Soybean Rust in Georgia

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A plant killing disease is affecting area farmers.

A soybean field was just harvested, but an airborne soybean disease commonly known as soybean rust has farmers like Dayne Parramore wondering if he should plant a different crop here next year.

Dayne says, "It affects the soybean crop. It kills the plant; it will affect us and probably stop us from growing soybeans. If we can't grow a crop then we can't depend on it maturing and have a harvest. It's just throwing money down in a barrel."

The disease was found in six Seminole County soybean fields. Luckily, it was late enough in the season, so the crop wasn't completely destroyed.

Seminole County Extension Coordinator Rome Ethredge says, "Farmers can use chemicals called fungicides to protect the soybean plant. The fungicides cost too much and farmers don't get much return from soybeans as it is."

Ethredge also said the disease should be dormant during the winter months, but farmers still worry soybean rust will pop up again in the spring.

A national pest alert warns that soybean rust can also affect snap beans, lima beans and kudzu.

Agriculture experts speculate the disease blew into the U.S. with the recent hurricanes. Soybean rust has also been found in Louisiana, Mississippi and Florida. Extended Web Coverage

Soybean Rust

Scientific Names
Phakopsora meibomiae (new world species) and Phakopsora pachyrhizi (more aggressive Australasian species).

Soybean rust is a serious disease that has caused significant crop losses in many soybean growing regions of the world. Until its discovery in Louisiana in November 2004, soybean rust had never been detected in the continental United States. The fact that it is spread by wind-blown spores places major soybean regions in this country at risk of introduction in the coming years. The purpose of this publication is to alert Minnesota’s soybean growers to this risk, provide disease characteristics for soybean rust identification and contact information to report suspected introductions.

Soybean rust has a wide host range of over 30 legume species. There are two rust causing species in soybeans. The more virulent species, P. pachyrhizi has long been distributed throughout much of Asia & Australia, and more recently Africa and South America. This species was found near Baton Rouge, Louisiana, in November 2004. Yield loss in infested regions typically runs between 10-90 percent.

Early detection of soybean rust is difficult as symptoms may be confused with other soybean foliar diseases. The earliest symptom of infection is a yellow mosaic discoloration on the lower leaves of maturing plants at or near flowering. Advancing infection spreads to middle and upper portions of the plant, causing leaves to turn yellow and lesions to appear as small brown pustules. Advanced symptoms include numerous tan or reddish brown surface lesions, necrosis and eventual defoliation.

Susceptibility and Management
When the pathogen is present, disease development is favored by extended periods of leaf wetness and temperatures between 50ºF and 80ºF. Because present soybean cultivars are all rust susceptible, development of rust resistant varieties is a national priority. At present, early detection and fungicide applications are the main management tools in reducing losses. Several safe and effective fungicides are approved for use against soybean rust.

Soybean rust has the potential to seriously impact Minnesota agriculture. Soybeans are Minnesota’s most valuable crop, generating $1.32 billion in 2000.