Coffee growers spar over poly wrap method to curb white stem borer

An ingenious method has been found to control the ruinous white stem borer in coffee estates where the arabica variety is grown. But coffee planters are split over the effect of the solution with some even questioning its impact on the environment.

According to A.K. Bhandari, coffee planter and former President of the United Planters Association of Southern India, wrapping the stem of the arabica plant with cellophane, called poly wrap, helps in containing the borer menace. The wrap prevents the female beetle from laying eggs in cracks and crevices of the plant.

“We came across this solution some two-and-a-half years ago when some planters used old plastic to wrap the stems. It prevented the borer from laying eggs and controlled the spread of the pest,” he said.

Coffee white stem borer, Xylotrechus quadripes, is a pest found in arabica coffee causing huge yield loss. A blackish brown coloured beetle, it can also be found on rosewood, sandalwood and teak.

Ten to 12 days after the female beetle lays the eggs on the stem, the larvae enter the woody tissue and burrow up to the roots. This leaves the plant impaired and the only known solution is uprooting the plant totally and burning it.

“Poly wrap physically stops the insect from laying eggs on the plant. Growers had, at one point of time, wrapped plants with old fertiliser bags. Now, they have begun to use strip wraps and the results have been good,” said Jawaid Akhtar, Coffee Board Chairman.

History traces the borer menace to 1837 and the first reference was made in 1838 by H. Stokes, Mysore Commissioner. In 1868, the Madras Commissioner had reported the ravages of the borer in Mysore and Coorg.

yield loss

“We have been suffering from the borer menace for over a decade now. It has affected arabica production. In some estates, nearly 50 per cent of plants had to be uprooted,” said Bose Mandanna, a grower in Kodagu and former vice-chairman of Coffee Board.

The borer menace has resulted in arabica production stagnating around one lakh tonnes annually for almost a decade after rising to a record 1.21 lakh tonnes in 2001-02 (October-September) season. Its share in total coffee production (robusta makes up the rest) has decreased from over 50 per cent in the 1980s to around 30 per cent now.

This year, out of the estimated 3.47 lakh tonnes production, arabica output has been pegged at 1.11 lakh tonnes. However, growers expect it to be lower than 90,000 tonnes.

“The poly wrap seems to be working very well. Most of the growers have reported 99 per cent success. About 10 estates can be taken and the experiment tried for 2-3 years,” said Bhandari.

The Coffee Board had sent an advisory on the poly wrap but not much progress seems to have been made.

“Labour shortage is the reason why poly wrap has not picked up. Also, there was short-supply of wraps. That has ended now as supply is ample. Results are encouraging and the wrap does not affect the plant’s growth,” said Akhtar.

But, there are voices of dissent too.

“The poly wrap was tried in small pockets and it has not been successful when tried on a large-scale. It prevents plants from growing. The bark growth is stunted and we feel this is not a scientific solution,” said the Karnataka Planters’ Association Chairman, Nishant Gurjer.

Some of the corporates involved in growing coffee have now begun to experiment the method. “We have begun the poly wrap on Coffee Board’s suggestion and are assessing the results,” said an official of Tata Coffee at its Margolly estate in Kodagu.

However, concerns are being raised over its effect on the environment.

“When the poly wrap gets old, it could lead to environment problems since it won’t disintegrate easily,” said Mandanna.

Gurjer agrees. “Plastic will add to the mechanical damage to the plants,” he said.

Other growers say that until a better solution is found, the poly wrap method should continue.

subramani.mancombu@thehindu.co.in

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