Karnal Bunt

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Karnal bunt (KB) is a minor disease of wheat that is caused by the fungus Tilletia indica. Infected wheat kernels contain masses of black fungal spores. Although yield losses are usually very low, flour milled from infected grain may have an unpleasant fishy odor.

Unlike many other bunt or smut diseases of cereal crops, KB cannot be easily controlled. Conventional methods such as seed treatment fungicides and certified seed are not effective once the fungus is established in a field. No commercial varieties of common wheat in the US are thought to have adequate resistance to KB. Durum (pasta) wheat is somewhat resistant.

T. indica is native to India and Pakistan and is not found in most other countries. It was reported in northwestern Mexico in 1972, presumably after introduction in infected seed. It was first reported in the USA in 1996 in a few counties in Arizona and adjacent parts of California. In 1997, it was found in two counties in central Texas. In 2001, it was found in four counties in north central Texas.

More than 70 countries, including the US, have quarantine restrictions on imports of grain with KB. Many have a zero tolerance standard for spores of T. indica. Efforts to convince our trading partners to relax the international quarantines on KB have not yet been fruitful.

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