Pulse School: Clipping wild oat panicles for weed seed control

Harvest weed seed control is one option when it comes to managing some of our resistant weeds across the prairies. However, when it comes to wild oats, they shed their weed seeds before harvest time comes around.

Breanne Tidemann, research scientist with Agriculture and Agri-Food Canada (AAFC), has published a paper on some of the exciting research that she has conducted surrounding clipping wild oats in your pulse crops earlier in the season.

“It came from the idea that when you drive across the prairies in July and August, you can always see when there are wild oats in the field. They are a weed that doesn’t hide well,” Tidemann explains in this Pulse School episode. “So the idea was since we can see them, that means they are above the crop. Maybe we can cut those off.”

This is especially of interest to organic farmers, and areas that face group 1 resistance to wild oats. One of the main questions that often comes up for producers is ‘when is that seed viable?’

“If the seed is not viable, and you cut it off before that seed can produce a new plant, fantastic. You just did seed control on the wild oat. But if the seed is already viable when you cut it off, and that seed head falls to the ground, all you did is put more seeds on the ground,” she explains.

To answer this question, the research team looked at when the wild oat panicles would rise above a lentil crop, since it is a short stature crop. Once the panicles were fully extended, they would clip them off. They started clipping when they were first above the crop, and would do it on a weekly basis to see the different results.

“What we did find, and it was a little surprise to me, from the first week that we started clipping in lentils, we had up to 10 per cent viability. And within a couple weeks after that — about five to six weeks after that — we were up to 95 per cent viability of our wild oats,” Tidemann explains. “So that viability increases really really quickly in those seeds, which means if you are looking at clipping as a management strategy, you have to be out there very soon after those panicles are visible.”

Obviously, it isn’t realistic for producers out in their fields to go out and clip every single panicle by hand. It simply isn’t an efficient use of time. However, there are ways this can be implemented into your farm management strategy.

There are commercialized pieces of equipment that could do this, and as Tidemann says, especially on a crop like lentils that don’t grow far off the ground. The equipment options are essentially mower blades, that you lift up above the crop, and take it across to mow those wild oats across.

Tidemann is still working on seeing what the impact is on the wild oat population the following year, but she sees this as something that could be a very important tool with where we are at with herbicide resistance.

“It’s something else that can be tried. There’s a lot more focus in the weed science community right now on managing the weed seed bank,” she explains. “It makes sense that instead of targeting the weeds that are already in the seed bank, you target what is going to go into them, which is where harvest weed seed control comes in. This is sort of the next step of how we can target that.”

Check out the full conversation with Breanne Tidemann and RealAgriculture’s Kara Oosterhuis, below:

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