Arkansas soybean growers watching for rust

By Associated Press

JONESBORO — Arkansas soybean growers have cold weather on their side. Asian soybean rust, a fungal disease that can ruin a crop, dies in the winter temperatures, though its spores survive.

The fungus was first confirmed in the United States in 2004, apparently after riding hurricane winds from Latin America.

Farmers and agriculture officials have kept a careful watch for the disease and quick action has kept it from causing widespread crop damage.

Treatments have been devised for fields that have been stricken. And an early warning system uses sentinel plots, field monitors, air monitors and host plant monitoring each season to help keep the disease in check.

"We're going into our fourth year," Craighead County Extension Agent Eric Grant said. He and another agent from the Jonesboro office, Branon Thiesse, were out Tuesday collecting samples from kudzu, the only known natural host plant in America.

Grant prepared sample leaves to send to the University of Arkansas Plant Disease Clinic at the Lonoke Agriculture Center Laboratory. Testing is the only surefire method of determining soybean rust. There are other rust diseases, and many of them look similar to Asian rust, which makes laboratory testing the only true test.

Soybean rust was confirmed in a southwest Arkansas field last year. Agents and technicians from the region visited the field to see the disease's effects firsthand.

"A lot of money is being spent on this," Grant told The Jonesboro Sun. "This can wipe you out."

The leaves sent for testing Tuesday were from two kudzu sites and one soybean field.

"Kudzu is highly susceptible to spores of soybean rust," Grant said. Kudzu is vulnerable probably more so than the actual soybean plant and therefore provides a valuable tool in early detection of the disease.

Grant said wet weather this year prevented planting a sentinel plot near the Cache River.

Thus far, no Asian rust has been found in Craighead County, but the disease was confirmed in Jackson and Clay counties last year.

"I think we will find the same thing this year as we did last year," the county agent said. "Every county has a form of scouting for the disease."

The disease attacks the foliage of a soybean plant causing the leaves to drop early, which inhibits pod setting and reduces yield. Soybean rust has continued to spread throughout Africa, Australia, Asia, South America and, more recently, North America. It has now been confirmed in southern states such as Louisiana, Mississippi, Florida, Georgia, Alabama, Arkansas, Missouri, South Carolina and Tennessee.

Several fungicides have been approved for use on soybean rust, but manufacturers say supplies would not cover a nationwide outbreak, a fact that prompts Grant to note how important early detection is.