FARMER'S NOTEBOOK
Managing bud rot in coconut
M.J. PRABU
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Palms of all age groups are susceptible to this infestation
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— PHOTO: CPCRI
Foul smell: One visible sign of the infestation is when that the affected spindle can easily be pulled out.
Bud rot is a fatal disease of coconut, which occurs commonly in all coconut growing countries. In India, it causes considerable economic loss in Kerala, Tamil Nadu, Karnataka and Andhra Pradesh, which are major coconut growing areas.
The infestation has also been reported in states such as Maharashtra, Madhya Pradesh and the Union Territory of Goa.
Palms of all age groups are susceptible to bud rot, which is caused by a fungal infestation . The initial visible symptom of the infestation is withering of the spear leaf or spindle (middle portion) which turns brown in colour and
bends down.
Early diagnosis
Early diagnosis of the disease is essential. But farmers often experience difficulties in the initial detection, according to Dr. R. Chandra Mohanan, Central Plantation Crops Research Institute, (CPCRI) Kasaragod, Kerala.
One visible sign of the infestation is when that the affected spindle can easily be pulled out, as the basal portion of the spindle is completely rotten. The spindle emits a foul smell.
The inner leaves fall away one by one leaving only the outer whorl of matured leaves in the crown. Ultimately the palm succumbs to the disease with the death of the bud.
Effective management
Effective disease management can be achieved only if integrated plant protection measures are adopted at the correct time, according to Dr. Chandra Mohanan.
Farmers are advised to cut and remove severely affected palms (beyond recovery) in affected gardens for better control of the disease. The spindle leaf and infested tissues should be cut, and destroyed by burning.
About 10 per cent bordeaux paste should be applied to the cut portion and covered with a polythene cover to prevent entry of rain water. The protective covering has to be retained till normal shoots emerge.
But these curative measures are effective only in the initial stage, that is when the spindle leaf has just started showing symptoms of withering.
Another method called prophylactic spraying (spraying 1 per cent bordeaux mixture) can be given to healthy palms, which are in the vicinity of diseased and treated ones.
The spraying has to be directed towards the spindle and at the base of 2-3 inner leaves. It is important to give prophylactic spraying to all palms before the onset of monsoon, in gardens with a previous history of bud rot incidence, according to him.
Nut shedding
In certain dwarf varieties such as Chowghat Orange Dwarf (COD) and Malayan Yellow Dwarf (MYD) brown sunken spots followed by nut shedding have been observed when bordeaux mixture was sprayed.
Keeping perforated sachets containing mancozeb (Indofil M-45) in the innermost leaf axil during monsoon is found to be effective for the above mentioned varieties.
Besides the above two methods, nutrient management for affected as well as healthy palms is also important for improving the yield.
Fertilizer dose
The fertilizer dose generally recommended for an adult palm is 1kg of urea, 1.5 kg of mussoriephos or rock phosphate and 2kg of muriate of potash.
The fertilizer can be applied by digging circular trenches of 1.8 m radius and 25 cm depth around the palms during September-October.
Organic manure in the form of compost or green leaves at the rate of 50 kg per palm in the basin may be applied in the trenches.
About two third of the recommended dose of fertilizer should be applied over the organic green manure and the trenches covered.
For more information readers can contact Dr. R. Chandra Mohanan, Principal Scientist and Head, Division of Crop Protection, Central Plantation Crops Research Institute, Kasaragod 671124, Kerala. email: rcmcpcri@yahoo.co.in, phone: 04994-232894 or 04994-232895.
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