounts of calcium and phosphorus (34 and 35 mg per 100 g). Its vitamin A content is modest, but it is a good source of thiamine, riboflavin, and niacin. 1 HORTICULTURE Because seedling trees usually bear fruits of varying quality, most commercial cherimoyas are propagated by budding or grafting clonal stock onto vigorous rootstock. However, a few forms come true from seed, and in some areas seed propagation is used exclusively. The trees are usually pruned during their brief deciduous period (in the spring) to keep them low and easy to manage. The branches are also pruned selectively after the fruit has set—for example, to prevent them rubbing against the fruits or to encourage them to shade the fruits. (Too much direct sunlight overheats the fruits, cracking them open.) Under favorable conditions, the trees begin bearing 3–4 years after planting. However, certain cultivars bear in 2–3 years, others in 5–6 years. Many growers prop or support the branches, which can get so heavily laden they break off. 1 Information from S. Dawes.

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Page 233 Pollination can be irregular and unreliable. The flowers have such a narrow opening to the stigmas and ovaries that it effectively bars most pollen-carrying insects. Honeybees, for instance, are ineffective. 2 In South America, tiny beetles provide pollination, 3 but in some other places (California, for instance) no reliable pollinators have been found. There, hand pollination is needed to ensure a high proportion of commercial-quality fruit. 4 HARVESTING AND HANDLING The fruits are harvested by hand when the skin becomes shiny and turns a lighter shade of green (about a week before full maturity). A heavy crop can produce over 11,000 kg of quality fruits per hectare. LIMITATIONS A cherimoya plantation is far from simple to manage. The trees are vulnerable to climatic adversity: heat and frost injure them, low humidity prevents pollination, and winds break off fruit-laden branches. They are also subject to some serious pests and diseases. Several types of scale insects, leaf miners, and mealy bugs can infect the trees, and wasps and fruit flies attack the fruits. Pollination is perhaps the cherimoya's biggest technical difficulty. Not only are reliable pollinators missing in some locations, but low humidity, especially when combined with high temperatures, causes pollination failure; these conditions dry out the sticky stigmas, and the heavy pollen falls off before it can germinate. Hand pollination is costly and time consuming. However, it improves fruit set of all cultivars under nearly all conditions. It enhances fruit size and shape. It allows the grower to extend or shorten the season (by holding off on pollination) as well as to simplify the harvesting (by pollinating only flowers that are easy to reach). 5 2 The male and female organs of a flower are fertile at different times. Honeybees visit male-phase flowers but not female-phase flowers, which offer no nectar or pollen. 3 Reviewer G.E. Schatz writes: “Pollination is undoubtedly effected by small beetles, most likely Nitidulidae. They are attracted to the flowers by the odor emitted during the female stage, a fruity odor that mimics their normal mating and ovipositing substrate, rotting fruit. There is no other “reward” per se, and hence it is a case of deception. The beetles often will stay in a flower 24 hours—the flower offers a sheltered mating site, safe from predators during daylight hours. Studies on odor could lead to improved pollination.” 4 California growers use artists' paint brushes with cut-down bristles to collect pollen in late afternoon. The next morning they apply it to receptive female flowers. 5 Schroeder, 1988.

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Page 234 The fruits are particularly vulnerable to climatic adversity: if caught by cold weather before maturity, they ripen imperfectly; if rains are heavy or sun excessive, the large ones crack open; and if humidity is high, they rot before they can be picked. The fruits must be picked by hand, and, because they mature at different times, each tree may have to be harvested as many as 10 times. In addition, the picked fruits are difficult to handle. Even when undamaged, they have short storage lives (for example, 3 weeks at 10°C) unless handled with extreme care. The fruit has a culinary drawback: the large black seeds annoy many consumers. However, fruits with a low number of seeds exist, 6 and there are unconfirmed reports of seedless types. So far, however, neither type has been produced on a large scale. RESEARCH NEEDS The following are six important areas for research and development. Germplasm The danger of losing unique and potentially valuable types is high. A fundamental step, therefore, is to make an inventory of cherimoya germplasm and to collect genetic material from the natural populations as well as from gardens and orchards, especially throughout the Andes. Selection Future commercialization will depend on the selection of cultivars that dependably produce large numbers of well-shaped fruit with few seeds and good flavor. Selection criteria could include: resistance to diseases and pests, regular heavy yields of uniform fruit with smooth green skin, juicy flesh of pleasant flavor, few or no seeds, resistance to bruising, and good keeping qualities. Pollination The whole process of pollination should be studied and its impediments clarified. Currently few, if any, specific insects have been definitely associated with cherimoya pollination. 7 The insects that now pollinate it in South America should be identified. Spain, where good natural fruit set is common in most orchards, might also teach much. 8 Selecting genotypes that naturally produce symmetrical, full-sized fruits may reduce or eliminate the need to hand pollinate, bringing the cherimoya a giant step forward in several countries. Cultural Practices Horticulturists have not learned enough to clearly understand the plant's behavior and requirements. Knowledge of the effects of pruning, soils, fertilization, and other cultural details is as 6 Flesh: seed weight ratios from 8:1 to 30:1 have been reported. 7 Schroeder, 1988. 8 Information from J. Farré.

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Page 235 yet insufficient. The current complexity of management should be simplified. Evaluation of the plants in the Andes, and the ways in which farmers handle them, could provide guidance for mastering the species' horticulture. Also, there is a need for practical trials to identify more precisely the limits of the tree's environmental and management requirements. Intensive cultural methods, such as trellising and espaliering, 9 may help achieve maximum production of high-quality fruits. These growing systems facilitate operations such as hand pollination; they also provide support for heavy crops. Breeding Ongoing testing of superior cultivars is needed. Low seed count, good keeping quality, and good flavor have yet to coincide in a cultivar that also has superior horticultural qualities. In addition, it is advisable to grow populations of seedling cherimoyas in all areas where this crop is adapted. From these variable seedling plants, selections based on local environmental conditions can be made. Elite seedling selections can be multiplied by budding or grafting. Mass propagation of superior genotypes by tissue culture could also provide large numbers of quality plants. Improved cherimoyas might be developed by controlled crosses and, perhaps, by making sterile, seedless triploids. Breeding for large flowers that can be more easily pollinated might even be possible. Hybridization Members of the genus Annona hybridize readily with each other (see sidebar), so there is considerable potential for producing new cherimoyalike fruits (perhaps seedless or pink-fleshed types) that have valuable commercial and agronomic traits. Handling Improved techniques for handling, shipping, and storing delicate fruits would go a long way to helping the cherimoya fulfill its potential. Ways to reduce the effects of ethylene should be explored. Cherimoyas produce this gas prodigiously, and in closed containers it causes them to ripen extremely fast. SPECIES INFORMATION Botanical Name Annona cherimola Miller Family Annonaceae (annona family) Common Names Quechua: chirimuya Aymara: yuructira 9 It has been reported that on Madeira, trees were espaliered so successfully that in some locations they have replaced grapes, the main crop of the island. The branches were trained so that fruit ripened in shade.

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Page 236 ATEMOYA ~ enlarge ~ Like the cherimoya, the atemoya has promise for widespread cultivation. This hybrid of the cherimoya and the sugar apple was developed in 1907 by P.J. Wester, a U.S. Department of Agriculture employee in Florida. (Similar crosses also appeared naturally in Australia in 1850 and in Palestine in 1930.) The best atemoya varieties combine the qualities of both cherimoya and sugar apple. However, the fruits are smaller and the plant is more sensitive to cold. The atemoya has been introduced into many places and is commercially grown in Australia, Central America, Florida, India, Israel, the Philippines, South Africa, and South America. In eastern Australia, for at least half a century, the fruit has been widely sold under the name “custard apple.” The atemoya grows on short trees—seldom more than 4 m high. The yellowish green fruit has pulp that is white, juicy, smooth, and subacid. It usually weighs about 0.5 kg, grows easily at sea level, and apparently has no pollination difficulties. The fruit may be harvested when mature but still firm, after which it will ripen to excellent eating quality. It finds a ready market because most people like the flavor at first trial. It is superb for fresh consumption, but the pulp can also be used in sherbets, ice creams, and yogurt. Seedling progeny are extremely variable, and possibilities for further variety improvement are very good. So far, however, little work has been done to select and propagate superior varieties.

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Page 237 Spanish: chirimoya, cherimoya, cherimalla, cherimoyales, anona del Perú, chirimoyo del Perú, cachimán de la China, catuche, momona, girimoya, masa Portuguese: cherimólia, anona do Chile, fruta do conde, cabeça de negro English: cherimoya, cherimoyer, annona French: chérimolier, anone Italian: cerimolia Dutch: cherimolia German: Chirimoyabaum, Cherimoyer, Cherimolia, peruanischer Flaschenbaum, Flachsbaum Origin. The cherimoya is apparently an ancient domesticate. Seeds have been found in Peruvian archeological sites hundreds of kilometers from its native habitat, and the fruit is depicted on pottery of pre-Inca peoples. The wild trees occur particularly in the Loja area of southwestern Ecuador, where extensive groves are present in sparsely inhabited areas. Description. A small, erect, or sometimes spreading tree, the cherimoya rarely reaches more than 8 m in height. It often divides at the ground into several main stems. The light-green, three-petaled, perfect flowers are about 2.5 cm long. The fruit is an aggregate, composed of many fused carpels. Depending on degree of pollination, the fruits are heart-shaped, conical, oval, or irregular in shape. They normally weigh about 0.5 kg, with some weighing up to 3 kg. Moss green in color, they have either a thin or thick skin; the surface can be nearly smooth, but usually bears scalelike impressions or prominent protuberances. Horticultural Varieties. A number of cultivars have been developed. Nearly every valley in Ecuador has a local favorite, as do most areas where the fruit has been introduced. Named commercial varieties include Booth, White, Pierce, Knight, Bonito, Chaffey, Ott, Whaley, and Oxhart. These exhibit great variation in climatic and soil requirements. In Spain, 200 cultivars from 10 countries are under observation. 10 Environmental Requirements Daylength. Apparently neutral. In its flower-bud formation, this plant does not respond to changes in photoperiod as most fruit species do. 10 Information from J. Farré.

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Page 238 Rainfall. The plant does not tolerate drought well. For good production, it needs a fairly constant source of water. In Latin America, the tree thrives under more than 1,200 mm rainfall during the growing season. As noted, high humidity assists pollen set, and a dry period during harvesting prevents water-induced damage to fruit. Also, water stress just before flowering may increase flower (and hence fruit) production. Altitude. The cherimoya does best in relatively cool (but not cold) regions, and is unsuited to the lowland tropics. (In equatorial regions it produces well only at altitudes above 1,500 m.) Low Temperature. The plant is frost sensitive and is even less hardy than avocados or oranges. Young specimens are hurt by temperatures of −2°C. High Temperature. The upper limits of its heat tolerance are uncertain, but is is said that the tree will not set fruit when temperatures exceed 30°C. Soil Type. Cherimoya can be grown on soils of many types. The optimum acidity is said to be pH 6.5–7.5. On the other hand, the tree seems particularly adapted to high-calcium soils, on which it bears abundant fruits of superior flavor. Because of sensitivity to root rot, the tree does not tolerate poorly drained sites. Related Species. The genus Annona, composed of perhaps 100 species mostly native to tropical America, includes some of the most delectable fruits in the tropics. Most are similar to the cherimoya in their structure. Examples are: Sugar apple, or sweetsop (Annona squamosa). Subtropical and tropical. The fruit is 0.5–1 kg, and yellowish green or bluish. It splits when ripe. The white, custardlike pulp has a sweet, delicious flavor. Soursop, or guanabana (A. muricata). This evergreen tree is the most tropical of the annonas. The yellow-green fruit—one of the best in the world—is the largest of the annonas, sometimes weighing up to 7 kg. The flesh resembles that of the cherimoya, but it is pure white, more fibrous, and the flavor, with its acidic tang, is “crisper.” Custard apple, or annona (A. reticulata). This beige to brownish red fruit often weighs more than 1 kg. Its creamy white flesh is sweet but is sometimes granular and is generally considered inferior to the other commonly cultivated annonas. However, this plant is the most vigorous of all, and types that produce seedless fruits are known. 10 Information from J. Farré.

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Page 239 Ilama (A. diversifolia). This fruit has a thick rind; its white or pinkish flesh has a subacid to sweet flavor and many seeds. It is inferior to the cherimoya in quality and flavor, but it is adapted to tropical lowlands where cherimoya cannot grow. A. longipes. This species is closely related to cherimoya and is known from only three localities in Veracruz, Mexico, where it occurs at near sea level. Its traits would probably complement cherimoya's if the two species were hybridized to create a new, man-made fruit. 11 11 Information from G.E. Schatz.