Slime molds…unsightly, but seldom injures your lawn (05-30-2005)

Even though much of Mississippi has been lacking in rainfall lately, eventually the rains will come. And once we receive a long extended wet period, my phone will ring with somewhat panicky callers alarmed about a devastating looking fungus or slime attacking their lawns.

The attack is not near the detriment that it appears. Slime molds, which appropriately describe these fungi, will cover the turf leaves with a dusty-gray, black, or even dirty yellow mass.

When you look closely, you see tiny, round balls scattered over the plant. If you rub these balls between your fingers, a minute sooty-like powder will cover them. This sooty-like powder is the reproductive spores of the fungi.

Slime molds normally live on the soil where they feed on decaying organic matter. They do not feed on living plants, but only use them for support during reproduction. The damage to turf and other plants would be only from shading them from sunlight, which may cause the leaf blades to temporarily turn yellow.

Slime molds most often occur in wet weather in spring, summer, and fall. They disappear rapidly as soon as it becomes dry. Control is usually not necessary. You can break up the masses by sweeping with a broom or by spraying with a strong stream of water. In prolonged damp weather, you can apply any good garden or turf fungicide to affected areas.

Published May 30, 2005

Dr. Wayne Wells is an Extension Professor and Turfgrass Specialist. His mailing address is Department of Plant and Soil Sciences, Mail Stop 9555, Mississippi State, MS 39762. wwells@ext.msstate.edu