Slime Molds

Encyclopedia Article

Image of slime mold on turf grass
Slime mold on turf grass

Overview of slime molds 

The presence of slime mold is more of a curiosity than a problem. Slime molds are primitive organisms that are considered fungi. They feed on decaying organic manner and other organisms in the thatch layer and soil.

Image of slime mold on a perennial
Slime mold on perennial

Signs and symptoms of slime molds

Slime molds often appear after a warm summer rain. At first a slimy growth, called the plasmodium, appears. This slimy growth dries into a powdery mass of spore-bearing structures that coat grass blades. Slime molds usually last one to two weeks and often are observed in the same spot year after year. Typically 4-6 inches patches of the fungus are formed. Although there are many species of slime mold on turf, Physarum cinereum seems to be the most common.

Image of slime mold on wood chips
Slime mold on wood chips 

Type of Sample Needed for Diagnosis and Confirmation

The Iowa State University Plant & Insect Diagnostic Clinic can help you to investigate and confirm if you plant has this problem. Please see our website for current forms, fees, and instructions on collecting and packing samples. Contact information for each states diagnostic laboratory for U.S. residents.  If your sample is from outside of Iowa please do not submit it to the Plant & Insect Diagnostic Clinic without contacting us

Management of slime molds  

Control measures are not usually necessary. If desired, slime mold can be removed by raking, sweeping with a broom or mowing.  However, it is possible that the slime mold will reappear under humid and war conditions.

Further information about slime molds

See this article for more information on slime molds.