I have 3 nice sized Flowering Crab trees. All are at least 20-25 years old. Up until about 10 or 12 years ago they were fine. Then they all came down with Crab tree blight (or whatever it is called. The first few years of it, they were bare by the end of July or early August. Then I started spraying with a fungicide about 5 years ago. Since then they are better, but far from perfect. They still loose leaves by early July each year, just not as bad as they were before being treated. Here is my question -- Is there any "cure" for this, so that I won't have to spray each year. Or will this last forever? I would hate to have to cut them down, because they are very pretty till this time of year. Thank you