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The Menace of Multiflora

rosa.jpg One of the pleasures that I anticipated in that settled age we would some day find was to walk the same paths and drive the same slow country lanes, to watch them change through the seasons, year after year-to know them like the back of my hand. We've settled here and Floyd is home. We know those winding roads well now, and as we have traveled them through the years, the pasture borders and roadside fence rows of those peaceful lanes have become dominated by an aggressive alien plant--multiflora rose. Have you noticed the arching canes of white flowers along your road this week? Unchecked, what will those open spaces look like by the turn of the next decade? I can only imagine. Multiflora rose-a self-inflicted wound.

A native of Japan, this woody plant was imported at various times since the late 1700s as root stock for ornamental roses, for preventing soil erosion, as food for wildlife (the seeds) and as a "living fence". It now infests more than 45 million acres throughout the eastern US and has been declared a noxious weed by ten states, including Virginia. Once established, it is very difficult to control, much less to permanently eradicate from productive cropland or pasture. Here's why.

Multiflora rose is a woody shrub that persists and grows larger year after year. Its canes, up to 25 feet long, are armed with sharp recurved thorns the plant is shunned by cattle. Flowers on a single long cane (of many canes that arise from roots of a single a plant) can produce up to 17,500 seeds that persist in the soil and continue producing seedlings for up to twenty years. Those seeds are eaten by songbirds (including starlings) and survive intact to be deposited in neighboring fields.

So there is good news, and there is bad news. The bad news is that this plant is especially difficult to control mechanically (by plowing or dozing it down to the ground) on steep or rocky hillsides-just the kind of terrain so common in some Floyd County areas. Chemical methods involve the application of strong herbicides like Roundup or Crossbow, and repeated applications are often necessary. Along fencerows, chemical means have been about the only choice for control.

The good news is that multiflora rose has natural enemies! It has been proposed that one of the reasons this plant "over-produces" seeds is that there are creatures that feed specifically on them and reduce the potential number of viable seeds. One such feeder is the tiny rose seed chalcid wasp that lays its eggs only in multiflora rose hips. In populations where the seed chalcid has spread, seed viability can be significantly reduced. This wasp's lifestyle has a negative impact on multiflora rose, and it is being spread slowly and naturally (probably traveling on birds) across all states that bear heavy rose infestation. I'll be curious to see if I can find the wasp larvae locally when, out of curiosity, I cut into multiflora rose hips with my pocket knife later this summer.

The second factor in the potential biological control of Rosa multiflora is rose rosette disease (RRD). This is a plant virus spread by a particular air-borne mite. When present, RRD causes "witches broom" growth on the rose plants. These abnormal growths are cold-sensitive and the canes usually killed during the winter. Mortality is high as ninety percent in those areas where RDD has spread. This plant pathogen would seem a natural solution to this thorny problem that confronts us along our favorite back roads. However, RDD infests ornamental roses as well, so some careful breeding for resistant or tolerant garden roses may be needed to keep everybody happy.

In the end, a few decades from now, the multiflora rose population explosion that plagues Floyd County today may be brought under control by a wasp, a mite and a virus-by predation and disease, the kinds of natural checks and balances that typically regulate excesses in natural systems. However, until then, the best offense is a good defense.

Catch them when they're small, and grub them up by the roots like we do along our logging roads here on Goose Creek. Or else stand back and watch them grow! You can stop and smell the roses as you walk your fields and woods this summer and fall. Then I'd suggest you whack the livin' daylights out of 'em. (Main source for facts in this column come from Invasive Plants of the Eastern US-see http://tinyurl.com/fjkdr )

This is the upcoming column for the local paper. Normally, I wouldn't post these pieces here until after they appear in the paper, but in this case, I've already waited too late for local roses to be clearly visible in flower. But maybe they're still flowering where you are, and this will make you notice them as you drive around your part of the country. Anybody know if there are ordinances or monies for eradication of this plant where you live? There ISN'T in Floyd.

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Comments

There is a stand of this rose at the entrance to our neighborhood, and every fall I harvest some arching canes with rose hips, to use in floral arrangements. I can attest to those thorns!! I didn't know it is considered such a pest. Too bad, since it is so pretty when it blooms.

Your article and post are very timely: a friend who drove US-29 south through Virginia two weeks ago asked me about the profusion of "wild roses" she saw - was this something new? The next day you had a brief post about it. The two of you spurred me to do some research then, finding out a lot of what you explain here.

We had these roses on the fence around the back yard when I was a child (40 years ago in Alabama); I had no idea they had become such a pest.

Interesting that until recently the powers-that-be were still encouraging people to plant them, I learned.

By the way, the ones on the fence at my Mom's house did die off. I'm not sure when - sometime in the past 20 years ... maybe those wasps or diseases got them.

I have some bound copies of the Missouri Conservationist magazine from the 1940s, and in them the department speaks of the wonderful qualities of this plant, encouraging farmers to grow it wherever they can. Irony at its best. (This was also the time when they spoke lovingly of a pesticide called DDT.) Change is good.

I have 13 acres in southwestern Pennsylvania and have a lot of problems with deer passing through my property. I've noticed that the deer avoid those sections of a fence line that have grown up with Multiflora rose and I would like to fill in the entire fence line with Multiflora. What's the best way to do this? Can I take cuttings from existing plants and lay them in the open areas? What's the best time of year to do this? I've started to mow the rest of the property, so I'm not worried about the Multiflora spreading.
Thank you

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