Abiu Fruit Tree - Pouteria caimito

A minor member of the Sapotaceae, the abiu, Pouteria caimito Radlk. (syns. Lucuma caimito Roem. & Schult.; Achras caimito Ruiz & Pavn), has acquired few vernacular names. In Colombia, it is called caimito, caimito amarilla, caimo or madura verde; in Ecuador, luma or cauje; in Venezuela, temare; in Brazil, abiu, abi, abio, abieiro or caimito. It is called yellow star apple in Trinidad.

Abiu Tree Description

The tree has a pyramidal or rounded crown; is generally about 33 ft (10 m) high but may reach 115 ft (35 m) in favorable situations. A gummy latex, white or reddish, exudes from wounds in the bark. The leaves are alternate and highly variable; may be ovate-oblong, obovate or elliptic; 4 to 8 in (10-20 cm) long, 1 1/4 to 2 3/8 in (3-6 cm) wide; short-pointed at the apex, sometimes long-tapering at the base; smooth or with a few scattered hairs.

The flowers, borne singly or in groups of 2 to 5 in the leaf axils, are cylindrical, 4- to 5-lobed, white or greenish; 1/6 to 1/3 in (4-8 mm) long.

The fruit, downy when young, is ovoid, elliptical or round; 1 1/2 to 4 in (4-10 cm) long, sometimes having a short nipple at the apex; with smooth, tough, pale-yellow skin when ripe and fragrant, white, mucilaginous, translucent, mild-flavored, sweet or insipid pulp containing 1 to 4 oblong seeds, brown, with a pale hilum on one side. Until fully ripe, the fruit is permeated with latex and is very gummy and astringent.

Abiu Tree Origin and Distribution

The abiu is a denizen of the headwaters of the Amazon. It grows wild on the lower eastern slopes of the Andes from southwestern Venezuela to Peru. It is often cultivated around Iquitos, Peru. In Ecuador, it is common in the Province of Guayas and the fruits are sold in the markets of Guayaquil. It is much grown around Par, Brazil; less frequently near Rio de Janeiro, and to a limited extent at Bahia. In Colombia, it is fairly common in the regions of Caquet, Meta and Vaups and it abounds in the adjacent areas of Amazonas, Venezuela. It has been growing for many years in Trinidad.

The plant explorers, Dorsett, Shamel and Popenoe, collected seeds for the United States Department of Agriculture in Bahia in 1914 (S.P.I. #37929). In 1915, seeds were received from Lavoras, Minas, Brazil (S.P.I. #41003). This species has been planted several times at the Agricultural Research and Education Center, Homestead, Florida, but most of the young plants have been killed by winter cold. A few trees planted in 1953 fruited in 1962.

Abiu Tree Varieties 
 
There is much variation in the form, size and quality of the fruits of seedling trees, some having firm flesh, some soft; and some are insipid, while others have agreeable flavor. At Puerto Ospina, along the Putamayo River in Colombia, there is a type that fruits in 4 years. The fruit is round and large. Near the River Inirida, in Vaups, Colombia, there is a type that bears in one year from seed, but the fruits are small with little pulp.

Abiu Tree Climate
 
The abiu is strictly tropical or near-tropical. It thrives best in a year-around warm and moist climate, yet Popenoe noted that it does well in somewhat cooler Rio de Janeiro. In Peru it has not been found above 2,000 ft (650 m), though in Colombia, it can be grown up to an elevation of 6,000 ft (1,900 m).

Abiu Tree Soil

The tree is naturally suited to fertile, wet soil. It is subject to chlorosis in the limestone of southern Florida.

Abiu Tree Season

The fruits are in season in March and April in Ecuador. They are sold in some Brazilian markets from September to April but only a few are seen in the much shorter season of February and March at Bahia. Fruits have matured in October in Florida. The abiu can be picked while underripe and firm for transport to markets.

Abiu Tree Propagation and Culture 
 
In Brazil, the washed seeds are dried in the shade and then planted, 3 together and 2 in (5 cm) deep in enriched soil. They will germinate in 15 to 20 days. When the seedlings are 4 in (10 cm) high, the 2 weakest are removed. The strong one is set out when 12 to 16 in (30-40 cm) high. Spacing is 17 x 20 ft (6 x 5 m). One year later, the lower branches are pruned. Fruiting will begin in 3 years; will be substantial in 5 years.

Abiu Tree Pests and Diseases
 
Actually, the fruit has little value commercially because it is commonly damaged by small insects (bichos in Spanish and Portuguese). In Brazil, the chief pests are said to be fruit flies.

Abiu Tree Food Uses 
 
In Colombia, people who wish to eat the abiu. are advised to grease their lips beforehand to keep the gummy latex from clinging to them. It is mostly eaten out-of-hand but, in Par, some types are used to make ices and ice cream.

Abiu Tree Other Uses

Wood: The wood is dense and heavy, hard, and valued for construction.
Medicinal Uses: In Brazil, the pulp, because of its mucilaginous nature, is eaten to relieve coughs, bronchitis and other pulmonary complaints. The latex is given as a vermifuge and purge and is applied on abscesses.

Article Source Purdue University Horticulture Department.
http://www.hort.purdue.edu/newcrop/Indices/index_ab.html

Avocado Fruit Tree - Persea americana

The avocado, unflatteringly known in the past as alligator pear, midshipman's butter, vegetable butter, or sometimes as butter pear, and called by Spanish-speaking people aguacate, cura, cupandra, or palta; in Portuguese, abacate; in French, avocatier; is the only important edible fruit of the laurel family, Lauraceae. It is botanically classified in three groups: A), Persea americana Mill. var. americana (P. gratissima Gaertn.), West Indian Avocado; B) P. americana Mill. var. drymifolia Blake (P. drymifolia Schlecht. & Cham.), the Mexican Avocado; C) P. nubigena var. guatemalensis L. Wms., the Guatemalan Avocado.

Avocado Tree Description

The avocado tree may be erect, usually to 30 ft (9 m) but sometimes to 60 ft (18 m) or more, with a trunk 12 to 24 in (30-60 cm) in diameter, (greater in very old trees) or it may be short and spreading with branches beginning close to the ground.

Almost evergreen, being shed briefly in dry seasons at blooming time, the leaves are alternate, dark-green and glossy on the upper surface, whitish on the underside; variable in shape (lanceolate, elliptic, oval, ovate or obovate), 3 to 16 in (7.5-40 cm) long. Those of the Mexican race are strongly anise-scented. Small, pale-green or yellow-green flowers are borne profusely in racemes near the branch tips. They lack petals but have 2 whorls of 3 perianth lobes, more or less pubescent, and 9 stamens with 2 basal orange nectar glands.

The fruit, pear-shaped, often more or less necked, oval, or nearly round, may be 3 to 13 in (7.5-33 cm) long and up to 6 in (15 cm) wide. The skin may be yellow-green, deep-green or very dark- green, reddish-purple, or so dark a purple as to appear almost black, and is sometimes speckled with tiny yellow dots, it may be smooth or pebbled, glossy or dull, thin or leathery and up to 1/4 in (6 mm) thick, pliable or granular and brittle.

In some fruits, immediately beneath the skin there is a thin layer of soft, bright-green flesh, but generally the flesh is entirely pale to rich-yellow, buttery and bland or nutlike in flavor. The single seed is oblate, round, conical or ovoid, 2 to 2 1\2 in (5-6.4 cm) long, hard and heavy, ivory in color but enclosed in two brown, thin, papery seedcoats often adhering to the flesh cavity, while the seed slips out readily. Some fruits are seedless because of lack of pollination or other factors.

Avocado Tree Origin and Distribution

The avocado may have originated in southern Mexico but was cultivated from the Rio Grande to central Peru long before the arrival of Europeans. Thereafter, it was carried not only to the West Indies (where it was first reported in Jamaica in 1696), but to nearly all parts of the tropical and subtropical world with suitable environmental conditions. It was taken to the Philippines near the end of the 16th Century; to the Dutch East Indies by 1750 and Mauritius in 1780; was first brought to Singapore between 1830 and 1840 but has never become common in Malaya.

It reached India in 1892 and is grown especially around Madras and Bangalore but has never become very popular because of the preference for sweet fruits. It was planted in Hawaii in 1825 and was common throughout the islands by 1910; it was introduced into Florida from Mexico by Dr. Henry Perrine in 1833 and into California, also from Mexico, in 1871. Vegetative propagation began in 1890 and stimulated the importation of budwood of various types, primarily to extend the season of fruiting. Some came from Hawaii in 1904 (S. P. I. Nos. 19377-19380).

Avocado Tree Pollination

Many isolated avocado trees fail to fruit from lack of pollination. Commercial growers are careful to match Class A cultivars whose flowers will receive pollen in the morning with Class B cultivars that release pollen in the morning and every grower must be sure to include compatible pollinators in his grove. Bulletin 29 (1971) of the Ministry of Agriculture in Guatemala tabulates the flowering periods (varying from August to April) of 48 introduced and locally selected cultivars, and the hours of the day when each is receptive to or shedding pollen.

Avocado Tree Climate

The West Indian race requires a tropical or near tropical (southern Florida) climate and high atmospheric humidity especially during flowering and fruitsetting. The Guatemalan race is somewhat hardier, having arisen in subtropical highlands of tropical America, and it is successful in coastal California. The Mexican race is the hardiest and the source of most of California avocados. It is not suited to southern Florida, Puerto Rico or other areas of similar climate. Temperatures as low as 25ºF (-4ºC) do it little harm. In areas of strong winds, wind-breaks are necessary. Wind reduces humidity, debydrates the flowers and interferes with pollination, and also causes many fruits to fall prematurely.

Avocado Tree Soil

The avocado tree is remarkably versatile as to soil adaptability, doing well on such diverse types as red clay, sand, volcanic loam, lateritic soils, or limestone. In Puerto Rico, it has been found healthier on nearly neutral or slightly alkaline soils than on moderately or highly acid soils. The desirable pH level is generally considered to be between 6 and 7, but, in southern Florida, avocados are grown on limestone soils ranging from 7.2 to 8.3. Mexican and Guatemalan cultivars have shown chlorosis on calcareous soils in Israel. The tree's primary requirement is good drainage. It cannot stand excessive soil moisture or even temporary water- logging. Sites with underlying hardpan must be avoided. The water table should be at least 3 ft (.9 m) below the surface. Salinity is prejudicial but certain cultivars (see 'Fuchs-20' and 'Maoz') have shown considerable salt-tolerance in Israel.

Avocados grafted onto 'Fuch-20' rootstocks and irrigated with water containing 380 to 400 ppm C1 performed well in a commercial orchard. In the Rio Grande Valley of Texas, cultivars of the Mexican race must be grafted onto salt tolerant West Indian rootstocks.

Avocado Tree Propagation

Normally, avocado seeds lose viability within a month. 'Lula' seeds can be stored up to 5 months if placed in non-perforated polyethylene bags and kept at 40ºF (4.4ºC), thus indicating that it may be possible to successfully store seeds of other cultivars ripening at different seasons for later simultaneous planting. Fresh seeds germinate in 4 to 6 weeks, and many people in metropolitan areas grow avocado trees as novelty house plants by piercing the seed partway through with toothpicks on both sides to hold it on the top of a tumbler with water just covering 1/2 in (1.25 cm) of the base.

When roots and leaves are well formed (in 2 to 6 weeks), the plant is set in potting soil. Of course, it must be given adequate light and ventilation. In nurseries, seeds that have been in contact with the soil are disinfected with hot water. Experiments with gibberellic acid and cutting of both ends of the seed with a view to achieving more uniform germination have not produced encouraging results. Seedlings will begin to bear in 4 or 5 years and the avocado tree will continue to bear for 50 years or more. Some bearing trees have been judged to be more than 100 years old.

In Australia, seeds planted in early fall germinate in 4 to 6 weeks; if planted later, they may remain dormant all winter and germinate in early spring. Seedlings should be kept in partial shade and not overwatered. While many important selections have originated from seeds, vegetative propagation is essential to early fruiting and the perpetuation of desirable cultivars. However, seedlings are grown for rootstocks.

For many years, shield budding was commonly practiced in Florida, but this method requires considerable skill and experience and is not successful with all cultivars. Therefore, it was largely replaced by whip, side-, or cleft-grafting, all of which make a stronger union than budding.

In the past, seedlings were grafted when 18 to 36 in (45-90 cm) high. It is now considered far better to graft when 6 to 9 in (15-23 cm) high, making the graft 1 to 3 in (2.5-7.5 cm) above ground level. West Indian rootstocks are desirable for overcoming chlorosis in avocados in Israel.

Avocado cuttings are generally difficult to root. Cuttings of West Indian cultivars will generally root only if they are taken from the tops or side shoots of young seed rings. But etiolated cuttings (new shoots) from gibberellin treated hardwood and semi hardwood cuttings of 'Pollock' as well as 'Lula' have been rooted with 50-60% success and, when treated with IBA, 66-83% success under mist in Trinidad. Cuttings of 'Fuchs-20' have rooted under mist with 40 to 50 or even 70% in Israel. Cuttings of 'Maoz' have rooted at the rate of 60% by a special technique developed in California.

An Israeli selection, 'G.A. 13' has given 70 to 90% success in rooting cuttings under mist for the purpose of utilizing them as rootstocks in saline and high lime situations. Air- layering is sometimes done to obtain uniform material uninfluenced by rootstock, for research on specific problems. Degree of success depends on the cultivar (those of the Mexican race rooting most quickly), and air-layering is best done in spring and early summer.

At times, mature avocado groves are top worked to change from an unsatisfactory cultivar, or one declining in popularity, to a more profitable one, or an assortment of cultivars for different markets. In 1957, 2,700 ";obsolete"; avocado trees in Ventura, California, were being grafted (top-worked) to mainly 'Hass', some to 'Bacon' and 'Rincon'. This procedure may involve thousands of trees in a given region. It is done in December and January in Florida.

Inasmuch as avocado roots are sensitive to transplanting, it is now considered advisable to raise planting material in plastic bags which can be slit and set in the field without disturbing the root system.

Avocado Tree Spacing

Spacing is determined by the habit of the cultivar and the character of the soil. In light soil, 25 x 25 ft (7.5x7.5 m) may be sufficient. In deep, rich soil, the tree makes its maximum growth and a spacing of 30 or 35 ft (9.1 or 10.7 m) may be necessary. If trees are planted so close that they will ultimately touch each other, the branches will die back. Some growers plant 10 to 15 ft (3-4.5 m) apart initially and remove every other tree at 7 to 8 years of age. If the surplus trees are not bulldozed but just cut down leaving a stump, application of herbicide may be needed to prevent regrowth. Ammonium sulfamate has been proven effective. In modernized plantings, space between rows is necessary for mechanical operations.
Holes at least 2 ft (0. 6 m) deep and wide are prepared well in advance with enriched soil formed into a mound.

After the young plant is put in place a mulch is beneficial, weeds should be controlled, and watering is necessary until the roots are well established. Generally small amounts of fertilizer are given every 2 months with the amount gradually increasing until fruiting begins. Bearing trees need, on the average, 3 to 4 lbs (1 1/2-2 kg) 3 times a year, beginning when the tree is making vegetative growth. No fertilizer should be given at blooming time; one must wait until the fruits are firmly set. Nitrogen has the greatest influence on tree growth, its resistance to cold temperatures, and on fruit size and yield. Fertilizer mixes vary greatly with the type of soil.

Mineral deficiencies determined by leaf analysis, are usually remedied by foliar spraying. Magnesium deficiency was formerly a serious handicap to avocado growers in Florida and Kenya. In California, zinc deficiency has been corrected by applying zinc chelates or zinc sulfate to the soil instead of spraying the foliage. Keeping the upper soil moist has been greatly facilitated by drip irrigation, which also may carry 80% of the fertilizer requirement.

Because some cultivars tend to grow too tall for practical purposes, commercial growers cut trees back to 16 or 18 ft (4.8-5.4 m), let them grow back to 30 ft (9.1 m) and top them again. But decapitation is not a perfect remedy because the tendency of the avocado tree is to grow a new top very quickly. Recently it has been found that the growth-inhibiting chemical, TIBA (triiodobenzoic acid) slows down terminal growth and encourages lateral shoots.

A system of pruning to encourage lower branching is being tried on 'Lula' in Martinique. Avocado branches frequently need propping to avoid breaking with the weight of the developing fruits. Some growers find it profitable to interplant bananas until the avocado trees reach bearing age.

Avocado Tree Maturity and Harvesting

Avocados will not ripen while they are still attached to the tree, apparently because of an inhibitor in the fruit stem. Homeowners usually consider the entire crop pickable when a few mature (full grown) fruits have fallen. This is not a dependable guide because the prolonged flowering of the avocado results in fruits in varying stages of development on the tree at the same time. The largest fruits, of course, should be picked first but the problem is to determine when the largest are full grown (perfectly mature for later perfect ripening). If picked when full grown and firm, avocados will ripen in 1 to 2 weeks at room temperature. If allowed to remain too long on the tree, the fruits may be blown down by wind and they will be bruised or broken by the fall.

Florida maturity standards for marketing have been determined by weight and time of year for each commercial cultivar so that immature fruits will not reach the market. Immature fruits do not ripen but become rubbery, shriveled and discolored. Most West Indian cultivars will ripen properly if picked when the specific gravity becomes 0. 96 or lower, but 'Waldin' is fully mature when the specific gravity is still above 0.98. Guatemalan and Guatemalan X West Indian cultivars generally are harvest-mature when the specific gravity is 0.98 or lower. In California, physiological maturity of 'Bacon', 'Fuerte,' 'Hess' and 'Zutano' has been determined by measurement of length, diameter and volume, but dry weight, correlating with oil content, is considered a better maturity index. California law has, since 1925, required a minimum of 8 % oil, but oil content varies greatly among cultivars and also the climatic region where the fruit is grown. Some people complain that the 8% standard is too low for some cultivars.

Maximum flavor of 'Fuerte' develops when the fruit is harvested at an oil content of 16%. Therefore, a minimum dry weight standard of 21 % has been recommended. Formerly, avocados were detached by means of a forked stick and allowed to fall, but this causes much damage and loss. Nowadays harvesters usually use clippers for lowhanging fruits and for those higher up a long handled picking pole with a sharp ";V"; on the metal rim to cut the stem and a strong cloth bag to catch the fruit. Gloves are worn to avoid fingernail scratches on the fruit. In California, studies have been made of the effects of hand clipping (leaving stem on), hand snapping (which removes the stem), tree- shaking, and limb shaking (which removes the stem from some of the fruits).

All methods are acceptable if the stem scar is waxed on stemless fruits to avoid weight loss before ripening at which time the stem detaches naturally. In Australia, some growers are using hydraulic lifts to facilitate hand- picking. A tractor fitted with a triple-decked picking platform has been adopted by some large growers in Chile. Efforts to develop dwarf avocado trees by means of sandwich interstocks from low growing types have been going on in California since 1964. Avocados must be handled with care and are packed and padded in single or double-layer boxes or cartons for shipment. A special ";Bruce box";, holding 32 lbs (14.5 kg) is used for large fruit. The fruits may be held in position in molded trays.

Avocado Tree Pests and Diseases

Avocados have no major insect enemies in Florida but migrating cedar waxwings feed on leaves, flowers and very young fruits and the fruits are commonly attacked by squirrels, rats and mice. The avocado red mite, Oligonychus yothersi; is the most common predator on the leaves in some groves and not in others. Red-banded thrips, Selenothrips rubrocinctus, the greenhouse thrips, Heliothrips haemorrhoidalis, and red-spider, Tetranychus mytilaspidis, may feed on avocado leaves and blemish the fruits from time to time.

There are several scales also which may feed on foliage, especially the Florida wax scale, Ceroplastes floridensis, the pyriform, or soft white, scale, Protopulvinaria pyriformis, Dictyospermum scale, Chrysomphalus dictyospermi; and the black scale, Saissetia oleae. Among two dozen other minor pests in Florida are the citrus mealybug, Pseudococcus citri and avocado mealybug, P. nipae. Stinkbugs may prick the fruits leaving little dents in the skin coupled with gritty areas at the same locations inside.

In California, 2 lepidopterous pests, Amorbia cuneana and the omnivorous looper, Sabulodes aegrotata, when present in large numbers, cause severe defoliation and fruit-scarring. Biological control is being achieved by release of the egg parasite, Trichogramma platneri; which is now commercially available to growers. Since 1949, the orange tortrix (a leaf roller), Argyrotaenia citrana, has been increasing as a menace to the avocado in California, the larvae feeding on twigs, terminal buds and foliage, flowers, and fruits. Since the pest requires shaded areas, it is best controlled by thinning out a close-planted grove or top-working to less susceptible cultivars.

The fruit-spotting bug, Amblypelta nitida, and banana spotting bug, A. Iutescens, are important pests requiring control in Queensland. The Mediterranean fruit fly is a major hazard in Israel, but very thick- skinned fruits such as 'Anaheim' are not attacked. The Queensland fruit fly, Dacus tryoni; seriously damages only Mexican cultivars or Guatemalan X Mexican hybrids in Australia. In 1971, a nematode survey in Bahia, Brazil, revealed 9 genera of known or suspected parasitic nematodes associated with avocado tree decline. Israeli avocado growers are seeking and testing means of biological control of the more serious of the 3 dozen insects and mites preying on the crop in that country. In Mexico, the avocado weevil, Heilipus lauri; tunnels into the seeds.

The major disease of avocados in South and Central America and some islands of the West Indies, in California, Hawaii, and various other areas, is root-rot caused by the fungus, Phytophthora cinnamomi, which is being combatted by the use of strict sanitary procedures and resistant rootstocks, especially 'Duke'. At the University of California, Riverside, over 750 seedlings and cuttings were being tested for root- rot resistance in 1976 and 1977 and the most promising tried out for grafting compatibility with commercial cultivars.

Also, soil fumigation experiments with methyl bromide and newly developed chemicals were being carried forward. The disease has been so devastating in the high rainfall areas of New South Wales and Queensland that plantings have expanded into the semi-arid Murray Valley in the hope of avoiding it. In New Zealand, it is not a problem on deep, volcanic soils, but occurs on shallow, heavier soils. It was allegedly introduced into Chile with balled trees from California and vigorous measures are being taken to control it.

Mushroom root-rot from Clitocybe tabescens may occasionally occur. Cercospora spot (brown spots on the leaves and fruits), caused by the fungus, Cercospora purpurea, may cause cracks in affected areas of the skin and thus allow entrance of the anthracnose fungus, Colletotrichum gloeosporioides, which invades and spoils the flesh. Glomerella cingulata is an important source of anthracnose in Queensland. Some cultivars are subject to scab which is readily controlled by copper sprays.

More than 30 other pathogens are variously responsible for wood rot, collar rot, dieback, leafspot, stem-and rot of fruit, branch canker, and powdery mildew. Sunblotch viroid cripples young trees and damages fruits in California and Israel. So far, it is unknown in New Zealand. Stems of young trees may be affected by sunburm, and hot, dry winds cause tipburm of leaves. The avocado tree may show copper or zinc deficiency or tipburm from an excess of mineral salts.

Article Source Purdue University Horticulture Department
http://www.hort.purdue.edu/newcrop/Indices/index_ab.html

Atemoya Fruit Tree - Annona squamosa

The atemoya, Annona squamosa x A. cherimola, is a hybrid of the sugar apple and cherimoya, qq.v. It was for many years mistakenly called custard apple or cherimoya in Queensland and New South Wales. The name applied in Venezuela is chirimorinon. 

Atemoya Fruit Tree Description

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. 

Atemoya Fruit Tree Origin and Distribution

The first cross was made by the horticulturist, P.J. Wester, at the United States Department of Agriculture's subtropical laboratory, Miami, in 1908. Seedlings were planted out in 1910. Other crosses made in 1910 fruited in 1911 and seeds were taken by Wester to the Philippines. The hybrids grew there to 7 1/2 ft (2.3 m) high in one year, had to be moved to another location; one bloomed in 1913 and was pollinated by the custard apple, q.v. The rest of the plants fruited in 1914. Resulting fruits were superior in quality to the sugar apple and were given the name "atemoya", a combinetion of "ate", an old Mexican name for sugar apple, and "moya" from cherimoya.

Cuttings of 9 of the hybrids were sent by Wester to the United States Department of Agriculture in January of 1915. (S.P.I. Nos. 39808-39816), #39809 representing the hybrid tree pollinated by the custard apple. In 1917, Wester sent cuttings of #39809 under the name "cuatemoya" to the United States Department of Agriculture (S.P.I. Nos. 44671-44673). In the meantime, Edward Simmons, at the Plant Introduction Field Station, Miami, had successfully grown hybrids and they had survived an early February 1917 drop in temperature to 26.5ºF (-3.10ºC), showing the hardiness derived from the cherimoya. Another introduction was received from the Philippines in 1918 (S.P.I. #45571).

A few experimental growers in southern Florida maintained atemoya trees (apparently distributed by the United States Department of Agriculture) for many years while there was a general lapse of interest in this fruit. Today, there are a few small commercial plantings and the fruits are being sent to some northern fruit dealers.

In the early 1930's or 1940's, what were apparently chance hybrids between adjacent sugar apple and cherimoya orchards attracted attention in Israel and work was begun to choose and standardize the best of these for vegetative propagation.

Atemoya Fruit Tree Pollination

The atemoya and other annona trees bear hermaphroditic protogynous flowers and self-pollination is rare. Atemoyas are sometimes misshapen, underdeveloped on one side, as the result of inadequate pollination. The flower, in its female stage, opens between 2 and 4 o'clock in the afternoon. Between 3 and 5 o'clock on the following afternoon, the flower converts to its male stage. In cold and humid climates it releases pollen even though it is sticky.

Where the climate is hot and the humidity low at the blooming season, the carpers are short lived and the stigmatic surface soon dries up and insects are necessary to transfer the pollen. Studies in Israel have identified the principal insect pollinators as nitidulid beetles-Carpophilus hemipterus, C. mutilatus, Haptoncus luteolus, and Uroporus humeralis. Even where these beetles are present, hand-pollination will enhance fruit-setting and this is commonly practiced in Egypt. Spraying the flowers several times with gibberellin at 1,000 ppm has increased fruit yield. The resulting fruits are seedless but smaller and less flavorful than fruits with seeds.

Atemoya Fruit Tree Climate

The atemoya is slightly hardier than the sugar apple but still is limited to tropical or near-tropical lowlands. In New South Wales, it is said to do best near the coast where rainfall and humidity are high and winters are warm. Rainy weather during the ripening season, however, may cause the fruits to split.

Atemoya Fruit Tree 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; waterlogging is fatal.

Atemoya Fruit Tree 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 (90 cm) apart. Grafting is done in the spring, using the whip- or tongue-graft. 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. In Florida and India, the atemoya is usually grafted onto the custard apple or sugar apple. Cherimoya is used as a rootstock in Israel.

Atemoya Fruit Tree 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. Half is given in the spring a month before flowering. Irrigation during flowering and fruit setting improves yield and fruit quality.

Atemoya Fruit Tree Season

In Florida, the atemoya ripens in the fall. In Queensland, the main blooming period is October and November and the fruits mature in April and May. If there is light fruit set in October/November, flowering may continue to February and the fruit from such late blooms may have to be picked prematurely and ripened artificially to avoid cold night temperatures, but it will not develop the highest quality.

Atemoya Fruit Tree 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.

Atemoya Fruit Tree Yield

The atemoya is a shy yielder, mainly for the reason mentioned under "Pollination". Trees 5 years old are expected to bear 50 fruits annually. In Queensland, commercial groves have produced 5 bushels of fruit per tree-67 bushels per acre (165.5 bu/ha). An exceptionally large atemoya tree in Florida yielded 11 bushels of fruits in the 1972 season.

Atemoya Fruit Tree 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.

Atemoya Fruit Tree 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.

In Queensland, the protective activities of the natural enemies of the mealybug are disrupted by the coastal brown ant, Pheidole megacephala, which carries mealybugs up the trunk and around between the fruits. Australian growers have tried sticky-banding the trunks and this has reduced the numbers of ants but not sufficiently.

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.

Atemoya Fruit Tree Food Uses

The atemoya, preferably chilled, is one of the most delicious of fruits. It needs no seasoning. It may be simply cut in half or quartered and the flesh eaten from the "shell" with a spoon. Slices or cubes of the pulp may be added to fruit cups or salads or various dessert recipes. Some people blend the pulp with orange juice, lime juice and cream and freeze as ice cream.

Atemoya Fruit Tree 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.

Article Source Purdue University Horticulture Department.
http://www.hort.purdue.edu/newcrop/Indices/index_ab.html