Soybean Rust

Soybean Rust Management a Growing Concern Worldwide

Along with numerous government agencies and private companies, the NAICC is vigilantly monitoring and preparing for soybean rust.

This highly destructive pathogen has not yet entered North America, and a number of research and management efforts have been implemented in areas where soybean rust has appeared (southeast Asia, the southwest Pacific and parts of Africa and South America).

This information, along with the summary below, is derived from information supplied by Kent L. Smith, Ph.D., USDA Office of Pest Management Policy. The NAICC will continue to work with Dr. Smith and others on the soybean rust issue, and is also engaged with Bayer Corporation’s efforts to make soybean rust sampling bags available in Brazil.

History of Soybean Rust

According to Dr. Smith, soybean rust was first reported in 1902 in Japan and later discovered in Southeast Asia, China, India, Taiwan, and Australia. In 1994 it appeared in the Hawaiian Islands, and in 1996 the pathogen entered Africa quickly spreading to Zimbabwe, South Africa, Nigeria and other parts of Africa.

Three years ago soybean rust was discovered in Paraguay and has since caused serious losses not only in Paraguay but also in Brazil, Argentina and Bolivia, reported Dr. Smith. He noted that a lesser form of soybean rust (caused by Phakopsora meibomiae), which does not cause significant yield losses, is present in the Caribbean and Central and South America.

The yield-reducing form of soybean rust (caused by Phakopsora pachyrhizi) has not been reported north of the equator in the western hemisphere, said Dr. Smith. He gave estimates based on a USDA Economic Research Service report published in April of this year that projected that soybean rust would cause losses to the U.S. economy of $0.2 to 2.0 billion per year. These projections were based on the assumption that fungicides and application equipment would be available to combat this disease, a situation currently in doubt.

Dr. Smith also noted that soybean rust has an impact on specialty leguminous crops, as it has a wide host range (lima beans, black-eyed peas, kidney beans, green beans, etc.).

Soybean Rust Research

Research efforts on soybean rust include screening of existing soybeans for host resistance by ARS, fungal genome sequencing and comparative efficacy trials, according to Dr. Smith. (He noted that in Africa trials are being funded by the United Soybean Board and directed by ARS, while in South America they’re being funded by registrants and, again, directed by ARS.)

Research on application methods is being funded by CSREES, while ARS is working on diagnostic methods and other biological studies.

Managing Soybean Rust

In his presentation, Dr. Smith noted that management efforts for soybean rust include as many as four fungicide treatments a season. Weather-based advisories, sentinel crops and timing (generally during reproductive growth) are taken into account in managing the pathogen.

Dr. Smith said that the ASA estimates the cost of fungicide treatments to be about $15 per acre per treatment. Currently, fungicides that are registered for soybean rust on soybeans include Azoxystrobin (Quadris) and Chlorothalonil (Bravo and Echo).

For other legumes (lima beans, green beans, kidney beans, cowpeas, pigeon peas, etc.), registered fungicides include Azoxystrobin (Quadris), Chlorothalonil (Bravo and Echo), Pyraclostrobin (Headline), Maneb on dry beans and Myclobutanil (Laredo, Rally) on green beans.

Fungicides requested to control soybean rust on soybeans under Quarantine Exemption (Section 18) by South Dakota and Minnesota include Propiconazole (Tilt, Propimax, Bumper) granted 4/23/04, Tebuconazole (Folicur), Myclobutanil (Laredo) granted 3/25/04, Trifloxystrobin + propiconazole (Stratego), Tetraconazole (Eminent), Pyraclostrobin (Headline) and Boscalid + pyraclostrobin (Pristine).

More information on soybean rust can be found at, and NAICC will provide updates as new information is available. Dr. Smith and Teung F. Chin, Ph.D., can also be contacted for further information.

Dr. Smith is available at 202-720-3186 or

Dr. Chin’s phone number is 301-734-8943 and his email address is