Greenfly infestation slashes tea yields by up to 55% in Assam and Bengal

Guwahati, April 5: The tea industry in Assam and West Bengal is currently facing a severe challenge due to widespread infestation of greenflies a pest that has emerged as a major threat over the past two years.

This sap-sucking insect has caused significant damage to tea plants, particularly during the dry months, leading to yield reductions ranging from 11 per cent to as high as 55 per cent across various tea-growing regions.

Greenflies primarily attack young green leaves, resulting in distinct symptoms such as uneven leaf surface, downward curling, and browning at the edges, collectively referred to as rim blight. These infestations are particularly devastating during the second flush period (May-July), a crucial time when tea gardens earn over 30 per cent of their annual revenue due to the high quality and demand for tea produced during this phase.

"Recent climatic shifts, including rising temperatures and reduced rainfall, have significantly accelerated greenfly reproduction. Once considered a seasonal pest mainly active between May and July, greenflies are now being reported throughout the year, indicating a troubling adaptation to environmental stress," Tea Research Association secretary Joydeep Phukan said.

Moreover, there are growing concerns about a possible invasion by modified or more aggressive greenfly strains, especially in tea plantations located near international borders. This has only heightened the urgency for effective pest control solutions.

Although tea estates have been using various chemicals approved under the Plant Protection Code (PPC), these have proven largely ineffective. The growing resistance of greenflies to these treatments has left planters with limited options.

"Compounding the problem, greenfly damage is also making tea bushes more vulnerable to secondary infections such as Fusarium dieback, which has been affecting plantations for several consecutive years," Phukan said.

In response, the Tea Board of India's PPC (Version 16.0, February 2024) has recommended nine specific chemical formulations (among a total of 56 for all pests), but these too have failed to curb the greenfly menace effectively.

Given the gravity of the situation, tea gardens across Assam and West Bengal are urgently seeking alternative chemical or biological solutions. Scientists at the Tocklai Tea Research Institute of Tea Research Association are actively investigating new strategies to combat this growing threat and one such compound is Chlofenapyr 10SC, which is found to be effective but needs label claim from Central Insecticides Board for use in tea.