Multiflora rose (Rosa multiflora Thunb.) is a thorned bramble perennial plant that now infests more than 45 million acres throughout the eastern half of the United States. This plant's name is derived from the many clusters of white flowers borne during May and June. Older bushes can attain a height and diameter of 15 feet or more, with a basal crown diameter of 8 inches.
Dense multiflora stands severely reduce pasture grazing for cattle, as well as the accessibility and usefulness of other noncultivated acres. Severe multiflora rose infestations may lower land values both for agriculture and for other uses, such as recreation and forestry.
Multiflora rose cannot be eradicated by a one-time destructive effort. Wherever multiflora has become naturalized, the soil near older plants soon contains a large seedbank. One plant can produce up to 1/2 million seeds yearly, many of which can remain viable in the soil for 10 to 20 years. Birds and other animals disperse seeds across a wide area, but the relatively few seeds brought by them into a property where multiflora already has become established are of minor consequence. This is why a pasture cleared of older plants will within a few years, if left untreated, re-establish primarily in areas where multiflora rose existed earlier.
Multiflora rose can also multiply by layering-the process whereby tips of canes that touch the ground develop roots. New plants can also arise from the shallow roots of older live plants. Several scattered multiflora roses, if left undisturbed, can form a dense thicket within a few years.
Many persons have the misconception that they cannot successfully suppress multiflora rose on their property as long as their neighbors fail to expend equal effort. Although adjacent landowners are frequently implicated, birds often range over a 1/2 to 1 mile area, or more, enabling them to transport seed easily beyond most contiguous properties. Rose control is possible using the methods suggested here even if adjacent landowners do nothing. Multiflora rose can be more easily controlled within a single unit of land than some other perennial weeds, such as quackgrass or Canada thistle. Because multiflora rose has become widely naturalized, its control may only realistically be justified on portions of a property where its presence is detrimental to present or future land usage.
To be successful, multiflora rose control must become an integral part of each owner/operator's continuing land management plan. Two important steps are necessary: 1) the destruction of existing plants, and 2) the initiation of a yearly program to control seedlings as they appear. While the destruction of existing rose plants can be accomplished by either herbicidal or mechanical treatments, control is most effective when these two methods are combined. An alternate method of control involves managed grazing by goats and/or sheep.
Increasingly, three biotic agents are providing significant natural biological control: 1) rose rosette disease, a virus; 2) rose seed chalcid, a wasp; and 3) the rose stem girdler, a beetle. Unfortunately, these agents have not yet sufficiently reduced multiflora stands in most areas to warrant ceasing use of chemical, mechanical, or grazing control. Rose rosette disease and rose seed chalcid wasp are expected to intensify in future years to provide widespread biological control.
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