Slime Mold on Wheat

If you are seeing this in your wheat or straw stubble-don’t panic! These little yellow globs are slime molds.

Slime molds are in the Myxomycota within the Kindgom Protozoa. These globs often get lumped together with fungi, but unlike fungi–which absorb their food–slime molds consume their food. The difference between slime molds and fungi is worth mentioning because there is a history of slime molds being studied, either academically or as a hobby, by mycologists (fungi experts). Slime molds are often found on decaying plant material, soil, or other substrates in wet or moist conditions. The spores of the slime molds move easily in water. What we see on the wheat is the fruiting structure and, similar to fungi, there is a lot more slime mold present than what we can see.

Slime molds are unsightly, but they rarely cause any harm to plants and are often responsible for helping breakdown organic matter. Instead of feeding on your plant like pathogens slime molds feed on bacteria, yeast, fungal spores, and other protozoa. On turf they can cause some yellowing as the mold is blocking sunlight but once the slime mold has dried the turf rebounds.

There is no need to worry or treat these slime molds as they will disappear in a few weeks or when the plant material, or weather, dries out. There is no need for a chemical option.  If you are concerned, (or if you’ve encountered the aptly named dog-vomit slime mold in a place you’d rather not have to look at it), you can collect up the material and throw it away; while it is not known to be harmful to humans, wearing gloves when handling and washing your hands afterwards is still suggested. Do not spray it with water as that will only spread the spores around. Be aware, that the slime mold will likely return if the environmental conditions favor the slime mold.

If you are seeing something similar in your fields and would like a confirmation, please contact the Plant Pathology Clinic for a sample submission form and sampling instructions.

For more information view the following articles:

Grass for Seed-Slime Molds

Great Balls of Slime

Slime in the Yard and Garden

Fuligo septica, the Gog Vomit Slime Mold by Thomas J. Volk, University of Wisconsin-La Crosse

Source: Introduction to Fungi, 3rd Edition. Webtser, J. and Weber, R.W.S. 2007. Cambridge University Press. New York. Pgs 40-53.

Washington State University