From the Handbook of Energy Crops, unpublished
by James A. Duke
Anacardium occidentale L.
Anacardiaceae
Cashew
Uses
Folk
Medicine
Chemistry
Toxicity
Description
Germplasm
Ecology
Distribution
Cultivation
Harvesting
Yields
and Economics
Energy
Biotic
Factors
References
Uses
Many
parts of the cashew plant are used. The cashew "apple," the enlarged
fully ripe, fruit may be eaten raw, or preserved as jam or sweetmeat.
The juice is made into a beverage (Brazil cajuado) or fermented into a
wine. Fruits or seeds of the cashew are consumed whole, roasted,
shelled and salted, in Madeira wine, or mixed in chocolates. Shelling
the roasted fruits yields the cashew nut of commerce. Seeds yield about
45% of a pale yellow, bland, edible oil, resembling almond oil. From
the shells or hulls is extracted a black, acrid, powerful vesicant oil,
used as a preservative and water-proofing agent in insulating
varnishes, in manufacture of typewriter rolls, in oil- and acid-proof
cements and tiles, in brake-linings, as an excellent lubricant in
magneto armatures in airplanes, and for termite proofing timbers.
Timber is used in furniture making, boat building, packing cases and in
the production of charcoal. Bark used in tanning. Stems exude a clear
gum, Cashawa gum, used in pharmaceuticals and as substitute for gum
arabic. Juice turns black on exposure to air and provides an indelible
ink. Along the coast of Orissa, shelter belts and wind breaks, planted
to stabilize sand dunes and protect the adjacent fertile agricultural
land from drifting sand, have yielded economic cashew crops 5 years
after planting (Patro and Behera, 1979).
Folk Medicine
The
fruit bark juice and the nut oil are both said to be folk remedies for
calluses, corns, and warts, cancerous ulcers, and even elephantiasis.
Anacardol and anacardic acid have shown some activity against Walker
carcinosarcoma 256. Decoction of the astringent bark given for severe
diarrhea and thrush. Old leaves are applied to skin afflictions and
burns (tannin applied to burns is liepatocarcinogenic). Oily substance
from pericarp used for cracks on the feet. Cuna Indians used the bark
in herb teas for asthma, colds,and congestion. The seed oil is believed
to be alexeritic and amebicidal; used to treat gingivitis, malaria, and
syphilitic ulcers. Ayurvedic medicin recommends the fruit for
anthelmintic, aphrodisiac, ascites, dysentery, fever, inappetence,
leucoderma, piles, tumors, and obstinate ulcers. In the Gold Coast, the
bark and leaves are used for sore gums and toothache. Juice of the
fruit is used for hemoptysis. Sap discutient, fungicidal, repellent.
Leaf decoction gargled for sore throat. Cubans use the resin for cold
treatments. The plant exhibits hypoglycemic acitivity. In Malaya, the
bark decoction is used for diarrhea. In Indonesia, older leaves are
poulticed onto burns and skin diseases. Juice from the apple is used to
treat quinsy in Indonesia, dysentery in the Philippines.
Toxicity
He who cuts the wood or eats cashew nuts or stirs his drink with a cashew swizzle stick is possibly subject to a dermatitis.
Chemistry
Per
100 g, the mature seed is reported to contain 542 calories, 7.6 g H2O,
17.4 g protein, 43.4 g fat, 29.2 g total carbohydrate, 1.4 g fiber, 2.4
g ash, 76 mg Ca, 578 mg P, 18.0 mg Fe, 0.65 mg thiamine, 0.25 mg
riboflavin, 1.6 mg niacin, and 7 mg ascorbic acid. Per 100 g, the
mature seed is reported to contain 561 calories, 5.2 g H2O, 17.2 g
protein, 45.7 g fat, 29.3 g total carbohydrate, 1.4 g fiber, 2.6 g ash,
38 mg Ca, 373 mg P, 3.8 mg Fe, 15 mg Na, 464 mg K, 60 mg b-carotene
equivalent, 0.43 mg thiamine, 0.25 mg riboflavin, and 1.8 mg niacin.
Per 100 g, the mature seed is reported to contain 533 calories, 2.7 g
H2O, 15.2 g protein, 37.0 g fat, 42.0 g total carbohydrate, 1.4 g
fiber, 3.1 g ash, 24 mg Ca, 580 mg P, 1.8 mg Fe, 0.85 mg thiamine, 0.32
mg riboflavin, and 2.1 mg niacin.
The apple contains 87.9% water,
0.2% protein, 0.1% fat, 11.6% carbohydrate, 0.2% ash, 0.01% Ca, 0.01%
P, .002% Fe, 0.26% vitamin C, and 0.09% carotene. The testa contains
a-catechin, b-sitosterol, and 1-epicatechin; also proanthocyanadine
leucocyanadine, and leucopelargodonidine. The dark color of the nut is
due to an iron-polyphenol complex.
The shell oil contains about 90%
anacardic acid (C22H32O3 and 10% cardol (C32H27O4). It yields
glycerides, linoleic, palmitic, stearic, and lignoceric acids, and
sitosterol. Examining 24 different cashews, Murthy and Yadava (1972)
reported that the oil content of the shell ranged from 16.6 to 32.9%,
of the kernel from 34.5 to 46.8%. Reducing sugars ranged from 0.9 to
3.2%, non-reducing sugars, 1.3 to 5.8%, total sugars from 2.4 to 8.7%,
starch from 4.7 to 11.2%. Gum exudates contain arabinose, galactose,
rhamnose, and xylose.
Description
Spreading
evergreen perennial tree to 12 m tall; leaves simple, alternate,
obovate, glabrous, penninerved, to 20 cm long, 15 cm wide, apically
rounded or notched, entire, short petiolate; flowers numerous in
terminal panicles, 10–20 cm long, male or female, green and reddish,
radially symmetrical nearly; sepals 5; petals 5; stamens 10; ovary
one-locular, one-ovulate, style simple; fruit a reniform achene, about
3 cm long, 2.5 cm wide, attached to the distal end of an enlarged
pedicel and hypocarp, called the cashew-apple; this shiny, red or
yellowish, pear-shaped, soft, juicy, 10–20 cm long, 4–8 cm broad; fruit
reniform, edible, with two large white cotyledons and a small embryo,
surrounded by a hard pericarp which is cellular and oily, oil is
poisonous causing allergenic reactions in some humans. Fl. variable.
Germplasm
Several
varieties have been selected based on yield and nut size. Reported from
the South America, and Middle America Centers of Diversity, cashew or
cvs thereof is reported to tolerate aluminum, drought, fire, insects,
laterite, low pH, poor soil, sand, shade, slope, and savanna. (2n = 42,
40).
Distribution
Native
to tropical America, from Mexico and West Indies to Brazil and Peru.
The cashew tree is pantropical, especially in coastal areas.
Ecology
Ranging
from Warm Temperate Moist to Tropical Very Dry to Wet Forest Life
Zones, cashew is reported to tolerate annual precipitation of 7 to 42
dm (mean of 32 cases = 19.6), annual temperature of 21 to 28°C (mean of
31 cases 25.2), and pH of 4.3 to 8.7 (mean of 21 cases = 64). Grows on
sterile, very shallow and impervious savanna soils, on which few other
trees or crops will grow, but is less tolerant of saline soil than most
coastal plants. Does not tolerate any frost. In Brazil, Johnson (1973)
summarizes "optimal ecological conditions;" annual rainfall 7–20 dm,
minimum temperature 17°C, maximum temperature 38°C; average annual
temperature 24–28°C, relative humidity 65–80%; insolation 1,500 to
2,000 hours per year, wind velocity 2.25 km/hr, and dry season 2–5
months long. It is recommended that cultivation be limited to nearly
level areas of red-yellow podzols, quartziferous sands, and red-yellow
latosols.
Cultivation
Cashew
germinates slowly and poorly; several nuts are usually planted to the
hole and thinned later. Propagation is generally by seeds, but may be
vegetative from grafting, air-layering or inarching. Planting should be
done in situ as cashew seedlings do not transplant easily. Recommended
spacing is 10 x 10 m, thinned to 20 x 20 m after about 10 years, with
maximum planting of 250 trees/ha. Once established, field needs little
care. Intercropping may be done the first few years, with cotton,
peanut, or yams. Fruits are produced after three years, during which
lower branches and suckers are removed. Full production is attained by
10th year and continues to bear until about 30 years old. In dry areas,
like Tanzania, flowering occurs in dry season, and fruits mature in 2–3
months. Flowers and fruits in various degrees of development are often
present in same panicle.
Harvesting
From
flowering stage to ripe fruit requires about 3 months. Mature fruit
falls to the ground where the 'apple' dries away. In wet weather, they
are gathered each day and dried for 1–3 days. Mechanical means for
shelling have been unsuccessful, so hand labor is required. Cashews are
usually roasted in the shell (to make it brittle and oil less
blistering), cracked, and nuts removed and vacuum packed. In India part
of nuts are harvested from wild trees by people who augment their
meager income from other crops grown on poor land. Kernels extracted by
people skilled in breaking open the shells with wooden hammers without
breaking the kernels. Nuts are separated from the fleshy pedicel and
receptacle, seed coat removed by hand, and nuts dried. Fresh green nuts
from Africa and the islands off southern India are shipped to
precessing plants in Western India.
Yields and Economics
Yields
are said to range from 0–48 kg/tree/year, with an average yield of
800–1,000 kg/ha. Heavy bearing trees often produce nuts considered too
small for the trade. Indian field trials showed that fertilizers could
increase yields of 15-year-old trees from less than 1 kg/tree to >4
and enabled 6 year olds to average 5.7. Regular applications of 250 g
N, 150 g P2O5 and 150 g K2O/tree resulted in average yield increases of
700–1600 kg/ha (Nambiar and Haridasan, 1979). In Pernambuco, trees
produced 1.5–24.0 kg each/year, averaging 10.3 kg per tree (Johnson,
1973). At Pacajus (Ceara, Brazil) trees average 17.4 kg/yr with one
tree bearing 48 kg/yr. Major producers of cashew nuts are India,
Tanzania, Mozambique, and Kenya. In 1968 India planted over 224,000 ha
in cashews to supply over 200 processing factories operating all year.
In 1971 India produced 90,000 MT, the bulk exported to United States
and USSR. Export price at US ports was $.33/kg. India imports green
nuts from the African countries and processes them for resale. Import
prices in 1971 in India was 1730 rupees/MT. Cashawa Gum is obtained
from the West Indies, Portuguese East Africa, Tanzania and Kenya.
Energy
A
perennial species, the cashew has already, in the past, yielded alcohol
from the "apple," oil from the nut, and charcoal from the wood. The
"apples" (ca 30–35 kg per tree per annum) yield each 20–25 cc juice,
which, rich in sugar, was once fermented in India for alcohol
production.
Biotic Factors
Cashew
tree has few serious diseases or pests. The following are reported
disease-causing agents, none of which are considered of economic
importance: Aspergillus chevalieri, A. niger, Atelosaccharomyces moachoi, Balladynastrum anacardii, Botryodiplodia theobromae, Cassytha filiformis, Cephaleuros mycoides, Ceratocystis sp., Cercospora anacardii, Colletotrichum capsici, Cytonaema sp., Endomyces anacardii, Fusarium decemcellulare, Gloeosporium sp., Glomerella
cingulata, Meliola anacardii, Nematospora corylii, Parasaccharomyces
giganteus, Pestaliopsis disseminata, Phyllosticta anacardicola, P.
mortoni, Phytophthora palmivora, Pythium spinosum, Schizotrichum
indicum, Sclerotium rolfsii, Trichomerium psidii, Trichothecium roseum,
Valsa eugeniae. Cuscuta chinensis attacks the tree. In Brazil, high populations of the nematodes Criconemoides, Scutellonema, and Xiphinema
are reported around cashew roots (Lima et al, 1975). Of insects,
Helopeltis spp. have been reported in Tanzania. Four insects are
considered major pests: the white fly (Aleurodicus cocois), a caterpillar (Anthistarcha binoculares), a red beetle (Crimissa sp.), and a thripe (Selenothrips rubrocinctus).
Flowers are visited by flies, ants and other insects, which may serve
as pollinators. Artificial pollination is practiced in some areas.
References
Johnson, D. 1973. Cashew cultivation in Brazil. Agron. Mocamb. Lourenco Marques 7(3):119–129.
Lima,
J.A.A., Menezes, M., Karan, M. de Q., and Martins, O.F.G. 1975. Genera
of pathogenic nematodes isolated from the rhizophere of cashew tree, Anacardium occidentale. Fitossanidad, Brazil 1(2):32–35.
Murthy, K.N. and Yadava, R.B.R. 1972. Indian J. Agr. Sci. 42(10):960–961.
Nambiar, M.C. and Haridasan, M. 1979. Fertilizing cashew for higher yields. Indian Farming 28(12):16–17.
Patro, C. and Behera, R.N. 1979. Cashew helps to fix sand dunes in Orissa. Indian Farming 28(12):31–32
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