Northern corn leaf blight

Northern corn leaf blight, caused by the fungal pathogen Trichometasphaeria turcica (teleomorph of Exserohilum turcicum), is a serious disease affecting maize crops worldwide. It is characterized by severe foliar symptoms that can lead to significant yield losses if not managed correctly during the growing season.

The fungus primarily attacks maize (corn), but it can also affect sorghum and other related grasses. The infection cycle starts when spores landing on leaves germinate under favorable environmental conditions, penetrating the plant tissue and initiating the development of characteristic lesions.

The initial symptoms appear as small, elliptical, water-soaked spots that progressively enlarge into long, cigar-shaped necrotic lesions of a tan or grayish-brown color. As the disease advances, these lesions may merge, causing the entire leaf to wither and die, which severely restricts the plant's ability to produce energy through photosynthesis.

Optimal conditions for the spread and development of the disease include high humidity, heavy dew, and moderate temperatures ranging from 20°C to 28°C. The pathogen survives between seasons in infected corn residue left on the soil surface, serving as a primary inoculum source for the subsequent crop cycle.

Effective management strategy involves several key pillars: utilizing resistant or tolerant corn hybrids, implementing crop rotation to break the disease cycle, and practicing tillage to bury infected residues. In cases of high disease pressure, the application of systemic fungicides during the early stages of symptom appearance is crucial to protect the crop canopy and ensure stable grain yield.