Question
I have a large maple tree in my yard.  It has an open knot hole approx. 3" in diameter.  There is a white Fungus that has coated and is growing inside the cavity (the inter cavity is approx. the size of a large canteloupe) and actively growing outwardly from the hole as well.  Is there anything that I can't use to effectively treat and kill this Fungus/Fungi without harming my maple tree?

Fred
TN.

Answer
This sounds like one of the decay type fungi. What you are seeing is the fruiting body of the fungus.Thsi is how a fungi spreads--spores on the under side of the "mushroom" will be spread by wind to other hosts that maybe wounded. a Natural cycle.  The fungus is located in the wood in the tree trunk. The wood is a non living part of the tree and is for structure and support. I would guess that the tree is hollow due to the decay. If the foliage is green and full there is no worry. The fungus will continue to live in the hollow tree but will not harm the health of the tree. The worst thing that could happen is the trunk could become weakened and break during high winds. If the fruiting body is a bother simply break it off and throw it away. There is not anything that can be sprayed on the fungus to kill it. It is similar to a decayed tooth it would take drilling and scraping of the inside of the trunk to rid the tree of the fungus --all this is not needed --the tree will be fine.


I would fertilize the tree with 10-10-10 fertilizer at the rate of  1 lb per inch of trunk diameter  scattered around the tree and watered in good. Apply just before a rain storm and you will not need to water. Apply the fertilizer this Fall and again in the spring.