Invasive Species

Invasive plants are categorized as invasive as they are not native to our region.  Many times they are from another continent and were introduced for gardens and landscapes.    One of the reasons that invasive species are able to succeed is that they often leave their predators and competitors behind in their native ecosystems. Without these natural checks and balances they are able to reproduce rapidly and out-compete native species. 

Why should you care?

Invasive plants often destroy plants that native pollinators and other animals depend on for survival.

They also degrade wildlife habitat and water quality, reduce the quality of land, increase soil erosion, and reduce recreational opportunities.  

How can you help?

  • Plant native plants. Consider removing invasive plants you already have and replacing with native varieties. Research before buying plants.
  • Prevent invasives from reproducing. Remove and dispose of seed heads before they mature.

The longer we wait, the more expensive it will be to control. We are all in this together!

 

Buckthorn
(R. frangula and R. cathartica)

This forms into a large shrub or tree up to 25 feet in height. Common buckthorn twigs often have thorns at their tips, between the terminal buds. Branches are dotted with light-colored vertical raised marks. The bark is brown to gray and peels with age. The inner bark is orange.

It is the first to leaf out in the spring and the last to loose its leaves in the fall.  Birds spread buckthorn seeds by eating its berries.  It emits a chemical called emodin into the soil which is toxic too.

Hand pulling removes the roots, preventing resprouting. Remove plants gently to prevent uncovering buckthorn seeds stored in the soil.

If buckthorn is larger than 1½ inches, saw or clip the stems near the ground. To prevent resprouts paint the cut stumps with glyphosate (Roundup®) immediately after cutting, being careful to avoid other plants since glyphosate kills all growing vegetation. The best time to use herbicide is in the fall when buckthorn is one of the few actively growing shrubs.

Learn More About Buckthorn 

Eurasian Bush Honeysuckles
(Lonicera spp)

5-20 feet in height.  Upright, shallow rooted

Originating in Eurasia, bush honeysuckles are problematic for many of the same reasons as buckthorn, and large bush honeysuckles are often found mixed into thick buckthorn stands. The ground below thick stands is often shaded out to the point of complete bareness.

Hand pulling removes the roots, preventing resprouting. Remove plants gently to prevent uncovering seeds stored in the soil.

If plant is larger than 1½ inches, saw or clip the stems near the ground. To prevent resprouts paint the cut stumps with glyphosate (Roundup®) immediately after cutting, being careful to avoid other plants since glyphosate kills all growing vegetation. The best time to use herbicide is in the fall.

 

Garlic Mustard
(Alliaria petiolate)

Garlic mustard is a biennial herb that grows 2- 6 feet tall. Lower leaves are kidney-shaped with scalloped edges. In spring, roots and new leaves smell like garlic, and small, four-petal white flowers appear clustered at stem ends, followed by long, skinny seedpods. This weed spreads by seed and can self-pollinate, helping it rapidly displace native plants along trails, in forests, and on riverbanks, among other areas.

All parts of the plant, including the roots, give off a strong odor like garlic.

Control: In small infestations or sensitive plant communities, hand clip or pull seedlings, rosettes or flowering plants prior to seed set.

Purple Loosestrife
(Lythrum salicaria)

The purple loosestrife plant, also called garden loosestrife, can grow 3 to 10 feet tall with its woody angular stem. It is disease and pest free, and blossoms into showy purple spikes from late June to August. Dying flowers are replaced by seed pods between July and September. Each mature purple loosestrife plant can produce a half million seeds per year leading to its abundance.

Control: The best time to control purple loosestrife is in late June, July and early August, when it is in flower, plants are easily recognized, and before it goes to seed. Once flower petals start to drop from the bottom of the spike, the plant begins to produce seed. Take great care so seeds are not shaken from the plant. At sites where plants have gone to seed, remove all of the flowering spikes first by bending them over a plastic bag and cutting them off into the bag. Further cutting of stems or pulling can now take place without fear of spreading the tiny seeds.

Dames Rocket
(Hesperis matronalis)

White in color, pink, or purple in color; 4 petals, borne in terminal clusters; fragrant, clove-like aroma in evening; blooms mid-May through July. Often confused with Native phlox (Phlox divaricata) which has five petals, rather than four.

 

Reed Canary Grass
(Phalaris arundinacea)

It is a perennial coarse cool-season grass that grows 2 – 6′ high. It is a threat to most wetlands and spreads by seed and well as rhizomes.