Global agricultural practices for successful cashew development
Practical Action
Spacing
To promote maximum development and reduce competition for available moisture, it is
recommended that the seedlings are planted 10-15 metres apart. This is considered to be the
most productive spacing for mature trees. The average yield per hectare will be 700-1000 kg
but yields outside these limits are encountered. However, cashew trees are normally planted
more closely, which results in overcrowding, and they are often intermixed with other trees
either in small orchards or in the wild.
Diseases and pests
Cashew seedlings can be affected by a number of different diseases. The fungus,
Col/etotrichum glocosporioides, is one of the most common pathogens in cashew (Ohler,
1979'). Initial symptoms show the development of reddish-brown, shiny, water-soaked lesions,
followed by resin oozing out onto the affected parts. As the lesions grow, the affected shoots
and inflorescences are killed and the leaves become crumpled. The affected nuts and apples
decay and shrivel, and the flowers turn black and fall off. The trees can be sprayed with
various fungicides, including Bordeaux mixture, to control the fungus.
Several diseases that result in the terminal twigs dying off are grouped under the name "die-
back" or "pink disease" which is produced by Glocosporium. There may be associated pitting
of the surface of the nut. This serious disease requires the affected branches to be pruned
and sprayed with a 1% Bordeaux mixture or other copper- based fungicides.
Characteristic symptoms of infections which attack cashew include wilting and withering; the
yellowing of the lower leaves; the seedlings turning pale and showing water-soaked girdles of
darkened tissue around the stems; or the rotting of the underground portion of the stem.
Powdery mildew may appear on young leaves and inflorescences during dry weather.
Insect pests are a major source of crop loss in all cashew-growing areas of the world. More
than 60 species of insects attack the crop during its different stages of growth. These pests
include sap- sucking bugs, leaf-chewing caterpillars, beetles, aphids, scales, thrips and
some mites. They can cause considerable damage to the tree and the crop by bringing about
the death of the floral- flushing shoots, the early abortion of young nuts and loss of yield.
Rodents, such as rats, squirrels and porcupines, may cause serious damage to cashew
seedlings, especially once they emerge above the ground. Cashew apples are sometimes
attacked by fruit flies. Monkeys are partial to ripe apples and can cause damage to the cashew
trees whilst foraging for the fruit. Bats and parrots also
like to eat cashew apples.
References
1 Ogler, J.G. 1979. Cashew. Amsterdam, Department of Agricultural Research
2 Carinnean Technological Consultancy Services (CTCS) Network, 1993. Information
package on cultivation, processing and marketing of cashews. St Michael, Barbados,
Caribbean technological Consultancy Services Network.
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