Selectivity of Iodosulfuron-Methyl Association with ACCase Inhibitors and 2.4-D in Wheat and Barley Crops

Abstract

ABSTRACT: This research aimed to assess the selectivity of treatments involving the commercial formulations tank mixtures of iodosulfuron-methyl with herbicides ACCase inhibitors (fenoxaprop-p-ethyl and clethodim) and synthetic auxins (2.4-D), applied in post-emergence of wheat (Triticum aestivum) and barley (Hordeum vulgare) crops. Three experiments were conducted in the field, during the 2014 crop year. A randomized complete block design was used with 11 treatments and five replications. Treatments consisted of (g ha-1): 1) iodosulfuron-methyl (6.5), 2) fenoxaprop-p-ethyl (82.5), 3) fenoxaprop-p-ethyl + clethodim (55 + 54); 4) 2.4-D (335), 5, 6 e 7) iodosulfuron-methyl + fenoxaprop-p-ethyl (6.5 + 82.5; 6.5 + 110 and 6.5 + 165), 8) iodosulfuron-methyl + fenoxaprop + clethodim (6.5 + 55 + 54), 9) iodosulfuron + fenoxaprop-p-ethyl + 2.4-D (6.5 + 110 + 335), 10) iodosulfuron-methyl + fenoxaprop-p-ethyl + clethodim + 2.4-D (6.5 + 82.5 + 72 + 335) and 11) check without weeds. Associations of iodosulfuron-methyl + fenoxaprop-p-ethyl (6.5 + 82.5; 6.5 + 110 and 6.5 + 165 g ha-1) associations, as well as of iodosulfuron-methyl + fenoxaprop-p-ethyl + 2.4-D (6.5 + 110 + 335 g ha-1) were selective for BRS Campeiro and BRS Gralha azul wheat cultivars and did not feature symptoms of intoxication and significant losses in grain yield and hectoliter weight, when compared to the treatment with no application. For BRS Brau barley cultivar, only iodosulfuron-methyl + fenoxaprop-p-ethyl associations, in doses of 6.5 + 82.5 and 6.5 + 110 g ha-1 were feasible for selectivity. Clethodim addition in iodosulfuron-methyl + fenoxaprop-p-ethyl or iodosulfuron-methyl + fenoxaprop-p-ethyl + 2.4-D associations caused negative effects for wheat and barley crops. Commercial formulation of iodosulfuron-methyl (Hussar™) resulted in protection for damage effects of fenoxaprop-p-ethyl (Podium EW™) for studied crops.