Global agricultural practices for successful cashew development
Practical Action
Approach-grafting or inarching
The technique of approach-grafting is relatively easy but labour intensive, and like air-layering
has to be done in the field. Seedlings to be grown as rootstocks are raised in containers. Once
they are 8-9 months old, they are cut back to half their height, and kept in grass baskets for a
month in the shade until new shoots appear. The basket is replaced by a sheet of 100 gauge
plastic to retain moisture and the seedling is joined to a year old branch of the same diameter
on a selected tree as described below (Figure 2).
From the stem of the seedling, and from the shoot with which it will be united, strips of bark
and inner wood, measuring about 5-8 cm in length, are removed. Both cut surfaces, which
should be of the same size, are bound together with twine and the join is firmly tied with
string, binding the seedling stem and the shoot together. In 90 days the union should be
complete, and the grafted plant is gradually separated from the parent. A "v" cut is made half
way through the branch 2 cm below the graft, and a similar cut is made in the rootstock 2 cm
above the graft. Seven or eight days later the cuts are deepened and after a further period of
four days the severing is completed. About 60% take is expected.
Figure 2: The processes involved in inarching.
Land preparation
Cashew seedlings are very sensitive to competition with weeds, but in many areas, especially
on sloping land, the vegetation should not be removed completely before planting because of
the danger of water and wind erosion. In tropical countries with a marked dry season, and
where the rainy season tends to start with torrential rains, the danger of erosion increases if
large areas of land have been cleared.
If the soil is very sandy and subject to strong winds, clearing the land may result in severe
wind erosion which is virtually impossible to stop. In these areas, the land should be cleared
in strips which are perpendicular to the direction of the prevailing winds. Once the cashew
trees have developed to such an extent that their rows act as wind breaks, the remaining land
can be cleared. Another important reason for leaving strips of natural vegetation is to ensure
that the insect population required for pollinating the cashew flowers is maintained.
The removal of tree stumps is an expensive but essential part of the clearing process. The
sprouting stumps need to be slashed each year as they compete with the cashew trees and
prevent a good view between the rows.
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