From Lost Crops of the Incas:
little-known plants of the Andes with promise for worldwide cultivation
by National Research Council
(U.S.) Advisory Committee on Technology Innovation
Cherimoya
Universally regarded as a premium fruit, the cherimoya (Annona cherimola)
has been called the “pearl of the Andes,” and the “queen of subtropical
fruits.” Mark Twain declared it to be “deliciousness itself!”
In the past, cherimoya (usually pronounced chair-i-moy-a in English)
could only be eaten in South America or Spain. The easily bruised, soft
fruits could not be transported any distance. But a combination of new
selections, advanced horticulture, and modern transportation methods
has removed the limitations. Cushioned by foam plastic, chilled to
precise temperatures, and protected by special cartons, cherimoyas are
now being shipped thousands of kilometers. They are even entering
international trade. Already, they can be found in supermarkets in many
parts of the United States, Japan, and Europe (mainly France, England,
Portugal, and Spain).
Native to the Ecuadorian Andes, the cherimoya is an important backyard
crop throughout much of Ecuador, Colombia, Venezuela, Bolivia, and
Peru. Chileans consider the cherimoya to be their “national fruit” and
produce it (notably in the Aconcagua Basin) on a considerable
commercial scale. In some cooler regions of Central America and Mexico,
the plant is naturalized and the fruit is common in several locales. In
the United States, the plant produces well along small sections of the
Southern California coast where commercial production has begun.
Outside the New World, a scattering of cherimoya trees can be found in
South Africa, South Asia, Australasia, and around the Mediterranean.
However, only in Spain and Portugal is there sizable production. In
fruit markets there, cherimoyas are sometimes piled as high as apples
and oranges.
A good cherimoya certainly has few equals. Cutting this large, green,
heart- shaped fruit in half reveals white flesh with black seeds. The
flesh has a soft, creamy texture. Chilled, it is like a tropical
sherbet—indeed, cherimoya has often been described as “ice-cream
fruit.” In Chile, it is a favorite filling for ice-cream wafers and
cookies. In Peru, it is popular in ice cream and yogurt.
World demand is strong. In North America and Japan, people pay more for
cherimoya than for almost any other fruit on the market. At present,
premium cherimoyas (which can weigh up to 1 kg each) are selling for up
to $20 per kg in the United States and more than $40 per kg in Japan.
Despite such enormous prices, sales are expanding. In four years, the
main U.S. supplier's weekly sales have increased from less than 50 kg a
week to more than 5,000 kg a week.
Today, the crop is far from reaching its potential peak. Modern
research is only now being applied—and in only a few places,
principally Chile, Argentina, Spain, the Canary Islands, and
California. Nonetheless, even limited research has produced a handful
of improved cultivars that produce fruit of good market size (300–600
g), smooth skin, round shape, good flavor, juiciness, low seed ratio,
resistance to bruising, and good storage qualities. With these
attributes, larger future production and expanded trade seem inevitable.
But growing cherimoyas for commercial consumption is a daunting
horticultural challenge. In order to produce large, uniform fruit with
an unbroken skin and a large proportion of pulp, the grower must attend
his trees constantly from planting to harvest; each tree must be
pruned, propped, and—at least in some countries—each flower must be
pollinated by hand.
Nevertheless, the expanding markets made possible by new cultivars and
greater world interest in exotic produce now justify the work necessary
to produce quality cherimoya fruits on a large scale. Eventually,
production could become a fair-sized industry in several dozen
countries.
PROSPECTS
The Andes.
Although cherimoyas are found in markets throughout the Andean region,
there has been little organized evaluation of the different types, the
horticultural methods used, or the problems growers encounter. Given
such attention, as well as improved quality control, the cherimoya
could become a much bigger cash crop for rural villages. With suitable
packaging increasingly available, a large and lucrative trade with even
distant cities seems likely. Moreover, increased production will allow
processed products—such as cherimoya concentrate for flavoring ice
cream—to be produced both for local consumption and for export.
Other
Developing Areas. Everywhere these fruits are grown, they
are immediately accepted as delicacies. Thus, the cherimoya promises to
become a major commercial crop for many subtropical areas. For example,
it is likely to become valuable to Brazil and its neighbors in South
America's “southern cone,” to the highlands of Central America and
Mexico, as well as to North Africa, southern and eastern Africa, and
subtropical areas of Asia.
Cherimoya has been grown for centuries in the highlands of Peru and
Ecuador, where it was highly prized by the Incas. Today, this
subtropical delight is gaining an excellent reputation in premium
markets in the United States, Europe, Japan, and elsewhere. (T. Brown)
Industrialized
Regions. The climatic conditions required by the cherimoya
are found in pockets of southern Europe (for example, Spain and Italy),
the eastern Mediterranean (Israel), the western United States, coastal
Australia, and northern New Zealand. In these areas, the fruit could
become a valuable crop. In Australia and South Africa, the cherimoya
hybrid known as atemoya is already commonly cultivated.
The cherimoya could have an impact on international fruit markets. The
United Kingdom is already a substantial importer, and, as superior
cultivars and improved packing become commonplace, cherimoyas could
become as familiar as bananas.
USES
The cherimoya is essentially a dessert fruit. It is most often broken
or cut open, held in the hand, and the flesh scooped out with a spoon.
It can also be pureed and used in sauces to be poured over ice creams,
mousses, and custards. In Chile, cherimoya ice cream is said to be the
most profitable use. It is also processed into nectars and fruit salad
mixes, and the juice makes a delicious wine.
NUTRITION
Cherimoya is basically a sweet fruit: sugar content is high; acids,
low. It has moderate amounts of calcium and phosphorus (34 and 35 mg
per 100 g). Its vitamin A content is modest, but it is a good source of
thiamine, riboflavin, and niacin. 1
HORTICULTURE
Because
seedling trees usually bear fruits of varying quality, most commercial
cherimoyas are propagated by budding or grafting clonal stock onto
vigorous rootstock. However, a few forms come true from seed, and in
some areas seed propagation is used exclusively.
The trees are usually pruned during their brief deciduous period (in
the spring) to keep them low and easy to manage. The branches are also
pruned selectively after the fruit has set—for example, to prevent them
rubbing against the fruits or to encourage them to shade the fruits.
(Too much direct sunlight overheats the fruits, cracking them open.)
Under favorable conditions, the trees begin bearing 3–4 years after
planting. However, certain cultivars bear in 2–3 years, others in 5–6
years. Many growers prop or support the branches, which can get so
heavily laden they break off.
Pollination can be irregular and unreliable. The flowers have such a
narrow opening to the stigmas and ovaries that it effectively bars most
pollen-carrying insects. Honeybees, for instance, are ineffective. 2
In South America, tiny beetles provide pollination, 3
but in some other places (California, for instance) no reliable
pollinators have been found. There, hand pollination is needed to
ensure a high proportion of commercial-quality fruit. 4
HARVESTING AND HANDLING
The fruits are harvested by hand when the skin becomes shiny and turns
a lighter shade of green (about a week before full maturity). A heavy
crop can produce over 11,000 kg of quality fruits per hectare.
LIMITATIONS
A cherimoya plantation is far from simple to manage. The trees are
vulnerable to climatic adversity: heat and frost injure them, low
humidity prevents pollination, and winds break off fruit-laden
branches. They are also subject to some serious pests and diseases.
Several types of scale insects, leaf miners, and mealy bugs can infect
the trees, and wasps and fruit flies attack the fruits.
Pollination is perhaps the cherimoya's biggest technical difficulty.
Not only are reliable pollinators missing in some locations, but low
humidity, especially when combined with high temperatures, causes
pollination failure; these conditions dry out the sticky stigmas, and
the heavy pollen falls off before it can germinate.
Hand pollination is costly and time consuming. However, it improves
fruit set of all cultivars under nearly all conditions. It enhances
fruit size and shape. It allows the grower to extend or shorten the
season (by holding off on pollination) as well as to simplify the
harvesting (by pollinating only flowers that are easy to reach). 5
The fruits are particularly vulnerable to climatic adversity: if caught
by cold weather before maturity, they ripen imperfectly; if rains are
heavy or sun excessive, the large ones crack open; and if humidity is
high, they rot before they can be picked.
The fruits must be picked by hand, and, because they mature at
different times, each tree may have to be harvested as many as 10
times. In addition, the picked fruits are difficult to handle. Even
when undamaged, they have short storage lives (for example, 3 weeks at
10°C) unless handled with extreme care. The fruit has a culinary
drawback: the large black seeds annoy many consumers. However, fruits
with a low number of seeds exist, 6 and there
are unconfirmed reports of seedless types. So far, however, neither
type has been produced on a large scale.
RESEARCH NEEDS
The following are six important areas for research and development.
Germplasm
The danger of losing unique and potentially valuable types is high. A
fundamental step, therefore, is to make an inventory of cherimoya
germplasm and to collect genetic material from the natural populations
as well as from gardens and orchards, especially throughout the Andes.
Selection
Future commercialization will depend on the selection of cultivars that
dependably produce large numbers of well-shaped fruit with few seeds
and good flavor. Selection criteria could include: resistance to
diseases and pests, regular heavy yields of uniform fruit with smooth
green skin, juicy flesh of pleasant flavor, few or no seeds, resistance
to bruising, and good keeping qualities.
Pollination
The whole process of pollination should be studied and its impediments
clarified. Currently few, if any, specific insects have been definitely
associated with cherimoya pollination. 7 The
insects that now pollinate it in South America should be identified.
Spain, where good natural fruit set is common in most orchards, might
also teach much. 8 Selecting genotypes that
naturally produce symmetrical, full-sized fruits may reduce or
eliminate the need to hand pollinate, bringing the cherimoya a giant
step forward in several countries.
Cultural
Practices Horticulturists have not learned enough to
clearly understand the plant's behavior and requirements. Knowledge of
the effects of pruning, soils, fertilization, and other cultural
details is as yet insufficient. The current complexity of management
should be simplified.
Evaluation of the plants in the Andes, and the ways in which farmers
handle them, could provide guidance for mastering the species'
horticulture. Also, there is a need for practical trials to identify
more precisely the limits of the tree's environmental and management
requirements.
Intensive cultural methods, such as trellising and espaliering, 9
may help achieve maximum production of high-quality fruits. These
growing systems facilitate operations such as hand pollination; they
also provide support for heavy crops.
Breeding
Ongoing testing of superior cultivars is needed. Low seed count, good
keeping quality, and good flavor have yet to coincide in a cultivar
that also has superior horticultural qualities. In addition, it is
advisable to grow populations of seedling cherimoyas in all areas where
this crop is adapted. From these variable seedling plants, selections
based on local environmental conditions can be made. Elite seedling
selections can be multiplied by budding or grafting. Mass propagation
of superior genotypes by tissue culture could also provide large
numbers of quality plants.
Improved cherimoyas might be developed by controlled crosses and,
perhaps, by making sterile, seedless triploids. Breeding for large
flowers that can be more easily pollinated might even be possible.
Hybridization
Members of the genus Annona
hybridize readily with each other, so there is considerable potential
for producing new cherimoyalike fruits (perhaps seedless or
pink-fleshed types) that have valuable commercial and agronomic traits.
Handling
Improved techniques for handling, shipping, and storing delicate fruits
would go a long way to helping the cherimoya fulfill its potential.
Ways to reduce the effects of ethylene should be explored. Cherimoyas
produce this gas prodigiously, and in closed containers it causes them
to ripen extremely fast.
SPECIES INFORMATION
Botanical Name
Annona
cherimola Miller
Family
Annonaceae (annona family)
Common Names
Quechua: chirimuya
Aymara: yuructira
Spanish: chirimoya, cherimoya, cherimalla, cherimoyales, anona del
Perú, chirimoyo del Perú, cachimán de la China, catuche, momona,
girimoya, masa
Portuguese: cherimólia, anona do Chile, fruta do conde, cabeça de negro
English: cherimoya, cherimoyer, annona
French: chérimolier, anone
Italian: cerimolia
Dutch: cherimolia
German: Chirimoyabaum, Cherimoyer, Cherimolia, peruanischer, Flaschenbaum, Flachsbaum
Origin.
The cherimoya is apparently an ancient domesticate. Seeds have been
found in Peruvian archeological sites hundreds of kilometers from its
native habitat, and the fruit is depicted on pottery of pre-Inca
peoples. The wild trees occur particularly in the Loja area of
southwestern Ecuador, where extensive groves are present in sparsely
inhabited areas.
Description. A small, erect, or sometimes spreading
tree, the cherimoya rarely reaches more than 8 m in height. It often
divides at the ground into several main stems. The light-green,
three-petaled, perfect flowers are about 2.5 cm long. The fruit is an
aggregate, composed of many fused carpels. Depending on degree of
pollination, the fruits are heart-shaped, conical, oval, or irregular
in shape. They normally weigh about 0.5 kg, with some weighing up to 3
kg. Moss green in color, they have either a thin or thick skin; the
surface can be nearly smooth, but usually bears scalelike impressions
or prominent protuberances.
Horticultural Varieties. A number of cultivars have been developed.
Nearly
every valley in Ecuador has a local favorite, as do most areas where
the fruit has been introduced. Named commercial varieties include
Booth, White, Pierce, Knight, Bonito, Chaffey, Ott, Whaley, and Oxhart.
These exhibit great variation in climatic and soil requirements.
In Spain, 200 cultivars from 10 countries are under observation. 10
Environmental Requirements
Daylength.
Apparently neutral. In its flower-bud formation, this plant does not
respond to changes in photoperiod as most fruit species do.
Rainfall.
The plant does not tolerate drought well. For good production, it needs
a fairly constant source of water. In Latin America, the tree thrives
under more than 1,200 mm rainfall during the growing season. As noted,
high humidity assists pollen set, and a dry period during harvesting
prevents water-induced damage to fruit. Also, water stress just before
flowering may increase flower (and hence fruit) production.
Altitude.
The cherimoya does best in relatively cool (but not cold) regions, and
is unsuited to the lowland tropics. (In equatorial regions it produces
well only at altitudes above 1,500 m.)
Low Temperature.
The plant is frost sensitive and is even less hardy than avocados or
oranges. Young specimens are hurt by temperatures of `2°C.
High Temperature.
The upper limits of its heat tolerance are uncertain, but is is said
that the tree will not set fruit when temperatures exceed 30°C.
Soil Type.
Cherimoya can be grown on soils of many types. The optimum acidity is
said to be pH 6.5–7.5. On the other hand, the tree seems particularly
adapted to high-calcium soils, on which it bears abundant fruits of
superior flavor. Because of sensitivity to root rot, the tree does not
tolerate poorly drained sites.
Related Species. The genus Annona,
composed of perhaps 100 species mostly native to tropical America,
includes some of the most delectable fruits in the tropics. Most are
similar to the cherimoya in their structure. Examples are:
• Sugar apple, or sweetsop (Annona squamosa).
Subtropical and tropical. The fruit is 0.5–1 kg, and yellowish green or
bluish. It splits when ripe. The white, custardlike pulp has a sweet,
delicious flavor.
• Soursop, or guanabana (A. muricata).
This evergreen tree is the most tropical of the annonas. The
yellow-green fruit—one of the best in the world—is the largest of the
annonas, sometimes weighing up to 7 kg. The flesh resembles that of the
cherimoya, but it is pure white, more fibrous, and the flavor, with its
acidic tang, is “crisper.”
• Custard apple, or annona (A. reticulata).
This beige to brownish red fruit often weighs more than 1 kg. Its
creamy white flesh is sweet but is sometimes granular and is generally
considered inferior to the other commonly cultivated annonas. However,
this plant is the most vigorous of all, and types that produce seedless
fruits are known.
• Ilama (A. diversifolia).
This fruit has a thick rind; its white or pinkish flesh has a subacid
to sweet flavor and many seeds. It is inferior to the cherimoya in
quality and flavor, but it is adapted to tropical lowlands where
cherimoya cannot grow.
• A. longipes.
This species is closely related to cherimoya and is known from only
three localities in Veracruz, Mexico, where it occurs at near sea
level. Its traits would probably complement cherimoya's if the two
species were hybridized to create a new, man-made fruit. 11
ATEMOYA
Like the cherimoya, the atemoya has promise for widespread cultivation.
This hybrid of the cherimoya and the sugar apple was developed in 1907
by P.J. Wester, a U.S. Department of Agriculture employee in Florida.
(Similar crosses also appeared naturally in Australia in 1850 and in
Palestine in 1930.) The best atemoya varieties combine the qualities of
both cherimoya and sugar apple. However, the fruits are smaller and the
plant is more sensitive to cold.
The atemoya has been introduced
into many places and is commercially grown in Australia, Central
America, Florida, India, Israel, the Philippines, South Africa, and
South America. In eastern Australia, for at least half a century, the
fruit has been widely sold under the name “custard apple.”
The
atemoya grows on short trees—seldom more than 4 m high. The yellowish
green fruit has pulp that is white, juicy, smooth, and subacid. It
usually weighs about 0.5 kg, grows easily at sea level, and apparently
has no pollination difficulties.
The fruit may be harvested when
mature but still firm, after which it will ripen to excellent eating
quality. It finds a ready market because most people like the flavor at
first trial. It is superb for fresh consumption, but the pulp can also
be used in sherbets, ice creams, and yogurt.
Seedling progeny are
extremely variable, and possibilities for further variety improvement
are very good. So far, however, little work has been done to select and
propagate superior varieties.
1 Information from S. Dawes.
2 The male and female organs of a
flower are fertile at different times. Honeybees visit male-phase
flowers but not female-phase flowers, which offer no nectar or pollen.
3 Reviewer G.E. Schatz writes:
"Pollination is undoubtedly effected by small beetles, most likely
Nitidulidae. They are attracted to the flowers by the odor emitted
during the female stage, a fruity odor that mimics their normal mating
and ovipositing substrate, rotting fruit. There is no other reward per
se, and hence it is a case of deception. The beetles often will stay in
a flower 24 hours the flower offers a sheltered mating site, safe from
predators during daylight hours. Studies on odor could lead to improved
pollination."
4 California growers use artists'
paint brushes with cut-down bristles to collect pollen in late
afternoon. The next morning they apply it to receptive female flowers.
5 Schroeder, 1988.
6 Flesh: seed weight ratios from 8:1
to 30:1 have been reported.
7 Schroeder, 1988.
8 Information from J. Farré.
9 It has been reported that on
Madeira, trees were espaliered so successfully that in some locations
they have replaced grapes, the main crop of the island. The branches
were trained so that fruit ripened in shade.
10 Information from J. Farré.
11 Information from G.E. Schatz
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