Assam's Best Termite Killer Also Tests Cleanest for Residue
A new Assam Agricultural University trial finds the most effective chemical against wood-eating termites in tea gardens also clears the leaf to a residue far below the safety limit within a week.
A new trial from Assam Agricultural University in Jorhat has found the most effective chemical against a destructive tea-garden termite. The same chemical also clears out of the leaf fastest, falling far below the safety limit within a week.
The termites in question, of the genera Microtermes and Microcerotermes, eat living tea wood, not just the stumps and dead timber termites are usually blamed for. Sudhansu Bhagawati and colleagues at Assam Agricultural University, working with the Institute of Pesticide Formulation Technology in Gurgaon, tested six insecticides against them in tea plantations.
Clothianidin 50 WDG, applied at 250 grams per hectare, came out on top for killing power: a 77.02 percent reduction in termite infestation after 60 days, holding the infested rate to 6.65 percent at 30 days and 8.31 percent at 60. The other five formulations, including three strengths of imidacloprid and a fipronil treatment, all trailed it.
It also clears fast. Researchers tested the plucked leaf for clothianidin residue by mass spectrometry and found 9.11 parts per billion at seven days, about a hundredth of the Tea Board's own 0.7 parts-per-million safety limit for the chemical in tea leaf, falling further still to 1.11 parts per billion at 14 days. A garden can knock down the termite and still send out leaf that clears the safety limit within the week, rather than holding the crop back on a longer clearance schedule.
Termites are a standing cost in Assam's gardens, weakening the woody frame of the bush itself rather than just the leaf, which is what makes a treatment that is both effective and quick-clearing worth certifying rather than filing away. The Tea Board's Plant Protection Code sets the residue limit a garden's leaf must clear, and this one clears it with room to spare.
Sources: Bhagawati et al., Novel Insecticides for the Management of Live Wood Eating Termites in Tea Plantations of Assam, Indian Journal of Entomology (published online February 6, 2026).
Correction, July 14, 2026: An earlier version misidentified the termite as Odontotermes obesus. The study identifies the termites as Microtermes and Microcerotermes species.
Correction, July 14, 2026: An earlier version reported no detectable pesticide residue in the leaf after a week. The study detected 9.11 parts per billion of clothianidin at seven days, about a hundredth of the Tea Board's 0.7 parts-per-million safety limit, falling to 1.11 parts per billion at 14 days.