Weed Control in Winter Wheat (&lt;i&gt;Triticum aestivum&lt;/i&gt; L.) with Preplant Applications of Glyphosate plus Mesotrione or Saflufenacil

Nader Soltani,Peter H Sikkema,Christy Shropshire,Lynette R Brown

doi:10.4236/as.2015.66058

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 clover 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.

Highlights

Canada is the 7th largest wheat (Triticum aestivum L.) producer in the world producing nearly 25,000,000 MT of wheat annually from which approximately 17,000,000 MT valued at $5.4 billion is exported to other countries [1]
There were no significant differences between treatments for controlling common ragweed and wild mustard 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 did not result in any commercially significant visible injury in winter wheat evaluated in the autumn and on May 1 and June 1 of the following spring

Summary

Introduction

Canada is the 7th largest wheat (Triticum aestivum L.) producer in the world producing nearly 25,000,000 MT of wheat annually from which approximately 17,000,000 MT valued at $5.4 billion is exported to other countries [1]. Growers in Ontario like to include winter wheat in the rotation with other crops such as soybean and corn to help maintain soil structure and break pest cycles including weeds. Herbicides registered for use in winter wheat have not changed significantly in the past 20 years in Ontario [2]. Mesotrione is a triketone herbicide that provides control of annual broadleaved weed species such as velvetleaf (Abutilon theophrasti Medic.), redroot pigweed (Amaranthus retroflexus L.), common lambsquarters (Chenopodium album L.), common cocklebur (Xanthium strumarium L.), ladysthumb (Polygonum persicaria L.) and giant ragweed (Ambrosia trifida L.). Mesotrione can control annual grass weeds such as barnyardgrass (Echinochloa crus-galli (L.) Beauv.) and large crabgrass (Digitaria sanguinalis (L.) Scop.) [2] [3]. Mesotrione injury symptoms in susceptible plants include bleaching of meristemic tissue followed by growth cessation and necrosis within 3 - 5 days [2] [3]

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