Re: mushrooms decomposing the wood on my house.
Considering that mushrooms (all rot, actually ) stem from moisture, I'd say you've got a moisture problem on that wall. Do you have any irrigation systems that hit that wall? If so, redirect the sprinklers off the structure. Is there a roof mounted AC who's condensate line runs down the roof and splashes on the window/siding? If so, extend the drip tube to the ground and away from the structure. Anything that causes that area to stay wet is going to be the cause of the mushrooms and rot.
I suffer from CDO ... Its like OCD, but in alphabetical order, LIKE IT SHOULD BE!!!