Identification

• Slime molds typically occur on lawn grass after periods of extended rain and humidity. Some lawns develop slime mold in the same areas each year. Although slime molds typically scatter in small patches on lawn grass, it can occur in large areas that cover most of the lawn. Slime molds also develop in mulched flower beds and on the lower leaf surfaces of plants.
  
  

Causes

• Slime molds are caused by fungi, the most common species of slime mold fungi are Fuligo, Mucilago crustacea and Physarum. This mold is composed of a single cell known as a plasmodium, which feeds on organic matter and bacteria on plant tissue. When weather conditions are favorable for its development, the plasmodium covers the grass, mulch or ornamental plants.
  
  

Effects

• Lawn grass with slime mold is characterized by the development of a slimy fungal growth, which is usually white but can be a variety of colors including orange, pink, purple or yellow. As time goes on, this slimy mold turns into a large mass of powdery fungal spores which are usually gray, blue or white. Lawn grass with slime mold does not suffer long-term damage, but some grass may turn yellow from a lack of sunlight. Prolonged periods of slime mold can weaken lawn grass, making it susceptible to other fungal diseases.
  
  

Control

• Since slime mold does not feed on lawn grass, it is not harmful to lawn health, but many homeowners do not like having large patches of slimy mold on their lawn. Removing slime mold is best accomplished by raking the mold or mowing over it. You can wash slime mold from your grass or plants, but this is discouraged because excess moisture can worsen slime mold development. If left alone, slime mold will disappear on its own, usually in a few weeks.