Asian soybean rust – a potentially serious fungus of soybean crops – has been found for the first time in Texas.
Dr. Tom Isakeit, Texas Cooperative Extension plant pathologist, found the fungus on kudzu leaves he collected on Nov. 2 near Dayton in Liberty County.

A preliminary diagnosis made at the Texas Plant Disease Diagnostic Laboratory in College Station was confirmed by a U.S. Department of Agriculture laboratory in Beltsville, Md., Isakeit said.

The rust has been reported in seven other states in the southeastern U.S.

Until the fungus was found in Texas, East Baton Rouge Parish in Louisiana was the westernmost point that soybean rust had been found in the continental U.S., Isakeit said.

Asian soybean rust can live on a variety of hosts but seems to aggressively attack only soybeans and kudzu, Isakeit said.

As of today, he had found it on no other plants in the county. His survey included 12 soybean fields in the vicinity of the kudzu. He did not expect the soybean rust to spread outside of the county this year nor did he expect major economic losses because of the find, he said.

"The kudzu should die back with a freeze," Isakeit said. "The rust spores cannot survive without a live host. The only way it could come back is if the spores blow in from somewhere else."

Plants are prone to yield loss from this disease between flowering and the pod-fill stages of growth. In Liberty County, the soybeans are past that stage, and harvest is nearly over.

According to the Texas Agricultural Statistics Service, about 270,000 acres of soybeans were harvested in the state in 2004. The average yield was 32 bushels per acre.

Isakeit believes Hurricane Rita could have been responsible for blowing the spores in, but he isn't certain. Louisiana was monitored aggressively after Hurricane Katrina, but no evidence was found the hurricane brought the year's first "find" in Louisiana about two weeks ago.

Still, he became concerned that spores might have been carried in Hurricane Rita's winds. That is when he began to closely monitor that area.

"The disease is still very much weather driven," he said.

Asian soybean rust was first reported in the continental U.S. in November 2004. Yield losses from Asian soybean rust have ranged from 10 percent to 80 percent in South Africa, Paraguay and Brazil, according to the USDA.

* Photo: USDA Soybean Rust Information Site