Vomitoxin can be the kiss of death for wheat and barley growers. The infection that causes it is fusarium head blight, and the U.S. and Canada are reporting more instances of the infection in the 2016 durum wheat crop than in the prior year's harvest. Wheat with vomitoxin will suffer severe quality discounts or even rejection by end users, causing farmers to lose money.
While oats, rye, corn and other grains can carry vomitoxin, you mostly hear about it occurring in wheat and barley. Wheat with vomitoxin levels above 2 parts per million (ppm) will either be discounted or rejected at grain elevators. The guideline for flour or other finished wheat products is 1 ppm. As for malt barley, the barley that makes beer, there is a 0.5 ppm tolerance for vomitoxin. It is also unacceptable in feed for hogs because it causes poor weight gain. In some cases, severely infected grain is deemed worthless.
North Dakota State University has explained what causes vomitoxin "Deoxynivalenol (DON), commonly referred to as vomitoxin, is a mycotoxin that may be produced in wheat and barley grain infected by Fusarium head blight (FHB) or scab. FHB may infect grain heads when wet weather occurs during the flowering and grain filling stages of plant development. The occurrence of FHB does not automatically mean that DON is present, but a high level of scabby kernels in the harvested grain means DON will likely be present. The concentrations of DON in grain are expressed as parts per million (ppm)."
One thing to remember is that levels of DON do not necessarily correlate with levels of physical damage in grain. Also, the mycotoxin can continue to accumulate until grain moisture levels fall below 13%, so DON levels can be very high when wheat is harvested late in the season, as we are witnessing in parts of the Northern Plains and Canada this year.
Vomitoxin in large doses can make humans and animals very sick, hence the nickname. Also, workers inhaling contaminated grain, chaff or dust can be susceptible to allergic or respiratory reactions. The typical standard used by the majority of world buyers is 2 ppm maximum. In Europe, some countries have lower limits, such as 1 ppm in the United Kingdom and 0.5 ppm in Norway, due to their own advisory levels. Japan has set a maximum DON level on imported wheat of 1.1 ppm. Here is the FDA regulatory guidance for three mycotoxins in the U.S. published by the NGFA: https://goo.gl/…
WHAT'S THE CURE?
There really isn't one. A producer can try to clean the infected grain. Cleaning will not eliminate DON, but it may reduce levels of it by removing lighter, more heavily infected kernels. However, NDSU says that "the process of milling wheat into white flour or durum semolina typically results in the reduction of DON by approximately 50%. Therefore, many grain handlers or processors purchase grain with DON levels up to 2 ppm without discounts. Manufacturers of whole-grain foods will have specifications that are more rigid."
While it's true the allowable level for wheat and durum is 2 ppm, mills and exporters are still skeptical of grain from areas where DON is present in high levels. It is extremely important to keep healthy wheat separate from high DON wheat. A miller told me that while blending high-vomitoxin-infected wheat with healthy wheat is done by elevators, not mills, the blending formula is not "linear," as say blending 13% protein wheat with 15% protein wheat in equal amounts to make 14% protein.
One ppm vomitoxin is equivalent to 1 wheat kernel in 80 pounds of wheat, and 60 pounds of wheat equals 1 bushel. The miller gave me an example that if you blend 0.5 ppm vomitoxin with 3 ppm vomitoxin, you should end up with an average of 1.6 ppm. When I was trading durum, a plant pathologist spoke at a meeting I attended, and he said that in his opinion, you would need to blend 100 kernels of heathy wheat with 1 kernel of toxic wheat to maybe have a successful blend. One of the problems with blended vomitoxin-infected wheat is that there is a risk of getting different levels when tested in a car load or bin when it is probed, as there could be pockets of various levels formed. If the grain tested at destination is above acceptable levels, the load will be rejected.
HOW WIDESPREAD IS DON IN 2016 NEW-CROP WHEAT?
U.S. Wheat Associates reported that "fusarium has been reported across the northern North Dakota and in northeast Montana durum area, and the final average DON value for durum is expected to be higher than normal in 2016." Producers who seeded late in May or early June have said their wheat is not showing signs of vomitoxin and also that the durum seems to be more affected than spring wheat. It all depends on what varieties were seeded and the timing of the planting this year.
However, Canada, who exports durum to the U.S., Morocco, Italy and Algeria, is reporting more incidents of vomitoxin in the 2016 durum crop in Saskatchewan where 80% to 85% of the country's durum is grown. In the weekly Crop Progress report from Saskatchewan on Sept. 20, all of the crop districts were reporting "downgrades in durum mostly due to fusarium." With only 57% of the durum wheat and 56% of the spring wheat harvested as of Sept. 19, it is still too early to tell exactly how much of the crop is infected.
Besides the vomitoxin, Canada's durum quality has been downgraded due to too much rain. In their Sept. 13 crop report, Saskatchewan said that, at that time, durum grades were being reported as 2% No. 1 CWAD (Canada Western Amber Durum), 17% No. 2 CWAD, 30% No. 3 CWAD and 51% No. 4 and No. 5 CWAD. While Stats Can has predicted Canada's durum crop production to be a record 6.8 million metric tons this year, others in the durum trade expect it to be closer to 8 million metric tons.
A U.S. miller told me that world durum production this year will outpace demand. But there will definitely be some challenges with the quality problems in Canada and even France who has suffered from too much rain as well. Grade discounts will be heavy and milling durum prices will likely remain firm.
Infected grain is on the radar of end users in the U.S. this year, maybe more than normal. A facility unable to blend the tainted grain cannot risk holding it on site and with new feed safety rules by the Food and Drug Administration implementing the Food Safety Modernization Act (FSMA), end users are more watchful of toxic grains coming in to their facilities. For more information about the implications of the FSMA, here is link to my April 4, 2016, blog on new feed safety rules for the handling, transportation and storage of food and animal feed: https://goo.gl/…
Mary Kennedy can be reached at Mary.Kennedy@dtn.com
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