LATIN NAME : Anacardium occidentale L.
ENGLISH : Cashew, Cashew nut
FRENCH : Pomme d'Acajou, Pommier Cajou, Acajou à Pomme, Anacardier
Particularities for easier identification: It is most easily recognised by its obovate coriaceous leaves and also its fruits that consist of a kidney shaped nut attached to a swollen pedicel (cashew apple).Cashew nuts are the true fruit, while the cashew apple, about eight to ten times as heavy as the nut, is the swollen stalk, or peduncle, which supports the flower. The nut shell is smooth, oily and about one-eighth of an inch thick. Its honeycombed, cellular, inner portion contains the cashew nut. The cashew nut kernel is approximately seven-eighths of an inch in length, and is wrapped in a testa or thin brown skin. This is the cashew nut of commerce. The nut shell with its side indentation pointed upward, looks like a heart. The generic name Anacardium means “shaped like a heart.” Cashew trees start bearing fruit usually in the third or fourth year and under favorable conditions reach maximum production in about seven years. Although yields vary considerably, a fair, average annual yield from a mature cashew tree is about one hundred to one hundred-fifty pounds of apples and nuts from which twenty pounds of un-hulled nuts and six pounds of kernels can be obtained. Cashew nuts have been called the poor man’s crop but a rich man’s food. The World Bank has estimated that at least 97% of world cashew production comes from wild growth and small peasant holdings.Cashews are more widely used in confectionery nut candies and chocolate bars than in bakery products. Cashews have become one of the most popular dessert nuts behind almonds. They are delicious in their natural state, or in a variety of candied varieties including chocolate covered and honey roasted cashews. Approximately 60% of cashew kernels are consumed as salted nuts.
Habit: A medium sized evergreen tree that can reach up to 12m in height with a diameter to 25cm.
Bark & Branches: It has a short stout bole surmounted by a rounded trunk that is characteristically grey and smooth or lightly fissured, slash pale red and exuding a brown coconut scented resinous gum. The branches are heavy and crooked; twigs are greyish stout and glabrous.
Leaves: are alternate, petiolate (1-2cm), simple, obovate, 6-20cm long by 4-15cm wide, have a recurved margin and are often crowed towards the ends of the branches. They are coriaceous, glabrous and bear prominent abaxial veins.
Inflorescences: arise as terminal panicles of about 5-20cm with large bracts enclosing the many flowers.
Flowers: are (male or hermaphrodite), small (5-10mm), star shaped and sweetly scented. They consist of a 5 lobed greenishwhite corolla; 5 (6) linear-lanceolate, red striped, petals, a long protruding stigma and 7-10 stamens shorter then the flower cup.
Fruits: are greyish-brown and approx. 3cm long, they consist of kidney shaped nuts (the cashew nut) which are encased in a hard shell (pericarp). The nut is attached to a swollen pedicel (cashew apple when ripe). The “Cashew Apple” is shaped slightly like a doum palm nut (Hypheane thebaica), measures 10-20cm long by 4-8cm wide, and is shiny red or yellow with a characteristic smell. Flowers November to May; fruits February to April.
Originates from the American tropics but has been widely spread throughout the tropics since the 16th century. It has become naturalised in numerous parts of Africa and is particularly common in coastal regions.
Rainfall : 500-4,000mm; 900+mm for good results; tolerates and requires a 4-6 month dry season for good fruiting.
Soil Type : Tolerates a wide variety of soils, except saline soils and indurated soil horizons. Prefers sandy soils with good drainage. Its resistance to drought is directly in proportion to the amount of soil available to the roots.
Altitude : 0 - 1,100 metres; best adapted to lower elevations (0-500m).
Temperature : Reported mean min. and max . monthly temperatures are as follows: 19 and 35° C. Tolerates high temperatures; frost sensitive.
Propagation : 150-300 seeds/kg. The seed is only viable for about a month. Seedlings can be grown in the nursery but are most commonly planted on site since this tree produces a taproot and is susceptible to root damage. Seeds do not need pretreatment but germination is rather poor and slow (starts after about 10 days). Seeds can be planted with or without the shell but taking the shell off requires great care and experience in avoiding the blistering juices. If shells have been removed then the nuts can be put in water and planted if they sink. Usually 3 seeds are planted (convex side up) per hole and this is later thinned out to 1 plant. Daily watering is required until established after about 6 months. After that watering can be reduced gradually. If planting in the nursery then long polythene pots are recommended. This tree can also be propagated vegetatively if certain characteristics are desired; however, further information should be sought on how to do this.
Grafting: Taking a bud or shoot from a good tree and grafting it onto a seedling.
Air layering: Make a ring cut in a pencil thickness branch towards the end. In this cut place a mixture of sawdust and woodshaving and keep it moist and covered with plastic for 1½ months. Roots should have formed by then. The roots should continue to be kept wet and the branch should be cut halfway through below the plastic. This cut should be slowly deepened until after another 1½ months the rooted tree can be planted out.
After Care : Once the tree is established then little care is required. When young, it needs weeding and some pruning to give it a good shape. When planted, spacing should between 10 and 15 metres apart. Fruit production starts after about 4 years reaching a maximum after 10 years: a maximum of 5-8kg of nuts and 50-60kg of apples can be expected per year.Pollination of the flowers is usually carried out by insects but in India this is sometimes done by hand. If a lot of fruit falls off after flowering then there is no need to be alarmed as this early fruit fall is quite normal with this species.
Folk MedicineThe 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.
Yields and EconomicsYields 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.
EnergyA 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 FactorsCashew 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.
A species that could be tried in lowland areas with a rainfall of more then 700mm. Production with lower rainfall might be possible with suitable water harvesting techniques. Although it grows well vegetatively, constant year round humidity impedes fruit production.
Related Useful Links:
Cashew Recipes – Cashew Recipes & Cooking Tips from About.com, Cashew Recipes from Cooks.com, Cashew Recipes from Mass Recipes
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Cashew in the Consuming Countries – Australia (RIRDC – The New Rural Industries)
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Cashew Uses – The Cashew Fact File – Uses of Cashew, Cashew – Profile, Facts & Uses (PDF),
Cashew Facts & Trivia - The Largest Cashew Tree of the World, Pirangi, Natal, Cashew Nuts – Food Facts & Trivia, Nuts Trivia from Fun Trivia, Cashew – More than Just a Nut, Nut Comparison – for Every Raw Food Eater, Eliminating Tooth Infection with Cashewnuts
Information on Cashew Grades and General Cashew Info
Cashew Nut Profile & Information from Botanical
Cashewnut Information from Wikipedia
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The Nut Factory
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Why Cashews Aren’t Sold in the Shell – A Moment of Science
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Cashew Nut – Definition & More from Answers.com
Cashew – Comprehensive Details (PDF)
Cashew Info from King’s American Dispensary
Exotic Tree Fruits & Nuts – Cashew Nuts