- Lesions on leaves are 1-6 inches and are cigar shaped, they start in the lower canopy and work towards the upper canopy. Early lesions are gray-green and turn pale gray or tan as they get older.
- Under moist conditions lesions produce dark gray spores in the center of the lesions, causing the lesions to appear dirty, grayish appearance
- Stay away from field edges and waterways when scouting
- Pick out 10 plants and count how many have the lesions on each plant, replicate throughout field to get NCLB population
- This fungus disease will not hurt yields unless established before the silking stage. If established before then, the yields can be reduced by 30-50%. The leaves damage the photosynthetic area of the plant, causing reductions in yield.
- The fungus overwinters in the residue at the soil surface. Spores are produced as the spring temperatures rise and are splashed or blown onto the leaves of the new crop. As the lesions grow, they produce more spores that are splashed onto other susceptible leaves.
- Use tillage and rotation to reduce risk of NCLB, the residue leaves a host for the fungus
- Planting resistant hybrids can help prevent the disease
- Catching NCLB early is key to applying fungicides to help control NCLB