Interaction between ACCase inhibitors and broadleaf herbicides to the control of Italian ryegrass

Management of Italian ryegrass is frequently done with tank-mix or sequential applications of herbicides. The aim of this study was to evaluate the interaction of haloxyfop-p-methyl or clethodim with 2,4-D, chlorimuron-ethyl and cloransulam-methyl applied in a tank mix or sequential in the control of Italian ryegrass. The three experiments were performed in a factorial arrangement and a randomized complete block was designed, with four replications. Factor A consisted of the haloxyfop (62.35 g a.i. ha-1), clethodim (108 g a.i. ha-1) and chlorimuron (20 g a.i. ha-1) (Experiment I); haloxyfop, clethodim and cloransulam (39.95g a.i. ha-1) (Experiment II); haloxyfop, clethodim and 2,4-D (1005 g a.e. ha-1) (Experiment III). Factor B consisted of tank-mix or sequential (same day) application. Treatments also included an untreated check and the isolated application of herbicides. Haloxyfop and clethodim alone, clethodim+2,4-D, haloxyfop+cloransulam, haloxyfop+chlorimuron, clethodim+cloransulam, clethodim+chlorimuron controlled Italian ryegrass. However, an antagonistic response of haloxyfop+2,4-D was observed. Based on this study, haloxyfop should not be applied associated with 2,4-D in the control of Italian ryegrass; however, the mixtures of ACCase+chlorimuron, ACCase+cloransulam, and clethodim+2,4-D were efficient in the control of the Italian ryegrass.