Dog Vomit Fungus
It’s foamy, slimy and rather disgusting to look at. And nothing describes it better than its common name – dog vomit fungus.
This slime mold often appears on woodchip and cocoa bean shell mulches during rainy weather. It starts out bright yellow and eventually turns tan, dries and disappears. It feeds on dead organic matter, such as mulch, and is not harmful to the plants. It’s just ugly to look at.
I have seen it slime up the sides of trees and flowers. Just wait for the weather to dry and it will disappear.
You can remove large patches in the mulch to improve the view, rake to break apart the mold and speed drying or just wait for the weather to improve and watch as it dries up and disintegrates.
Prevent the problem by lightly raking the mulch during extended wet periods. This dries the mulch, creating a less desirable location for the slime mold to form. And for those using cocoa bean shell mulch, you may want to mix in rice hulls to help reduce this problem.
A bit more information: Avoid using mulch from black walnut trees. All parts of this tree, including leaves, nuts, husks and woodchips, contain juglone which is toxic to many plants. Instead, compost this material. Once it is fully decomposed, you can use it as a soil amendment in your landscape.
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