Please help me identify a killing substance in my garden that just appeared this year. I noticed it about a month ago, thinking it was animal barf. I cleared away the material and disposed of it along with the soil around it. A few weeks later I discovered yet another spot with this same substance. Upon closer inspection I found it had totally rotted my primrose and was continuing into the garden. It appears almost like a spreading mushroom with vents around it, hardens into something resembling cement, grayish white to an off yellow color. When I picked it up (with a sheet of plastic) it became brittle and released some sort of powder. Thinking it might be spores and could easily become airborne, I again bagged the material and kept it. I do not know how to contain it, or if it is hazardous to the rest of the garden. I have no idea where it came from but I do want to be rid of it.
What you are describing sounds very much like dog vomit slime mold, Fuligo septica.
See if the links below are depicting the same thing you have observed:
- Tom Volk’s Fungi
- Wayne’s Word online textbook of natural history, slime mold page
- Mushroom Expert
Do you have wood chips or other wood-based mulch in your garden? This slime mold thrives on decaying wood. I’ve never heard of it harming plants, unless the plant matter is already decaying from other causes. I imagine it would be next to impossible to eradicate, unless you want to remove any woody material around your plants. It’s possible that extreme heat (such as fire) might kill some of the spores, but it wouldn’t be too good for your plants!
If you can tolerate it, it really is not known to devour and kill plants. Your primroses may have succumbed to something else, and the slime mold was just being opportunistic. See the following article by Kathryn Richardson, from Harvard University’s Arnold Arboretum publication, Arnoldia:
“Dog vomit slime mold is motile, but moves quite slowly. It is not harmful to animals or plants and usually vanishes in a short period of time. This species and similar slime molds feed on bacteria, fungal spores, and smaller protozoa found on wood chips. Slime molds feed much like an amoeba feeds; they ingest their food and then digest it (unlike fungi, which digest and then ingest). If conditions are favorable, these slime molds will produce reproductive structures (sporangia) that produce spores. When conditions are unfavorable (loss of food, dry conditions), the plasmodium will form hard, dormant, protective structures called sclerotia. Inside the sclerotia the plasmodium will divide into cells containing up to four nuclei. When conditions become favorable each cell will form a new plasmodium. Dog vomit slime mold is primarily an aesthetic problem in mulched garden beds. It can be physically removed, but more is likely to return. So, before panicking and taking your dog to the veterinarian, take a closer look and consider that that stuff is likely just Fuligo septica working away at cleaning the mulch.”