Sourgrass and fleabane are controlled by haloxyfop-p-methyl and cloransulam-methyl interaction and interval of application

Background Areas simultaneously infested with both glyphosate-resistant sourgrass (Digitaria insularis L.) and fleabane (Conyza spp.) are usual in Brazil. However, there are no effective management strategies to control both species concurrently. Objective The aim was to evaluate the interaction and interval of application of haloxyfop-P-methyl and cloransulam-methyl to effective control sourgrass (from 3- to 4-tillers to flowering stages) and fleabane (12- to 15-cm at the vegetative stage). Methods The experiment was conducted twice in a randomized complete blocks design with four biological replicates. The treatments were composed of sequential applications of haloxyfop-P-methyl (firstly applied) and cloransulam-methyl (secondly applied) and vice-versa. After the first application, the second one was applied in intervals of 3, 6 and 12 days. Haloxyfop-P-methyl and cloransulam-methyl were also applied in sequential (without interval), stand-alone applications of both herbicides and an untreated check. Results All treatments effectively controlled all fleabane plants. Haloxyfop-P-methyl applied ≥ 6 days before cloransulam-methyl controlled 100% of 3- to 4-tillers sourgrass and 60% of flowering sourgrass. Conclusions Therefore, haloxyfop-P-methyl may be applied ≥ 6 days before cloransulam-methyl in a sequential application structure to effectively control fleabane and sourgrass (3- to 4-tillers stage), when present concurrently.