"Dog vomit fungus" is one of those oddities of nature that just makes you say "eww eww." Even if you've never had it in your garden before, it's pretty safe to say that you'll know it when you have it; its nickname couldn't be more precise.
The fungus, which has the scientific name Fuligo septicai, is also sometimes called "scrambled egg fungus." It is most likely to show up during warm, wet periods, sometimes seeming to pop up out of nowhere overnight.
It often grows in wood mulches or along the sides of untreated wood, and sometimes in lawn grass.
Their less-than-attractive appearance may cause concern that they're harming garden plants, but they are actually really interesting (if you have kids, they'll get a kick out of learning more about this disgusting fungus.) Slime molds, such as Fuligo septicai, are saprophytic, which means that they feed on decaying organic materials. They are not diseases, and won't really harm your plants. Occasionally, they'll grow on plants that are growing in mulch, and if a large enough colony forms, they may smother the plant. This is uncommon, however, and you'll usually just find the mold in the mulch itself.
Dog vomit fungus, like other slime molds, are most often found in moist, shady areas, where they thrive. Crevices, mulch, rotting logs, leaf litter and along untreated lumber are all very common places to find it.
Description of Dog Vomit Fungus
Its name is fairly accurate. If you've had a dog, you'll know it when you see it. It is also known as "scrambled egg fungus," because the fruiting bodies (the part you see) is light yellowish in color and looks a bit like scrambled egg curds. It usually appears in small clumps, clinging to mulch, the bases of rotting tree trunks, or other wooden objects.
Life Cycle of Dog Mold Fungus
Slime molds like the dog mold fungus produce spores that are wind-borne. They are very resistant and can survive even during hot, dry weather. The spores can remain viable for several years, waiting for conditions to be right. When warm, moist conditions are present, those dormant spores absorb moisture and crack open to release a swarm sphere, and shortly after, gardeners will see that tell-tale, disgusting looking fungus appear.
Controlling Dog Vomit Fungus
As mentioned above, generally dog vomit fungus poses no threat to plants. It's really just an unattractive nuisance. The best way to control it is to break it up and dry it out. Dog vomit fungus growing in mulch or leaf litter can simply be raked out and disposed of (probably not in your compost, unless you either practice hot composting or want more of it to show up in your garden later.) Dog vomit fungus growing along lumber or tree stumps can be scraped away with a trowel or small shovel and disposed of. If you have it growing in your lawn or in plants, gently rake it out as best you can and get rid of it. A strong jet of water will also dislodge any of the remaining fungi still clinging to the plants (though it may pop up again later.)
If dog vomit fungus continues to be a problem, you may want to consider switching from wood-based mulches to something else, such as gravel. In general, it doesn't pop up often enough to be a real issue.
So, if you see this unattractive fungus in your garden, don't panic. Its primary crime is being unpleasant to look at. Leave it (if it doesn't bother you too much), or scrape it up and get rid of it, and hope for drier conditions in the future so you won't have to see it again anytime soon.