Crop disease has drought-like symptoms

A disease of soybean crops in the Midwest is proving hard to diagnose because the symptoms resemble drought stress already hitting the fields, researchers say. Caused by a fungus, so-called charcoal rot could reduce the yields in farmers' field that have otherwise survived the summer's excessively dry weather, Purdue University researchers reported. The fungus infects seedlings early in the growing season but the symptoms, which mimic drought stress, usually don't appear until mid-season or later, researchers said. "Charcoal rot will be hard to diagnose in years like 2012, since it is difficult to distinguish it from symptoms of general drought stress," Kiersten Wise, Purdue plant pathologist. "Plants on hillsides or sandy areas will typically exhibit symptoms first." While there are no in-season treatments to control charcoal rot, Wise said, it's important that soybean growers look for the disease and know which fields are susceptible, as charcoal rot can build up in soil and can survive for several years. "We need to know which fields have charcoal rot this year so we can manage it in future crops," she said. "The fungus can infect a number of crops, including corn, which limits the effectiveness of tillage and rotations for managing disease," she said.