Georgia Wheat Growers Survive Karnal Bunt Scare

By for CAES News

When the U.S. Department of Agriculture announced it's not quarantining the Southeastern wheat crop, growers and millers let out a sigh of relief.

"We saw a lot of people sweating out a very difficult decision," said Dewey Lee, an agronomist with the University of Georgia Extension Service.

A quarantine could have killed the wheat industry in Georgia, Lee said. The dollar loss to farmers alone could have topped $75 million. Throughout the industry, losses could have soared as high as $150 million.

Last December, USDA scientists began examining Georgia-grown wheat kernels and ryegrass seeds thought to be infected with the Karnal bunt fungus.

Since the fungus was found in wheat seed in Arizona in March 1996, USDA has made concerted efforts to contain its spread. While Karnal bunt doesn't cause severe crop losses, the disease is significant with export markets. U.S. wheat exports in 1995 were valued at $5.5 billion.

Lee said he and other UGA scientists suspected the fungus spores found in the wheat weren't the type that normally infects wheat plants.

That turned out to be the case.

What USDA found were spores that infect ryegrass but have no effect on wheat. Making that decision was tough, said Barry Cunfer, a plant pathologist with the Georgia Experiment Station in Griffin.

"The USDA conducted DNA tests on cultures from the suspected Karnal bunt spores to determine positive identification of the disease," Cunfer said. "However, they later learned that spores from ryegrass gave the same reaction as the true Karnal bunt in the DNA test."

While wheat farmers were waiting for word one way or the other, many may not have managed their crop as carefully as they could have.

"At that point, they didn't know if their crop would have any value at all," Lee said. "If the USDA quarantined the crop, they didn't want to have a lot of dollars or time in it."

Cunfer said Karnal bunt causes little economic loss in the field. "Using standard farming practices, losses greater than 1 percent would be unlikely," he said. In comparison, leaf rust can cause up to 40 percent loss.

"Compared to other wheat diseases, it (Karnal bunt) doesn't cause much damage," Cunfer said.

But wheat with Karnal bunt can be sold for food only under very restricted conditions. The farmer may be paid less for wheat with spores in it.

The potential USDA quarantine, however, had millers and processors shying away from Georgia wheat. Many growers couldn't even find someone to contract their wheat crop.

"We've missed a lot of opportunities," Lee said.

The Karnal bunt fungus produces a chemical called trimethylamine. It's the same compound a dead fish produces when it rots. Usually, the first sign growers, millers or shippers have is that fishy smell.

If more than 3 percent of the wheat is infected and is converted into flour, it will have the fishy smell and thus be unacceptable. "It's not toxic," Cunfer said. "It's just not palatable."

Georgia farmers grow soft red winter wheat. This type is used for making all-purpose flour for cooking and baked goods like cookies, crackers and pizza dough. Most wheat for bread flour is grown in the Midwest and Great Plains.

Lee said that he's glad the USDA decision was based on science and research.

"It's important to know that Karnal bunt is a relatively minor disease," he said. "Georgia wheat farmers probably lost more to the quarantine scare than they would have to the actual damage caused by the disease."

Sharon Omahen is a news editor with the University of Georgia College of Agricultural and Environmental Sciences.