Multiflora rose, Rosa multiflora, is a member of the rose family (Rosaceae).
Originally introduced to North America from Asia as rootstock for ornamental roses. It was later promoted by a variety of government agencies in both Canada and the US for its use in erosion control, as a “living fence” and to attract wildlife. Seeds are spread widely by birds.
Medium-sized, thorny, perennial shrub.
Can grow to 5m tall.
Canes form wide arches that re-root when their tips touch the ground, facilitating spread.
Leaves divided into sharply toothed leaflets (from five to eleven).
Flat-topped clusters of many small, fragrant, white or pink flowers.
Blooms in May or June.
Small bright red hips are produced in mid-late summer and remain on the plant through the winter. Hips are much smaller than those of native species.
What it does in the ecosystem
Multiflora rose has a wide tolerance for various soil, moisture, and light conditions. It occurs in dense woods, along stream banks and roadsides and in open fields and pastures. Multiflora rose is extremely prolific and can form impenetrable thickets that exclude native plant species. Multiflora rose is relatively widespread across PEI.
Before selecting a control method, consider the following
The size of the infestation.
The amount of effort you are willing/able to expend.
Often, multiple control methods are used simultaneously.
Consider the local ecosystem and what other organisms or ecological processes may be affected by management.
If managing during the spring and summer, it is important to watch for nesting birds that may call the infestation home.
Focus on smaller, younger populations first and foremost in your removal efforts. These are known as satellite populations, and are generally responsible for the bulk of an invasive species’ outward expansion.
As multiflora rose is covered with sharp thorns, it is important to protect yourself during management.
Wearing thick gloves, eye protection, and clothing that covers the arms and legs is recommended.
Control efforts should begin before fruit forms to prevent further spread of the plant.
Fruit begins to form in July.
Physical removal is a recommended method of control. This can be accomplished by digging up the plant, roots and all. If roots are not removed, the plant will resprout.
It may be necessary to cut the stems down to access the roots. Using a shovel, winch, or mechanical lever will prove effective in uprooting the plant. Seedlings can be hand-pulled.
Mowing multiflora rose can be an effective control measure if regularly repeated.
Mowing an infestation three to six times annually for several years has been proven to kill the plants over time, but will not provide immediate results.
This may be the best option for larger patches or for those without many labour resources.
Disturbed soil should be tamped down to prevent exposure of additional seeds.
The site can be covered with a thick black tarp to suffocate any new growth that appears after management.
The tarp should extend at least three feet out from the infestation’s perimeter
Weigh down the tarp with soil, debris, or other heavy objects.
Maintain the tarp in place for several years, checking beneath the tarp regularly until no new growth is noted.
Patch any holes in the tarp and redistribute weight to ensure proper coverage.
The PEIISC does not provide advice on chemical control measures at this time. If using chemical controls, it is imperative that all local legislation and manufacturer’s instructions be followed during application.
FOLLOW-UP AND REMEDIATION
In any case, you will need to revisit the site regularly to remove any new growth, as multiflora rose has a long-lived seed bank.
After work is completed, it is important that all equipment be cleaned thoroughly and that all plant parts are removed from boots and clothing before leaving the area.
All plant parts must be collected, bagged, and properly disposed of.
Multiflora rose can re-root from stem tips that touch the ground, fruits will release more seeds into the environment, and roots will resprout if not properly disposed of.
Multiflora rose, like other invasive species, should never be composted. This is especially true when managed after flowering, as the flowers can still go to seed in a compost heap!
Collect plant parts in clear plastic bags marked with “invasive plant” or “multiflora rose”.
As this plant is sharp, it would be well advised to double bag the plants to prevent any accidental dispersal during transit and help keep any waste handlers safe.
Place the bags in your normal residential waste collection (BLACK BIN).
Up to two additional bags can be placed beside the waste cart if it is full.
Loads larger than this but less than a half ton truck bed, material can be taken to any waste watch disposal drop-off. Indicate to operators that this is invasive species waste. It is to be piled with the “burnable waste”
For loads larger than what will fit in a half ton truck bed, reach out to the PEIISC for specific disposal instructions. You may need to obtain a special waste permit.
Be sure to thoroughly clean all gear and clothing before moving offsite to prevent further spread of multiflora rose.
Revisit the area year after year to continue management, as the plant will resprout until its seed bank is depleted (up to 20 years).
If possible, replant the area with an appropriate native species to help regenerate the ecosystem.