Corn School: Developing a better DON test

Testing for DON in Ontario’s 2018 corn crop was an incredibly frustrating process for growers.

With gibberella ear rot infecting a wide swath of corn in the province, many growers were exasperated when samples from the same load of corn taken from a field would show wide variation in DON levels — sometimes from 3 ppm to 12ppm, or more.

“It was very clear that more work needed to be done to find a way to reduce variability in DON testing,” says University of Guelph researcher Dave Hooker. On this episode of RealAgriculture’s Corn School, Hooker and Ontario Ministry of Agriculture, Food and Rural Affairs pathologist Albert Tenuta discuss plans to field test a new and improved DON testing protocol this fall.

The protocol is based on extensive sampling efforts last fall led by another University of Guelph professor, Art Schaafsma, to identify the leading sources causing the DON testing variability. This research identified a host of contributing factors ranging from subsampling from the 2 kg of grain collected by probes before grinding, the grinding amount (50 grams), extraction amount, test kit used, and the test kit operator. (Story continues after the video.)

As Hooker and Tenuta explain, Schaafsma’s research indicates that grinding the complete 2 kg sample would create a more uniform sample; a smaller sub sample could be then finely ground and tested for DON. Using this method, Hooker says the results are “greatly improved and actually represent the DON levels in the field.”

Tenuta notes the next step is to run a pilot project with elevators and industry stakeholders this fall to “validate the new protocol, improve accuracy and decrease that variability in the weigh scale and in the test house.”

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