P&PDL Picture of the Week for
July 28, 2014

Slime Molds

Gail Ruhl, Senior Plant Disease Diagnostician, Purdue University

The rain events during the past few weeks have ‘revived’ the bright yellow, white and brown blobs appearing on wood chip mulch.  These fungal-like growths are known as slime molds. Slime molds are saprobes, meaning that they get their nutrients from bacteria and small bits of organic matter which is why it is common to see them growing on mulch. They are not parasitic and thus do cause plant disease.  One particular slime mold, aptly named  "dog vomit slime mold," Fuligo septica, (Figure 1) which belongs in the phylum Myxomycota in the Kingdom Protista, has been the subject of primary concern.

The initial bubbling or slimy vegetative (plasmodial) stage may quickly transform into the reproductive stage, producing masses of brownish-black powdery spores within the oft-times crusty exterior. Although slime molds may grow up onto nearby plants (figure 2), they do not usually cover enough of the plant’s surface to smother and cause harm to the plant. There is no way to get rid of slime molds other than removal of their food source (the mulch or other organic matter on which they are feeding). After several days (especially dry days) slime molds will usually become less noticeable.

More information on slime molds and other “mulch dwellers”- may be accessed at the following web addresses:

More slime molds


Click on image to enlarge

Figure 1. Fuligo septica 'Dog vomit' slime mold

Figure 2. Slime mold on barberry branch

Purdue Plant & Pest Diagnostic Lab Purdue Cooperative Extension Service