Plants affected:

• Lawns, particularly those that contain a high proportion of annual bluegrass (Poa annua)

Symptoms:

• patches of grass become yellow and die, often merging to form large areas
• in damp weather, a white fungal growth appears, causing the grass blades to stick together.
• it is most prevalent in late winter and early spring, especially on areas of grass that have been waled on while snow covered

Cause:

• principally the fungus Fusarium nivale, which is encouraged by poor aeration and the overuse of nitrogen fertilizers

Control:

• Regularly aerate and scarify the lawn. Use winter-hardy grass species. Avoid using high-nitrogen fertilizers in late summer to early fall and rake thoroughly after mowing to prevent building up a water-holding mat. Cut grass short in late fall.
• see “Fusarium Wilt” for other ideas on controlling Fusarium