Co-application of glyphosate plus an insecticide or fungicide in glyphosate-resistant soybean

Abstract

Six field trials were conducted from 2008 to 2010 in Ontario to evaluate soybean injury and weed control efficacy with glyphosate tankmixed with various insecticides or fungicides. There was minimal visual injury (less than 4%) in glyphosate-resistant soybean and no adverse effect on soybean height and yield when cyhalothrin-lambda (Matador®), dimethoate (Lagon®), imidacloprid/deltamethrin (Concept®), spirotetramat (Movento®), pyraclostrobin (Headline®), azoxystrobin (Quadris®), propiconazole (Tilt®), azoxystrobin/propiconazole (Quilt®), tebuconazole (Folicur®) and trifloxystrobin/propiconazole (Stratego®) were tankmixed with glyphosate. Velvetleaf, pigweed species, common ragweed, common lambsquarters and green foxtail control ranged from 91-97, 94-99, 92-99, 80-94 and 98-100%, respectively. However, there was no adverse effect on velvetleaf, pigweed, common ragweed, common lambsquarters and green foxtail control, density and dry weight when one of the insecticides or fungicides evaluated was tankmixed with glyphosate. Based on these results, glyphosate tankmixed with cyhalothrinlambda, dimethoate, imidacloprid/deltamethrin, spirotetramat, pyraclostrobin, azoxystrobin, propiconazole, azoxystrobin/propiconazole, tebuconazole or trifloxystrobin/propiconazole causes minimal crop injury and has no adverse effect on weed control in glyphosate-resistant soybean under Ontario environmental conditions.