A U.S. National Wheat Foundation document released Sept. 8 claims that less than two percent of wheat acres in the United States are treated with glyphosate before harvest.
The foundation said the data, which is based on farmer surveys conducted by a consumer research firm, proves that American wheat growers do not “drench” or “douse” their wheat crops in glyphosate before harvest, contrary to the claims of anti-chemical activists.
Weed scientists and agronomists in Western Canada can only guess what percentage of producers apply glyphosate to wheat before harvest because no such data is available.
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“There’s nobody tracking it that we’re aware of,” said Mitchell Japp, a cereal crop specialist with Sask-atchewan Agriculture.
Other herbicide specialists offered the same answer: the agric-chemical companies might have the information, but it is not routinely shared.
“That information would be available, it’s just not publicly available,” said Eric Johnson, a University of Saskatchewan weed scientist. “We really never had good statistics on that sort of thing…. Any information I’ve required I had to get (from) industry.”
Most experts were surprised by the U.S. data but said it might be because of the prevalence of winter wheat south of the border.
“The longer frost-free period in the U.S. and the fact that a high percentage (70 to 80 percent) of the wheat in the U.S. is winter wheat means that there is a much longer time frame for weed management post-harvest and time for dry-down of green plant material,” Johnson said.
“(In Western Canada), applying glyphosate pre-harvest is optimum timing for controlling perennial weeds like Canada thistle, quack grass…. At this stage, perennials are moving their carbohydrate reserves from above ground to below ground, which also facilitates the translocation of glyphosate to the roots.”
The wheat foundation said in a July blog post that U.S. wheat growers do not apply glyphosate before harvest as a matter of routine. It’s only done in extreme situations to “enable a harvest that would otherwise not be possible.”
Canadian farmers may apply glyphosate before harvest more frequently and for different reasons, but data is not readily available.
