Daren Mueller, Extension Plant Pathologist
If the risk of soybean rust development is high and the crop is before growth stage R6, fungicides may be needed. For fungicides to be most effective, they need to be applied as close to the time soybean rust initially infects plants in a field.
In most cases, this means that fungicide decisions will have to be made at a time when the risk is high, but before the time when rust is detectable in the field. Detecting low levels of soybean rust (<10 percent) typically requires incubating leaves and observing them under laboratory conditions by a trained diagnostician.
A bulletin titled Using Foliar Fungicides to Manage Soybean Rust was originally published in 2005 and recently was updated and expanded. This book reviews the factors involved in making fungicide spray decisions and basic fungicide information, including mode of action, application and use strategies. An updated list of available products also is posted in Appendix B.
This book was prepared by soybean pathologists working in many regions of North America. This full-color publication contains numerous illustrations, photographs, maps, tables, and charts, as well as a glossary of terms and a list of sources for additional information.
Daren Mueller is an extension specialist in the Department of Plant Pathology.