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New Mexico State University

New Mexico State University

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Extension Establishes Karnal Bunt Detection Lab

LAS CRUCES -- New Mexico State University's Cooperative Extension Service is opening a karnal bunt detection laboratory to test wheat from quarantined counties and check wheat samples statewide, said Natalie Goldberg, Extension plant pathologist.


"The lab will test pre-harvest wheat samples from the four quarantined counties: Dona Ana, Luna, Sierra and Hidalgo," Goldberg said. The mandatory plowdown of New Mexico wheat fields planted with infected seed is almost complete.

All wheat fields in the quarantined counties that were not planted with infected seed will be tested. "We're anticipating approximately 150 samples from the quarantined counties," Goldberg said.

Wheat samples from non-quarantined counties in the state also will be tested as part of a national karnal bunt survey that will continue for at least five years. In these counties, post-harvest samples will be collected from elevators or storage bins, Goldberg said. "The U.S. is trying to assure its international wheat importers that the karnal bunt fungus is limited geographically to a small portion of the Southwest. This will be accomplished by randomly sampling grain in each state," she added.

In Curry, Quay and Roosevelt counties, 92 wheat samples from 1995 seed lots were collected and tested by the New Mexico Department of Agriculture. "No karnal bunt was detected in any of these samples," Goldberg said. "That's a pretty good indication that we don't have a disease problem on the eastern side of the state."

The karnal bunt detection laboratory, housed at NMSU's College of Agricultural, Consumer and Environmental Sciences , will open in late May and operate 12 hours a day, from 7 a.m. to 7 p.m. The laboratory is hiring student workers to help with the testing and Emroy Shannon, a retired Extension plant pathologist, also will assist.

Growers in the quarantined counties are advised to contact the U.S. Department of Agriculture (USDA) or the New Mexico Department of Agriculture one week prior to their scheduled harvest date and someone will be sent to collect samples from their fields. The laboratory will strive to provide test results within 24 hours.

Seed contaminated with the karnal bunt fungus was planted in four counties in southern New Mexico. The fungus affects wheat quality, giving the kernels a fishy odor and unpleasant taste.

Growers who planted infected seed are required to disc their fields at least twice to destroy the crop and are being compensated by the USDA. Twenty- two of 24 growers affected have finished plowing down their wheat, Goldberg said. So far, 81 fields in the quarantined counties have been approved for payment by the USDA and nine growers have received checks, she said.

With the contaminated wheat destroyed, the possibility of the disease spreading to other fields is unlikely, Goldberg said. "The healthy wheat is heading now, making it susceptible. But the weather is too dry and too warm to sustain the infection." Once farmers stop irrigating their wheat fields, contamination will be even more unlikely, she added.