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Anacardium occidentale L.

Anacardiaceae
Cashew

Source: James A. Duke. 1983. Handbook of Energy Crops. unpublished.


  1. Uses
  2. Folk Medicine
  3. Toxicity
  4. Chemistry
  5. Description
  6. Germplasm
  7. Distribution
  8. Ecology
  9. Cultivation
  10. Harvesting
  11. Yields and Economics
  12. Energy
  13. Biotic Factors
  14. 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

Complete list of references for Duke, Handbook of Energy Crops
Last update December 22, 1997