Invasive plants are a problem around the country and around the world. Some invasive plants are much more damaging to the local flora than others. Removing invasive plants allows native plants to grow better. The result, native animal species often thrive on their native food
source. Identification of invasive plants can be tricky. If you click here
you will find a brochure that outlines many invasive plants in North America. Additionally, I have put a write-up from the New England Wild Flower Society below that speaks to how to safely remove many of the most common invasive plants.
How to and against what:
Compiled by Chris Mattrick, Hannah Vollmer, Bill Brumback, and Ted Elliman
New England Wild Flower Society-Framingham, MA
Norway Maple (Acer platanoides)
Mature trees in vicinity of natural areas should be removed to eliminate potential seed sources.
Cut-stem application or basal bark application of 25%-35% Glyphosate.
Garlic Mustard (Alliaria petiolata)
Plant is a biennial. Pull plants or cut to ground before or during blooming in spring. Can also pull rosettes in the fall.
Can also spray foliage with 1% Glyphosate in early spring
Japanese Barberry (Berberis thunbergii)
Can pull out plants and seedlings.
Cut-stem application of 25% Glyphosate in late summer/fall is effective
Oriental Bittersweet (Celastrus orbiculatus)
Can pull small plants, but must get entire root.
In late summer or early fall, apply 25% solution of triclopyr to cut stems – more established stands may require cutting earlier in season and then spraying resprouted foliage 1 month later.
Black Swallow-wort (Cynanchum louiseae) and pale swallow-wort (Cynanchum rossicum)
Small infestations can be repeatedly removed by digging out roots for several years – each small piece of root will produce a new plant.
Can cut in mid July to prevent spread of seeds but cutting will not kill plant – plants cut during the flowering period will recover, flower, and produce seeds.
Best option is spraying foliage using 1%% triclopyr at flowering in June – Can also cut stems and apply Glyphosate to cut stems, but stems are very small, and this treatment may not be as effective as foliar applications.
Winged Euonymus / Burning Bush (Euonymus alatus)
Pull smaller plants when soil is moist.
Cut-stem application of 25% Glyphosate in fall.
Japanese Knotweed (Fallopia japonica)
Mowing or cutting to ground can be effective, but must be continuously treated.
Can use rugs or heavy black polyethylene to smother plants.
Best method is to cut stems off at about 3 feet high just below a stem node – use a squirt bottle and fill hollow stem up ¼ of the way with 25 % Glyphosate (Rodeo if in a wetland). In all cases, dispose of cut stems properly, since the plant can resprout from stem or root pieces
Glossy Buckthorn (Frangula alnus) and Common Buckthorn (Rhamnus cathartica)
Seedlings and small plants can be pulled in early spring and summer.
Annual burning for 5 or 6 years will kill most seeds and older stems.
Cut stem and treat with 25% Glyphosate (Rodeo if in a wetland).
Morrow’s Honeysuckle (Lonicera morrowii) and other shrubby honeysuckles
Can dig plants but entire root must be removed.
Cut stems and treat with 25% Glyphosate (Rodeo if in a wetland).
Purple Loosestrife (Lythrum salicaria)
Can hand dig when there are only a few plants (less than 10).
Spray plants just as they are beginning to flower with 1% Glyphosate (use Rodeo since this plant is found in wetlands). In some small stands, cutting plants ahead of time and spraying resprout will increase effectiveness of control but also increase disturbance
Biological control, Galerucella beetles eat leaf and roots, can be used on large stands.
Japanese Stiltgrass (Microstegium vimineum)
This annual plant, similar-looking to native whitegrass (Leersia virginica), flowers and seeds in the fall. Repeated annual pulling or weedwacking before flowering will diminish populations.
Foliar spray of 1% Glyphosate (Rodeo if in a wetland) – or Journey (active ingredients are Imazapic, a pre-emergent herbicide, plus Glyphosate) may be used in upland situations.
Common Reed (Phragmites australis)
Cutting 3-4 times a growing season for 3-4 consecutive years can work, but if you don’t cut enough or skip a year, the stand can increase in density and still spread by rhizomes– if possible, remove shoots to prevent resprouting.
Can use cut-stem method – 25%-35% Glyphosate (use Rodeo, since Phragmites is found in wetlands) generally in early August through September. Foliar spraying will also work, but should be used primarily on monocultures since foliar spray can also reach non-target plants in the area.
Note: There is a native subspecies of Phragmites, which is not invasive, so be sure to properly ID your plants.
Multiflora Rose (Rosa multiflora)
Plants can be pulled in spring. Use a weed wrench on large plants. Some resprout will probably occur.
Repeated cutting 3-6 times a growing season for several years can be effective.
Can spray foliage with 5% Glyphosate but best to cut stem in late summer followed by 25% Glyphosate (use Rodeo if in a wetland).