Annona cherimola Mill.
Common Names: Cherimoya (U.S., Latin America), Custard Apple (U.K. and Commonwealth), Chirimoya, Chirimolla.
Related species: Ilama (Annona diversifolia), Pond Apple (A. glabra), Manrito (A. jahnii). Mountain Soursop (A. montana), Soursop (A. muricata), Soncoya (A. purpurea), Bullock’s Heart (A. reticulata), Sugar Apple (Annona squamosa), Atemoya (A. cherimola X A. squamosa).
Distant affinity: Pawpaw (Asimina triloba), Biriba (Rollinia deliciosa), Wild Sweetsop (R. mucosa), Keppel Apple (Stelechocarpus burakol).
Origin: The cherimoya is believed to be native to the inter-andean valleys of Ecuador, Colombia and Peru. Seeds from Mexico were planted in California (Carpinteria) in 1871.
Adaptation: The cherimoya is subtropical or mild-temperate and will tolerate light frosts. Young growing tips are killed at 29° F and and mature trees are killed or severely injured at 25° F. If cherimoyas do not receive enough chilling, the trees will go dormant slowly and then experience delayed foliation. The amount of chilling needed is estimated to be between 50 and 100 hours. The tree grows well in the coastal and foothill areas of southern California, doing best at a slight elevation, 3 to 15 miles from ocean. It is worth attempting in sunny, south-facing, nearly frost-free locations from San Francisco Bay Area to Lompoc, and may survive to fruit in a very few protected Central Valley foothill locations from Chico to Arvin. Resentful of the excessive dry heat of the interior, it is not for the desert. Cherimoyas are not recommended for container culture.
Growth Habit: The cherimoya is a fairly fairly dense, fast-growing, evergreen tree, briefly deciduous in California from February through April. The tree can reach 30 feet or more, but is fairly easily restrained. Young trees “harp,” forming opposite branches as a natural espalier. These can be trained against a surface, or pruned off to form a regular free-standing trunk. Growth is in one long flush, beginning in April. The roots commence as taproot, but the slow-growing root system is rather weak, superficial, and ungreedy. Young plants need staking.
Foliage: The attractive leaves are single and alternate, 2 to 8 inches long and up to 4 inches wide. They are dark green on top and velvety green on the bottom, with prominent veins. New growth is recurved, like a fiddle-neck. Axillary buds are hidden beneath fleshy leaf petioles.
Flowers: The fragrant flowers are borne solitary or in groups of 2 or 3 on short, hairy stalks along the branches. They appear with new growth flushes, continuing as new growth proceeds and on old wood until midsummer. The flowers are made up of three fleshy, greenish-brown, oblong, downy outer petals and three smaller, pinkish inner petals. They are perfect but dichogamous, lasting approximately two days, and opening in two stages, first as female flowers for approximately 36 hours. and later as male flowers. The flower has a declining receptivity to pollen during the female stage and is unlikely to be pollinated by its own pollen in the male stage.
Fruits: The compound fruit is conical or somewhat heart-shaped, 4 to 8 inches long and up to 4 inches in width, weighing on the average 5-1/2 to 18 ounces, but the largest fruits may reach 5 pounds in weight. The skin, thin or thick, may be smooth with fingerprint-like markings or covered with conical or rounded protuberances. The sweet, juicy, white flesh is melting, subacid and very fragrant. The fruit is of a primitive form with spirally arranged carpels, resembling a raspberry. Each segment of flesh surrounds a single hard black bean-like seed. The fruit size is generally proportional to the number of seeds within. They ripen October to May.
Location: Cherimoyas prefer a sunny exposure, buoyant marine air and cool nights. In southern California do not plant where heat collects on barren hillside or against a wall, since the leaves and fruit may sunburn badly. In the north, do the opposite: plant against a south facing wall to collect heat and encourage early bud-break and fruit ripening. The trees need protection from constant ocean or Santa Ana winds which may damage them and interfere with pollination and fruit set.
Soil: The cherimoya performs well on a wide range of soil types from light to heavy, but seems to do best on a well-drained, medium soil of moderate fertility. The optimum pH ranges from 6.5 to 7.6.
Irrigation: Cherimoyas need plenty of moisture while they are growing actively, but should not be watered when they are dormant. The trees are susceptible to root rot in soggy soils, especially in cool weather. Commence deep watering biweekly in April. Drip irrigation is also an excellent way to supply water. It is best to avoid poor water to prevent salt build-up. Drought-stressed trees will drop their leaves, exposing the fruit to sunburn.
Fertilization: Cherimoyas should be fertilized on a regular basis. Apply a balanced fertilizer, such as 8-8-8 NPK, in midwinter, then every three months. Increase the amount of fertilizer each year until the trees begin to bear fruit. Mature trees require an annual application of 4 ounces of actual nitrogen per inch of trunk diameter. Cherimoyas also respond to organic amendments. It should be kept in mind that yellow leaves may mean that the soil too dry or the weather too cold, not always a need for fertilizer.
Pruning: Cherimoyas have rather brittle wood. Prune during the dormant period to develop strong branches that can support the heavy fruit. Train the tree to two scaffold branches at 2 feet of trunk, pruning them to a 2 foot length. Save only the strongest single shoots, preferably those at 60 to 90 degree angle, and remove the others. In the following years, remove two-thirds of the previous year’s growth, leaving six or seven good buds, at time of new growth. This will keep fruiting wood within reach of the ground. Thin out crossing branches.
Frost Protection: Young trees are very frost sensitive. Wrap the trunk and scaffold with sponge foam for protection, or cover the entire tree. In cooler areas plant next to a south-facing wall or under the eaves to trap house heat.
Pollination: Since natural pollinators are not present in California, the flowers must be pollinated by hand. This is best done in mid-season of bloom, over a period of two to three months. In early evening, collect in a small bottle the anthers and pollen from the interior of fully open male flowers with a #2 or #3 artists brush. Anthers will be tan colored and the white pollen falling from them will be obvious. The pollen has its highest viability at the time it is shed and declines significantly with time. Immediately apply freshly collected pollen with a small brush to the flowers in partially open, female stage. If no female stage flowers are available, pollen may be saved in the sealed container under refrigeration overnight. Pollen may then be applied to female stage flowers in the morning. In large scale operations the pollen may be mixed with inert Lycopodium spores, PVC, starch or talc powder and applied with aspirator-type Japanese apple-pollinators, to save time and pollen. Pollinate every two or three days, and only flowers easily reached inside the tree, to avoid sunburned and wind-damaged fruit. If pollination efforts are quite successful, it may be necessary to thin the fruit. Too much fruit may result in small size and adversely effect future yields.
Propagation: Since there are no recognized rootstocks for cherimoyas, seedlings are universally utilized. Seeds from the White cultivar (Dr. White) are thought by some to produce superior rootstocks, however there does not appear to be a great deal of objective data to support this position. Seeds remain viable for two to three years if kept dry and protected from weevil and fungi. With 70° F bottom heat, seed will germinate in about 21 days, but will require about 40 days under normal ambient growing conditions. Seedlings should be transplanted to deep containers (approximately 18″) when they are 3″ tall to promote development of the tap root. In frost-free areas, it is recommended that seedlings for spring grafting be planted in their ultimate location in the fall and grafted in the ground the following spring.
Grafting is most successful in January through May provided previous years leaves have not been shed from the potential scionwood. During this period no scion preparation is required other than removal of leaves. All normal grafting techniques appear to be equally successful. However in topworking, nurse branches are desirable if not essential for success. To bud, collect budwood in July store refrigerated for 10 days in plastic. Petioles will drop exposing dormant buds. Bud at once using chip bud technique and wrap well against dehydration. Grafted plants will bear in two to three years.
Pests and Diseases: Mealybugs and snails are the main pests of cherimoyas. Keep ducks or apply copper strips to the trunks for control of snails. Mealybugs are brought by ants which can be controlled to some extent by maintaining fresh Tanglefoot on masking tape around the trunk. The masking tape is important to prevent damage to the tree. Skirt the tree to prevent ant access from the ground or weeds. No chemicals are registered for use on Cherimoyas.
Cherimoyas are susceptible to Armillaria (Oak Root Fungus) and Verticillium. Do not plant in old vegetable gardens, or near tomatoes, eggplant or asters. Crown rot can kill trees damaged by frost or growing in saturated soil, as well as from trunks hit by frequent, superficial lawn sprinkling.
Harvest: The fruit turns a pale green or creamy yellow color as they reach maturity. Color change is not marked in cool weather. They should be picked when still firm and allowed to soften at room temperature. Ripe fruit will give to soft pressure. Overripe fruit will be dark brown. Fruit left on the tree too long will usually crack or split and begin to decay. The fruit should be clipped rather than pulled from the tree. Cut the stem close to the fruit so it won’t puncture other fruit during storage.
Store mature fruit above 55° F to prevent chilling injury to the skin and flesh. Ripe fruit will deteriorate quickly but can be stored at temperatures lower than 55° F for short periods. Ripe cherimoyas can be frozen and eaten like ice cream. Cherimoyas are best served chilled, cut in half or quartered and eaten with a spoon. The fruit can also be juiced or used to make delicious sorbets or milkshakes.
Commercial Potential: Though unusual in appearance, cherimoyas are readily accepted by western tastes and has become a favorite tropical fruit. Demand greatly exceeds supply in all U.S. markets as most fruit never leaves California, the only producing state. The fruit commands high wholesale and retail prices, but costs are high and major crop losses from frost and fruit splitting are an ever present possibility. The major labor costs are pruning, pollination, ant control and irrigation.
- Origin James Bays, Ventura, Calif., 1920. Tree broad, to 20 ft. Best in Carpenteria area. Fruits round, medium size, light green, skin shows fingerprint like marks (impressa type). Flavor good, almost lemony.
- Big Sister
- Origin James Neitzel, San Diego, Calif., 1979. Sibling of Sabor. Fruit large, very smooth, good flavor; impressa type. Often self-fruitful.
- Origin A. F. Booth, Hollywood, Calif., 1921. Among hardiest of cherimoya, does well in most present growing areas. Tree 20 to 30 feet high. Fruit is conical, impressa type, medium size, rather seedy, with flavor that suggests papaya.
- Origin A.M. Chaffey, West Los Angeles, Calif., 1945. Seed from Salta, Argentina. Tree rather open, fast growing. For coastal areas. Fruit small to medium, round, impressa type, with high, lemony flavor.
- Tree broad, branches limber, spreading. Selected for superior hardiness. Fruit medium, quite dark green, mammillated, flavor good.
- El Bumpo
- Origin Rudy Haluza, Villa Park, Calif., 1986. Fruit conical, medium size, mammillated, not suited for commerce. Skin soft, practically edible. Flavor among the finest.
- Medium, skin smooth, plated, yellowish green. Pulp has smooth texture, excellent flavor, very juicy. Ripens November to March.
- Knight (syns. DV, Pierce, M&N Pierce)
- Origin a Mr. Knight, Orange, Calif., 1930’s. Scions imported from Mexico. Recovered from Dr. Pierce’s ranch, Goleta, in 1950’s and propagated under several names. Tree has medium vigor, medium-sized pale green wavy leaves. Fruit has minor protuberances, a thin skin, a slightly grainy texture and is quite sweet.
- Origin Rudy Haluza, Villa Park, Calif.,1986. Tree large. Fruit impressa type, round conical; early harvest. Sweet, strong flavor.
- McPherson (syn. Spain)
- Tree pyramidal, vigorous, to 30 ft. Fruits small to medium in size, conical, dark green, impressa type, not seedy. Flavor suggests banana, sweetness varies with temperature while maturing.
- Origin George Emerich, Fallbrook, Calif., 1983. From Ecuadorian seed. Tree vigorous, bears quickly, flowers profuse, tendency to self-pollinating. Fruits smooth, light green, conical, 1-1/2 to 2-1/2 pounds. Skin thin, tender. Flavor has good sweet-acid balance.
- Origin William Ott, La Habra Heights, Calif., 1936. Plant patent #656. Seed from Mexico, D.F. Tree strong growing. Fruit medium, heart shaped tuberculate, flesh yellow, seedy, very sweet. Matures early.
- Pierce (syns. Knight, Escondido White, Ryerson, Thomson-Spain, & Bayott)
- Believed to be from a group of scions imported from Mexico in the 1930’s by a Mr. Knight of Orange. Dr. H. F. Pierce planted a grove in Goleta in that period made up largely of trees produced by Knight. This cultivar was Dr. Pierce’s favorite and was named “Pierce” by him. Tree is vigorous with large dark green leaves. Fruit is medium sized elongated conically shaped with very smooth skin and a high sugar content.
- Origin James Neitzel, San Diego, Calif., 1979. Sibling of “Big Sister”. Fruit mammillated, varies in size, not usually large. Among the best in flavor.
- Origin Hollywood, Calif., 1924. Tree moderately vigorous. Fruit medium to large elongated conical, tuberculate, light green, flavor good. Seed enclosed in an obtrusive sac of flesh.
- White (syn. Dr.White)
- Origin J. H. MacPherson, Lemon Grove, Calif., 1928. Tree open, unkempt; to 35 feet, needs forming. A commercial favorite at Carpinteria. Best near coast. Fruit large, to 4 pounds, conical, with superficial small lumps (umbonate). Flesh juicy, flavor weak, suggesting mango-papaya.
- California Avocado Society Yearbook, 1947 pp 67-70.
- Morton, Julia F. Fruits of Warm Climates. Creative Resources Systems, Inc. 1987. pp. 65-69.
- Ortho Books. All About Citrus and Subtropical Fruits. Chevron Chemical Co. 1985. pp. 23-25.
- Popenoe, Wilson. Manual of Tropical and Subtropical Fruits. Hafner Press. 1974. Facsimile of the 1920 edition. pp. 161-177.
- Sanewski, G. M. Growing Custard Apples, Brisbane, Queensland Department of Primary Industries, Horticulture Branch, 1987.
- Smithsonian Institution, U.S. National Herbarium Contributions, Vol. 18 (1927).