Development of Controlled Release Phorate Formulations and Their Evaluation for Pest Control and Grain Yield on Sorghum Rao K. Narasimha, Srivastava K.P.@, Parmar B.S.* Division of Agricultural Chemicals, Indian Agricultural Research Institute, New Delhi-110 012, India Contribution No. 425 from; the Division of Agricultural Chemicals, Indian Agricultural Research Institute, New Delhi-110 012, India @Division of Antomology, Indian Agricultural Research Institute, New Delhi-110 012, India Online published on 15 December, 2011. Abstract Controlled release polymeric formulations of phorate were prepared employing polyvinyl chloride, polystyrene, polymethylmethacrylate, cellulose acetate, ethyl cellulose and polyethylene glycol 6000 matrices. Their phorate release in water was extended upto 21–35 days as compared to 9 days in the case of Thimet 10G, an encapsulated proprietory product. In soil over,40% of unreleased phorate was recovered from the residual polymeric products on the 60th day after application, except in the case of polyethylene glycol 6000. Only 10% phorate on 40th day and 5% on the 30th day were recovered from Thimet 10G and polyethylene glycol 6000,respectively. Apparently, the phorate content of the soil at a given time was a function of its release rate from the polymer. In two field experiments on sorghum crop, polyethylene glycol based product revealed a superior control of Atherigona soc-cata. The performance of other polymers varied in both the experiments. Against Chilo partellus, Thimet 10 G was not significantly superior over control whereas the polymeric products were generally superior than even Thimet 10G. All the-treatments significantly increased the sorghum grain yield over control. Cellulose acetate in both the experiments and polystyrene and ethyl cellulose in one experiment each gave a significantly better yield increase over Thimet 10G. Top |