|Mushroom, probably a Pisolithus sp., cracking through solid asphalt.|
Q. Once every year or two, this guy devised to push up, right through the asphalt in our parking lot. In the past we have dug out what we could and patched the asphalt.
Any suggestions? Is there an anti-fungal or something we could spray to knock it back before it pushes up more asphalt?
A. The mushroom is probably a Pisolithus species (commonly known as the 'Dog Turd Fungus' for its passing resemblance to canine excreta). The fungus that produces the mushroom lives in and on tree roots and is a ‘mycorrhizal’ mushroom that benefits the tree by helping it to absorb nutrients and fight off infestation of disease causing fungi. You have three options as there is no known fungicide that will kill it -and some fungicides, like Benomyl, actually make it stronger:
- 1. Remove the tree that provides the root for the mycorrhizal mushroom to grow on. This could be a problem if there are more than one candidates or the tree provides much needed shade.
- 2. Replace your asphalt with concrete. I have yet to see one penetrate through more than 3" of reinforced concrete.
- 3. Keep replacing the asphalt and consider the mushroom’s appearance evidence of the tenacity of nature.
Spot treatment with bleach, creosote or some other grossly toxic agent? Since the fungus is present on and in most of the roots of the host tree you might be playing ‘Whack-a-mole' with it until you've killed off enough of your trees roots to cause some serious damage -to your trees.