NDSU Extension - Mercer County

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High Levels of DON Being Reported in Small Grains

DON, vomitoxin, small grains

Submitted by Craig Askim, Extension Agent, Agriculture and Natural Resources

High deoxynivalenol (DON) levels have been reported in the harvested crop.

DON, also referred to as vomitoxin, is a mycotoxin that can be produced by Fusarium graminearum and is found in kernels and on other parts of the wheat spike. DON levels as high as 30 ppm and 5 ppm have been reported this year in winter wheat and barley, respectively. Furthermore, some elevators are no longer taking winter wheat over certain DON levels. Contributing to this problem is the lack of market for high DON level wheat and the inability to move the crop out of the state using the railroad.

Winter Wheat

Numerous limiting factors were experienced by the winter wheat crop this year. The below average winter temperatures and lack of snowfall had a considerable impact on the crop’s survival. This resulted in a significant portion of acres being taken out of production and fields that were left had stand variability. Most of the winter wheat crop was flowering during the last week of June into early July. During this time frame, the risk of scab development was high for a majority of the state. However, growers found it difficult to apply properly timed fungicides due to uneven flowering and wet conditions. Scab development in winter wheat was exacerbated by the lack of genetic resistance in currently available varieties. The vast majority of the winter wheat acres were planted to varieties that, when compared to spring wheat, would be rated as having little or no resistance.

Barley

Barley producers are noticing considerable levels of DON in their crop. Malting barley markets are more stringent and DON levels above 1 ppm do not meet quality guidelines.

Strategies for handling grain with DON

At this point, there are no management tools to prevent the small grain crop from having DON. However, there are a few options on how to handle the grain.

Cleaning – Cleaning the seed will reduce the number of scabby kernels in the seed lot. This can be accomplished using an airflow system or a gravity table. If you harvest a field with a relatively high scab incidence, consider turning up the fan speed to eliminate the incidence of scabby kernels in the hopper.

Store the grain – Discounts for grains is generally strictest at the beginning of harvest. Holding onto the grain will allow time for the markets to stabilize and open avenues into alternative markets. When storing the grain, make sure to have adequate aeration and store at levels lower than 22% moisture. Even though research has shown that Fusarium growth and DON accumulation stop at levels below 22% moisture, make sure that you are moving air through the grain until it reaches safe storage moisture (13% for longer term storage).

As a point of reference, here are the Food and Drug Administration advisory levels for DON in feed and food products: 1 ppm for finished grain products for human consumption; 10 ppm for cattle over 4 months, provided the grain doesn’t exceed 50% of the diet; 10 ppm for poultry, provided the grain doesn’t exceed 50% of the diet; 5 ppm for swine, provided the grain doesn’t exceed 20% of the ration; and 5 ppm for all other animals, provided the grain doesn’t exceed 40% of the diet

For more information on handling wheat with DON, go to: www.ag.ndsu.edu/pubs/plantsci/pests/pp1302.pdf

Source: Andrew Friskop, Extension Plant Pathology, Cereal Crops; Joel Ransom, Extension Agronomist for Cereal Crops; Venkat Chapara, Minot Area Extension Specialist/Crop Protection NCREC; Shana Pederson, Area Extension Specialist/Cropping System.

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