Question
How can I tell if my roses have black spot?  When does it appear in the spring?

Answer
This is a good time to be asking that question.  But, the prevention of black spot is something that you can take care of right now, even before the spring buds open up.  Clean up all debris from the base of the plant, and begin a spraying regime with powdered sulfur.  This is particularly important after rains where water splashes spores onto the leaf surfaces.