Sudden death syndrome on soybean leaf.
Wet weather this season has increased the risk for sudden death syndrome (SDS) in soybeans, says Darren Mueller, Extension soybean pathologist at Iowa State University. “Unlike last year, most of the soybean crop was planted before the bulk of the rains started which further increases the risk of SDS. The early wet weather we have experienced so far in 2014 helps increase the root rot phase of the disease,” he says.
One of the driving factors for late-season SDS development is significant rainfall during the late-vegetative and early reproductive stages. The totals in June 2014 are near the numbers in the SDS years throughout much of Iowa. For example, the precipitation total in Ames during June was 10.23 inches.
Remember there are a few other diseases that may be confused with SDS such as brown stem rot and stem canker. Look for lesions on the outside (stem canker) and browning in the pith (brown stem rot) to distinguish from SDS.