The hot, dry weather that has dogged the upper Southeast since mid-April appears to have at least one silver lining — the threat of soybean rust is just about gone and an additional diagnostic tool is coming online to give Southeastern growers even more tools to avoid rust damage in the future.
Limit fungicide applications
Mueller urged South Carolina soybean growers to wait until small pods develop and try to limit this year’s crop to one application of fungicides. “If spraying for diseases other than rust, it’s still better to wait for those small pods to form. Unless we get a series of tropical storms, we don’t need to be spraying for these other diseases, if all we’re getting is afternoon thunderstorms,” Mueller says.
Multiple spraying of any pesticide on soybeans this year is going to be a management challenge because when soybeans in many areas of the Upper Southeast were in full bloom, they were hit with 95 degree temperatures and higher. When daytime temperatures reach 95 degrees, soybeans shed flowers.
As a result of the heat, most soybean growers in the Southeast are going to have to manage two crops of soybeans on one plant. This makes limiting fungicide applications to one all the more important, Mueller adds.
In addition to the good news/bad news about winter cold and summer heat and its affect on soybean rust, growers will have a new tool to use to better manage the threat of damage from Asian soybean rust.
This new tool, dubbed Soybean Rust Yield Loss Prediction Tool has been developed by several Southeast universities in cooperation with the USDA and their counterpart in Brazil — EMBRAPA.
Growers can access the new tool by going to the University of Kentucky’s Web site (Kentucky scientists took the lead in developing the new tool). The Web address is: http://dept.ca.uky.edu/sbrtool.
The new tool turns data about potential yield and the presence of soybean rust into a prediction of economic outcomes. Using the tool, growers can make data-based management decisions as to managing the risk of rust.
Though Asian soybean rust has been a constant threat to soybean growers for the past five years, it has never caused any widespread economic losses — nothing even close to damage caused in Brazil’s soybean crop virtually every cropping year.
The new tool will further reduce the risk to U.S. soybean growers. To use the tool, users enter information about cost of a fungicide application, predicted yield and expected crop sale price. When soybean rust appears in a field, the user enters the soybean growth stage at the time. The tool does the rest.