Turf samples showing the presence of slime mold have been arriving in the Plant Disease Clinic. Slime molds are fungi that grow on decaying organic matter. During wet weather they "ooze" onto leaf blades. This growth at first may appear black, yellow, or other color, and slimy. Eventually it turns to a powdery substance (usually white or grayish). Slime molds are common on turf, strawberries, or in plant beds with high organic matter.
Dormant periods of slime molds are spent in the soil and in the thatch. During or just after a warm rain or heavy watering, slime mold spores absorb moisture and move up the plant surface. They often reappear in the same area year after year, and last one to two weeks.
Slime molds are more of a curiosity than a threat to the turf. They use plants for support, and really only cause injury if they smother the plant surface. Control measures are not necessary, but if desired, they are relatively simple. Slime molds can be removed by vigorous raking, brushing, mowing, or hosing down with a fast stream of water. Slime molds will disappear with changing weather conditions.
This article originally appeared in the June 16, 1995 issue, p. 89.