Ok, I found an identification: mossy rose gall. Oh goody.
So I'm amending my questions:
1. They don't appear to cause problems for the plant, but would YOU prune them off and why?
2. Would this be a good time to prune (if one were to prune them off)?

Thanks!

I have this amount and type of galls on sweetbriar, but have not seen it on Nootka rose. As far as can be seen the stem prickles and leaflet shapes in your picture look like those of sweetbriar. Does your plant have an apple-like fragrance during the summer?

Hi bboy, No they don't have that fragrance (wish they did) . The plants originally were from the Whatcom County Native Plant sale and identified as Nootka Rose.

Got any more pictures? Really looks like sweet briar here. Species is naturalized (weedy) on the Pacific Coast, could have been collected by mistake as Nootka rose and put on the market under the wrong name. Same thing has happened with Pontic rhododendron (still being sold as the native, even though I pointed out to the grower who was the original source of the misidentification (he found it growing on its own, so it must have been the native, right?)) and cranberry viburnum (Viburnum opulus, another locally naturalized Old world species, being sold as the really quite different and not found natively in the lowlands V. edule).

Weirdly enough, I don't have any of the flowers. Would close-ups on a leaf do? No flowers now, though I could probably find some hips. Just let me know what to shoot and how close. I wouldn't be at all surprised at a misidentification. I've seen it happen at plant sales especially when it comes to native plants (the ones even I can identify correctly).

Shoot with prickles, leaves and hips should make it possible to tell.

Mossy rose galls. The most I've ever seen on one rose!

I saw a Rosa glauca (R. rubrifolia) full of those galls on a garden tour in Alderwood Manor last month.

Here are the shots bboy asked for.

So, do I prune the galls out? If so, would now be a good time? And were they the reason for a lack of blooms?

Thanks!

No relation to fewer blooms.

A tiny, speck-sized wasp lays eggs in the plant tissue -- stem or leaf. When larvae begin feeding, they inject salivary juices into plant cells that eventually create the galls.

You *may* be able to limit the population for the following year if the galls are removed and discarded (or burn) before the adults emerge. (You can split a gall in half to look.)

My Rosa glauca began having galls in its 3rd or 4th year, and I removed those few galls each successive year. We left the property 2 years ago so I can't say if removing the galls helped limit galls or not.

Again quite like sweet briar. If there is no smell then must be a dog rose. Would never expect this to be Nootka rose - it appears you were supplied one of the aforementioned weedy species instead of the native.

I have just discovered, September 19, 2022, these fuzzy galls on wild Nootka Rose, definitely Nootka Rose here in British Columbia.

I have just discovered, September 19, 2022, these fuzzy galls on wild Nootka Rose, definitely Nootka Rose here in British Columbia.

Rose (Rosa)-Gall wasp | Pacific Northwest Pest Management Handbooks (pnwhandbooks.org)