Karnal bunt

Karnal bunt (also known as partial bunt) is a fungal disease of wheat, durum wheat, and triticale. The smut fungus Tilletia indica invades the kernels and obtains its nutrition from the endosperm, leaving behind waste products with a disagreeable odor that makes bunted kernels too unpalatable for use in flour.

Origin and Spread

Karnal bunt was named after Karnal, the district in the Indian state of Haryana where it was first reported in 1931. It was soon discovered in other nearby wheat-producing regions, including Iraq, Nepal, Pakistan, and Afghanistan. It was introduced to Mexico in the 1960s, and it was first discovered in the United States in 1996 in Arizona. Since then, it has also been found in California, New Mexico, and Texas. Quarantines, some of them controversial, were imposed there. A few of them have since been lifted, but the USDA continues to monitor the disease in the United States.

Disease Cycle

The disease is primarily spread through contaminated seed or farm equipment, although it may also be carried short distances by the wind. The fungal spores can then remain viable for several years, germinating when weather conditions become favorable for development. Once the spores germinate, they infest the wheat flowers and develop large masses of spores on the embryo end of the kernels (the entire kernel is not usually...
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