See:
Thanks for posting this nice review Henry. It was interesting to read that in MN the idea was that R. multiflora as a rootstock didn’t seem to be used anymore. There are a few, more specialty, nurseries that sell roses on R. multiflora (I won’t name them now). The roses actually grow very very nicely on it. The bud union doesn’t get as swollen and have sections die out as routinely like with ‘Dr. Huey’ for us here in MN/WI. I was trying to find information recently if with R. multiflora being deemed a noxious weed in many states, if it was legal to sell roses budded on it in those states. I can’t really find anything specific. For a plant to be a noxious weed though, the general idea is that it can’t be sold. Maybe if it is just providing the root system of a grafted plant there may be some exception???
Not being from the USA and so not really needing to know such things…that would be such a giant oversight given potential suckering or the grafted plant dying resulting in the rootstock taking off. Having said that, even here laws often aren’t particularly consistent or without giant grey area’s or lack of clarification when getting to even slightly below the surface.
It’s interesting seeing the picture of the thorns and references to thorns, multiflora here is often from thornless varieties, finding a thorn variety here is probably a challenge.
American Rose Annual 49: 159-164 (1964)
Stock-Scion Relationships in Roses
Griffith J. Buck
…it has been observed that when the same scion variety of hybrid tea rose is grafted upon different understocks there is definite understock-stem effect upon scion growth. If understocks with chilling requirements of varying length (f_ortuniana, odorata, manetti_, Clarke and Welch multifloras and multiflora seedlings), when budded with a hybrid tea, are allowed to become fully dormant, differing growth responses can be observed when growth is resumed. On those understocks which have little or no chilling requirement as a condition to breaking dormancy — seedling multiflora, odorata and fortuniana —, the scion variety will promptly begin growth. On the other stocks, the scions begin growth after a delay corresponding to the length of the chilling requirement for each understock. This enforced dormancy, more frequently referred to as rest period or winter rest, is initiated by a complex of growth inhibiting compounds which are dissipated by exposure to cold: the chilling requirement. On its own roots, the typical hybrid tea has a very low chilling requirement comparable to that of such evergreen stocks as odorata and fortuniana. The root systems of plants have no chilling requirement. It is partly for this reason that florists producing potted rose plants for Easter and Mother’s Day prefer plants budded upon seedling multiflora roots.
http://bulbnrose.x10.mx/Roses/breeding/Buck/Buck_stock.html
I was trying to find information recently if with R. multiflora being deemed a noxious weed in many states, if it was legal to sell roses budded on it in those states. I can’t really find anything specific.
David, I am rather familiar with the Pennsylvania Controlled Plant and Noxious Weed Act (2017), and I am almost certain that selling/distributing/planting a rose budded onto R. multiflora rootstock would be a technical violation. Of course, whether there is any active enforcement of such an offense is another matter entirely, but I believe it would be a violation.
Obviously if any nursery owner is interested in selling multiflora-budded roses in Pennsylvania, he or she should independently research this, in case any of my details are incorrect. But this is my understanding of the situation: As I understand it, the act outlines that “No person may research, market, distribute, transport, cultivate, hold, retail, wholesale, propagate or display a noxious weed…without obtaining a permit” and outlines that “For noxious weeds…a permit may allow for the cultivation and propagation…for research and educational purposes only.” (Notice no permits for horticultural uses of plants classed as noxious weeds.) Important to the question of whether roses grafted onto R. multiflora would be permitted, a noxious weed is defined by the act as “a plant part or plant in any stage of development that is determined to be injurious.” I think the “any stage of development” covers seeds, and the “plant part” covers rootstocks.
All in all, it is an unfortunate situation. Here in Pennsylvania, multiflora rose is ubiquitous and probably at or near its biological carrying capacity. This is a classic “closing the barn door after the horse has bolted” situation, and the idea that the state will be able to limit the environmental impact of multiflora rose by limiting rose enthusiasts’ ability to use this useful (and in some cases free) source of rootstocks is ludicrous.
I believe that the previous (1982) version had accommodation for horticultural uses, but the more recent version does not. When the 2017 version was being considered by the legislature, I contacted the offices of a number of state legislators and brought up this issue, along with some scientific problems with the updated version, but apparently to no avail. My understanding is that it passed with a wide margin.
For more information, one can do an internet search for “Pennsylvania noxious weed control act.”
Thank you Matt for all your insights and for advocating to the legislature. That sure makes a lot of sense about “closing he barn door after the horse has bolted.” I’m glad there is the allowance or research and educational purposes. I got some ‘Burr Multiflora’ from UC Davis and their clean stock program to use in the future to graft roses onto as a biological indicator for virus as it is so sensitive and shows symptoms so readily when infected. We are hopefully getting a grant funded for some growth chambers and I hope to try to clean some roses up of virus using the heat treatment method used by Dr. Malcolm Manners and/or meristem isolation and tissue culture like UC Davis. I’ve cleaned hydrangeas of virus through meristem isolation, but roses seem really tricky and finicky for their growth in tissue culture…, so it would be nice to try both methods. I’d love to help Jesse and Lindsey at Reiman Gardens clean up some Buck roses where there are only infected versions we know of out there.
Dave, please let us know how your attempts at PNRSV clean ups go.