Ontario Grain Farmer April/May 2023

BLUEGRASS COMPETITION IN winter wheat can result in up to 50 per cent yield losses. Over the past two seasons, three herbicides (Simplicity GoDri, Varro and Axial) have shown promising results and have prevented significant yield loss in winter wheat. These competitive grassy weeds emerge in the fall and early spring. Plants smaller than 10 centimetres in height are easier to control with herbicides, and early spring applications provide better control than fall applications. Some bluegrass seedlings — that are missed by fall applications — emerge in early spring. Both fall and early spring applications provide better control than late spring applications. Acknowledgements: A huge thanks to Steve Lake, Peter Smith and François Tardif for supporting this research. l Managing bluegrass CROP SIDE WITH... Crop side ONTARIO GRAIN FARMER 25 APRIL/MAY 2023 SIMPLICITY GODRI, VARRO, AND AXIAL PROVIDED GOOD CONTROL OF BLUEGRASS COMPARED TO THE UN-SPRAYED CHECK, WHERE BLUEGRASS HEADED ABOVE WINTER WHEAT. PHOTO COURTESY OF MIKE COWBROUGH. Mike Cowbrough, Weed Specialist, Ontario Ministry of Agriculture, Food and Rural Affairs THE DENSE STAND OF BLUEGRASS LODGED WINTER WHEAT (LEFT) COMPARED TO WHERE ADEQUATE CONTROL WAS ACHIEVED (RIGHT). IN 2022, BLUEGRASS COMPETITION REDUCED WINTER WHEAT YIELDS BY 50 PER CENT AND REDUCED HARVEST SPEED BY 30 PER CENT. PHOTO COURTESY OF MIKE COWBROUGH. Herbicide Average control (%) Range in control (%) Yield (bu/ac*) Simplicity GoDri + Agral 90 81.5 73 - 90 122 Varro + Agral 90 82.5 75 - 90 122 Axial** 81 72 - 90 114 Unsprayed 0 0 60.7 * 2022 yields only. ** Axial does not control broadleaf weeds, so grain yield was lower. When Axial was tank-mixed with a broadleaf herbicide, grain yield was the same as Simplicity and Varro. TABLE 1. WINTER WHEAT YIELD (BU/ACRE), AVERAGE AND RANGE IN BLUEGRASS CONTROL ACHIEVED WITH THREE POST-EMERGENT HERBICIDES.

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