Soybean rust is a serious foliar disease in soybeans in many parts of Asia. Penn State Plant Pathologist Erick De Wolf reports in 2001 the disease was detected in South America, and has become wide spread in Brazil and northern Argentina. The disease is reported to cause yield losses ranging from 10 to 80%. If soybean rust finds it's way to the U.S. it may quickly become a major limitation to soybean production in some areas. However, to date, soybean rust has not been reported in the continental U.S.

Rapid and accurate diagnosis will be critical for initiating our efforts to manage soybean rust if and when the disease arrives here in the U.S. The United States Department of Agriculture (USDA) has been working with representatives from Departments of Agriculture from various states and University personnel to make sure that infrastructure and training required for a rapid diagnosis of soybean rust is in place.

At this time we do not know for certain where the rust fungus can survive the winter in the U.S. However, research from Iowa State University indicates the pathogen is likely to survive only in southern most points in states such as Florida and Louisiana in association with Kudzu or other legumes. In the spring the pathogen will likely be brought to northern states by wind. The timing of the annual introduction of the pathogen, and local weather conditions will influence the severity of disease at a given location.

USDA scientists have evaluated all soybean varieties currently grown in the U.S. and found no resistance to soybean rust. Only a few genes are known to provide high levels of resistance to soybean rust, but these genes can already be overcome by the diverse race structure of the pathogen population. Breeding efforts are underway and will likely focus on finding varieties that slow the development of the disease. This type of resistance is effective against all races and tends to be stable for long periods of time. It will likely take years to develop resistant varieties that have acceptable agronomic qualities.

Fungicides are likely to be a significant tool in the management of soybean rust. Data from the USDA suggests that many fungicide products can be effectively used to manage this disease. Currently only a limited number of products are labeled for use on soybean including Quadris and Bravo. The Pennsylvania Department of Agriculture and Penn State have worked together to submit applications to the EPA for Section 18's covering additional fungicide products. Some of these applications have been approved, but application of Section 18 products remains illegal until the USDA has confirmed soybean rust in the continental U.S. However, when needed, these products will increase the number of tools available for rust management.

Penn State has also joined a national effort to develop extension materials for soybean rust including diagnostic guides and a manual on fungicide applications to soybeans. We hope to have many of these resources available in time for the 2005 growing season. Additional information on soybean rust symptoms and management can be found on line at: "http://www.aphis.usda.gov/ppq/ep/soybean_rust/".