An annual survey conducted by the province has confirmed higher-than-normal levels of vomitoxin in this year’s Ontario corn crop.
Released Wednesday, the results of the Ontario corn ear mould and mycotoxin survey showed almost one-quarter (23%) of the 192 samples collected tested at 2 parts per million or greater for deoxynivalenol (DON) - well above just 3% last year. On the other end of the spectrum, a relatively modest 77% of the samples tested at 2 ppm or below, compared to the 10-year average of 88%.
The 2 ppm level is generally considered the maximum threshold at which DON levels are not a significant quality or marketing concern. The larger percentage of this year’s crop above that level suggests producers could run into grade discounts or outright rejections at the elevator, depending on the local severity of the problem. The survey revealed 5% of the samples were at 5 ppm or above for DON, versus just 1% last year.
As the map below shows, the worst of the DON levels were found in the southwestern portion of the province, especially in Essex and Elgin counties.
But while producers will need to be cognizant of what is coming out of their fields this year, the DON problem is not nearly as bad as in 2018. In that year, just one-third of the samples tested below 0.5 ppm, while 25% were at 5 ppm or above. A significant portion of the 2018 crop turned out to be virtually unmarketable, costing producers millions of dollars in lost sales.
Farmers experienced another difficult year for DON in 2016, when less than half of the samples tested at 0.5 ppm or below.
This year’s elevated DON levels are not a major surprise, given the wetter growing season the province experienced, especially during the month of July.
The province warned the survey does not capture all regions of the province and results can vary from field to field depending on a variety of factors, including local weather, hybrid, planting date, insect feeding, rotation, residue levels, fungicide practices and moisture.
Farmers are encouraged to monitor their fields for DON and harvest any fields with elevated levels quickly, given that contamination rises as the crop is left out. In high risk or severely infected fields, growers should consider harvesting at higher moisture and drying below 15%.
