For this reason, late fall/early winter is the best time to treat it. A fungicidal application after the leaves have fallen is the best way to kill off the spores and reduce the number that can infect new leaves next spring.
As it happens, that's right now! Call us ASAP for a winter dormant spray. Remember-we have to work around the wind and the rain, so the more notice you give us, the better we can plan.