Soybean rust found in the U.S.

By Ben Holman

Nevada Herald

Wednesday, the USDA's Animal and Plant Health Inspection Service confirmed the presence of soybean rust in the United States. The rust was found on soybean leaf samples taken from two Louisiana State University research farm plots on Nov. 6.

While this is the first case of soybean rust to be identified in the United States, its arrival at the end of the harvest season is fortunate as the disease will not have much effect on this year's crop.

Soybean rust is spread mainly by wind-borne spores that are capable of being carried over long distances. APHIS believes that the spores that produced the Louisiana find were carried into the U.S. because of this year's active hurricane season.

The USDA and others have been expecting soybean rust for several years now and are preparing to deal with the problem.

"I'm glad that it's come at the end of the year and we've got the winter to prepare for the next growing season," said Pat Miller, University of Missouri Extension.

"My concern was not having enough fungicide for it," she said, "Now that we know we have it, suppliers can prepare for what might happen. The worst would have been a widespread outbreak in June."

Now that soybean rust's presence is confirmed, ag entities across the country are reviewing plans for dealing with the fungus. "It's come at the end of the growing season," said Becky Grisham, communications director for the Missouri Department of Agriculture, "once the leaves have dropped (there's not much damage it can do)."

She said the agency is reviewing its plan and preparing to battle the fungus during the next growing season. "We're gearing up on how to educate farmers on how to scout their fields and useful herbicides. We're going to be working closely with extension agents on educating producers."

Grisham said that they are going to work hard to keep farmers informed on approved herbicides and other tools they have available to them.

Farmers will be the front line in the battle against the spread of soybean rust. According to Miller, it is vitally important that growers keep a close eye on their fields and know what to look for. Soybean rust is manageable if identified early.

Due to the timing of this first U.S. occurrence, farmers have ample time to develop a plan of action for dealing with the fungus. Miller suggests that farmers educate themselves on the identification of soybean rust and on approved herbicides for dealing with an outbreak.

Symptoms of soybean rust are small lesions on the lower leaves of the infected plant that increase in size and change from gray to tan or reddish brown on the undersides of the leaves. There are two types of lesions, tan and reddish brown. Tan lesions, when mature, are made up of small pustules surrounded by a slightly discolored necrotic area with masses of tan spores on the lower leaf surface. Reddish brown lesions have a larger reddish brown necrotic area, with a limited number of pustules and few visible spores on the lower leaf surface.

Once pod set begins on soybeans, infection can spread rapidly to the middle and upper leaves of the plant. Yield losses of 10 to 80 percent have been associated with soybean rust.

While soybean rust is controllable with proper spraying, it does come at a cost.

The USDA estimates that the cost for treatment to U.S. producers could be as much as $25 per acre -- about a 15 percent increase in costs for those producers who are affected.

For information on identification of soybean rust and approved treatment methods, contact the University of Missouri Extension Office at (417) 448-2560.