Slime Molds Now Active on Mulch

Gail Ruhl, Sr. Plant Disease Diagnostician, Department of Botany & Plant Pathology, Purdue University

Thanks to our warm, wet conditions, moisture-loving slime molds are appearing abundantly in mulch. Initially some may appear as a bubbling yellow mass, however, as the days progress, and the fungus matures, the slime mold will usually become more powdery in appearance, drying to a white, yellow, tan or dark brown ‘blob’.

Slime molds get their nutrients from bacteria and small bits of organic matter which is why it is common to see them growing on mulch. Although slime molds may grow up onto nearby plants, they do not harm plants.

Preventive chemical treatments tried over the years have been found ineffective. Slime molds are more of a curiosity or nuisance than a threat to gardens or lawns. After several days slime molds will usually become less
noticeable. Allowing mulch to dry out, or using a garden or leaf rake in the affected area helps break up the colony and will usually provide some control.

What Is Growing in My Landscape Mulch? - Information from Penn State University on a number of different “Mulch dwellers” (pdf file)

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Information listed is valid only for the state of Indiana

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Photo courtesy of Mike Weiss