Slime molds usually develop after rainy periods or the application of freshly-ground wood mulch. They can be white, gray, yellow, purple, orange or brown in color.
Some people say the patches look like vomit from a dog or other animal.
The good news is that slime molds, a group of fast-growing, primitive fungi, are more unsightly than harmful and don't cause any plant diseases. They use plants, wood mulch and other organic materials to support their spore-producing reproductive structures. Slime-molds that grow on plants may decrease the amount of sunlight that reaches the leaves. Control of slime molds generally is unnecessary. If management is required for cosmetic reasons, decrease irrigation.