By current and former members of the Society's Conservation Department:

Once an invasive species gets a foothold, removing it from an area takes dedication and effort. We believe the results are well worth the trouble! Controlling invasive plant species around your home improves wildlife habitat and decreases seed sources from which invasive plant species spread.

Definition of “Invasive”

Non-native species that have, or are likely to, spread into native or minimally-managed plant systems and cause economic or environmental harm by developing self-sustaining populations and becoming dominant or disruptive to those systems.

– Massachusetts Invasive Plant Advisory Group

Where do you begin?

The following is a general introduction to methods for eradicating invasive plant species. Images and information about the most common invasive plant species are available in the Photo Gallery. Visit Common Invasive Species and Management Options to learn about particular techniques used to combat some oft-encountered invasive plant species. Check out a  pdf of the Society's list of most common invasive plants in the New England region.

Now, you're almost ready...

What you should know before you start

 Wetlands and buffer zones

• Any activities in wetlands (from removing invasives by hand to applying herbicides) require a special permit under the Wetlands Protection Act Be sure to get a permit from before you act.  See “Controlling Invasive Plants in Wetlands” on page 23 in the Society’s magazine Conservation Notes, “Invaders... We’re fighting back” on the website for more information.

Use of herbicides

When using herbicides to treat invasive plants, certain precautions must be emphasized:

• Follow all precautions on the label. 
• Not your land? Applying herbicides to control invasive plants on property you do not personally own requires a pesticide applicator’s license issued by your state.
• Wetland conditions require special herbicides. Moreover, application of herbicide near or in wetland, aquatic, or riverfront zones and buffers requires a permit under wetlands laws in many states. 
• Remember to dispose of pesticide containers properly—read the herbicide label for correct procedures.

The first steps in controlling invasive plants

• Correctly identify the invasive plant. Invasive plants are often considered invasive in one area, but not in another. To be sure that the plant is considered invasive in your area, check your state’s list of invasive species before you begin. Links to state lists are available on the Web Sites page. 
• Identify your goals and priorities for management. Don’t pick a fight you can’t win. Rationally assess the infestation and decide if you are willing to tackle the invasive plants, perhaps for several years. In general, if you are living next to a relatively uninvaded natural area, you should consider controlling the invasive plants on your property. If the surrounding areas are completely infested with the target invasive plant, you should think carefully about what you hope to achieve before you begin.  
• Choose the best control method for the situation. Remember that there are different methods for different plants in different situations at different times. Each method requires commitment and persistence.

METHODS FOR CONTROLLING INVASIVE PLANTS

Mechanical treatments

• Most mechanical options are labor intensive, but often require less permitting and, of course, introduce no chemicals into the environment. Desirable for small infestations.
• Mechanical control usually causes a great deal of soil disturbance. Invasive plants thrive on disturbance. In some cases, the act of controlling them, may exacerbate the problem. There is no solution for this problem, but should be factored into the planning of any project.
• Permits are required for some mechanical treatments done in a wetland, even on your own property. Talk to your town Conservation Commission. Getting a permit may not be difficult.

Pulling and digging

• Woody stems less than 1” in diameter can be pulled out by hand, if they have not been previously cut.
• Well-rooted herbaceous plants and smaller woody plants can also be dug in limited quantities.
• A shovel can be used, but often severs the root system thereby leaving some behind to continue to grow. A digging fork is preferred if digging is the prescribed treatment.
• For larger stems, a weed wrench can be used on woody stems up to about 3” in diameter.
• Best time to attempt this type of treatment is spring, when the soils are moist and plants pull out more easily.

Cutting and mowing

• Goal is to interrupt the plant's ability to photosynthesize by removing as much leafy material as possible.
• By preventing effective photosynthesis, the plant must use its stored energy reserves to grow. Ultimately those reserves will be exhausted and the plants will die.
• Rule of thumb: Every time targeted material gets to knee-high or forms buds, cut it down.
• To be effective, this method must be employed at least three or four times a year for three to five years.

Chemical treatments

• Most invasive plants can be treated using one of two herbicides – glyphosate (the active ingredient in "Round-up" and "Rodeo") or triclopyr (the active ingredient in "Brush-B-Gone" and "Garlon").
• These are herbicides made up of nontoxic organic compounds that, when combined, become toxic to plants. Both bind with soil particles and break down rapidly into harmless organic compounds.
• Glyphosate is non-selective. Triclopyr is selective for broadleaf plants and may not have an affect on monocots.
• It is best to buy the liquid concentrates. "Rodeo" (formulated for aquatic and wetland situations) comes at a 53% concentration of the active ingredient. "Round-up Pro" comes at a 41% concentration. If you buy pre-mixed solutions, you are purchasing mostly inert ingredients.
• More is not better: Using the appropriate mixture of active ingredient saves money and saves the environment.
• When using chemicals to control invasive plants, it is always best to put a dye in the herbicide to track what has been treated.
• Permits are required for herbicide application in a wetland, even on your own property. Talk to your town Conservation Commission. 
• You may NOT apply herbicides to someone else’s property unless you obtain a state-issued pesticide applicator’s license.
• Make sure you read and understand (and follow) the herbicide label instructions!
• Safety gear: long pants, long-sleeved shirt, goggles, rubber boots, elbow-length plastic gloves.
• Take measures to keep others (people and pets) out of the area after herbiciding. Check label for safe re-entry times.

Foliar applications

• Excellent for large monocultures or spot treatment of herbaceous plants that are difficult to remove mechanically.
• Best used in locations where non-target effects are not a major concern. Not for use in or near sensitive sites.
• Most effectively applied when plants are actively growing and flowering.
• Some studies have found a greater effect by cutting plants to ground, allowing them to resprout, and treating the resprouts.
• Herbicide mixture should contain about 1-3% of the active ingredient for herbaceous plants and 5-10% of the active ingredient for woody plants.
• Surfactant is used to allow herbicide to stick to leaves. Most herbicides come with a surfactant mixed in, but not all. Surfactants should not be used in wetlands as they may affect amphibian life.

Cut-stem treatment on solid stems

• 25%-35% active ingredient solution should be used for all cut-stem treatments. Follow label instructions.
• Translocates herbicide directly to root system.
• Very target specific and can be highly successful in a single treatment.
• Useful for most woody plants 1” in diameter or more.
• Best done in autumn; from September – mid-November.
• Stems should be cut as close to ground level as possible, but not so low as to lose track of them.
• Stems should be treated as soon a possible after cutting – preferably no more than two hours following cutting.

Cut-stem treatment on hollow stems

• Useful on Phragmites and Polysonum cuspibatum (Japanese knotweed), or any hollow stemmed invasive.
• Best done just prior to flowering in each species. Also best done on the hottest, most humid day of the summer.
• Cut stems halfway between two of the swollen leaf nodes.
• Inject a 25%-35% active ingredient solution of typically aquatic-formulated glyphosate ("Rodeo") into the exposed chamber of the stem.
• Following cutting of stems, resulting debris must be removed from the area and dried or incinerated since both of these species reproduce vigorously from plant fragments.
• Devices for injecting herbicide into soft stems are also available.

Basal bark treatment

• Typically used on large specimens 4” in diameter or more.
• Produces a standing dead tree which can either be viewed as wildlife habitat or a hazard.
• Make alternating slashes in bark of specimen to be removed. Do not girdle!
• Spray a 25%-35% solution of herbicide into slashes. Allow to soak in for 5 minutes. Re-apply.
• Best done in autumn from late August – end of October.
• May take two to three years of treatment depending on size of specimen.

Biological control

• Widely available for only one species – purple loosestrife (Lythrum salicaria).
• Not likely to be the best method for a small backyard population.

For Additional Information

• Continue exploring the invasive plant information on the Society's website.
• Learn about particular techniques used to combat some oft-encountered invasive plant species at Common Invasive Species and Management Options. 
• Visit the Invasive Plant Atlas of New England website for more pictures and species identification information.
• See the The Nature Conservancy Invasives website for in-depth species control information.