rose garden

Question

Main stem has black mold.

Answer 1

Do you have a photo of it? It's hard to know what the problem is without seeing the plant and without knowing under what conditions you've been growing your rose. You would be better served if you take a sample (an ailing cane that had both healthy and ailing tissue on it) of your ailing plant to your local cooperative extension for a proper diagnosis. Call them first to let them know you are coming to visit them.