Abstract
A field study was conducted to evaluate the effect of dimethenamid and imazethapyr followed by clethodim and bromoxynil, on rhizoma perennial peanut (Arachis glabrata) during and after establishment.There were no significant differences in any of the parameters measured among rhizoma perennial peanut accessions as a result of the effects of herbicides. Excellent grass control was obtained when dimethenamid (preemergence) at 1.68 and 3.36 kg ai/ha was applied during the first month as compared with the use of imazethapyr. At 26 weeks after herbicide application (WAH) excellent grass control was obtained in all herbicide treatments. At 52 WAH no differences were observed for broadleaf and grass density. No differences were detected for dry weight of rhizoma perennial peanut and weeds among herbicide treatments at the 26- and 52-WAH harvests. Plots receiving imazethapyr as an early postemergence (POE) had 44 g/m2 more dry weight of weeds than plots with dimethenamid at the lowest rate, but no differences were found among the other treatments. The lowest weight of rhizoma perennial peanut was with imazethapyr early POE, as compared with the three other herbicide treatments. No difference was observed with dimethenamid at either rate. After two years, density of broadleaves was the highest (55.6 plants per square meter) with imazethapyr applied early POE. Density of grasses was lower with imazethapyr preemergence and dimethenamid at a lower rate than with the other two herbicide treatments. Overall, taking into account all rates and dates of herbicide applications, the best weed control was obtained with the early application dates.