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Processing peas herbicide screening trial

Project Code: SCR07-002

Project Lead

Rob Grohs - University of Guelph


To evaluate reduced-risk herbicides for potential to control broadleaf weeds (including Kochia, Russian Thistle, and Nightshade) in processing peas, and to provide recommendations for reduced-risk candidate herbicides to be pursued for registration in Canada

Summary of Results

Growers have expressed a need for more products for weed control in processing peas. A number of reduced-risk herbicides that may be suitable for this crop have never been evaluated for this purpose. It would therefore be desirable to identify one or more herbicides for possible minor use label expansion or that could be registered under Agriculture and Agri-Food Canada's Minor Use Pesticides.

This project evaluated the efficacy of a number of reduced-risk herbicides in controlling broadleaf weeds in processing peas (Pisum sp., var. Encore). The phytotoxicity of those herbicides was also evaluated.

Field trials were conducted in 2007 at the Simcoe Research Station of the University of Guelph, in Ontario. The experimental design was a randomized complete block design with four replications. Plots were 2.25 meters by 8 meters. The seven herbicides evaluated were applied at three rates: 0.5×, 1× and 2×. The herbicide treatments were either pre-emergence or post-emergence to the weeds. Data were collected on injury to peas and efficacy in controlling broadleaf weeds.

The data obtained show that four of the herbicides evaluated in this study are considered safe to peas. These four herbicides are: Odyssey (imazamox + imazethapyr), Chateau (flumioxazin), Outlook (dimethenamid-P) and Sandea (halosulfuron-methyl). Odyssey (imazamox + imazethapyr) and Chateau (flumioxazin) caused no crop injury and were very effective in controlling broadleaf weeds. Outlook (dimethenamid-P) did not cause any crop injury, but was not effective in controlling redroot pigweed (Amaranthus retroflexus) or lamb's quarters (Chenopodium album), while Sandea (halosulfuron-methyl) was effective in controlling redroot pigweed (Amaranthus retroflexus) only.

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