Question
Jim,  I have a large European Ash tree (about 50' tall & 2.5' in diameter) in my back yard.  I built a large treehouse in the tree about 4 years ago.  I recently re-did my yard and patio, adding an expensive patio cover.  I want to keep the treehouse but avoid root & branch damage to my yard and patio as well as keep the tree from eventually destroying the treehouse as it grows.  I added supports to the treehouse to insure it's stability if the tree ever gives way.  How can I kill the tree to stop it's growth and still keep it standing?

your advise is appreciated,

Robert

Answer
You can cut through the bark just into the wood all the way around the tree trunk about two inch gap of bark cut off. This is its self will more than likely kill the tree by girdling. To make sure I would paint a herbicide called Roundup in the cuts and this will be transported to the roots killing the roots. NOW Depending on where you are located the tree trunk will start to decay. The speed of this rotting will depend on your local climate. Here is the Southern US a tree kill in this manner would fall within a couple of years. --In the western US it may stay fro 10 or more years. The branches will die first and fall from the tree so you need to be aware of the possibility.