Initial growth of cowpea-beans after application of post-emergence herbicides

Abstract

The objective of this work was to evaluate the tolerance of cowpea, BSR Aracê, to different herbicides applied in the post-emergence period, in the initial phase of plant growth. The experiment was conducted in a greenhouse, in a completely randomized design, with four replications. The treatments evaluated were: haloxyfop (60 g ha^-1), lactofen (180 g ha^-1), chlorimuron-ethyl (17,5 g ha^-1), bentazon (576 g ha^-1), bentazon + imazamox (600 + 28 g ha^-1), imazethapyr (100 g ha^-1), fomesafen (250 g ha^-1), quizalofop-P-ethyl (62,5 g ha^-1), lactofen + quizalofop-P-ethyl (180 + 62,5 g ha^-1), fomesafen + quizalofop-P-ethyl (250 + 62,5 g ha^-1) and a control. Were realized visual evaluations of intoxication, plant height, dry leaf mass, stem, root, total dry mass and leaf area. The herbicides haloxyfop and quizalofop-P-ethyl they caused minor damage to the development of cowpea plants. The chlorimuron-ethyl caused severe damage to the crop, interrupting their growth. The lactofen + quizalofop-P-ethyl and fomesafen + quizalofop-P-ethyl mixtures caused high damage to the culture, with lactofen + quizalofop-P-ethyl causing the plants to die at 21 DAAH. It was concluded that cowpea, cv. BRS Aracê, have tolerance to haloxyfop and quizalofop-P-ethyl herbicides, and moderate tolerance to imazethapyr and bentazon + imazamox. The lactofen + quizalofop-P-ethyl and fomesafen + quizalofop-P-ethyl mixtures showed a synergistic effect on bean cowpea. The lactofen + quizalofop-P-ethyl mixture and the chlorimuron-ethyl herbicide cause irreversible damage to the bean cowpea crop.