Hydrangea pruning often puzzles gardeners. Toward month's end, prune and fertilize roses. Many growers, after pruning off old growth, treat the bush immediately with a fungicide, helping to control diseases such as black spot that overwinter on the old canes. Wetable sulfur is also registered, and is also less toxic than other fungicides currently registered for use on rose diseases. Read the label carefully and wear appropriate protective gear, including goggles, gloves, and a hat when using any pesticides.
Eye protection is particularly necessary when mixing pesticides.