Researcher weighs risks of glyphosate for malt barley dry-down

It’s fine to hit malting barley with glyphosate, at least theoretically.

But the challenge of doing it in the field in true farming conditions was highlighted by long-time barley researcher John O’Donovan at the Canadian Barley Symposium.

“If the farmer does everything right — correct stage, uniform dry-down is achieved — the residue levels will likely not exceed the allowable threshold,” said O’Donovan, the Agriculture Canada researcher who opened the symposium June 26.

“Assuming that the grower does everything right … the greatest risk may lie in non-uniform drydown.”

Using pre-harvest glyphosate on malting barley is a big no-no if the farmer plans to try to sell the crop to a maltster or to anybody else who plans to use it to make malt.

Maltsters and brewers fear glyphosate residue will damage the germination of barley kernels.

“There is not a maltster or brewer in Western Canada that will accept barley that has been treated with pre-harvest glyphosate.”

O’Donovan said Canadian Grain Commission and other research has shown that it is possible, at least in small-plot research conditions, to apply pre-harvest glyphosate to malting barley and neither exceed maximum residue levels nor damage germination of malting barley.

However, in real farming conditions, that could be hard to achieve because not all parts of a crop can be assumed to have the exact same level of maturity and might not dry down perfectly.

That leaves the possibility of residue and germination problems, even if rates and crops stage have been correct, O’Donovan said.

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