Text adapted from Turfgrass Pest Management: A Guide to Major Turfgrass Pests in Oklahoma. Oklahoma Cooperative Extension Service.

CAUSE: Slime molds do not cause disease; however, their sudden appearance on turfgrass can cause much alarm. Slime molds are caused by many different fungi, but most commonly by species of Physarum and Fuligo.

HOSTS: All turfgrasses.

SYMPTOMS: Many small, purplish, white, gray, or brown fruiting bodies of these fungi suddenly appear in the morning on leaves of turfgrass in small patches (Figure 1). During the day, ruptured fruiting bodies may cover grass leaves with a black, soot-like substance.

DISEASE CYCLE: These fungi live on dead organic matter in the soil. During warm, wet weather, they use the leaves and stems of turfgrass to support their reproductive structures. These produce spores that are released and facilitate their spread to surrounding areas.

FACTORS FAVORING DISEASE DEVELOPMENT: Spores survive in the soil and on thatch. Cool, humid weather favors spore germination and colony development. Warm, wet weather favors the development of the reproductive structures.

CONTROL: Mechanical removal by brushing, raking, mowing, or washing the turfgrass with a hose is usually all that is necessary for control. Fungicides are not needed.