Northern Corn Blight

Pathogen: Exserohilum turcicum

Symptoms: Symptoms appear as long, narrow, tan lesions that form parallel to leaf margins. The lesions produce olive-green or black fungal spores when humidity is high, which can give the lesions a dark or dirty appearance.

Epidemiology: Infections are favored by temperatures (15–25°C), dew periods of at least 4 h, and high relative humidity (90–100%).

Disease cycle: Pathogen overwinters on host plant debris as dormant mycelium or as chlamydospores in the soil.

Primary infections result from airborne conidia produced on maize debris which are transported by wind, rain, and seed-borne inoculum.