Crisis on the Homefront

This is one of our first experiences as homeowners/landlords.....

One of the trees that made us love our house so much has totally failed us! As far as we know, this was not the result of any high winds, tornadoes or lightning but rather the tree just deciding to give out and fall over into our neighbors yard taking part of their tree with it - that's the branch you see pinned under our tree. The part that fell is only one of three parts of the tree (as you can sort of see in the second picture) so our newest concern is whether or not the other two parts, particularly the one leaning directly over our house, are going to give out any time soon. I'm feeling like we are already on borrowed time where that is concerned and the whole thing needs to go as soon as possible. We are looking into whether the tree was/is diseased at all or if this is just the result of age and weight. Stay tuned for the latest developments. We are very thankful no one was hurt. I am sad to see it go and can only think how puny a new tree will look in its place. :(