Algae are primitive green plants. They can be a problem in turfgrass when surface conditions are overly wet. They tend to occur in low, shaded, or compacted areas. Algae form a greenish to black scum on the soil or in thin turf. As this blackish scum dries, it appears as a crust that later cracks. Turfgrass plants may become chlorotic (yellowed), weak, and eventually die.
Algal scums can be controlled by:
- improving surface and subsurface drainage
- avoiding frequent waterings, especially at night
- aerifying compacted areas
- maintaining proper pH and nutritional levels
- increasing mowing height
- improving light penetration to the turf
- using shade tolerant grasses in shady areas
Algaecides or fungicides can help control algae problems when wet conditions are also corrected. For up to date information on recommending fungicides, visit "Chemical Control of Cooperative Extension Service Turfgrass Diseases" available for free at this link. Remember always read and follow pesticide labels.