Rice is an important food crop in India, but its average yield is rather low. It faces various production constraints, including competition from weeds that can reduce yield by 25-53%. Infestation commonly occurs 15-45 d after transplanting (DAT) (Subhaiah and Sreedevi 2000).
In recent years, a number of preemergence herbicides, including butachlor and thiobencarb, were applied to control weeds. These herbicides effectively controlled many grass weeds, except for some sedges and broadleaves.
Repeated use of herbicides may have resulted in weeds developing resistance and shifts in weed flora, leading to low weed control efficiency (Kathiresan 2001). The current study examined a wider range of herbicides.