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Play it safe with pre-harvest glyphosate

Follow the label and consult grain buyers for guidelines

When it comes to pre-harvest perennial weed control, Prairie farmers need to play it safe this fall.

As of this year, grain from crops treated with glyphosate might have market access concerns, according to the Keeping it Clean program, a joint initiative of the Canola Council of Canada, Cereals Canada and Pulse Canada.

“Glyphosate residues are getting greater scrutiny around the world, mostly in Europe but I wouldn’t restrict my comments to the European Union,” says Cam Dahl, president of Cereals Canada. “I can’t comment on other crops beyond cereals, but it’s being given scrutiny above the scientific justification.”

Dahl says a crucial starting point for the discussion around glyphosate is that the product has been found to be safe by agencies around the world, including Health Canada, the United States Environmental Protection Agency and others.

“Closely followed up on that is the need to have trade that is based on sound science, and maximum residue limits that are based on scientific principals,” he says.

Different maximum residue limits (MRLs) are set by each importing country. Manitoba Agriculture and the Saskatchewan Ministry of Agriculture post information on products with potential MRL issues, but note that these might not be complete listings.

But producers can control residue levels in their crops by watching when they apply glyphosate pre-harvest.

Glyphosate guidelines

Saskatchewan’s Guide to Crop Protection offers some guidelines. As a general rule, it states, glyphosate products should be applied to crops when grain moisture is less than 30 per cent (except forages, where products should be applied three to seven days prior to the last cut before rotation or forage renovation).

In wheat, malting barley and tame milling oats, the 30 per cent moisture stage is indicated when the crop has reached the hard dough stage, or a thumbnail impression remains on the seed, notes the Guide.

In flax, 75 to 80 per cent of bolls will be brown.

In lentils, the bottom 15 per cent of pods will be brown and rattle when shaken. In peas, the majority of pods should be brown. In chickpeas, lupins, faba beans and dry beans, the stems should be green to brown in colour, and pods should be mature, although the Guide notes that those who apply glyphosate to chickpea, lupin and faba bean do so at their own risk as these uses are registered under the User Requested Minor Use Label Expansion program.

In canola, pods will appear green to yellow, with most seeds appearing yellow to brown.

In soybeans, stems will appear green to brown, with pod tissue appearing brown and dry.

As always, producers should consult specific glyphosate labels for guidelines on pre-harvest use. They should also consult grain buyers to inquire about potential contract restrictions on crops treated with glyphosate.

Our buyers

Megan Kemp, an agronomist with Zeghers Seed in Holland, Man., says importing countries have been asking for verification that glyphosate hasn’t been sprayed as a desiccant on flax and specialty crops.

“As long as producers are following harvest intervals and being cautious I don’t think we’ll have a problem,” she says. “At this point, follow proper protocol when spraying, the proper amount of days prior to harvest, read product labels and understand those.”

About the author

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Julienne Isaacs is a Winnipeg-based freelance writer and editor. Contact her at [email protected]

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Comments

  • neil

    I think it is very important farmers stick to the label guidelines and not spray preharvest glyphosate too early or we could lose the use of it gor preharvest weed control.