From Boon to Bane: rosa multiflora

Above is an example of rosa multiflora in the Mark Twain National Forest. A century ago it was imported from China due to its vigour and usefulness as a windbreak; later, multiflora rootstock was used as the foundation for many grafted rose hybrids, a use which continues to this day. For example, it is used as a rootstock in the overly used and celebrated Knockout series of roses which flood every home improvement store in the growing season. Their seeming invincible quality and need for virtually no maintenance have convinced the blackest of thumbs that they are able to grow roses by just dumping the plants into holes in the ground…and sure enough, roses on multiflora rootstock often will grow and flourish beyond a black thumb’s dream. My cynicism steps up and says—a boon such as this is not without consequences of a less positive nature…as the saying goes, “if it sounds too good to be true…” But average Joe Consumer is so seduced by the belief that they can have a real rose in their yard for eternity, along with a vision of old world European gardens and whatever else their imagination allows…Because, unfortunately, imagination is all there is after all is said and done. Beyond the vigour and repeating bloom habit there is very little in the way of “old world” rose quality. These roses lack the bloom form, the growth habit variation, bloom variety (grandiflora, floribunda, etc) , color, and last, but perhaps most important—they are completely odorless; people often wonder why modern roses lack a smell but they do not bother to do the research on why. What you do have are a few shades of pink, white and yellow: bright pink, white, dark pink (called RED on labels–hah!),  and pale yellow–blooms that repeat and repeat and repeat. Aside from very little options in appearance, and no smell, you have a rose that is virtually impossible to kill. People love a “what you see is what you get” rose and will sacrifice smell and something unique for no maintenance. And moderns hybrids repeat! Many heirloom roses lack the repeat bloom, but they have amazing perfumes that vary like the finest wines, from musks to citrus, sweet to dry and complex. But many of the most durable, boring, odorless modern hybrids outweigh all these benefits to consumers in the mass market. And that’s it…or wait…is it???? Unfortunately, no…I hate to be the bearer of such depressing news for fans of this marketing hype, but multiflora and hybrids on its rootstock don’t come without further price. A BIG price that might cost the rose world it’s complex and fascinating heritage. A century ago, no one foresaw that multiflora would bring along two things that might prove to be disastrous to the rose world. One is its invasiveness. All one has to do is visit the Mark Twain National forest in May to see how invasive multiflora is. It climbs, winds, seeds EVERYWHERE it establishes. It establishes very very rapidly with a massive, suckering root system….and it is not alone. It’s  a favorite host to a very very tiny tiny mite, called the eriophyid mite. It seems such a harmless, small creature, leaving only minor cosmetic scars on plants it feeds upon…this would not be such a concern if multiflora weren’t a main susceptible carrier species for a deadly virus called RRD, “Rose Rosacea Disease”. RRD is fatal to all roses that get it.

The Eriophyid mite is so small that it cannot travel far on its own. It relies on wind currents to carry it—-to other roses, all of which are vulnerable to the RRD virus, especially those grafted on r. multiflora rootstock, such as Knockouts and many modern hybrids widely sold roses on the market and in every other backyard. Just when knockouts seemed invincible, they now are possible pathogen carriers/ attractants/ and Eriophyid hosts and spreaders of RRD. No rose is immune to RRD, but “own root” and old heirloom roses are a bit more “resistant” for what it is worth. That is why I grow own root roses, but until there is a cure, it is just a matter of time before my own root roses contract the disease and have to be destroyed. It does not stop me from growing roses, even as RRD creeps closer and closer. There are already heavy cases in Kansas, and most of the ones I have seen are on Knockout roses outside unwitting owners of restaurants, shopping malls, apartment complexes and commercial establishments that probably would not remove the affected roses anyway. The good news is that massive stands of r.multiflora  in the wild are dying from RRD, but rosarians are wary and not celebrating just yet…another slow but sure and positive factor is that many folks are beginning to look into heirloom roses once again, and in some cases, bringing back some that were once thought gone forever, such as rosa Gallica, a very durable species that has been around since Roman times.

To read more about RRD, please click on the links below.

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