I had super vigorous new growth on my rugosa roses (fj grootendorst) and panicked, but they were ok. This doesn't help your question, but if anyone else has suspect new growth on their rugosas, feel free to post them. They have SO many thorns and grow so crazily (mine do anyways) that the new red growth honestly looked like RRD.

Patty, that is an interesting question. Professor Roush (see his blog at http://kansasgardenmusings.blogspot.com/) brought up a related question after RRD decimated his Buck rose collection. Roush wondered if roses from different genetics, in his case the OGRs like the gallicas, were more resistant. I have never seen, knock on wood, RRD in my big patch of native roses, but I just found it in a plant of Rosa canina. I have a huge (20' by 25') plant of Rosa setigera next to the Rosa canina, so I will be watching...The R. setigera leaves are kind of fuzzy -- very different from both R. canina or the leaves of typical HTs. I will be curious to see what answers you get!

Sunny

I've seen it on a half rugosa and it was different. Comparison of leaf margins, number of compound leaves per leaf axil and the growth form of the stem. From a distance, it was just a different density. Only looking up close did differences stand out , because they were there, just (to me) more subtle.

Mike in Chicago has a brother who is also a rose grower and his brother had something that sounds a lot like RRD on a R. setigera. (Henry, both are PhD chemists and wise in the ways of herbicides.)

Patty, my FJ Groot grows like a maniac. The canes bend in circles like yours, it is impossible to prune, and impossible to tell where the new growth is going to come from!

Thank you Ann its good to know to have an idea and to know that I'll likely notice it.

K JM, They grow crazy mine just had its self a wild growth spurt. We finally had a few storms with lightening and she went wild.