I've also had trouble with canker some years. What I did was to cut off the cane below the affected area, then dip my pruners in a bleach solution before proceeding to the next cut. In my case the canker was so virulent in its progress that a day or two of delay would have meant dead plants. Trimming off the canker saved them and they bounced back. If anyone has a better treatment, please share!

Hi Jeff,

The advice mille_fleurs provided is what all my zillion rose books say you need to do, and that has worked for me so far. A couple of wrinkles: When you make the final cut you are going to leave on the plant, paint across the cut end with Elmer's Glue or clear nail polish to seal it off so it's not especially easy for a new infestation to get started there. And if you try using Chloraseptic mouth wash to spray on your clippers, that might work like bleach to disinfect them. (Tried that here and didn't notice any problems, though I'm not sure/really knowledgeable about its use for that purpose.)

Best wishes,
Mary

What is the difference between canker and winter damage? I have had a real problem with winter damage this year. When I see those dreaded purple spots or lines of red or purple, I just cut under them. It is very hard to do, but to me it means that the cane will die in a year or so. In the meantime, it will give me diseased junk since it is weak and not very productive.

The canes have saved up energy for a first bloom, then it is a disaster after that. If we want that first bloom, then by the time we cut, it is too late for the rose to grow well and get re-established. (The heat here is awful.)

I have wondered if the canker spreads or if it is just a sign of winter damage, and will stay put. In other words, I wonder if I should leave some canes in certain situations so they can absorb the water and sun and help the plant grow, or if those spots will spread down the cane and destroy the plant.
Sammy

I pretty much agree with what's been previously said. I think, regardless of the exact cause, it's a function of plant vigor. I used to let myself get frustrated over it. I found the very best solution is to grow roses that are generally winter hardy, disease resistant, and vigorous for my area. I still get some, but most of the time it's limited to the upper canes, canes that are past their prime anyway or roses that are less than 1 season old.

It's the one's I have to nurse during the year that are the worst offenders. No fungicide has ever had any effect for me.