My maple has a hole where a limb had been removed and sometimes large fungus grows out of it. Upon inspection I can run a stick two thirds of the way through the tree. How do I repair? I'm afraid if water keeps seeping in it will rot out the tree.

Old stand by was cement in the hole; mine has cement in a hole and it is doing fine. Must be 100 years old and thriving. I love it, so much shade in the hot summer months.

Tickle has the best remedy but I used spray styrofoam once and it worked pretty well and even aged and turned brownish to match the tree. But mine was not a deep hole like the one you describe. Water into that cavity will definitely destroy your tree in short order, and very possibly attract varmints. I took a tree down near my house, a nearly 100 foot tall poplar which was full of carpenter ants seeking the moisture. Hope yours isn't a threat to the house like mine was. If it is, have it evaluated by an expert from a reliable tree service. Your tree may be too far gone already.

Years ago cement was made with lye; but nowadays the cement is of a better quality and you CAN use it to fill up this hole.