Iowa State University plant pathologist Alison Robertson says ear and stalk rots will likely become prevalent in Iowa as the growing season draws to a close. In the past week, she said there have been a few reports of Diplodia ear rot from the northeast, central and southeastern parts of the state. This ear rot is not as common as Fusarium or Gibberella ear rot in Iowa.
"Diplodia ear rot is favored by cool, wet weather during grain fill. Infection occurs through the silks and/or ear shank, or via the base of the husks of the ear," says Robertson.
Robertson says although Diplodia ear rot does not appear to produce mycotoxins in the grain under typical Iowa field conditions, infected kernels are lightweight and have reduced nutritional value. "Damage caused by Diplodia ear rot is usually limited to the field, but the pathogen can be a problem in storage if grain moisture is 20 percent or above," she adds.