Slime molds occasionally cause concern when they appear on lawns, but they do not kill the grass. They vary greatly in their color, size and form, however it's the grey color we see most where I'm at in central Georgia. Others are more gold or yellow in color. Their spore-producing structures are often very fragile, disintegrating when touched.
What are slime molds?
A slime mold is a primitive organism, sharing some similarities with both fungi and single-celled animals. The spore-producing structures of slime molds can appear on lawns quite suddenly, sometimes overnight. Slime molds may be found throughout the year, but are most common during rainy summers when humidity is high.
Symptoms
These are variable and dependent on the species of slime mold. Those seen most commonly on lawns or other grassy areas include:
Physarum cinereum: Clusters of grey-black pin-heads covering grass blades
Mucilago crustaceum: Irregular, crumbly yellow-white masses
Fuligo septica: Irregular yellowish cushions (this has the common name of dog vomit fungus)
The structures of Mucilago and Fuligo are commonly 3/4 to 1.5 inches in diameter. All of these species produce masses of tiny, black spores as their fruiting structures disintegrate.
Control
Here's the good news. No control is required as the slime mold is simply using the grass as a support on which to produce its fruiting structures. These will often vanish as quickly as they have appeared. If they are particularly unsightly they can be dispersed with a jet of water.
