Wheat School: Is that second herbicide application necessary?

(courtesy Breanne Tidemann)

Herbicide resistance is not new in Canadian agriculture, but managing it is becoming a higher priority as the scope of herbicide resistant weeds grows.

In Western Canada, number one on the ‘economically important’ list is resistant wild oats, notes Bob Blackshaw, weed scientist with Agriculture and Agri-Food Canada, in this Wheat School episode.

“It’s the one that causes the biggest yield losses in our crops, and its the one that farmers probably pay attention to the most and spray the most herbicide on, and because of that it it’s our number one weed in terms of resistance problems” says Blackshaw.

He reminds us there are trade-offs when it comes to managing weeds while managing against resistance, as we sometime’s  ‘jump the gun’ when it comes to a second application of herbicide.

“If you have a really good crop stand, that crop canopy will close in, and shade out that second flush and those yield losses will be minimal. And so you may not be spending a lot of money on that second application, but you know, each time you apply Roundup, you are increasing the selection pressure. So that’s a tradeoff, a balance that you have to decide on yourself and on your own farm.”

Check out our latest Wheat School episode with Bob Blackshaw, filmed at Farming Smarter’s Plot Hop in Lethbridge, Alberta:

Find more Wheat School videos and podcasts here.



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