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APHIS Amends Karnal Bunt (Tilletia indica) Regulated Areas in La Paz, Maricopa, and Pinal Counties in Arizona

August 17, 2022 

To:   State and Territory Agricultural Regulatory Officials

Effective immediately, the Animal and Plant Health Inspection Service (APHIS) is amending the Karnal bunt regulated areas in La Paz, Maricopa, and Pinal Counties in Arizona.

 APHIS is removing seven fields (199 acres) from the list of regulated areas. One field has been regulated for twenty-one years, four fields for twenty-three years, and two fields for twenty-four years. Thirty-seven (37) acres in La Paz County are on the Colorado River Indian Reservation of the Colorado River Indian Tribes; 32 acres are non-tribal land in Maricopa County; and 130 acres in Pinal County are on the Gila River Indian Reservation of the Gila River Indian Community.

 In 1999, APHIS regulated four fields in Pinal County, not because they were positive for Karnal bunt, but because they were planted with non-fungicide treated wheat seed. On February 5, 2003, APHIS published a final rule removing the requirement that host seed be fungicide-treated before planting. Therefore, APHIS is removing these four fields from regulation because the fields never tested positive for Karnal bunt and seed treatment is no longer a requirement in 7 C.F.R. § 301.89.

 A recent APHIS analysis concluded that the likelihood of any teliospores of T. indica remaining viable in three additional fields (one each in La Paz, Maricopa, and Pinal counties) is negligible because: they had a low initial population of T. indica when first regulated, a sustained host-free period (more than twenty years) after their first planting, and a record of both tillage and irrigation that enhances population reduction through suicidal germination of teliospores in the soil. Accordingly, APHIS is deregulating these seven fields (199 acres). However, other portions of La Paz, Maricopa, and Pinal Counties remain regulated.

 APHIS regulates Karnal bunt because many trading partners require that U.S. wheat be certified as grown in areas free of this plant disease. APHIS will follow this emergency action by publishing a notice in the Federal Register.

 More information on Karnal bunt is available at the following website: 

For additional information about the Karnal bunt program, please call National Policy Manager, Lynn Evans-Goldner, at (301) 851-2286.


Dr. Mark L Davidson
Deputy Administrator
Plant Protection and Quarantine

Attachment: Federal Order

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