Gray leaf spot of maize

Cercospora zeina is a fungal pathogen belonging to the genus Cercospora that causes the disease known as Gray Leaf Spot in maize. It is a significant phytopathogen capable of causing devastating yield losses in corn production globally, particularly in areas with humid climatic conditions.

The characteristic symptoms of the disease are rectangular, grayish-brown lesions that develop along the leaf veins. As the disease advances, these lesions expand and merge, resulting in large areas of necrotic tissue, which drastically reduces the plant's ability to photosynthesize and limits grain filling.

The biological cycle of the fungus is characterized by its survival on infested corn debris remaining in the field. Under favorable weather conditions, conidia are produced and disseminated by wind and rain splashes to healthy leaf tissue, where the infection process begins through the stomata.

Disease development is highly dependent on environmental factors, specifically high relative humidity (above 90%), prolonged periods of leaf wetness, and temperatures ranging from 20°C to 30°C. These conditions facilitate rapid sporulation and secondary infections throughout the growing season.

Effective management strategies for Cercospora zeina are essential for maintaining crop productivity and include:

• Selecting corn hybrids with genetic resistance to Gray Leaf Spot.
• Implementing crop rotation cycles to reduce the inoculum level in the field.
• Using deep tillage practices to bury infected crop residues.
• Application of foliar fungicides at the appropriate growth stage if disease pressure is high.