University of Maryland Extension

Soybean Rust

Author: 
David Clement, Extension Specialist, Home and Garden Information Center
Soybean rust symptoms

(More plant diseases from HGIC)

Soybean rust is a devastating fungal disease of soybeans as well as other garden beans. It is caused by either of two species, Phakospora pachyrhizi known as Asian soybean rust of P. meibomiae, know as the New World species. The more aggressive of the two is Asian soybean rust. This disease is threatening to invade Maryland and the central Atlantic region from infected areas to the south. This disease is spread by prevailing winds since the spores can travel long distances. Obviously, the economic threat to the soybean industry is immense; severe damage can result in crop losses up to 80%. The disease can be controlled by using fungicides, but the cost is enormous. It is extremely important that the migratory progress of this disease be monitored.

Soybean rust attacks many plants other than soybeans and many of these plants are grown in homeowners' backyards. If you are growing peas, beans or other leguminous plants, you are encouraged to monitor the plants carefully for any signs of rust disease. One widespread host is kudzu. Although there are other fungal rust diseases capable of attacking beans and peas, the incidence of Asian soybean rust in a Maryland gardener's patch could be an important indicator of the severity of the outbreak and direction the disease is travelling. If you suspect the appearance of rust disease on your legumes this spring or summer, please contact us for more specific information and instructions.

soybean rust soybean rust spores
Rust symptoms on leaves Close-up of rust spores
soybean rust upper
Close-up of rust symptoms on upper leaf surface

Additonal information:

Thank you to Reed Frederick, USDA-ARS-FDWSRU, Ft. Detrick, MD for the use of his photographs.

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