Hi! I have an old apple tree that has a large hole in it where a large branch fell off 7-8 years ago. The tree is very large, about 20 feet wide and 30 feet tall. I noticed this spring that there were mushrooms growing in the hole. It did rain a lot this winter. The tree still looks beautiful with the blossoms coming in now. I get the tree pruned every 2 years for the last 17 years. I live in Toronto in the Junction. Is there anything I can do about the hole or to remove the mushrooms?
I will attach a picture
Thank-you for contacting Toronto Master Gardeners.
Fungi (including mushrooms) tend to grow on dying or decaying wood and trees. They can be an indicator of an underlying problem with your tree, and they can herald other incoming diseases and conditions. It sounds, however, like this is an isolated problem on your otherwise healthy apple tree (Malus ssp.).
You may wish to take a look at this thorough article on the subject of Tree wounds – Invitations to woody decay fungi put out by the University of Kentucky. Trees often respond to pruning (and other) wounds by compartmentalizing the wound so that the fungi and bacteria that cause decay cannot penetrate into the healthy tissue of the tree. This may mean the fungus you are seeing in the hole is being blocked from entering the rest of the tree. Sometimes, however, this appears to be the case and the tree seems fine for years, but the pathogens have in fact penetrated beyond the compartmentalized area. The tree may eventually succumb and die.
In general, treatments to the affected area or the wound itself are not recommended. They can cause more harm than good. In any case, the mushrooms are the fruiting bodies of an underlying fungus and removing them will not remove the fungus itself.
The best course of action is to work at keeping your tree as healthy as possible. Mulching the root zone is a good practice. It helps to retain moisture, moderates temperature and suppresses weeds. Just remember to keep the mulch away from the trunk itself, so that air circulation is maintained. Regular watering, especially during periods of drought, is essential. You can also apply a mild fertilizer, based on a soil test.
Good luck with your tree.