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 watering, 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. Remember to always read and follow pesticide labels.
Photo credits: Lee Butler and Jim Kerns, North Carolina State University