Almost all of us, whether homeowner or landscape professional, have dealt with invasive plants in our outdoor spaces. Burning bush (Euonymus alatus) is routinely planted in new housing developments and is almost a requirement in front of every post office and McDonalds along the eastern seaboard. Bittersweet (Celastrus orbiculatus) is pervasive, and knotweed (Reynoutria japonica) is as challenging to remove. Some hide among your garden plants and require a keen eye. Mugwort (Artemesia vulgaris) pops up in the back of a bed, or among taller plants in the meadow and garlic mustard (Allaria petiolata) suddenly appears one spring when you didn’t even know it was around.
Dealing with each of these plants (and the many more that have taken over parts of our landscapes) can require different techniques. Most professionals will tell you to look for these plants and find them when they first appear in your landscape. The goal being to stop them when the infestation is small and prevent a bigger more complicated method of removal and restoration. If you are a steward of a natural area or you monitor the trails at a local nature area, this is the best advice we can give you.
There are plenty of resources out there for you to use, and some good research can be helpful. First, and foremost, leave chemical treatment to the professionals. More harm than good can be done to both humans and the ecosystem with improper use of herbicides. There are opportunities for mechanical control that can be extremely effective. One method is simply removing the flowers so that seeds are not produced. Purple loosestrife (Lythrum salicaria) produces copious amounts of seed; by cutting off the flowers, seed production is halted and spread is reduced. Plants with berries, like multiflora rose (Rosa multiflora) and buckthorn (Rhamnus cathartica or Frangula alnus), may seem like they produce good food for birds. However, these berries do not produce the kind of nutrition that our migrating songbirds need for their long flight. Removing the berries, thus also the seed, can help minimize the spread of these species. Digging out individuals and allowing the plant to desiccate in the sun is an easy remedy for individuals or small shrubs.
Understanding the growth habit and spread mechanism of each plant you are trying to control is important. Take the time to read about your target plant. Does it spread by seed or by underground root or rhizome? Determine when the best time is to work on controlling the spread or the plant as a whole. Use the information available to determine when and how to begin. These steps can help you be more effective and eradicate unwanted plant material growing around your property.
Resources:
Invasive Plant Atlas of the United States A National site, this is a collaborative project between the National Park Service, The University of Georgia Center for Invasive Species, Ecosystem Health, the Invasive Plant Atlas of New England and the Lady Bird Johnson Wildflower Center.
Mass Audubon provides photos and information on about 30 species of plants found in the northeast that are considered invasive.
Mass.gov also has a site where you can get information on 72 species recognized as ‘Invasive’, ‘Likely Invasive’ or ‘Potentially Invasive. There is also a link to the Massachusetts Invasive Plant Advisory Group (MIPAG) web page.
U.S. Forest Service also have some good information about invasive plant species outside of the New England region.
Cornell Cooperative Extension has information on 12 species, but also links to the Invasive Plant Atlas of the United States and has a monthly webinar series and the Invasive Species curriculum for Middle and High School students.
The College of the Environment contains more information about plants that are considered invasive on the west coast, specifically in Washington State!
Invasive Species Awareness from the Trustees of Reservations provides some good tips and further links and information sources
Connecticut Invasive Plant Working Group provides not only information, but also native plant alternatives. This group also holds events, workshops and an annual symposium on invasive plants out of UConn in Storrs, Connecticut.
The Center For Invasive Species and Ecosystem Health offers a primer on invasive species, concerns, an extensive catalog of species, and suggestions for detection and control.
North Carolina Invasive Plant Council The Council is made up of land conservationists and land managers, ecological consultants, researchers, plant nursery industries, botanical gardens, environmental stewards and concerned citizens. Invasive plant list
Pennsylvania Invasive Plant Fact Sheets detailed at this site. It lists trees, shrubs, vines, grasses, aquatic, and herbaceous plants.
California Invasive Plant Council has photos and information on invasive plants as well as watch list species.
