Tolerance of cowpea cultivars to pre-emergence application of sulfentrazone

ABSTRACT Improved methods of weed control are required to support expansion of large-scale cowpea cultivation in mid-west Brazil. With the aim of testing our hypothesis that the tolerance of cowpea cultivars to sulfentrazone is dose- and genotype-dependent, we assessed the effects of increasing doses (0, 250, 500 and 1,000 g ha-1 of sulfentrazone) on the cultivars BRS Imponente, BRS Novaera, BRS Tumucumaque and BRS Itaim. The phytotoxic effects of sulfentrazone varied according to the dose of herbicide applied, although the symptoms were mild and only observable at the initial stages of development and at the highest dose tested. No statistically significant interactions were detected between cultivars and doses, and there were no significant differences between doses regarding population density, plant height, yield components and grain yield. Our results demonstrate that sulfentrazone is highly selective and can be applied to the studied cultivars without affecting growth or yield.