Karnal bunt is a fungal disease of wheat caused by Tilletia indica. Named after a city in India where it was first described, karnal bunt is among a group of diseases broadly known as smuts. All the smut diseases involve the development of fungal spores within the seed heads of plants, usually small grains. The fungus reduces yields and destroys the quality of wheat grain. Some smut diseases also are known as bunts. Common bunt already occurs in the U.S., but is well controlled by seed treatments and certified seed.

Karnal bunt is native to Asia and has been present in Mexico since 1971. It was not found in the U.S. until March, 1996. Although it is a quarantined pathogen by the USDA, some contaminated seed lots apparently were used to plant fields in Arizona, New Mexico, California, and Texas. The USDA and/or state Departments of Agriculture have quarantined wheat from Arizona and part of the other three states. Efforts are underway to identify contaminated fields in other areas of the country. There have been ongoing surveys for this disease in the U.S. for several years, so there is a good chance that the fungus will be detected if it is present elsewhere. Surveys in Kansas have not detected the fungus or the disease.

This fungus can infect all types of wheat and some types of triticale, but not other crops. The contaminated seed lots in Arizona are durum wheat, and some hard red wheat stored in California also tested positive.

There is a good chance that this infestation will be contained and not affect wheat grown in Iowa. Nevertheless, the presence of this fungus in the U.S. may have an impact on the export of wheat from anywhere in the country. Many of our trading partners have agreed to keep accepting U.S. wheat, but others have not, so there will be at least a temporary disruption of wheat exports.

This situation is changing rapidly. The most current information is on the World Wide Web at the USDA-APHIS Karnal Bunt site.