The tree closely resembles that of the cherimoya; is fast growing; may reach 25 to 30 ft (7.5-9 m) and is short-bunked, the branches typically drooping and the lowest touching the ground. The leaves are deciduous, alternate, elliptical, leathery, less hairy than those of the cherimoya; and up to 6 in (15 cm) in length. The flowers are long-stalked, triangular, yellow, 2 3/8 in (6 cm) long and 1 1/2 to 2 in (4-5 cm) wide. The fruit is conical or heart-shaped, generally to 4 in (10 cm) long and to 3 3/4 in(9.5 cm) wide; some weighing as much as 5 lbs(2.25 kg); pale bluish-green or pea-green, and slightly yellowish between the areoles. The rind, 1/8 in (3 mm) thick, is composed of fused areoles more prominent and angular than those of the sugar apple, with tips that are rounded or slightly upturned; firm, pliable, and indehiscent. The fragrant flesh is snowy-white, of fine texture, almost solid, not conspicuously divided into segments, with fewer seeds than the sugar apple; sweet and subacid at the same time and resemblirig the cherimoya in flavor. The seeds are cylindrical, 3/4 in (2 cm) long and 5/16 in (8 mm) wide; so dark a brown as to appear black; hard and smooth.
Scientific name
Annona cherimola x A. squamosa
A. cherimola x A. squamosa hybrids
Common names
Annon, custard apple.
Other members of the family that are grown for their fruit are:
Cherimoya (A. cherimola)
Soursop (A.muricata)
Sugar apple (A. squamosa)
Ilama (A. diversifolia)
Custard Apple (A. reticulata)
Biriba (Rollinia mucosa, A. mucosa)
Poshte (A. scleroderma)
Relatives
Sugar apple (A. squamosa), cherimoya (A. cherimola), soursop (A. muricata), custard apple (A.reticulata), pond apple (A. glabra), ilama (A. diversifolia)
Family
Annonaceae
Soil
The tree thrives in various types of soil, from sandy loam to red basalt or heavy clay, but best growth and productivity occur in deep, rich loam of medium texture, with good organic content and a moderate amount of moisture. Good drainage is essential; water logging is fatal.
Propagation
Atemoyas for rootstocks are raised from seeds which germinate in about 4 weeks in seedbeds. Seedlings are transplanted to nursery rows when they are a year old and they are placed 18 in (45 cm) apart in rows 3 ft (90cm) apart. If older trees are top worked, it is done by cleft- or bark-grafting. Scion wood is taken from selected cultivars after the leaves have fallen.
Culture
When transferred to the field at the near-dormant period, grafted plants are spaced 28 to 30 ft (8.5-9 m) apart each way and cut back to a height of 24 to 30 in (60-75 cm). Weeds are eliminated to avoid competition with the spreading, shallow root system. During the next 2 or 3 years, the trees are kept pruned to form a strong frame. Thereafter, only light pruning is done. No fertilizer is applied until after the trees are well established, since the young roots are very sensitive. A 6-10-16 formula is recommended for broadcasting over the root area, the amount gradually increased to 10 to 12 lbs (4.5-5.4 kg) annually for mature trees. Irrigation during flowering and fruit setting improves yield and fruit quality.
Harvesting
The fruits must be clipped from the branch, taking care that the stalk left on the fruit does not protrude beyond the shoulders. Frequent picking is necessary to harvest the fruit at the ideal stage, that is, when creamy lines appear around the areoles showing that the spaces between them are widening. If picked too soon, the fruit will not ripen but will darken and shrivel. Fruits colonized by mealybugs have to be cleaned by brushing or the use of compressed air before marketing. The fruits should not be wrapped because this will speed ripening, but they need to be packed in boxes with padding between layers. Because of the irregular form, the fruits must be carefully fitted together with the base of each fruit against the wall of the container and the more delicate apex inward.
Yield
The atemoya is a shy yielder. Trees 5 years old are expected to bear 50 fruits annually.
Keeping Quality
Atemoyas keep very well in cool, shady, well-ventilated storage for at least 3 weeks. The rind may darken before the interior shows any signs of spoilage. The ideal temperature for refrigerated storage is 68ºF (20ºC), though an acceptable temperature range is 59º to 77ºF (15º-25ºC). Lower temperatures cause chilling injury.
Toxicity
The seeds, like those of all Annona species, are toxic and care should be taken to seed the pulp before it is mechanically blended.
Pests and Diseases
The citrus mealybug, Planococcus citri; which congregates around the base of the fruit, is the most common pest, and sooty mold develops on its exodate.
The chalcid fly that lays eggs in the seeds and makes exit holes in the fruit permitting entrance of fungi, occasionally causes mummification of the atemoya. White wax, pink wax, and brown olive scales may be found on the foliage but are shed along with the leaves.
A condition called "littleleaf" is not a disease but zinc deficiency which can be corrected by foliar spraying.
Atemoyas are prone to collar rot (Phytophthora sp.), the first sign being an exudation of gum near the base of the trunk and on the crown roots
