NPIPM:Northern corn leaf blight
Authors: Byamukama, E. and Yabwalo, D.
Causal Organism
Northern corn leaf blight is caused by a fungal pathogen Setosphaeria turcica (Synonym: Exserohilum turcicum)
Symptoms and Signs
Northern corn leaf blight starts as pale-gray-green, elliptical or cigar-shaped lesions. These can expand to reach > 6”and as they mature, the lesion color becomes tan to dirty gray with dark zones. Unlike gray leaf spot, lesions of northern corn leaf blight are not restricted by leaf veins. The distinct symptom of northern corn leaf blight is the elliptical cigar shape. However this symptom can be confused with Goss’s wilt except that northern corn leaf blight lesion lacks black freckles.
Disease Impacts
Northern corn leaf blight can be severe leading to heavy yield losses in susceptible hybrids. Severe infections can lead up to 50% yield loss. Late season severe infections may look like frost injury.
Life Cycle and Epidemiology
The northern corn leaf blight pathogen overwinters on leaf debris. Spores are blown by wind and can be carried over long distances. Symptoms are more abundant at tasseling and these start in the lower leaves and move to upper leaves mainly from secondary spores produced from initial infection. Infection is promoted by prolonged heavy dew on leaves under warm temperatures (64-81 oF).
Management Approaches
• Select resistant hybrids especially for corn on corn and no-till fields
• Rotate crops to break the disease cycle
• Manage corn residue through tillage where practical
• Apply a foliar fungicide between tasseling to early silking growth stages (VT-R1) if disease pressure and environmental conditions warrant the fungicide.
Other Online Resources
Iowa State University. Northern corn leaf blight. https://crops.extension.iastate.edu/northern-corn-leaf-blight
Crop Protection Network. Northern corn leaf blight. https://cropprotectionnetwork.org/encyclopedia/corn-disease-management/foliar-diseases/northern-corn-leaf-blight/
