Mushrooms or conks growing at the base of a tree are a sign of a fungal root or wood decay problem inside the tree, most often one of three types of root rot. It's a serious warning sign that calls for identifying which fungus is involved before deciding on treatment.

What Causes Mushrooms or Conks to Appear at a Tree's Base?

Root rot is the most common cause, coming from one of three fungi: Armillaria, Phytophthora, or Phymatotrichum, each of which decays roots and lower trunk tissue and can produce small white mushrooms or white fan-like fungal growths at the base as a visible symptom.

Can Fungicide Treat the Fungus Causing These Growths?

Only some causes respond to fungicide. Applying Garden Phos Systemic Fungicide as a soil drench or foliar spray treats Phytophthora-related root rot specifically, though Armillaria and Phymatotrichum root rot aren't listed among the diseases it controls, and Armillaria in particular has no reliable fungicide treatment in general use.

What Non-Chemical Steps Help a Tree With Root Rot?

Removing dead or severely decayed roots helps stop the fungus from spreading into healthy tissue nearby. Exposing the base of the trunk by pulling back soil and mulch also helps by drying out the area around the root collar, since these fungi generally thrive in consistently moist conditions.

Frequently Asked Questions

How much does treating root rot with fungicide cost?

$24.95 for Garden Phos Systemic Fungicide, sold as a 1-pint concentrate that can be mixed as a soil drench or foliar spray.

Do the mushrooms themselves need to be removed?

Removing the visible mushrooms doesn't treat the underlying problem, though clearing them away can reduce spore spread to other trees nearby while the actual fungus is addressed in the roots.

Can a tree survive once mushrooms appear at its base?

Sometimes, depending on how much root and trunk tissue has already decayed. A tree with mushrooms appearing for the first time has a better chance than one with a long history of dieback and decline.

Should a certified arborist be consulted before treating root rot?

Yes, especially since the three causes call for different responses. A certified arborist can confirm which fungus is involved and whether the tree is stable enough to keep, since some cases call for removal rather than treatment.