Fight the rot

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Miguel Braganza

It is not just raindrops falling on the head that is worrying the farmers in the hinterland, rather it is the immature areca nuts falling all over the kulaghar. The solution they seek is the now-familiar compensation of the loss by the government of Goa. Actually, the solution that they need is the Bordeaux mixture, the very first fungicide discovered by Pierre-Marie-Alexis Millardet in Bordeaux, France, in 1885. Nelson Figueiredo and I wrote about it in a book titled ‘Pest Management’ published by the Agriculture Officers’ Association (AOA) in 1991 – copies of which have been read by members and farmers until Nelson updated it in 1999 with the book ‘Integrated Pest Management’ when Nevil Alphonso was the AOA secretary. Two of them have become directors of agriculture but the farmers will just not take any advice as long as the government gives them doles as assured support price (ASP) for a non-food item, instead of subsidising the treatment.

The genus Phytophthora is the one that we have to fight off our crops in Goa. It is not only the areca nut but also the ‘State Tree’ of Goa, the coconut tree, and the food of the future or the jackfruit tree, that has been affected by this fungus. It is also a major cause of spoilage in mangoes. And not only does it cause nuts to drop and fruits to rot, it also causes bud rot and root rot in various trees and vegetable crops. Of this genera, P meadii, P palmivora and P parasitica are the most common species in a warm, humid, high rainfall coastal region like Goa.

The ‘mahali’ disease or ‘kole roga’ is as common as the rain in Goa. Dark green, water-soaked spots appear on the tender areca nuts which then fall without the calyx. A white, thread-like fungal growth soon covers the fallen nuts. Heavy rain with intermittent periods of sunshine is ideal for the spread of the fungus. This is invariably the condition in Goa during August and September. A spray of one per cent Bordeaux mixture or of four grams of copper oxychloride per litre at the end of May followed by another on a sunny day at the end of July and end of August is recommended. That hardly anyone follows the recommendation is more a matter of government policy than of labour shortage. 

Two innovative farmers, Pandurang Patil in Rivona-Sanguem and Ashok Joshi in Hedode-Sattari have demonstrated how areca nut trees can be sprayed from the ground using a bamboo or a rigid PVC pipe between the trigger and the nozzle to effectively extend the spray lance in a rocker-arm or foot-operated sprayer. Lime powder and copper sulphate to make the Bordeaux mixture are easily available. The safer-to-use copper oxychloride is also in the market. What it needs are farmers to use it to protect their crops. Soon it will be time to spray the mango trees.

Organic agriculture seeks to reduce the dependence on these copper compounds that it permits for want of efficacious alternatives. Pseudomonas fluorescens has proved effective against anthracnose disease and Trichoderma viride prevents soil-borne fungus. With increasing popularity, other biological control measures are bound to be discovered for the diseases-affected crops. Panchagavya and effective microorganisms (EM) help to suppress diseases but not to entirely control them. The search is on. Perhaps, some of our own students of agriculture or biotechnology will discover some!