Seletividade e eficácia de herbicidas inibidores da enzima accase na cultura da mamona

Abstract

This experiment aimed to evaluate the selectivity and efficacy of ACCase-inhibiting herbicides in castor bean crop, at Paraguaçu Paulista, São Paulo, during the 2002/03 agricultural season. The experimental design used was randomized complete blocks, with eleven treatments and four replicates, constituted by the following herbicides and adjuvants: fluazifop-p-butyl (313 g ha -1) + Agral™ (0.2% v/v); sethoxydim (322 g ha -1) + Assistl™ (0.5% v/v); haloxyfop-methyl (120 g ha -1) + Assistl™ (0.5% v/v); clethodim+fenoxaprop-p-ethyl (75 g ha -1) + Assistl™ (0.5% v/v); quizalofop-pethyl (125 g ha -1) + Assistl™ (0.5% v/v); clethodim (156 g ha -1) + Assistl™ (0.5% v/v); propaquizafop (175 g ha -1) + Assistl™ (0.5% v/v); tepraloxydim (400 g ha -1) + DashTM (0.5% v/v); butroxydim (100 g ha -1) + DashTM (0.5% v/v); isoxaflutole (60 g ha -1) and weed-free check. At the moment of application, castor bean plants presented 4 to 6 leaves and Cenchrus echinatus, 1 to 5 tillers. AL Guarany 2002 cultivar presented high selectivity to ACCase-inhibiting herbicides, without visible symptoms of phytotoxicity in 14 DAA (days after application), except for tepraloxydim, whose symptoms persisted until 21 DAA, and isoxaflutole (HPPD inhibiting), which showed injuries in older leaves and significant yield reduction. C. echinatus infestation was efficiently controlled by ACCase-inhibiting herbicides between 14 and 21 DAA (≥ 95.0%).