Early testing results suggest high levels of DON in the Ontario corn crop


Farmers across Ontario are facing concerns over the level of toxins that could be in this year’s corn crop, due to wet conditions in-season and through this fall.

Many farmers have not-so-good memories about 2016 and 2018 and the levels of deoxynivalenol (DON) that was present in the corn crop. Early testing results at the elevator are showing a correlation between 2016 and this year.

Peter Johnson, RealAgriculture’s resident agronomist, says some fields are testing over five ppm of DON, but that the majority of fields right now are testing below the 2 ppm threshold.

Reports from early harvested corn indicate DON levels may be even higher in some fields than initially thought. According to Johnson, one farmer shared via text that they had a field testing over seven ppm of DON — despite it being sprayed.

“You just go wow, that is going to be a challenge to deal with,” says Johnson, while reminding farmers that although we often look for visual mould on the cob, visual symptoms don’t always correlate with DON levels.

So, what next? Higher DON levels that develop in the crop will cost far more than what most will pay for on-farm or commercial drying, Johnson says. What’s more, DON levels continue to increase the longer the crop is left in the field.

“It’s usually better to get the crop out of the field as soon as possible, rather than trying to save on drying and risking much larger losses,” he explains.


Three options for high DON corn

Corn School: Developing a better DON test

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