Effect of cyhalofop-butyl for annual grass weed control in rain-fed rice.

In 2002, two experiments werecarried out in the municipality of Tres Valles, Ver., Mexico, inorder to evaluate the effectiveness of cyhalofop-butyl on theannual grass weed control in rain-fed rice cv MilagroFilipino. A randomized complete block design with seventreatments and four replications was utilized for bothexperiments. Cyhalofop-butyl was evaluated at 180, 225,270, 315 y 360 g/ha, propanil at 4320 g/ha and a weedy checkwere also included. The treatments were applied when therice plants had a height of 25 cm. Annual grass weeds presentin the experiments, were junglerice and Southern crabgrass[Digitaria ciliaris (Retz.) Koeler]. Grass weed control andtoxicity to rice were evaluated at 15, 30 and 45 days afterapplication. The highest junglerice and Southern crabgrasscontrols were obtained when cyhalofop-butyl was applied at315 and 360 g/ha. The different dosages of this herbicide, didnot cause any toxicity to rice. The effect of propanil on weedswas similar to that of cyhalofop-butyl at 360 g/ha during thefirst 15 days after application.