A common landscape annoyance you can expect to see as a result of the moist weather of late is slime mold. Formerly considered to be fungi, these organisms are now categorized as amoeboid-like cells. There are many variations in appearance of these organisms, most of which prefer warm weather. As temperatures rise, more of the slime molds appear. Look for them on bark mulches, on wood chips in play areas, on low-lying objects, or growing on any object that can be used as a perch. We usually see species of Physarum, Fuligo, and Stemonitis.
Although slime molds cause much concern to the homeowner, they do not absorb nutrients from live plant material. They feed on decaying organic matter, fungi, and bacteria in the soil and the turfgrass’s thatch layer. The slimy, amoeba-like stage may be watery-white, gray, cream to light yellow, violet, blue, green, or purple–brown greasy masses as large as 1 to 2 feet in diameter. This stage soon develops into colorful, crusty, fruiting bodies filled with masses of dusty spores. Slime molds are primitive organisms that flow (too slowly to watch) over low-lying objects such as mulches, sidewalks, or driveways, or over vegetation such as turfgrasses, strawberries, flowers, ground covers, weeds, and the base of woody plants.
Most gardeners want to know what to put on slime molds to kill them. Chemicals do not provide control. Instead, for abundant molds, remove the spore masses in a plastic bag, and break up the remaining masses by vigorous raking, brushing, or hosing down with a stream of water. Mowing the lawn usually removes the spore masses in turfgrasses. For more information about slime molds, read Report on Plant Disease, no. 401, which discusses slime molds in turf. The publication is available in Illinois Extension offices or on the U of I Vista Web site. A Web search using Google as your search engine yields many sites with pictures of slime molds.