Terbufos biodegradability and efficacy against Radopholus similis in soils from banana cultivation having different histories of nematicide use,and the effect of terbufos on plant growth of in vitro-propagated Musa AAA cv. Grande Naine

The aims of this investigation were to: (1) determine whether there is enhanced biodegradability of terbufos in soils of banana plantations infested with Radopholus similis; (2) whether nematicide use history affects the degree of biodegradation; and (3) establish whether terbufos has phytotoxic side-effects on banana root growth. A greenhouse bioassay, using soils collected from different banana fields in Costa Rica, revealed that terbufos underwent enhanced biodegradation in the soil of a plantation having a long history of terbufos use. In the soils of two other plantations, where terbufos had never been used, and in another where the most recent terbufos application had occurred over a year before soil collection, high nematicide activity against R. similis was obtained even 60 days after application. Our study demonstrated that terbufos efficacy lasted longer in soils with no or low history of terbufos than in soils that had been treated several times. Terbufos did not reduce root fresh weight of in vitro-propagated bananas, and its positive effect was related to a control of R. similis.