Published on 09/29/97

New Disease Threatens Georgia Sorghum's Future

Ergot, a fast-spreading disease that recently caused million- dollar losses in Australia, is now in Georgia, says a U.S. Department of Agriculture scientist.

Jeff Wilson, a USDA plant pathologist, has found the disease in sorghum fields at the University of Georgia Coastal Plain Experiment Station in Tifton, Ga.

Georgia farmers grow sorghum mainly as a hog, poultry and wild bird feed. Each year they harvest an average of 30,000 acres of sorghum for grain.

Also known as honeydew disease, ergot attacks sorghum florets before the seeds are formed. The infected flowers don't produce grain, which reduces the grain yield.

The obvious external sign of the disease, Wilson said, is a sweet, sticky fluid exuding from the flowers. As the disease progresses, the sticky honeydew drops onto the seeds, leaves and ground, making the grain hard to harvest.

Ergot was found in Australian sorghum fields in 1996. Less than a year later the disease has spread across the continent into all sorghum-producing areas.

Today, after living with the disease for two seasons, Australian sorghum growers are reporting losses from 10 percent to 100 percent in hybrid seed production.

"They've been spraying with fungicides which have added $20 to the grower's cost of a 50-pound bag of seed," Wilson said.

Wilson identified the first report of ergot in Georgia on Sept. 8 in a Tifton field. The first sighting consisted of "a few isolated seed-heads."

Ten days later, the disease had spread across the entire field. "This is evidence of the disease's tremendous capability of spreading," he said.

Ergot is spread by wind, rain, insects and humans. It can be transferred from field to field on clothing and farm equipment.

The disease was first found on the Western Hemisphere in 1995 in Brazil. By '96 it had entered Mexico. Ergot was found in Texas in March '97. One month ago, it was reported in Kansas.

Wilson said this is the first time he has seen a disease progress from "insignificant to global impact" in just two years.

The good news for Georgia growers is the disease's timing.

"It most likely won't affect this year's crop," Wilson said. "I'd be surprised if any farmers even see it this year."

In future years, however, Wilson said farmers may have harvesting problems with their late-planted sorghum due to the disease's sticky nature.

Preliminary reports from Australia include several detrimental affects on animals fed infected sorghum grain. Dairy and hog producers report poor weight gain, feed refusal and reduced milk production in their animals.

"When it costs more to produce grain," Wilson said, "it costs more to feed animals and buy meat products."

Researchers expect the disease to spread through Georgia. But it's unlikely to greatly affect meat prices here, said George Shumaker, an Extension Service economist with the UGA College of Agricultural and Environmental Sciences.

"Georgia sorghum is no more than 1 percent of the grain used for feed in the state," Shumaker said. "It is hardly fed to cattle at all. Georgia farmers grow sorghum grain mainly as a feed for hogs and poultry."

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