There was considerable black spot on the climbing roses and the defoliation that goes with it. Black spot is probably the No. 1 disease of roses. The best way to treat it is to prevent it. The spray I use and recommend for black spot on roses is neem oil.
Neem oil is an organic insecticide, fungicide, and miticide.
In addition to being an excellent control for black spot and other fungal diseases that affect roses and other plants, it also controls more than 200 insects as well as mites. To prevent black spot, begin spraying the roses now as new growth emerges and continue spraying on a regular basis every seven to 10 days all season long. Be sure to coat the leaves and the canes when spraying. I would like to apply Milky Spore to my lawn. Milky Spore will remain in the soil as the main, long-term control.