Time of application of pre-emergence herbicides in dry-sown rice

Abstract

A field experiment was conducted at the Agricultural Research Station, Mannuthy under the Kerala Agricultural University during the first crop season of 1988 to find out the optimum time of application of the pre-emergence herbicides, butachlor and thiobencarb and to assess the scope of second application of these herbicides for efficient weed control in dry-sown rice. Major part of the weed flora of the experimental field was constituted by grasses and sedges. Control of Eehinochloa colons and other grasses was very effective in the treatments where thiobencarb was applied at 0, 3 or 6 days after sowing (DAS) and repeated at 25 DAS whereas almost all the butachlor treatments gave complete control of sedges. The population and drymatter production of weeds were appreciably reduced by the repeated application of thiobencarb and resulted in improvement of growth, yield attributes and yield of rice. These treatments also reduced the crop-weed competition for major nutrients N, I' and K.