Issue No. 7, Article 7/May 6, 2005
Second Update for 2005 on Management of Soybean Rust with Fungicides in Illinois
Additional fungicides and up to three applications of Section 18 fungicides have been recently approved by the U.S. EPA for soybean rust management in Illinois. Fungicide applications will be the primary management strategy for soybean rust caused by Phakopsora pachyrhizi.
Fungicide applications should be considered when the disease has been detected in nearby areas, when disease forecasts and other risk factors suggest that the risk of disease is high, or when soybean rust is first detected in a field at low levels of severity and incidence. The appropriate fungicides must be applied correctly and at the proper time to achieve satisfactory control of soybean rust. The list of fungicides with Section 18 labels for management of soybean rust continues to lengthen as new products are approved for use in Illinois.
The fungicides that are effective primarily as preventive products are the chlorothalonil products and the strobilurin products, such as azoxystrobin, pyraclostrobin, and trifloxystrobin. The other main group of fungicides is the triazole group, which has both curative and preventive activity. A list of fungicide products available for soybean rust management in Illinois as of May 4, 2005, is shown in Table 2. The following U.S. EPA Web site is a good place to check for updates on fungicide registration for soybean rust management: http://www.epa.gov/oppfod01/cb/csb_page/updates/soybean_rust.htm.
Another new development is approval for up to three applications of Section 18 compounds for soybean rust management in a season in Illinois. A maximum of three total applications using approved Section 18 products collectively may be made under the revised soybean rust Section 18, but no more than two applications may be made with any given active ingredient per field per year.
Please watch reports for new developments related to distribution of soybean rust and fungicide options for managing this disease. This information is changing frequently. Additional information and links to useful Web sites related to soybean rust can be found on the new and developing Illinois Soybean Rust Web site at http://soyrust.cropsci.uiuc.edu/.
Soybean rust plants in Brazilian soybean fields.
For more information on managing soybean rust with fungicides, a new publication has been completed. Using Foliar Fungicides to Manage Soybean Rust can be seen in PDF format at http://www.oardc.ohio-state.edu/SoyRust/index.htm. Here is a quote: "This publication reviews basic fungicide information and the factors involved in making fungicide spray decisions, including mode of action, application, and use strategies. It contains illustrations, photographs, maps, tables, and charts, as well as a glossary of terms and a list of sources for additional information."--Dean Malvick