Top Working in Cashew
Authors: Ashok Yadav , Mocha Ajang , Madhumita Mallick, Nagaraja A and K.Usha
Division of Fruits and Horticultural Technology, IARI, New Delhi
Top working is a technique evolved to rejuvenate unproductive and senile cashew trees. Top working can successfully rejuvenate poor yielders in the age group of 5-20 years. Better management practices no doubt will increase the yields marginally but boosting cashew production 3-4 folds in a short span of time is perhaps possible only by "genetic transformation" of the existing plantations with high yielding varieties. It is reported that this genetic transformation can be effected through top working. The rejuvenation of unthrift cashew plantations through top working involves beheading of trees, allowing juvenile shoots to start-out and taking up of in-situ grafting using procured scions of high yielding varieties. It has been observed that the top worked trees within a period of two years have not only put forth a canopy of 3-4 m in diameter and 5-6 m in height (as that of 8-10 year old trees) but also have given an yield of 3 to 5 kg nuts per tree in their first bearing itself.
The unproductive trees are to be beheaded at a height of 0.75 to 1.00 m from ground level. The stem should be cut with a saw to avoid stump splitting. The best season for beheading trees is May-September. Soon after beheading, the stumps and cut portions should be given a swabbing with copper oxychloride and carbaryl 50 WP (50 g each per litre of water). Sprouts emerge 30-45 days after beheading. Sprouting will be profuse in young trees. New, 20-25 days old shoots should be grafted with scions of high yielding varieties using softwood grafting technique. To ensure at least six or seven successful grafts, 10-15 grafting are to be done on the new shoots of every tree. The best season for grafting is July-November. Thinning of the extra shoots arising from the stumps should be done to obtain better growth of the grafts. Removal of sprouts below the graft joint and removal of polythene strip from the graft joint should be done. Top working is simple and can be done by farmers after getting proper training.
The top worked trees start yielding right from the second year after top working. Thus precocity can be considered as one of the best advantages of this technique. The major disadvantage associated with top working is the huge casualty of trees due to stem borer attack. Intensive care and management to ward off stem borer is essential. As such, adoption of top working on a larger scale would be difficult.
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