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Cover Crops: A Component of an Integrated Weed Management Strategy for Ontario Field Crops

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Title: Cover Crops: A Component of an Integrated Weed Management Strategy for Ontario Field Crops
Author: Cholette, Taïga B.
Department: Department of Plant Agriculture
Program: Plant Agriculture
Advisor: Sikkema, PeterRobinson, Darren
Abstract: Cover crops have many desirable attributes including reduced soil erosion, increased soil organic matter and reduced weed density. However, cover crops can be injured by residues from herbicides used for weed control in the previous crop and cover crops can negatively impact the main cash-generating crop through resource competition. Three field studies were conducted to determine the impact of winter wheat and soybean herbicides on the establishment and growth of oilseed radish, the suppression of glyphosate-resistant Canada fleabane in corn with cover crops seeded the previous summer/fall after winter wheat harvest and the suppression of annual ryegrass in corn with nicosulfuron to prevent grain corn yield losses due to cover crop interference. Winter wheat herbicides applied in the spring caused <5% oilseed radish injury and there was no reduction in oilseed radish density and biomass. Imazethapyr, applied preemergence and postemergence to soybean caused 48 and 59% oilseed radish injury 28 days after emergence, respectively. Imazethapyr did not reduce oilseed radish density; however, when applied postemergence it reduced oilseed radish biomass by 65%. All 17 cover crops seeded after winter wheat combining suppressed glyphosate-resistant Canada fleabane from May to September in corn grown the year after winter wheat. Crimson clover plus annual ryegrass was the only cover crop that resulted in a glyphosate-resistant Canada fleabane density similar to the weed-free control. Grain corn yields were not affected by the cover crops evaluated. There was no difference between nicosulfuron (0.8, 1.6, 3.1, 6.3, 12.5, 25 and 50 g ai ha-1) applied at either the 2-3 leaf stage or the 4-5 leaf/1-tiller stage of annual ryegrass that was planted at the same time as corn for all parameters evaluated. Grain corn yield ranged from 14.5 to 15.0 t ha-1 when annual ryegrass was treated with nicosulfuron at 0.8 and 25 g ai ha-1 while the weed-free control had yield of 15.5 t ha-1.
URI: http://hdl.handle.net/10214/10343
Date: 2017-05-03


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