There truly is nothing new on the earth.  Take mulch, for instance.  As long as leaves fall off of trees, you have mulch.  Prairie grasses die and prevent weeds from coming up, and you have mulch.  We hire people to bring us yards of mulch to spread amongst our gardens every year.  Even the Egyptians used mulches.  Well, they probably didn’t call it “mulch” but the Hanging Gardens of Babylon probably would have been far less spectacular without it.

We use mulch to control weeds, to cut down on evaporation from the soil, to keep the soil warmer in the autumn and cooler in the summer, to prevent soil erosion, and to control diseases.
And yet, mulch itself is susceptible to a disgusting looking, yet relatively harmless fungus that resembles nothing so much as dog vomit.  Tapioca Slime (Brefeldia maxima) is one of the largest slime molds, resembling tapioca in its early stages-shiny, white and lumpy.  It matures to a cushion-like shape, taking on a pinkish hue or a white-yellow that eventually darkens to black.  A garden filled with partially decomposed wood mulch is Eden for Tapioca slime, also known as “dog vomit fungus.”

While somewhat disgusting in appearance, slime molds are harmless, and appear during warm to hot weather following heavy rains or watering.  Primitive organisms, they feed on decaying organic matter, hence their proclivity for our beneficial mulches. 

They are fairly rare in frequency, cause very little damage, but may appear in maintained turf grass as well as in our flower beds which we’ve been so assiduously responsible to mulch.  The following turfs may be affected, but aside from a little yellowing, the damage will be minimal. 

Turf

The solution to this icky problem?  Leave the slime molds alone.  They will soon disappear.  Accelerate the process by raking or mowing off the mushrooms as they appear.  Aerating the mulch will help, as will a heavy stream of water to disperse the mat.