Another reason why we prune roses in Jan(& Feb) in SoCal is to get rid of diseases. If you've been following along this month you've seen the many things I've found while pruning roses. I love detective work! This photo shows the fungal disease called Rust on the underside of rose leaves. I think that it looks like Cheese Puff dust! But it's yucky and blows all over when disturbed. Sometimes the orange parts turn black too. It won't kill a plant. But it will make the leaves look crappy and lots may fall off prematurely. Be sure to strip all the leaves off your rose when pruning. You might be able to prevent this by diligent fungicide spraying from Spring- Autumn. I am a terrible sprayer.