Efficacy of Chlorpyrifos 48% EC Against Cnaphalocrocis medinalis(Guenee)

Chlorpyrifos 48% EC provided excellent control of Cnaphalocrocis medinalis(Guenee) medinalis in field demonstration trials.Chlorpyrifos 48% EC application improved the light conditions in field,and photosynthesis and transpiration rate increased with the dosage of herbicide.The application of chlorpyrifos had no effect on 1 000-seed weight and plant height,whereas panicles per plant,grains per panicle,spikelets per panicle,seed set rate and yield per plant were markedly influenced,resulting in a significant yield increase of rice.It is indicated that the efficiency of chlorpyrifos 48% EC was much better trichlorfon 30% EC applied at 562.5 g/hm2.