By Connor Lynch
GUELPH — Corn going into the ground invariably conjures images of it coming out, which might bring back bad memories of last year’s DON-infested harvest.
The infestation of the toxin (a byproduct of the gibberala ear rot mould) was and is costly for farmers, whether that meant expensive investment in grain cleaners or simply crop they couldn’t sell, or sold at a discount.
There are no silver bullets for dealing with DON. But there are things farmers can do, said OMAFRA field crop pathologist Albert Tenuta.
OMAFRA’s field crop survey, released earlier this year, garnered some insights for farmers.
For one, DON — or vomitoxin, as it’s sometimes called — is far from a new problem in Ontario. Last year was Ontario’s worst year since 2011 for severe infestation that saw corn with more than 5 parts per million of DON), but more moderate infestations that can still be costly for farmers weren’t unique. In both 2016 and 2011, Ontario corn was carrying between 0.5 ppm and 5 ppm at similar rates to last year.
But the problem does seem to have gotten worse in the last decade or so, said Tenuta, and last year was, if not a perfect storm, pretty close to it. “Environmental conditions were extremely favourable for (DON) development,” he said, but another factor played a role: Hybrid selection. Testing by OMAFRA found that hybrid selection, and variability, both played significant roles in DON infestation. Farmers obviously can’t do anything about the weather but selecting resistant hybrids is in their control. Varying those hybrids is important as well; if all your corn is silking at the same time, it’s vulnerable to DON infection at the same time, Tenuta said. That makes it that much easier for an infection to spread to other plants.
Tenuta also suggested that come harvest, as far away as it might seem, get your most vulnerable (or infected) corn off earlier. Then, dry it down. The mould stops growing once the corn is below 15 per cent moisture.
