News that soybean rust was found in Louisiana on Nov. 6 marked the first time the disease has been detected in the United States. That means that the industry will need to ramp up its education about the disease, say government and university officials.
USDA's Animal and Plant Health Inspection Service confirmed soybean rust on soybean leaf samples taken from two plots associated with a Louisiana State University research farm.
"The fact that it was found in the fall gives us the winter to prepare ahead of the 2005 growing season," says Doug Jardine, Kansas State University plant pathologist. "We had an active education program last winter, but this winter we'll have to intensify it, because it's important to educate producers and ag industry personnel about the symptoms and management of the disease."
The disease can be managed with judicious use of fungicides, however, some require Environmental Protection Agency approval. In some cases that has already happened.
Soybean rust is caused by either of two fungal species, Phakopsora pachyrhizi, also known as the Asian species, and Phakopsora meibomiae, the New World species. The Asian species, the one found in Louisiana, is the more aggressive of the two species, causing more damage to soybean plants, noted Jardine.
The disease is spread by wind-borne spores that can be transported over long distances. APHIS scientists believe the disease was most likely brought into the United States by this year's active hurricane season.
During next year's growing season, producers will need to watch for symptoms of the fungus that begin as small lesions on the lower leaves of the infected plant. These lesions increase in size and change from gray to tan or reddish brown on the undersides of the leaves. If the disease goes untreated, the plant may become entirely defoliated in 10 to 14 days.
The fungus resembles brown spot, a common disease in soybean, and the less common bacterial pustule, which might make it a bit difficult to diagnose, says Jardine.
The disease can dramatically reduce soybean yields. It disease favors high precipitation and high humidity. It also likes cool weather, which can make late -maturing variety soybeans vulnerable.
Information about soybean rust is available at USDA Web sites:
http://www.aphis.usda.gov/ppq/ep/soybean_rust/ and http://www.aphis.usda.gov/lpa/issues/sbr/sbr.html. Information is also available at http://www.planthealth.info and http://www.soybeanrustinfo.com .
Kansas State University Research and Extension, USDA.