Financial Times

Coconut mite threat grows despite control efforts
Coconut growers are concerned about the spread of the coconut mite, aceria guerreronis, that has resisted control efforts, resulting in fears that it could significantly reduce crops during the lean cropping months.

The current high prices for nuts paid by consumers is the result of the drop in crop owing to the lagged effects of drought and worsened by the mite infestation which causes immature nuts to fall and reduces nut size, growers said.

Growers and scientists said the mite, which has spread to most of the coconut growing areas, could cause yield reductions of 5-20 percent. The mite infestation affects crops in two ways - by reducing the number of nuts and reducing their weight.

"We can't see any immediate solution," said a spokesman for Coconut Growers Association. "It appears we might have to live with it. We don't think the entire crop could get wiped out but nuts infested with the mite have low kernel weight inside, which means they are not good for industrial purposes like desiccated coconut."

Even a 10 percent drop in the crop could be significant during lean months, he said."The annual crop is about 2.4 billion nuts. We have shortages from October to March. Even a 10 percent drop means 240 million nuts lost. So that's a lot."

He said the industry acknowledged that fighting the mite was not easy, with efforts in the Caribbean and West Africa where it first appeared, and in India too, being unsuccessful. "So it needs extra effort by way of funds and scientific input, which the industry doubts is happening."

Scientists at the Coconut Research Institute (CRI) have been experimenting with biological control methods since the mite was first detected in the late 1990s in Puttalam district.

CRI has also suggested chemical solutions to prevent the spread of the mite, which growers said were not practical, especially on big estates. Planters said they find it difficult to find labour to climb trees to apply the chemicals on nuts.

The mite has spread to Mannar, Vavuniya, Jaffna, and the Eastern province. Only the southern part of the Western province and the south of the island have been spared.

CRI director Dr Chitranganie Jayasekera said they have a national mite control programme to improve awareness among growers to prevent the mite spreading.The CRI has suggested interim measures like chemical controls while working on developing biological control methods.

She said that some of the chemical control methods like insecticide sprays and application of chemical mixtures on nuts were difficult to implement and costly. The CRI has recommended to growers the application of margosa oil and garlic mixture every two months and burnt engine oil with soap every three months.

"It is true that big plantations find it difficult to use these methods," Dr Jayasekera said. "We have to implement biological control methods. We're now working on another predator mite and a fungus but these are still in the experimental stage."

Nuts become small and immature nuts fall because of the mite attack, she said."The current high nut prices are a result of the last two consecutive years of drought. Nut sizes are small even in areas where the mite is not there."

She said the nut size becomes small as the mite sucks the coconut juice but said the impact on the DC industry was not significant."By April we expect a very good crop because we had good rains last year," Dr Jayasekera said. Growers said that one way of managing the mite was using good cultural practices like applying fertiliser well.

"No where in the world have they been able to combat the mite by biological control," he said. "Indians also has not got biological control methods." The mite is known to have affected almost all the coconut trees in southern India.

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