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Herbicide Resistant Wild Oats in Manitoba

Crop Types
  • Whole Farm

Wild oats are one of the most important grassy weeds in Western Canada, causing significant yield and dockage loss. Of increasing concern is the development of herbicide-resistant (HR) wild oats with resistance to multiple modes of action, resulting in fewer herbicide options to manage this problem weed.

Based on a HR weed survey performed in 2016, among Manitoba fields where there are wild oats, 79 per cent had a HR wild oat population, a significant increase from the previous survey. Group 1 HR wild oat was identified in 78 per cent of fields, Group 2 HR wild oat was found in 43 per cent of fields, and Group 1+2 HR wild oat was found in 42 per cent of fields. In Manitoba, wild oats with resistance to multiple combinations of several other modes of action have also been identified.

The Resistant Wild Oat Action Committee (RWOAC) aims to slow the development of herbicide resistance in wild oats and increase awareness regarding this issue across Western Canada. The RWOAC has developed several infographics that cover issues surrounding HR wild oat management, as well as the following video:

Click the image to view the video

Identifying wild oats

Early in the season, it can be difficult to differentiate between wild oats and other volunteer cereals. The RWOAC has developed this infographic, which lists some helpful identifying features. The following table compares the features of wild oats with wheat, barley and tame oats.

Table 1: Identifying features of wild oats, wheat, barley and tame oats.


Scouting techniques

When scouting for HR wild oats, it is important to identify when a herbicide application has failed due to application error, versus when a herbicide has failed due to the development of resistance. The RWOAC has developed this infographic with some tips for what to look out for when scouting for possible herbicide resistance.

Suspect HR wild oats?

If you suspect the presence of HR wild oats on your farm, it can be valuable to confirm by sending samples for herbicide-resistance testing. There are several labs across the Prairies that will accept seed samples for herbicide-resistance testing. The RWOAC provides information on these labs in this infographic, as well as instructions on how to sample and package wild oats for testing in this infographic.

Prevention and management of HR wild oats

Once HR wild oats have been identified, the next challenge is managing the population. When HR wild oat populations have resistance to multiple modes of action, management can be especially difficult. Wherever possible, it is recommended that farmers incorporate integrated weed management strategies to prevent the development of HR weeds. The RWOAC has several infographics that contain important information on strategies to prevent and manage HR wild oats:

Additional resources

Manitoba Agriculture:

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Field Issues

  • Weeds