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.