Can I cut down my old rose bush now?

"I have 2 very old rose bushes in my front yard. They both produced some very beautiful flowers this spring. I deadheaded the spent roses and new ones bloomed. However, one of the rose bushes has only stems sticking out and no leaves and the other has some blooms but has yellow leaves with black spots. I have sprayed with a germicidal spray. Could I trim the bushes way down now and spray again or wait until the fall to do this. I am in New York. Help! -Chris