Damage Pattern
The first symptoms appear from early to mid-July as gray-green, elongated spots on the lower leaves. Under favourable conditions (persistent leaf moisture and high temperatures), the spots expand, and by early September, the entire leaves become infested
and turn light brown and die. The disease also halts starch storage in the grains, leading to small grains and significant yield losses.
Biology
The fungus does not spread through seed. It overwinters on crop residues and stubble. With sufficient moisture and temperatures between 18 and 27°C, conidiospores form and are spread by wind and rain to infect maize leaves. The fungus can overwinter in the field on leftover plant matter. Areas with high moisture, such as near water bodies, and high temperatures are particularly at risk.
Control
Choosing late-maturing, less susceptible varieties is essential. Additionally, careful shredding of harvest residues and proper ploughing under stubble can help break the infection cycle. Fungicide application at the onset of infection may also be effective.