I have just done battle with a formidable opponent—one that is tenacious, heavily armed and fully equipped to go on fighting for decades. This enemy of civilized horticulture has no scruples, guiding ethos or any closet-bound skeletons that would make it susceptible to blackmail. It is, in short, Rosa multiflora, occasionally known as “the Japanese rose” or the “seven sisters rose”.
Rosa multiflora looks innocent enough, especially when it is young. The canes are covered with groups of five to eleven toothed leaflets borne on arching stems. In the spring, flowers burst forth, opening in profuse clusters that amply justify the plant’s Latin name. Individual blooms are only about half an inch wide, with five white petals apiece ranged around a center of golden stamens. Rosa multiflora has the gift of fragrance and the flowers issue a strong invitation to passing pollinators. Later on, the petals pass away and the plants develop ripe, red hips that offer the same temptations to passing birds and small animals.
All of that makes it sound as if Rosa multiflora is a godsend, rather than the scourge that it has become. While no plant is intrinsically good or evil, the multiflora rose is a textbook example of a non-native plant that adapted to its adopted country by taking on thuggish tendencies. In the century and a half since its North American introduction, the species has gone from being a blessing to an officially-condemned curse in forty-six U.S. states and parts of Canada. Its hardiness redefines the word “vigor”.
Back in 1866, plantsmen in North America were looking for a hardy rose species that could be used as a rootstock in commercial rose propagation. They found one in a hardy Asian native, Rosa multiflora. Once the rose succeeded here, landscapers, government agencies and property owners found other uses for it. The thicket-forming habit made it perfect for erosion control and beginning in the 1930’s, the U.S. Soil Conservation Service began giving away free cuttings for that purpose. The rose was also planted in highway median strips and proved to be a boon for barrier hedging. In rural areas, it was planted to provide cover and food for wildlife. Some sources even note the fact that it made excellent fodder for another tough, hardy species—domestic goats.
The shrub is perfectly capable of spreading far and wide, simply by rooting so readily. However, Nature also provided Rosa multiflora with a backup survival mechanism in the form of the thousands of seeds contained in the rose hips. Once consumed and passed through birds’ intestinal tracts, the seeds are distributed by air like miniature environmental bombs. Inhospitable soil or climatic conditions are not necessarily a problem, as the multiflora seeds can remain dormant in the soil for twenty years or more. By the second half of the twentieth century, naturalists were concerned that the rose was invading natural areas, including woodland clearings, the edges of farm fields and roadside right-of-ways. Like many non-native species, multiflora roses have no natural predators, so they tend to spread unimpeded and in the process outcompete native plants, as well as just about anything in their path.
My pitched battle with Rosa multiflora took place this past week on the north end of our summer cottage in central New York State. The fight really began few years ago, when I noticed a weak-looking rose cane emerging from the embankment next to the cottage. It was so puny that I figured the harsh winter would kill it off. Other chores took my attention and by last spring when I noticed the rose again, it had grown to be seven feet tall in spots and at least as wide. Its arching canes had done what Rosa multiflora canes always do—rooted wherever they touched the ground, creating a thicket of prickly canes and foliage. Multifloras will also climb if they find support and this one targeted a healthy rose of Sharon shrub to facilitate its skyward journey. To make the combat situation just a bit more difficult, the thicket had been affected by summer drought, so that half of the twisting mass of canes were dead and half were vibrantly alive. All were prickly.
I am not a faint-hearted multi-flora fighter and I did not face the shrub unarmed. When I attacked the thicket, I wore stout gloves, long pants, insect repellent and sunscreen. I armed myself with sharp clippers and strong loppers. Balancing on the slope and brandishing those tools, I liberated the rose of Sharon from the nefarious clutches of the multiflora. I went to work on the dead canes, clearing them out and tossing them on a pile. I wrestled about half of the thicket into submission before heat, humidity and exhaustion took over. Despite all my precautions, I did not emerge unscathed—an assortment of scratches and bug bites required follow up treatment with antibacterial ointment and hydrocortisone cream.
I expect to re-engage the multiflora over Labor Day Weekend, but I am no fool. It is very hard to eradicate. If, as I plan, I get rid of the rest of the thicket, I know that it will resprout in the spring and probably put all its energies into recovering lost ground. If my schedule cooperates, I will counter attack by removing the regrowth, preferably before it has time to produce flowers and those seed-bearing hips. Controlling multiflora rose in this way means cutting the plant back to the ground multiple times. If you don’t mind using a relatively benign herbicide like glycophosphate, you can also paint it on the cut stumps.
Plant scientists are still exploring biological controls for the multiflora rose. The problem is the same one presented by the rose itself—the potential unintended consequences of something that looks like a perfect solution to a tough problem. An effective biological control may kill the multifloras, but it might be equally toxic to desirable rose species and varieties. An entire industry and countless wonderful rose plants might be at risk. Plant scientists, horticulturists and plain dirt gardeners like me know the lessons of horticultural history—it is hard to get a genie back into the bottle, even if that genie seems ready to grant all your wishes.
As I hung up my garden gloves last week, I turned to the remnants of the multiflora and said, Clint Eastwood-style, “It ain’t over yet.” Plants are not capable of smirking and maybe the sun was in my eyes, but I would swear that I saw at least a twitch from the rose.