Some varieties are prone to it. In my garden, The Bishop and Desiree Parmentier specifically proliferate. Both didn't do it when very young, but grew into it.

Years ago, somebody mentioned that HTs seemed to do it only after heavy fertilizing. So I stopped that. It didn't seem to help. Moving roses to horrible locations helps, but that may be because they haven't grown into it again yet.

Mme. Franziska Krueger, a tea rose, was a champ at proliferation in my garden, along with numerous other faults, and it showed no inclination to clean up its act. I have the feeling that certain roses are just prone to this and the dreaded shovel pruning may be the only solution. Hopefully someone else will come up with a less draconian measure.

Ingrid

I certainly hope so, but I have been led to believe that it tends to repeat.

This year my Asta von Parpart looked just awful.

Here is a link that might be useful: Proliferation on Asta von Parpart

I suspect that blaming fertilizer was just somebody's guess that got repeated because it sounds plausible. It is a genetic predisposition that gets expressed (probably) because of certain weather conditions. I do know that researchers have determined that bullnose (bullhead) blooms, a similar deformity, occur only on certain varieties and only when the tiny flower buds are chilled to a certain point. Proliferation creeps me out, and I discard varieties that do it.

Yikes!! That looks like something from outer space. I had a white mini that proliferated, but nothing that creepy looking. It is no more. That's almost as scary looking as RRD or Dodder, if you've ever seen it.

I also discard roses that repeatedly proliferate.

I'm not even all that crazy about the prominent green eyes you find on some OGRs such as Madame Hardy, because it looks like it's thinking of proliferating. I won't be adding any more OGRs to my garden that are described that way.

Rosefolly

Desiree Parmentier was a terrible proliferator in my garden so I got rid of it. I grow Duc de Guiche and it has a button eye that sticks out like an "outtie", sometimes fringe is long on the button, but does not proliferate and I've grown it for years. So maybe you have some freak weather that has disposed it? Perhaps you should see if it does it again next year, and I would shovel-prune it if it does it two years in a row.

well, we did have a very mild winter then right out of the blue, a completely brutal 2 week freeze - you know, one of those coldest in 100 years record breakers (-18C. and probably laughable up there in the far north but for the UK....) Many plants have been acting oddly for me this year so I will give DdG a stay of execution for another year but any more of this horrible behaviour and it is compost. I am not a getting rid sort of gardener (too mean, too cheap) and a plant has to be seriously diseased or utterly grim before it gets the chop but definately, this is a contender for the post hole shovel.