Abstract
Halosulfuron was recently registered as the second soil-applied herbicide for broadleaf weed control in Ontario dry beans, but does not provide an alternative mode of action. Sulfentrazone is used to control broadleaf weeds in soybean and other pulse crops, and its registration for Ontario dry beans would provide a different mode of action for broadleaf weed control. Five field studies were conducted over two years (2014, 2015) to determine if the spectrum of broadleaf weed control is improved by adding a half-rate of halosulfuron to sulfentrazone PRE, and to determine the tolerance of white bean to sulfentrazone (140 or 210 g ai ha-1), s-metolachlor (1050 g ai ha-1), and halosulfuron (17.5 g ai ha-1) applied alone and in combination. Crop injury was assessed at 2 and 4 weeks after crop emergence. Weed control was assessed at 4 and 8 weeks after herbicide application (WAA), and weed density and biomass were determined at 8 WAA. Seed moisture and yield were determined at harvest. Halosulfuron added to sulfentrazone improved the control of Ambrosia artemisiifolia and Sinapis arvensis. Sulfentrazone + s-metolachlor + halosulfuron caused up to 23% crop injury. Therefore, this study concludes that sulfentrazone + s-metolachlor + halosulfuron provides broad spectrum weed control, but is too injurious to white bean for registration in Ontario.
Highlights
IntroductionOntario crop rotation of corn, soybean and wheat
Five field studies were conducted over two years (2014, 2015) to determine if the spectrum of broadleaf weed control is improved by adding a half-rate of halosulfuron to sulfentrazone PRE, and to determine the tolerance of white bean to sulfentrazone (140 or 210 g ai ha−1), s-metolachlor (1050 g ai ha−1), and halosulfuron (17.5 g ai ha−1) applied alone and in combination
When a low rate of halosulfuron was added to sulfentrazone, the spectrum of broadleaf weed control was improved
Summary
Ontario crop rotation of corn, soybean and wheat. Several market classes of dry beans are grown in Ontario including cranberry, black, Dutch brown, kidney, small red Mexican, otebo, pinto, yellow eye and white (navy) bean. White bean is the predominant class of dry bean grown in Ontario, accounting for approximately 50% of production [1] [2]. One of the most critical aspects of crop management for dry bean producers is weed control, as dry beans are poor competitors [3]. In Ontario, weed interference has caused white bean yield losses of 68% to 77% [4] [5] [6]. When used in efficacious tank mix combinations that do not injure the crop, herbicides are effective tools for controlling weeds
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