Stalk Rots (fungi - several species): Stalk rots are the world's most destructive corn diseases. They are caused by a complex of fungi and bacteria that attack the stalks near maturity. Stalk rots are favored by conditions that encourage heavy kernel set followed by late season stress, such as leaf blights, extended cloudiness, heavy plant stands, drought, hail, and low K with high N. Most stalk rots are favored by dry conditions early and warm, wet weather after silking. Symptoms include destruction of pith in the stalk and lodging. Interior discoloration ranges from pink with Gibberella to gray with charcoal rot (photo). Yield reductions of 10 - 20% are common with susceptible hybrids. Losses occur from both poorly filled ears and harvest losses due to lodging. Controls include using disease-free seed of resistant hybrids, crop rotation, balanced N and K fertility, sanitation, stress reduction such as pest control, and reduced plant populations.
