Effectiveness of Repeated Reduced Rates of Selective Broadleaf Herbicides for Postemergence Weed Control in Sugar Beet ( Beta V ulgaris )

Abstract

Field experiments were conducted at three sites (Karaj, Mashhad and Orumieh, Iran), during 2005 to determine the influence of reduced rates of broadleaf herbicides in different combinations on sugar beet and weeds. Experiments were laid out in a randomized complete block design with factorial arrangement of the treatments and three replications. The treatments were 10 different combined herbicides that applied at recommended (full rates) and reduced rates (half rates). Data were recorded 30 days after herbicide application on percentage of weed density and biomass reductions. The data for individual traits were subjected to the ANOVA technique and significant means were separated by the 's multiple range test. The analysis of the data showed that herbicide combinations and herbicide doses were statistically significant for all the parameters investigated except weed frequency reduction at and Orumieh. The interaction of herbicide combinations and doses could not reach the level of significance in any of the traits examined. The results indicated more efficacies of herbicides combinations when they used repeatedly in low-than labeled dose.