ASSOCIAÇÃO DE HERBICIDAS COM MOLIBDÊNIO NA CULTURA DO FEIJÃO-CAUPI

Abstract

Tank mixing between phytosanitary products and foliar fertilizers is common practice in agriculture. However, adverse effects on crop productivity may occur due to antagonism between products. The objective of this research was to evaluate the effects of the association of molybdenum (Mo) in a tank mixture with herbicides on the yield of cowpea variety BRS Guariba and on weed control. The experimental design used was a randomized block design with four replications in a 6x2 factorial arrangement. The first factor consisted of six weed management: weeding, non-weeding and the application of the herbicides bentazone, imazetapyr and the mixtures bentazone + imazamoxy and bentazone + imazetapir and the second factor for the absence and application of 80 g ha-1. from Mo. Weed density and dry mass, phytointoxication, main stem length, stem diameter, chlorophyll a and b contents and cowpea yield components were evaluated. The application of Mo associated to the herbicides bentazone, imazetapyr, bentazone + imazamoxy, bentazone + imazetapir does not affect the weed control efficiency nor the selectivity of herbicides for the BRS Guariba cowpea crop. The phytointoxication promoted by herbicides was mild (<5%) at 7 days after treatment application, with symptoms disappearing at 14 DAA. Mo application, even in combination with herbicides, increases chlorophyll a and b content at flowering, the length of the main stem and the number of pods per plant at harvest time. Weeds reduce cowpea grain yield, regardless of Mo application.