My wife and I planted a royal pawlonia this last spring/summer. It quickly grew to about 5 feet with very large leaves. Starting about a month ago the leaves started turning patchy brown and diseased looking, and now they are falling off. Is there something wrong with it or is this normal fall behavior? We live in the bay area (sj, ca) so it isnt too too cold, but the nights have turned chilly at about this same time.