Weather woes could lead to market headaches, says agronomist

Grain buyers are testing like never before, so glyphosate timing is especially critical this year

Before applying glyphosate, see if the peduncle has yellowed or browned and, if so, give the kernel the thumbnail test. If the kernel squishes between your fingers, it’s too early to apply glyphosate, says agronomist Jeremy Boychyn.
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Alberta farmers have seen some occasionally dry, mostly wet, often cold, but sometimes sunny conditions this summer — and the all-over-the-place weather has wreaked havoc in cereal fields across the province.

“When you have cool weather on top of really moist conditions, you’ll get plants slowing down that much more,” said Jeremy Boychyn, agronomy research extension specialist for Alberta Wheat and Barley.

“So then you get a delayed crop that’s variable, and that poses a lot of problems as we head into the latter part of the season.”

Harvest is ticking along in southern Alberta, but a dry start to the season, coupled with late rain in July, has created some variability in fields in the southern part of the province. And while the central region generally looks pretty good, fields around Edmonton got hit with more moisture than they needed, creating variability there as well. But cool, wet conditions in northern Alberta have delayed the crops by six to 10 days (and in some cases, even longer), putting pressure on harvest timing.

“The south is moving along with harvest pretty quickly, but the northwest is still waiting for things to arrive,” Boychyn said in an Aug. 26 interview.

“It becomes a race to get that crop off before environmental conditions can cause more impact to yield and quality.”

And at this point, farmers are also in a race against time with their pre-harvest glyphosate application, he added. “Glyphosate poses more of a risk when we have those variable crops. We have to try and time it correctly.”

If you don’t get the timing just right, you could find yourself over the maximum residue limit, risking your market access — and making it harder for other farmers to market their grain as well.

“What happens then is we either potentially lose this very important tool or — even worse — we potentially lose international markets,” he said.

Canada’s trading partners have been keeping a closer eye on Canadian grain shipments in recent years, turning away shipments for low-level pest-control residues, weed seeds, and diseases. That scrutiny has only increased in the past year, as non-tariff trade barriers have cropped up in key trading partners like China, Italy, India, Vietnam, Saudi Arabia, and Peru.

“We want to make sure we’re keeping our end-users happy,” said Boychyn.

Timing it right

But figuring out the right timing can be tricky in fields where the plants are at different growth stages. So the first thing you should check is whether it’s even necessary to spray in the first place.

“Glyphosate is a pre-harvest weed control tool. It’s not to help with evening out the crop,” said Boychyn.

“So the question should be, ‘Am I seeing weeds in my field that need to be controlled?’ If yes, then you need to make sure that your timing is correct on the main crop.”

If you’re going by the label (and you should be, he said), glyphosate should be applied only once the least advanced part of the field reaches 30 per cent moisture, and it can be hard to spot that in a variable crop.

“Making sure that the latest part of your crop is at that 30 per cent or less moisture level is critical, so the first thing you’re going to look for is where your most advanced and your least advanced areas are,” said Boychyn, adding farmers should keep an eye out for late tillers and any low or high areas in the field.

Next, look for any colour change at the peduncle, or the area between the stem and the head of the plant. Once the peduncle has yellowed or browned, hand-thresh a few of the heads and give them the thumbnail test. If the kernel squishes between your fingers, it’s too early to apply glyphosate. If the indent left by your nail pushes back out, it’s still too early. But if the seed holds solid and the indent remains, you’ve found the sweet spot, and it’s time to spray.

“Most producers are doing their best to wait for the ideal timing, but early application of glyphosate means that what you apply on that crop will be taken up by the plant and shuttled up into the grain,” said Boychyn. “So if you don’t wait, then we have potential issues with residue in the kernels.”

Once you’ve sprayed, though, you’ll also need to pay attention to your pre-harvest interval. For glyphosate, that interval is typically seven days after spraying. For other pre-harvest products, it ranges between one to 60 days, so it’s important to read the label, Boychyn added.

“If you harvest too soon (after spraying), that glyphosate is still on the crop, and it’s going to show up in your grain,” he said.

So farmers who can wait for the right timing should do so, “though as we get further into the season, that becomes less and less of an option,” said Boychyn. Another option is to manage the delayed parts of the field differently from the rest, avoiding them with the sprayer or the swather if possible.

The Keep It Clean website can also help farmers make those decisions, he added.

“The website has a bunch of tools to make sure that your application timing is aligned with your harvest timing to reduce any potential residue issues.”

But ultimately, timing a pre-harvest glyphosate application will depend on the farm, said Boychyn. In some cases, farmers will need to weigh how much yield they could gain by waiting or managing their fields differently against the risk of bad weather rolling in.

“It’s going to be different for almost every producer,” he said. “It was a challenging spring, and each farm has had its own conditions. It’s not one size fits all.

“There are going to be some challenging decisions ahead on when to time some of this harvest management.”

About the author


Jennifer Blair

Jennifer Blair is a Red Deer-based reporter with a post-secondary education in professional writing and nearly 10 years of experience in corporate communications, policy development, and journalism. She's spent half of her career telling stories about an industry she loves for an audience she admires--the farmers who work every day to build a better agriculture industry in Alberta.



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