You state in your article, "The leaves develop spots before they turn yellow so check the leaves closely for spotting." but you did not give a cure or solution to the problem. When do river birches begin to lose their leaves, i.e. what month in the fall?

Jim. I assume you mean this article:

http://garden.org/nga/searchqa...

I would imagine there is no solution offered because it is not necessary to treat with a fungicide, at least according to this Mississippi State University Extension article on birch leaf blight. The article below does make some suggestions for management however:

http://extension.msstate.edu/n...

I don't know when they lose their leaves in your area but it will vary depending on geographical location. Maybe someone in the area can answer.