DON outbreak impacting pockets of U.S. and Canadian wheat

Wheat_HeadScab_blog1The harvesting of winter wheat in the United States and Canada has brought reports of wheat contaminated with deoxynivalenol (a.k.a., DON and vomitoxin) far in excess of the maximum allowable amounts for use in human food and animal feed.

“Our highest that we’ve seen is 30 parts per million. Typically, the market likes to see it at two or less, and they [the USDA] will not accept it over 10,” said grain broker Kayla Burkhart, as reported by KFYR-TV in North Dakota. “Grains into the high teens and above that, it’s going to be really hard to find a home for.” 

DON is a by-product of a fungus, Fusarium graminearum, that causes head blight (a.k.a., head scab) infection in wheat and other grain crops.

“This is the worst I’ve ever seen it,” says Dave Wiechert, of Nashville, Ill., owner of Wiechert Seed Inc, as reported in AgWeek. The business is 50 miles southeast of St. Louis, Mo., near the epicenter of another DON outbreak. “We’re trying to get the vomitoxin down to a sellable level and trying to get the test weights up.”

Pigs have been shown to be highly sensitive to DON, and will refuse to eat feed when levels are above 1 part per million (ppm). DON also causes toxic effects in other species, with varying degrees of sensitivity. The toxin has been implicated as causing problems in processed human food, including off flavor in ready-to-eat cereals and adverse effects on dough quality.

Purdue University’s Extension Service explains how infection occurs: “As little as two or three days of light to moderate rainfall can favor infection. Optimum temperatures for infection are between 75°F and 85°F, but during prolonged periods of high humidity and moisture, infection will occur at lower temperatures. The initial infection on the wheat head may produce additional spores that can infect other wheat heads. This secondary infection can be especially problematic in uneven wheat stands with late flowering tillers. Infection will continue as long as weather conditions are favorable and wheat plants are at susceptible growth stages.”

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