Use of Algaecide on Lawn

Chemicals

• Algaecides are herbicides specifically used to kill various species of algae. As a pesticide, algaecides are regulated in the United States for safety and composition. Algaecides formulated for use on garden plants such as lawn grasses and perennials contain many of the same active ingredients as algaecides used in water. Various salts and elements, especially copper, are harmful to algae, but not to other plants as long as these ingredients are not applied in excessive, non-recommended amounts.

Causes

• Any lawn, regardless of grass species used, that experiences an algal infestation experiences less-than-ideal growing conditions. Soggy or inundated soils, warm temperatures and abundant nutrients from the soil, organic matter or fertilizers combine to favor alga growth rather than grass health. Lawn grasses excel in fertile, moist but well-drained soils. For densest growth and best color, lawns need at least six hours of uninterrupted sunlight daily.

Effects of Use

• Although algaecides may be applied to lawns to curb an algal problem, algaecides offer a temporary solution. Proper equipment, both to apply the chemicals and protect your skin, lungs and eyes from harm, are required, adding to the amount of time and resources expended. While a treatment may knock back algae growth in a lawn, if the warm, overly wet and shady conditions remain afterward, the algae again grows back.

Solutions

• Rather than relying on algaecides to clean up an infected lawn, modify the growing conditions first. Improve soil drainage from the soggy soil areas. Alter irrigation schedules to ensure already moist lawn soil is not being saturated unnecessarily with additional water. In lawn areas where shading from a building or house causes moist soil and thin, weak grass, consider changing that area from lawn to other garden materials. Many herbaceous perennials or woody shrubs tolerate wetter soil conditions and may be planted instead of lawn. Once mulch is placed over the soil, the lack of light prevents algae. Increasing air flow and direct sunlight in an well-drained area, such as by pruning plants, can diminish the severity of algal problems, too.