Lawn and Turf: Algae
categories: Lawn and Turf Lawn and Turf Diseases
revision date: 2022-10-30 11:14
Photo by: G. Stahnke
Biology
Algae are tiny, single-celled plants commonly found in lakes and wet areas. Algal growth on lawns is common in the coastal regions of the Pacific Northwest, particularly on grass planted in wet, low-lying, or shaded areas. Also at risk are lawns with compacted soils that prevent proper drainage. Algae form a slick greenish to black scum on the surface of the soil, particularly over thin turfgrass. It can look like an oil spot. The grass is usually not killed, but growth is reduced because of shading and reduced air and light penetration. The algal scum becomes a black, water-repellent crust in dry conditions.
Management Options
Use Integrated Pest Management (IPM) for successful plant problem management.
Non-chemical Management
Select non-chemical management options as your first choice!
- Improve soil drainage.
- Soil aeration and thatch removal may be useful.
- Improve light penetration in shady areas by thinning shrubs and trees.
- Maintain a healthy, vigorous lawn by providing proper culture including proper irrigation and fertilization.
- Avoid excessive use of nitrogen fertilizer.
Chemical Management
IMPORTANT: Visit Home and Garden Fact Sheets for more information on using pesticides.
- These give only temporary control.
- Identify and correct the causes of turf deterioration for more lasting results.
Approved Pesticides
Listed below are examples of pesticides that are legal in Washington. Always read and follow all label directions.