Atemoya - Annona cherimola x A. squamosa
Atemoya
Fig. 1 
Atemoya fruit

Atemoya flowers
Fig. 2 magnifying glass
Atemoya flowers

Atemoya flower
Fig. 3 magnifying glass
Flower

Atemoya flower
Fig. 4
Female flower

Sap beetle entering an atemoya flower.
Fig. 5 magnifying glass
Sap beetle entering an atemoya flower

Annona × atemoya from Taiwan
Fig. 6 magnifying glass

Atemoya seeds
Fig. 7 

Atemoya
Fig. 8 magnifying glass

Atemoya in NZ Grocery store
Fig. 9
Atemoya in NZ Grocery store

São Paulo - Sé: Mercado Municipal de São Paulo - Atemoya
Fig. 10
São Paulo - Sé: Mercado Municipal de São Paulo - Atemoya

Atemoya tree
Fig. 11 magnifying glass


Scientific name
Annona cherimola x A. squamosa and A. cherimola x A. squamosa hybrids
Pronunciation
ä-tə-ˈmȯi-ə, a
Common names
Annon, custard apple. It was for many years mistakenly called custard apple or cherimoya in Queensland and New South Wales. The name applied in Venezuela is chirimorinon 5
Relatives
Sugar apple (A. squamosa), cherimoya (A. cherimola), soursop (A. muricata), custard apple (A. reticulata), pond apple (A. glabra), ilama (A. diversifolia) 2
Family
Annonaceae
Origin
Derived from man-made and natural hybrids
USDA hardiness zones
10-11
Height
25-30 ft (7.5-9 m)
Crown
Trees may have a rounded or posess a asymetrical canopy
Plant habit
Short-bunked, the branches typically drooping and the lowest touching the ground
Growth rate
Fast
Pruning requirement
Regular pruning in the spring to maintain height to 6-8 feet
Leaf
Semi-deciduous, alternate, elliptical, leathery, less hairy than those of the cherimoya; and up to 6 in (15 cm) in length
Flower
Long-stalked, triangular, yellow, 2 3/8 in. (6 cm) long and 1 1/2 to 2 in. (4-5 cm) wide; produced along with new growth in the spring following a winter dormancy period; bears protogynous, hermaphroditic flowers, and self-pollination is rare; may have multiple blooms, with the main bloom from April through June and a smaller bloom during July
Fruit
Aggregate fruit; conical to ovate; 3-5 in. (7.6-12.7 cm) ; weighs 8-32 oz (227-908 g); surface smooth, bumpy, or pronounced protuberances; pulp is white/creamy white, with a custard-like, sweet flavor; dark brown seeds
Season
From Aug. to Oct.; sometimes during Dec.and Jan. if no frost occurs and leaves remain on the tree
Light requirement
Full sun
Soil tolerances
Well adapted to most well drained soil types including the sands and limestone based soils of south Florida
PH preference
6.0-7.0
Drought tolerance
The drought tolerance of atemoya is less well understood; prolonged drought stress may reduce the percent fruit set, fruit size, and crop yields 2
Flood stress
Atemoya trees may be grafted onto various rootstocks and their flood tolerance varies with rootstock 2
Soil salt tolerance
Is not tolerant of saline soil and water conditions
Cold tolerance
28-29°F (-2°C) Due to their superior cold tolerance atemoya trees should be more widely planted in south Florida
Plant spacing
At least 25-30 ft (6.7-7.6 m) from adjacent trees and structures 2
Roots
Relatively shallow and weak root system
Invasive potential *
None reported
Pest resistance
See Annona Pest Page
Known hazard
Seeds contain toxic insecticidal substances



Reading Material

Atemoya Growing in the Florida Home Landscape from the University of Florida pdf 8 pages
Atemoya from Julia Morton's Book Fruits of Warm Climates
The Atemoya by G. Joyner from the Archives of the Rare Fruit Council of Autralia
The Atemoya by G. Joyner from the Miami Rare Fruit Council International



Origin

Not a species, but a hybrid created in Florida between cherimoya (Annona cherimola) and sugar apple (A. squamosa). One of the best  Annonas, often sweeter and fruitier flavored than the cherimoya. Typically 1 ½ to 2 lb, custard-like flesh. Grows in hot tropical areas.
The first cross was made in 1908 by P.J. Wester, a horticulturist at the USDA’s Subtropical Laboratory in Miami. Subsequently, in 1917, Edward Simmons at Miami’s Plant Introduction Station successfully grew hybrids that survived a drop in temperature to 26.5°F, showing atemoya’s hardiness derived from one of its parents, the cherimoya. 3
The fruit resulting from the cross between the sugar apple and the custard apple were given the name "atemoya", a combination of "ate", an old Mexican name for sugar apple, and "moya" from cherimoya. 3

Description
Small to medium sized tree, reaching 30 ft (~10 m) in height and spread. Trees may have a rounded or posess a asymetrical canopy.
Leaves are green, hairy when young, smooth when mature, elliptic, ovate or lanceolate in shape. Leaves are often variable in shape on the same tree. Leaves may be 4 to 8 inches (10-20 cm) long and 1.5 to 3.25 inches (4-8 cm) wide. Trees are semi-deciduous; however, the rate of leaf drop depends upon the severity of cool winter temperatures and leaf disease pressure, which is exacerbated by late summer-fall rainfall. 2

Flowers
An atemoya flower, in its female stage, opens between 2:00 and 4:00 pm; between 3:00 pm and 5:00 pm on the following afternoon, the flower converts to its male stage. 3
Flowers in the female stage are characterized by only a slight opening of the petals (Fig. 4) and a glistening appearance to the stigmatic surfaces. Flowers in the male stage are characterized by flower petals being wide open, petals may easily fall when touched and stamens may have a brownish color. This arrangement of having male and female flower parts functional at different times during the day makes cross pollination among different flowers necessary. 2
Flowers emerge during mid- to late spring as trees flush with new vegetative growth. Flowers are produced singly or in clusters of 2 to 4 from leaf axils on one-year-old shoots or new growth. The flowers are composed of 3 green colored, fleshy petals, 3 small, inconspicuous sepals, and numerous unicarpellate (single ovary) pistils on a common receptacle. 2
Atemoya trees produce flowers on 1- to 2-year old wood and newly emerging shoots. 2

Fruit
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. 5

Varieties
The most satisfactory variety under Florida conditions has been 'Gefner' which does not require hand pollination and produces fruit of good quality. Fruit production of 'Page' is good but fruit tends to split on the tree at maturity. 'African Pride' ('Kaller') and 'Bradley' usually produce few fruit without hand pollination. 'African Pride' fruit may develop internal disorders upon ripening. Other varieties such as 'Bernitski', 'Caves', 'Chirimoriñon A', 'Chirimoriñon B', and 'Chirimoriñon C', 'Hette', 'Island Gem', 'Lindstrom', 'Kabri', 'Malali', 'Malamud', 'Mammoth' ('Pink Mammoth'), 'Priestly' and 'Stermer' have not proven viable for commercial production. 2

Atemoya Varieties Page

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. 5

Pollination
The majority of Annonaceae are pollinated by beetles, although some are pollinated by thrips. The activities of beetles in the flowers, including feeding, mating, and quiescence, result in prolonged visits from several hours to a few days while the flowers advance from the female to the male phase. 1
In Florida, flowering of atemoyas begins in April, and sugar apples in May, and continues until early August. Atemoyas and sugar apples are most often pollinated by nitidulid beetles, which breed and feed in decaying fruits or sap flows. The beetles are attracted to the fruity, fermenting odor of Annona flowers, especially when they are hungry. The number of beetles per flower affects the likelihood of fruit set, and also the quality of the fruit in some cases. All studies provide evidence for increased fruit set as numbers of visiting beetles increase. In Florida, about nine species of native and exotic nitidulids (sap beetles) visit the flowers
(Fig. 5), but Carpophilus mutilatus is the most important pollinator in terms of efficacy and abundance in flowers, followed by C. fumatus and Haptoncus luteolus. 1
Artificial, hand pollination almost always guarantees superior quality fruits. One variety, 'Geffner', produces well without hand pollination. 'Bradley' also produces fair crops without hand pollination, but the fruit has a habit of splitting on the tree. Atemoyas are sometimes misshapen, underdeveloped on one side, as the result of inadequate pollination. 3
The best pollination time for sugar apple is in the morning (5 - 8 AM). For atemoya, the best time for pollination is in the evening (4 - 8 PM). 6

Artificial pollination of sugar apple and atemoya from AgriFoodGateway pdf
Flowering Behavior, Pollination and Fruit Set from the University of Florida
Hand Pollination of the Custard Apple from the Archives of the Rare Fruit Council of Australia

Propagation
Atemoya trees grown from seed are extremely variable, grow vigorously and begin to fruit at 3 to 5 years of age. Superior varieties must be vegetatively propagated and are veneer and cleft grafted or shield and patch budded onto suitable rootstocks. Propagation is most successful near the end of the winter (dormant period) when buds are beginning to break. 2
Atemoya grafted on to seedling atemoya rootstock produces a fast growing, vigorous tree that begins fruit production in 2 to 4 years. However, mature trees on this rootstock are vigorous and may be difficult to control in size. In contrast, atemoya grafted onto sugar apple seedling rootstock tends to be somewhat less vigorous, may take a year or two to reach the production level of atemoya grafted onto atemoya but is generally easier to control in size. 2

Planting
Atemoya trees and fruit production may benefit from wind protection. Properly placed and managed wind-breaks may enhance tree growth, decrease the drying effect of winds, and increase the relative humidity within the canopy of atemoya trees. 2
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. 3

Rootstock and flood stress
Atemoya grafted on to sugar apple is intolerant of flooded soil conditions. Grafting atemoya on to pond apple, custard apple, and soursop appears to impart flood tolerance to the scion. However, growth of trees grafted onto custard apple and soursop was dramatically reduced compared to trees on pond apple. Soursop is not tolerant of cold temperatures and therefore may not be suitable as a rootstock in subtropical areas like Florida. 2

Calendar of Cultural Practices for Mature Atemoya Trees

Pruning
Periodic pruning of atemoya trees can easily maintain trees at or below 8 to 12 ft in height. To maintain optimum fruit production trees should be selectively pruned annually. In general, about one third of the previous years vegetative growth should be removed during early spring as trees commence bud break. The goal is to maintain fruit production in the lower tree canopy, improve light penetration into the canopy, and limit tree size. 2

How to Espalier your tree

Fertilizing
During the first 2 to 3 years after planting, growing a strong, vigorous tree is the goal. It is recommended that any fruit that sets during the first year or so be removed so the tree grows vigorously. After the third year, the emphasis changes to cultural practices that enhance flowering, fruit set, and fruit development. These include reduced frequency of N-P2O5-K2O applications and close attention to watering trees from flowering to harvest during prolonged dry periods. 2

Irrigation
Atemoya trees are tolerant of drought conditions, however, fruit set and fruit size may be reduced and defoliation may occur due to drought stress. Mild to severe drought stress has been demonstrated to reduce atemoya fruit size by 10 to 50%. Therefore, periodically watering atemoya trees is recommended from flowering through fruit development to enhance fruit quality and production. Watering of young and mature trees should be reduced during the fall and cease once leaves have mostly dropped. Over watering during the fall and winter may lead to root rot and loss of tree vigor and health. 2

Harvest Calendar
Atemoya trees may have multiple blooms, with the main bloom from April through June and a smaller bloom during July. Fruit are harvested from August to October and sometimes during December and January if no frost occurs and leaves remain on the tree.
Harvest of immature fruit should be avoided. Immature fruit will not ripen satisfactorily but remain hard, turn brown, and slowly decay. As atemoya fruit mature, fruit color changes from green to yellowish green, the area between protuberances swells and becomes yellowish, and the fruit becomes covered with a white or bluish bloom. Fruit should be picked at the mature stage and allowed to ripen (soften) at room temperature before being refrigerated. 2

Annona Pests Page

Diseases
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. 5
Dry fruit rot or mummification of the fruit is caused by several fungi. Fruit appear purplish-black to black in color and may remain on the tree for sometime. Usually fruit are colonized by these fungi after emergence of the adult Annona seed borer from the fruit. 2
Fruit may be attacked by fungi which cause the fruit to rot before or after harvest. Fruit symptoms are very similar to Dry fruit rot. 2

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 icecream. 5

Other Uses
Landscape tree

General
Har Mahdeem, popular horticultural circuit speaker and authority on Annonaceae, has talked about the importance of hand pollination to produce good quality fruit. Read his publication on the Custard Apples

Other members of the family that are grown for their fruit are:
Cherimoya (Annona cherimola)
Soursop (Annona muricata)  
Sugar apple (Annona squamosa)
Ilama (Annona diversifolia)
Custard Apple (Annona reticulata
Biriba (Rollinia mucosa, Annona mucosa)
Poshte (Annona scleroderma)


List of Growers and Vendors


Bibliography

1 Peña, Jorge E. and Crane, Jonathan H. "Insect/Mite Management in Annona spp." edis.ifas.ufl.edu. This document is ENY-834, one of a series of the Entomology and Nematology Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Original publication date July 2006. Reviewed Jan. 2015.  Web. 24 Apr. 2017.
2 Crane, Jonathan H., Balerdi, Carlos F. and Maguire, Ian. "Atemoya Growing in the Florida Home Landscape". edis.ifas.ufl.edu. This document is HS64, one of a series of the Horticultural Sciences Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Original publication date 1980. Revised Nov. 2016. Web. 24 Apr. 2017.
3 "Atemoya'. wikipedia.org. Web. 23 Sept. 2014.
4 Joyner, Gene. "The Atemoya." rfcarchives.org.au. Archives of the Rare Fruit Council of Australia. Mar. 1994. Web. 9 Apr. 2015.
5 Morton, Julia. "Atemoya." hort.purdue.edu. Fruits of warm climates. p. 72-75. 1987.  Web. 3 Oct. 2015.
6 Taitung District Agricultural Improvement Station, Taiwan ROC. "Artificial pollination of sugar apple and atemoya." agnet.org. Food and Fertilizer Technology Center for the Asian and Pacific Region. Web. 23 JUne 2016.

Photographs

Fig. 1 A-giâu. Atemoya (cross of Annona cherimola and Annona squamosa). 2004. wikimedia.org. Under (CC By-SA 3.0). Web. 23 Sept. 2014.
Fig. 2,4 Annona cherimola x Annona squamosa. N.d. Top Tropicals Plant Catalog. toptropicals.com. Web. 29 Jan. 2014.
Fig. 3 Jackson, Karen. "Atemoya series". 2013. growables.org. JPEG file.
Fig. 5 Sap beetle entering an atemoya flower. N.d. edis.ifas.ufl.edu. University of Florida. Web. 10 apr. 2015.
Fig. 6,7 Takoradee. Annona × atemoya from Taiwan. 2007.  wikimedia.org. Under (CC BY 2.5). Web. 23 Sept. 2014.
Fig. 8 Kwiecień, Agnieszka. Fruits. N.d.  tropical.theferns.info. Under (CC-BY 3.0). Web. 10 apr. 2015.
Fig. 9 Molekuel. Atemoya in NZ Grocery store. 2007. wikimedia.org. Under (CC-BY-SA-2.5). Web. 26 Dec. 2015.
Fig. 10 Wally Gobetz. São Paulo - Sé: Mercado Municipal de São Paulo - Atemoya. 2012. flickr.com. Under  (CC BY-NC-ND 2.0). Web. 30 Jan. 2016.
Fig. 11 Sample, Jane. Atemoya tree. 2015. flickr.com. Web.26 Dec. 2015.

UF/IFAS Assessment of Non-native Plants in Florida's Natural Areas

Published 12 Apr. 2014 LR. Last Update 24 Apr. 2017 LR
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