Northern corn leaf blight

Northern corn leaf blight, caused by the fungus Setosphaeria turcica, is a significant fungal disease affecting corn production globally. This pathogen survives in crop residues, making it a persistent threat in fields where minimum tillage or continuous corn cultivation is practiced. The fungus primarily targets the leaves, but in severe cases, it can affect the entire plant.

Symptoms are identified by long, elliptical lesions on the leaves, which are initially tan or gray-green. As the disease advances, these lesions turn tan and necrotic with dark, olive-colored fungal spores appearing on the surface during humid conditions. When numerous lesions merge, the entire leaf surface can wither, giving the plant a scorched appearance.

The infection thrives in moderate temperatures ranging from 18°C to 27°C and high humidity or frequent rainfall. Moisture is essential for spore germination and infection, which typically occurs from the lower leaves upwards. Spores are easily disseminated by wind and splashing rain, allowing the disease to spread rapidly throughout the canopy during the growing season.

The economic impact of Northern corn leaf blight is substantial, as it significantly impairs the plant's photosynthetic capacity. When the leaves are damaged before or during grain fill, the size of the kernels and the overall yield are drastically reduced. Severe outbreaks can lead to lodging and increased susceptibility to secondary stalk rot infections.

Management strategies focus on integrating cultural and chemical controls to minimize yield loss. Planting resistant hybrids remains the most effective strategy for managing the disease. Cultural practices, such as crop rotation and tillage to bury infected debris, reduce the initial inoculum. During favorable weather for disease development, systemic fungicides can be applied to protect the crop.

• Planting hybrids with genetic resistance to NCLB.
• Implementing crop rotation to break the disease cycle.
• Deep plowing to bury infected crop residues.
• Scouting fields regularly starting from the vegetative stages.
• Applying recommended fungicides when environmental conditions favor spread.