During an on-going testing and monitoring program, USDA recently found wheat fields in Texas, California, and Arizona that tested positive for Karnal bunt. There are positive properties in Texas in Throckmorton and Young Counties, which are outside of the areas previously regulated for Karnal bunt. Other positive finds in Texas and in Arizona and California were restricted to fields in areas already quarantined for the fungus.

“USDA is taking aggressive actions to contain and prevent the spread of Karnal bunt,” said Bill Hawks, undersecretary of agriculture for marketing and regulatory programs. “USDA will continue to work cooperatively with local, state, and industry officials to safeguard the vital U.S. grain infrastructure.”

USDA has sampled potentially affected wheat fields and storage facilities, imposed necessary regulatory measures to prevent the spread of the fungus, identified custom harvesters operating in the area, and notified states where they may be headed.

As soon as the Texas fields were confirmed positive for Karnal bunt, USDA immediately halted grain movement, began trace-back surveys, and tested surrounding fields.

To date, USDA has found very low levels of Karnal bunt in the newly regulated areas, with only a few bunted kernels in the 4﷓pound samples that tested positive. Approximately 90 percent of the fields tested in the newly regulated area have shown no signs of Karnal bunt.

Karnal bunt is caused by the smut fungus Tilletia indica and is spread by spores, primarily through the movement of infected or contaminated seed. While the fungus does not threaten human health, flour made from heavily infected wheat has an unpleasant odor and taste, jeopardizing its marketability; the disease also reduces crop yields.

Karnal bunt was first detected in Arizona in 1996. Later that same year, USDA established a quarantine in Arizona, Texas, New Mexico, and California.