Hi Melissa: You are right that moisture on a wound cause canker. I posted "A delight blog on pruning Old Garden Rose", which the blogger advised using Elmer Glue to seal the pruning cut. Elmer is the liquid white glue that kids use.

Someone asked a question about canker in the Roses Forum. This is what I answered: Die back often result from rose stem canker. U of Illinois Extension has a good article (see below). A few points: 1) use 70% alcohol to sterilize cutting shears 2) cut to 1/4" above a bud, but NOT longer 3) use lime-sulfur spray before putting in winter-protection 4) rose dieback is often caused by WETness, either from poor drainage, or the stuff that piled on top (wet leaves).

I get cane dieback from POOR-Drainage indoor plants that sit on a saucer (indoor herbs like basil). I learn to use better drainage potting soil, rather than MiracleGro with too much peat moss and water retention. I get rose dieback from piling wet leaves for winter protection, or putting wet soil in a bucket (bottom cut off) to winter-protect. The roses that are green to tip are protected the dry-way, like piling up bark mulch to 12". David Austin Catalog recommends putting evergreen branches on top to winter-protect. Evergreen needles are very dry and good-insulation.

On winter-protection, U of Illinois stated that roses dieback more from rose cane canker (wetness around the stem). Keeping the root moist, but the stems dry is the key to prevent rose dieback from cane canker.

Here is a link that might be useful: University of Ilinois on cane canker

None of those problems sound like canker to me. The first sounds like an insect. I used to get them in R. palustris. The usual recommendation is to prune and dispose of the issue before the bug gets a chance to reproduce.

The second is probably crown gall. Did both of the roses come from the same source? The bacterium is endemic in American soils, but most cases seem to come infected from the nursery when the plants were dug.

Winter canker is a brown or black oval of damage on the cane, often with a red edge.

Yes -- I had the same reaction as Mad Gallica. Sounds like crown gall to me.

And, yes, every plant I've ever had manifest Crown Gall came from one specific nursery.

Jeri

European usage of the word may be different from US usage, where it refers to a fungal infection of the bark. I agree that the cauliflower thing sounds like crown gall, which can affect stems or roots as well as crowns. Cut well below the lesion. Sterilize the cut and the tools with a bactericide.

We have a stem girdler like (c) but it is a beetle of a different genus (Agrilus). Your (a) could also be an insect.

Okay, crown gall sounds like it is the second kind of damage. My plants have both been in place for a number of years, with this problem showing up for the first time this fall. Both roses are home-propagated, one by me and one by a friend. I think the bacterium was just there and found a point of entrance. I will keep Michael's tips in mind. (Is there a common substance, bleach perhaps, that's a bactericide?) I used the wrong terms because I didn't know better.
Canker doesn't appear to be the problem, to judge by the pictures in the UI article Strawberryhill linked--thank you for the link and for your information! I still don't know about the first set of symptoms. I'll keep insect damage in mind. I appreciate everybody's feedback!
Melissa

Melissa -- CG can be spread on pruning shears -- which is why it's easy for the bacteria to spread in a close population -- for instance, a nursery where they are regularly taking cuttings.

Some folks sterilize their pruners between plants, so inhibit the spread of something like this.

There is something called "GALLTROL" which is a specific against the bacterium. I've heard people say it was effective, and others say it was ineffective.

One thing for sure -- you can carry it from your infected plants to others in your garden on pruners, if you don't take precautions.

If I were going to remove a plant that was galled, and it was in the ground, I really think I would remove all the soil I could, and treat the area with chlorine bleach -- and THEN let it sit for several months. But that's just me.

Here is a link that might be useful: GALLTROL INFO

Jeri,
Thanks for the tips. For some time now I've been conscious of the risks of spreading disease by way of my pruners, and I carry a bottle of strong bleach solution with my gear and use it on my pruners between plants and after cutting off some particularly ugly growth. In the two cases of crown gall (as it seems to be) that I found, I broke of the branch and carried it away. I checked 'Cornelia' yesterday and didn't see where the cane came from, so will await developments, and I still need to see what's going on with 'Ghislaine de Feligonde'. I notice she has some tired looking canes, but they could just be old. I hope I took cuttings from 'Ghislaine' because, while I'm not particularly fond of this cultivar, I have only the one plant of her. I think I would like her much better in a different position, in with the warm climate roses rather than among the European old roses in whose company she finds herself.