Weed Control in Winter Wheat (<i>Triticum aestivum</i> L.) with Preplant Applications of Glyphosate plus Mesotrione or Saflufenacil

Abstract

There is limited information on weed control with glyphosate plus mesotrione or saflufenacil when applied prior to seeding winter wheat in the autumn. A total of 12 field trials (six for each herbicide tankmix) were conducted over a three-year (2010-2012) at two locations (Ridgetown and Exeter, Ontario) to evaluate the effect of glyphosate plus mesotrione or saflufenacil at various rates for broadleaf weed control and red clo ver establishment in winter wheat. Glyphosate (900 g ae ha -1 ) and tankmixes of glyphosate (900 g ae ha -1 ) plus mesotrione or saflufenacil at 12.5, 25, 50, 75, 100, 150 and 200 g ai ha -1 applied preplant (PP) in the autumn resulted in minimal visible injury (0% - 2%) in the autumn and on May 1 and June 1 of the following spring in winter wheat. The PP application of glyphosate alone or in combination with mesotrione or saflufenacil provided only 1% - 30% control of common ragweed in the following spring. The PP application of glyphosate in combination with mesotrione or saflufenacil provided 74% - 100% control of wild mustard at 2 and 4 weeks after emergence (WAE) in autumn but the control was only 0% - 35% on June 1 of the following spring. Glyphosate plus mesotrione or saflufenacil did not have any effect on seed moisture content and yield of winter wheat compared to glyphosate alone. Clover establishment was reduced with glyphosate plus mesotrione at the two highest rates but was not affected with glyphosate plus saflufenacil compared to glyphosate alone. Based on these results, glyphosate alone and in combination with mesotrione or saflufenacil applied PP in the autumn at rates evaluated did not provide adequate residual control of common ragweed, common lambsquarters and wild mustard in the spring of the following year in winter wheat.