Residue and bio-efficacy evaluation of controlled release formulations of metribuzin against weeds in wheat.

Controlled release formulations of metribuzin in polyvinyl chloride, (emulsion); carboxy methyl cellulose, CMC and carboxy methyl cellulose- kaolinite composite, CMC-KAO are reported. The MET-CMC-KAO-3 (T(9)) formulation provided a superior control (76.1%) of weeds in field grown wheat in comparison to metribuzin 75 DF (57.14%) at the dose (350 g a.i. ha(-1)) after 90 days of sowing. The treatment (T(9)) reduced the dry weight of the weed flora after 30 days of sowing (4.0 g m(-2)) and significantly superior over metribuzin 75 DF (6.0 g m(-2)) and control (17.72 g m(-2)). There were nil to negligible metribuzin residue in soil at harvest of wheat crop and were within prescribed limit of 10 mg L(-1) in drinking water (EPA).