One week ago, my neighbors forgot to turn off their hose and flooded part of my back yard. My Cottonwood tree was in this part of the yard and after 2 days, 3/4 of the leaves on the tree are turning yellow and dying. Could this be from the water or are there other diseases that could be harming the tree? At the same time, my other neighbors were having their air conditioner worked on. Is it possible that some Freon got airborn and ended up on my tree? My tree seems to be the only tree in the area that is affected, and it is also the largest tree. Please help!!!!