What is Asian soybean rust (ASR)? ASR is a disease caused by the
fungus Phakopsora pachyrhizi . The disease causes numerous
lesions to appear on the plant that could lead to premature
defoliation and yield loss. What will ASR mean for Virginia’s
soybean crop? If ASR moves into Virginia, it is manageable.
Correct fungicide selection and application timing can minimize
yield loss. If conditions are favorable for the disease and
fungicides are not applied properly, yield losses of 10 percent
or greater can occur. The cost of production will increase with
fungicide application; therefore, soybean profitability may
decrease. How much yield loss from ASR can farmers expect? Risk
analyses indicate that ASR could cause yield losses of greater
than 10 percent in any United States soybean-growing region. In
the southeastern coastal states, losses of up to 50 percent are
possible because of more favorable environmental conditions and
earlier infection due to the closer proximity to overwintering
sources of ASR. Actual l