Page Banner

United States Department of Agriculture

Agricultural Research Service

FHB Epidemic in wheat and barley - overview
headline bar

The scab epidemic in wheat and barley

A scab (Fusarium Head Blight) epidemic has ravaged the Red River Valley of northwest Minnesota since 1993. Unusually wet weather and high temperatures caused the outbreak in which farmers have lost an estimated $2 billion. Scab damages wheat and barley crops, reducing yields, damaging quality and sometimes producing vomitoxin, a substance harmful to animals and humans.

 

Why is scab a problem?

When infected with scab wheat and barley don't produce as much grain as healthy plants. The grain produced is of poor quality, so it brings a lower price if it can be sold at all. Millers will not buy scabby wheat for flour. Brewers will not make beer from scabby barley. Farmers who have some scab in their grain may sell it for reduced prices for use in animal feed, but even that market is not available when the grain has too much scab. In the worst infected areas, the only choice is to destroy the grain field without harvesting it. Continued crop failures from scab have driven many Minnesota wheat and barley farmers into bankruptcy. Other agriculture-related industries have suffered with fewer customers and loss of income.

What causes it?

Scab is caused by the Fusarium fungus, which grows especially well on dead straw or corn stalks left on the ground after harvest. During wet weather, Fusarium produces masses of spores that spread through the air or splash onto grain heads in rain storms. Scab is usually worse following long periods of high moisture. It is also worse when wheat or barley is grown near corn fields or in fields where corn was grown the previous year.

Am I in danger?

The vomitoxin that scab sometimes produces can make animals and humans sick if they eat too much of it. However, the possibility of a person ingesting it is very low. Grain sold for use as animal feed must meet strict federal standards, even though little vomitoxin is transferred into the meat or milk of animals that eat contaminated grain. Federal regulations also pose strict limits on the amount of vomitoxin allowed in grain purchased for human food. Milling and baking further reduce vomitoxin levels. Brewing companies will not purchase grain with even a trace of a vomitoxin. In the unlikely event that vomitoxin ends up in the food supply despite all the industry safeguards, a person will have to eat enormous quantities of the product for the toxin to have any effect.

The Cereal Disease Lab is investigating ways to control and prevent scab.

Last Modified: 10/28/2005