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Field studies were carried out at the Punjab Agricultural University, Ludhiana during 1987 and 1988 to work out critical period of competition between wrinkle grass and transplanted paddy. Wrinkle grass allowed to compete for the entire crop season caused 69.4 per cent reduction in paddy yield, A weed free period for initial 30 days, was insufficient as late emerged weeds significantly reduced paddy yield as compared to weed free treatment. The removal of the weed late even at 70 days after transplanting proved beneficial and increased paddy yield signficantly. The critical period of competition between wrinkle grass and transplanted paddy was found between 40 and 70 days after transplanting.
