Maybe 12 years ago, I wrote the article linked below. The 3. at the end is a foornote to the 3 after susceptibility. George Mander "has made arrangements with a wholesale rosegrower, Jan Verschuren, to graft his budwood on R. canina. Jan prefers R. canina currently. R. canina is what was used there before WW2. The original canina was notorious for suckering. There are new canina selections since then. R. canina cv. "Inermis" is the most widely used variety. Much less suckering takes place, but it still suckers. R. canina cv."Heinsohn's Rekord" is regarded as the very best for Hybrid Teas (Jan agrees out of experience). R. corymbifera cv. "Laxa" or R. dumetorum cv. "Laxa" is more and more being grown on Europe's mainland. It was always used as a rootstock for Great Britain only. Because it suckers little and is, therefore, a cheaper way of growing roses, the mainland now also grows more and more on Laxa. However, Laxa is not as winterhardy as R. canina. For treeroses, R. canina cv. "Pfander" is the best one (his family has a well established R. canina cv."Pfander" weeping treerose of The Fairy in their garden at home surviving at some -24 degrees C unprotected, its budunion up in the air). Cheap fast production for big box stores has opened a market for multiflora cutting rootstocks for treeroses in Holland, but they have little winterhardiness. He also points out that R. multiflora is softer and the grafts a little more likely to be weak during the first year (Brad had one of George's Canadian White Star break right at the bud union; it can happen in a strong wind). Multiflora is much faster in production, but has a shorter lifespan than canina. Brad's experience is roses grafted on R. canina suckered freely and didn't produce as many basal shoots as R. multiflora or own-root roses. However, Jan points out that multiflora was shipped to Sweden because they had guaranteed snow cover in their winters. All other parts never wanted multiflora because of its frost susceptibility 3. Obviously, there is great debate going on here concerning the relative merits of various rootstocks." "3. This has always been a hot topic for Jan. Another former local grower here lost his crop on multiflora when temperatures went down to minus 24 degrees C. "I should have put more straw on" was his thinking... Jan hills up his budunions in fall and sleeps easy, even with minus 24. In his opinion, multiflora is never as winterhardy as R. canina selections are. As his father mentioned when he said to him that all growers use multiflora in Canada. " What?! Are they backward there?" The name Verschuren is closely related to rosegrowing in Holland. They are rootstock specialists. They produce seed, stratify and produce rootstock (about 6,000,000/ yr); and are only a medium size rootstock grower! Combined with Germany and the huge rosegrowers, competition is immense. Out of the competition, the best emerges because of the scale in which things are done there. The scales are different in Canada: here, rose production is done on a hobbyfarm basis. Multiflora is easy to grow; that is why it is used here; that is Jan's conclusion. When he met Otto Palleck, the just retired Ontario rosegrower, Palleck said, "What? You grow on canina? That is the best rootstock there is, but we cannot get No.1 quality here...." That was most likely not his only problem, as seed germination with canina requires 2 years of stratifying. Brian Minter told Jan initially when he started out doubtfully here with canina rootstock, "Do the best you can and grow the best product possible, and you will succeed" Now, Jan has customers who are coming back raving to buy more. His treeroses did not blink their eyes at the cold last winter." Here is a link that might be useful: A Visit with B.C. Rosemen

Yes. It is possible. A recent paper by Golino et al discussed in detail the root to root transmission of RMV. The abstract for that paper is on line at the link below. Golino works at UC Davis with the collections of grapes, strawberries and roses that are there to provide disease free plant material. The paper on root to root came about because they were seeing RMV where it shouldn't have been. I talked to her several weeks ago and the info in the paper still stands. In addition, there are a lot of papers about other root-to-root transmission of other viruses in other plants in Rosaceae. If you have access to a university library, you should be able to get the full paper from that library. It's well worth the effort. And there is also the possibility that Chamblees might have RMV in some of their roses. RMV in my garden definitely shows in times of stress. Here is a link that might be useful: Abstract :Transmission of RMVs

Today January 2, I dug up Comte de Chambord, grafted of Multiflora rootstock. Bluegirl had it for a few years in her alkaline Texas, didn't bloom well so she gave to me, since I have more rain. As multiflora-rootstock, Comte bloomed OK in spring but stingy afterwards, while my 2 other Comte as OWN-ROOT bloom profusely with 4 flushes until snow hit. I have Comte-on-multiflora for 2 years. It's so stingy in the summer I moved it next to the rain-spout in July. Its root was the same size as my marigold !! It became even stingier, despite my using the entire bag of coarse sand to make my clay fluffy. So I dug up Comte grafted on multiflora today, Jan 2, and IT WAS THE MOST PATHETIC multiflora rootstock that I had ever seen in my 3 decades of growing roses !! I already posted the study that showed Fortuniana-rootstock produces more blooms than Dr. Huey, and Dr. Huey produces more blooms than multiflora-rootstock. Left side is Comte de Chambord grafted on multiflora rootstock, right side is a snapdragon annual flower root (sown from seed !!). The snapdragon-flower root is actually larger than the multiflora-rootstock. This 4+ year-old Multiflora-rootstock actually SHRANK in my alkaline clay, despite tons of acidic rain. And it REFUSED to give me own-roots at the side like Dr. Huey-rootstock. Picture taken today, Jan 2 at 39 F or 4 C. Re-post info. from Oct. 2016: Comparing Dr. Huey-rootstock, Multiflora-rootstock, and Fortuniana-rootstock from below link, worth reading: http://roses4az-mevrs.org/wp-content/uploads/An-Overview-of-Fortuniana.pdf Here in the Desert Southwest, with our generally alkaline soils and extreme temperatures, we find that r. multiflora has a shorter life span, losing its vigor after five years. While fortuniana bushes had superior root systems, they had difficulty with the harsh & cold English climate. In a study over several years, Dr. McFadden budded two hybrid tea varieties, Queen Elizabeth and Tiffany, onto three different rootstocks. After counting the number of blooms produced over many growing seasons, the varieties budded onto fortuniana produced significantly more blooms. The fortuniana plants produced about THREE TIMES the number of blooms as those on multiflora and TWICE as many as on Dr. Huey. Additional benefits of Fortuniana include increased resistance to gall, stem dieback, and root disease, such as Phytophtora and Pythium. Bushes planted over 40 years ago in Florida are still thriving. On this rootstock, plants are heavier feeders, as they have five times the feeder roots of more common varieties." http://roses4az-mevrs.org/wp-content/uploads/An-Overview-of-Fortuniana.pdf

Rooting roses teach me what cause black canker on canes: 1) Acidic & too wet soil 2) Pockets of wetness, either a clump of wet clay, or wet sand Perlite helps to create "air pockets" and fast drainage of water so canes don't rot in rooting roses. In OUTSIDE garden, can't use perlite (it decompose & flatten out), but pine-bark-mulch in planting hole is FANTASTIC for fast-drainage, and help tremendously with winter-survival: prevents feeder-roots from being frozen & destroyed. Digging roses up from Dec. 26 to Jan 1, at 40 to 37 F, here's what I notice: Dee-lish bought end of June is green to the tip, with green leaves, the soil below is made fluffy with pine-bark mulch, drains very fast, upper soil is alkaline clay to retain moisture. Same with W.S. 2000 with green & healthy leaves this Jan: excellent drainage dug down to 3 feet. While digging up Comte (grafted-on-multiflora), I notice where I mixed sand with clay: it's frozen into solid-ice. But where I have gypsum and pine-bark mixed it .. that PREVENTED SOIL FROM BEING FROZEN. I once spent 1 hour researching on whether potassium fertilizer helps with winter-survival: some site said it helps, other studies showed it did not. With my own eyes, my verdict is "No". Where I put high-potassium cocoa mulch: it's frozen solid at 40 F, same with soil below high-potassium red-lava-rock. But high calcium, esp. gypsum helps to keep soil fluffy, thus prevent roots from being frozen solid. I used gritty lime to de-ice my front-walkway, and it worked great in the winter. There are studies that backed this. CONCLUSION: Digging deep for drainage, plus make soil fluffy with gypsum & pine-bark-mulch helps with winter survival: leaves are still green & lush as OWN-ROOTS despite previous weeks of -10 to -13 below zero. Below are green & lush leaves of Dee-lish rose, picked on December 26, in my zone 5a: