|
Tropical Plant "Atemoya"
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 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 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 Varieties
One
of the first named selections of atemoya was the 'Page',
so-named by Roy Page of Coral Gables who took budwood from
superior atemoya trees on the property of Morrison Page in
the Redlands. Perhaps the second was the 'Bradley'
which the Newcomb Nursery sold grafted onto custard apple.
An
early hybrid that arose in Queensland after the introduction
of cherimoya seeds from South America, was named 'Mammoth'
(or 'Pink's Prolific', or 'Pink's Mammoth') and became the
basis of the commercial production of atemoyas there and on
the north coast of New South Wales, though the flesh of this
cultivar immediately below the rind is usually brownish and
bitter. 'Island Beauty', a vigorous selection
with excellent fruit quality was grown to a lesser extent.
'Mammoth' was introduced into Hawaii from Queensland in 1960
and grafted plants were soon being distributed by agricultural
stations of the University of Hawaii in Kona and Hilo, and
being sold by nurseries in Honolulu.
'African
Pride' is an improved clone that originated in South
Africa. It was introduced into Queensland by Langbecker Nurseries
and 3,000 trees were released for commercial planting in July
1961. It was quickly adopted as a replacement for 'Mammoth'
as it was free of the discoloration and bitterness next to
the skin. In 1963, 6 plants of 'African Pride' were obtained
from Landbecker's by private experimenters and planted at
several locations in southern Florida. They began fruiting
in 1965. The fruits appeared to be superior in quality to
the 'Page' and 'Bradley'.
Israeli
selections tried at the University of Florida's Agricultural
Research and Education Center, Homestead, and the United States
Department of Agriculture's Subtropical Horticulture Research
Unit, Miami, are 'Geffner', 'Malamud', 'Bernitski',
'Kabri' and 'Malai #1'. Other named selections
that have been grown in Florida over the years are 'Caves',
Chirimorinon A, B and C, 'Island Gem',
'Keller', 'Lindstrom', 'Priestly' and
'Stermer'. 'Geffner' is being propagated at the AREC,
Homestead; 'Priestly' by the Zill Nursery in Boynton Beach.
None of the others have outstanding features; some develop
hard spots in the flesh. In 'Keller' there is frequently a
black membrane around each seed-containing carper.
'Cherimata'
and 'Finny' are Egyptian clones. 'Finny' is somewhat
cylindrical, is more productive than'Cherimata', has been
grown in Egypt for many years and is considered the best for
commercial production in coastal districts.
Atemoya 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 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 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 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 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 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 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 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 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 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 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 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.
|
DestinationTropicals.com 
