A tea garden can now treat its worst termite problem with a chemical that testing found no detectable trace of in the leaf a week later, according to a new trial from Assam Agricultural University in Jorhat.

The termite in question, Odontotermes obesus, eats living tea wood, not just the stumps and dead timber it is usually blamed for. Sudhansu Bhagawati and colleagues in the university's Department of Entomology, working with the Institute of Pesticide Formulation Technology in Gurgaon, tested six insecticides against it in tea plantations, at doses set by the Tea Board's own Plant Protection Code.

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 two strengths of imidacloprid and a fipronil treatment, all trailed it.

It also cleared fastest. Researchers tested the plucked leaf for chemical residue after treatment and reported none detectable, even seven days out. A garden can knock down the termite and still send out leaf that tests clean 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 exists precisely so a chemical strong enough to work is also one a garden is permitted to use.

This office does not run trials. It reads the ones that hold up, and this one holds up: a bush kept alive at the root, and a cup that tested clean a week later.

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).