Handling Scabby and DON-Affected Wheat Grain
June 20, 2008
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This article outlines strategies for dealing with grain from fields with Fusarium head blight or scab.
Harvesting. Increasing the fan speed on the harvest combine can remove some of the heavily infected grain, which usually is lighter than healthy grain.
Keeping scabby grain separate. Consider keeping grain from heavily affected fields separate. Incidence and severity of scab varies from field to field depending on the variety planted and local environmental conditions.
Testing for DON. Scabby grain is likely to contain the toxins deoxynivalenol (DON) and, to a lesser extent, zearalenone. However, presence of scabby grain does not necessarily indicate high levels of these toxins and vice versa. Consider testing grain from affected fields for DON and zearalenone concentration. The sample submitted for toxin testing should be representative of the entire truckload or bin of grain.
Cleaning. If the proportion of scabby grain is high, consider using seed cleaning equipment to remove or reduce scabby kernels. Cleaning does not necessarily reduce DON levels as apparently healthy grain can have elevated concentrations of this toxin.
Staying safe. When handling grain, wear appropriate personal protective gear such as masks to prevent inhaling mold spores and grain dust which can cause allergy and breathing problems.
Storing contaminated grain. Scabby grain should be stored at or below 12% moisture content. This will reduce the potential for deterioration during storage. Aerate the grain to cool it soon after storage and continue cooling periodically as outdoor temperatures decline until the grain is at approximately 25°F. Fungal growth and DON production stop after grain dries to a moisture content of 22%. Therefore, DON production will not occur under the recommended storage conditions.
Marketing. If possible, DON-affected grain should be kept separate from healthy grain. The marketing strategy for this grain will be influenced by many factors, including DON level, cleaning and/or blending costs, and contract obligations with elevators. In general, elevator discounts are highest at harvest and increase with the concentration of DON above 2 ppm. Therefore, weigh the pros and cons, including the economics, of deferring DON-affected contracted wheat in the hope that discounts will reduce with time. Deferring delivery also gives time to clean and/or blend the wheat to improve quality.
Feeding. Scabby or DON-affected grain can be used as livestock feed. For recommendations on using feed contaminated with DON or zearalenone, consult the UNL Extension publication Fusarium Head Blight of Wheat (EC1896).
- Using scabby grain as seed. To prevent or reduce seedling blights, scabby grain should be thoroughly cleaned and treated with fungicide before being used as seed for next season's crop.
Extension Plant Pathologist
Diagnostic Toxicologist/Analytical Chemist