Nigrospora Ear Rot or Cob Rot
Symptoms
- Symptoms most apparent after harvest
- The cob often shreds at the butt end during mechanical shelling
- Kernels may be partly covered with gray mycelium with many tiny, black spores
- Kernels may be bleached
Pathogen Involved
- Nigrospora oryzae (a fungus)
- This pathogen is a weak parasite that attacks plants that have been stressed or killed before maturity
- Overwinters on corn residue
Time of Occurrence
- Occurs late in the season
Conditions Favoring Disease
- Occurs when corn is killed or weakened by a factor such as frost, drought, root injury, leaf blight, or stalk rot
- Corn grown on infertile soils
- Damaged kernels and ears
Disease Management
- Cultural practices that reduce ear damage may be beneficial