Eyespot in corn can show up throughout the growing season. Circular lesions are roughly one-eighth to one-quarter of an inch in diameter. They look water soaked and appear in clusters. The leaf tissue in the center of each spot will die and turn a tan color with a brownish-purple ring around it. Every spot is also surrounded by a yellow halo that can be seen clearly when held up to the light.
Eyespot overwinters in corn residue, and in wet conditions, it will produce spores that can be spread by wind and rain. This disease is more common in fields with a history of eyespot, corn following corn, reduced tillage and favors cool temperatures (roughly 70 degrees) with wet conditions.
- Plant hybrids resistant to eyespot in corn.
- Rotate crops.
- Tillage will break up the residue and allow the microbes within the soil to break down the residue faster.
- Use fungicides labeled for use against eyespot.