April's Ag Advice by April Borders Word has recently come down from the USDA that Asian soybean rust (Phakopsora pachyrihizi) has been confirmed in the continental U.S. The initial collection was made from plots at two experiment station farms in southern Louisiana. On one farm the disease was not very severe, but the fields were nearing maturity. The other farm had fields that were not as mature and the disease was very severe.
According to Marty Draper, Extension plant pathologist, due to the late stage of crop development, he did not expect that fungicides will be used in 2004. He also said that this introduction does not mean that we will have soybean rust in 2005; however, it does dramatically increase the chances of the disease occurring in South Dakota.
It is believed this year's active hurricane season brought the wind-borne spores into the U.S. Surveys are beginning to determine how widespread the disease is and the severity of soybean rust across the infested area. It is not yet known if kudzu, sweet clover, kidney beans or other alternative hosts have been infected.
The rust spores will likely survive in places like southern Florida and the Gulf Coast region where it remains green. But research suggests that soybean rust will not overwinter in the cold climates of northern soybean-growing areas.
Despite the discovery of the disease in the U.S., soybean researchers say the timing of its arrival is a best-case scenario for two reasons: 1) since most soybeans have already been harvested across the country, the impact of the fungus to the 2004 U.S. soybean crop should be minimal, and 2) with several months before the next growing season, producers have adequate time to prepare to combat the disease next spring.
Producers should not panic. David Wright, director of Production Technologies for Iowa Soybean Association, said, "We do have the tools available to manage this disease. Those tools include early disease
detection and aggressive
fungicide control programs. Producers will need to become familiar with these strategies and programs this winter. At present there are no rust-resistant soybean varieties available."
With the first confirmed case of soybean rust, growers across the country will be asked to be on the alert for signs of the disease. Because the disease is spread through wind-borne spores it's difficult to contain, but early detection during the growing season next spring will be critical to help minimize the impact of the disease.
Extension educators will be working to keep you updated as we learn more about the spread of the soybean rust. I will be working closely with Marty Draper and we will be setting up sentinel plots in local soybean fields this spring to monitor for the disease.
There is a National Pest Alert flyer that is available on the soybean rust. If you are interested in the flyer or learning more about this disease, contact the Clay County Extension Office at 677-7111.