I have a Albizia julibrissin (mimosa tree) and it is End of April where the branches usually grow extremely fast. This one I planted from seed in a pot and transplanted to the garden a year-and-a-half ago. It grew to 15 feet and I cut it back last winter to 8 feet as I wanted to keep it small. The branches are now only a couple of feet long and they are falling off. My soil is clay which I know it grows in because I have had them in another home with the same soil. However the part of the yard has a small hill and half the roots from the tree flow down the hill where the water runs off into a slight ditch in the center of the yard. I planted another on the side of the house in a dry spot and it is doing great. Is it the amount of water it is getting that is causing this. The tree looks fine. I don't see any beetles on it. The birds are all over it which their weight keeps making the branches fall sooner. Please help.