Coconut growers' hope nipped in the bud

Rotting away

There seems to be no respite from woes­ for coconut growers. Following stem bleeding disease, a large number of trees have now withered due to bud rot disease.

The coconut in the taluk is grown exclusively in farms or only on the borders of the farms. The coconut are sold either full grows or as tender coconut. The appearance of the bud rot disease in the taluk has created panic among the farmers, who earned some income from coconut farming.

Coconut bud rot is a disease of the coconut palm caused by a fungus (Phytophthora palmivora) that destroys the terminal bud and adjacent leaves finally killing the tree
It affects palms of all ages, but young palms are found to be most vulnerable.

The disease is caused by fungus and the incidence is found to be severe during monsoon when the relative humidity is high. With the onset of dry weather the infection becomes less severe and the fungus remains dormant in the leaf base, says Senior Assistant Director of Horticulture Department, B M Mallikarjun Babu.

Starting point

The first visible symptom is the withering of the spindle marked with pale colour. The spear leaf or spindle turns brown and bends down. Such symptoms are later observed in younger leaves next to the spindle.

On dissecting such affected spindles, rotting of internal tissues could be observed, the tissues show pale pink colour with a brown border. The affected spindle can be easily pulled out at this stage.

The spindle droops down among the neighbouring leaves in the crown. A foul smell is emitted by the rotting tissue. The palm ultimately succumbs to the diseases with the death of the spindle.

At initial stage of the disease when the spindle is just withering, application of a mixture of 100 g copper sulphate and 100 g quick lime each dissolved in 500 ml of water separately and mixed together to make one litre) on the crown after removing the infected tissue and a thorough cleaning prevents the spread.

All the healthy palms around diseased plants should be sprayed. If the disease is detected when the central shoot is just withering, application of the mixture on the affected portion can check the dis­ease. Firstly remove all the rotting tissue using a sickle or knife then clean the portion using water and apply mixture for the cut portion. ­

The treated portion should be covered by polythene sheet to prevent washing off of the paste during rains. Soon after the development of the new spear leaf, remove the plastic cover. The removed af­fected tissues should be burnt in order to prevent the spread of the disease to other palms.

Adjacent healthy palms should be sprayed with 1 per cent of the mixture or with any other copper based fungicide. A pre and post-monsoon sprays of the above fungicide is rec­ommended for the management of the. disease.

The 1 per cent mixture can he prepared by dissolving one kg of copper sulphate in 50 litres of water; dissolving 1 kg of quick lime in fifty litres of water seperately; pour copper sulphate solution into the lime­ water slowly with constant stirring.

To check the quality of the mixture, dip a pol­ished knife in the solution for two minutes. If the knife gets a reddish stain, then the mixture is acidic and harmful to the plant, if sprayed. To neutralize the mixture, add more limewater, till the non-deposition of the red­dish stain on the knife.

 The 10 per cent mixture can be prepared by dissolving one kg of copper sulphate in five litres of water; dissolve one kg of quick lime in another five litres of water seperately and mixing the two solutions to get the paste.