Gray Leaf spot
scouted Aug. 26, 2026
- Scientific Name
- Cercospora zea-maydis
- Background
- In August 2026, signs of black circular- to oval-shaped fungal structures (stromata) were observed on corn (Zea mays L.) leaves on Dekalb 68-35, Dyna-Gro D60TC45, and Revere 1307 in multiple fields in Randolph County, North Carolina. Signs were only observed on a few plants within the larger field, with disease affecting 5 to 80% of fields at 1 to 60% severity on individual leaves. In addition to the fungal structures, the green leaves also exhibited small tan specks on approximately 40% of the individual leaves.
- Conclusion
- The leaves had signs of gray leaf spot as well as tar spot. Gray leaf spot of corn is caused by the fungus Cercospora zea-maydis. This disease is present in almost all growing seasons, but it only causes economic losses if the conditions favor disease development. There are fungicides labeled for gray leaf spot; there are resistant hybrids available, and crop rotation and tillage reduce the survival of the fungus.
- Resources