In October, I visited a field of corn in Jackson County.  Plants had dark brown, circular spots on stalks and the midribs of leaves (Figure 1).  Associated with the dark spots on the midrib were smaller spots on the leaf blade that looked like southern rust.  There also was a repeating pattern associated with these spots.  The disease was Physoderma brown spot, caused by the fungus Physoderma maydis.  I confirmed it by examining spores from spots under the microscope.  Previously, the only time I’ve seen this disease was… Read More →