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Invasive Exotic Plants and What to Do About Them

What Are Invasive Plants?

An invasive plant has the ability to thrive and spread aggressively outside its native range. A naturally aggressive plant may be especially invasive when it is introduced to a new habitat. Examples of invasive plants include mosses, herbs, shrubs, flowering plants, trees, vines, etc.(From www.invasivespeciesinfo.gov)

In your yard, many plants that are considered invasive won't appear to be a problem, but they may escape into our ecosystems and overtake native species by shading native plants, taking up root space, gobbling up nutrients, changing the hydrology of an area and even changing the chemistry of the soil. They also affect the lives of birds, bees and butterflies.

What You Can Do
  • learn about invasive plants in Worcester County by visiting www.invasivespeciesinfo.gov
  • identify the invasive plants on our property
  • If you have numerous invasive plants, tackle the ones that are just taking root. Pull them and plant native species in their place
  • Properly dispose of pulled invasive plants to ensure they won't reseed or reroot
  • Invasive plants are aggressive such as oriental bittersweet, so you may have to monitor the area for several years
  • Collaborate with your neighbors, property lines don't stop them from spreading
  • Plant native shrubs and trees - visit www.newfs.org/grow for a list of natives to plant

Invasive Plant Alert!
Water Chestnut (Trapa natans)
From the State of Connecticut Department of Environmental Protection and the U. S. Fish and Wildlife Service
October, 2012
Please be on the lookout for this non-native invasive plant, and immediately report any sightings! It has recently been found in Keeney Cove in Glastonbury and in the Hockanum River in East Hartford. There are also dense infestations in two coves along the Connecticut Riber above the Holyoke Dam in Massachusetts. Early detection is the key to protecting our aquatic ecosystems!
How to Identify Water Chestnut
Description: Water Chestnut is a rooted, aquatic plant with floating and submersed leaves. The floating leaves are green, glossy and triangular, with toothed edges. The submersed leaves are feathery, and are found whorled around the stem. Plant stems are cordlike and can attain lengths of up to 16 feet. Water chestnut is an annual, overwintering entirely by seed. The fruit of this plant is a hard nut-like seed with 4 sharp spines; it is green when fresh or black when dry. Seeds may remain viable in the sediment for 5 years or more. (Please note: this plant species is not the same as the "water chestnut" used in Asian cooking.)
Habitat: Shallow areas of freshwater lakes and ponds, and slow-moving streams and rivers.
Threats: The dense growth of water chestnut can effectively choke a waterbody, making boating, fishing and swimming nearly impossible. This weed also shades out native aquatic plants and offers little value to wildlife. The seeds have sharp spines that can inflict puncture wounds. Should chestnut become established in Connecticut, it has the potential to become the dominant plant in the shallow waters of all Connecticut River coves, including the tidal freshwater coves from Hartford to Essex. All shallow (<16 ft.) lakes and ponds are also at risk.
Distribution: Water chestnut's native range is Europe, Asia and Africa. Since its introduction into North America in the late 1800's, it has become a nuisance species because of its ability to reproduce rapidly and form dense floating mats. Water chestnut is presently found in Massachusettts, Vermont, New York, Pennsylvania and Maryland. It was first identified in Connecticut in July, 1999. Two small coves along the Connecticut River in Holyoke, MA have infestations of this aquatic weed. Seeds may have drifted downstream, and ducks and geese may also be responsible for dispersal. Canada geese have been seen with the spiny nuts attached to their feathers.
Control: Early detection is the key to control since smaller populations are easier to eliminate than larger ones. It also costs less to control a small infestation because plants can be individually hand-pulled. Large populations require the use of mechanical harvesters or application of aquatic herbicides to achieve control. Infested waters must be treated for 5-12 years to eliminate the invading population. However, some infestations are so extensive (e.g. >300 acres in Lake Champlain in Vermont) that complete eradication may never be achieved. Because prevention is so important and control efforts so costly, many states, including Massachusetts, New Hampshire, South Carolina, Florida and Arizona, have adopted laws that prohibit the possession, transport or distribution of water chestnut.
References: A Guide to Invasive Non-native Aquatic Plants in Massachusetts. C.B. Hellquist, North Adams State College, and Massachusetts Department of Environmental Management, Lakes and Ponds Program. June, 1997.
Vermont Invasive Exotic Plant Fact Sheet Series: Water Chestnut.  Vermont Agency of Natural Resources and the Nature Conservancy, Vermont Chapter. June, 1998.
Please report any sightings of water chestnut to:
Harry Yamalis
Connecticut Department of Environmental Protection
Office of Long Island Sound Programs
79 Elm Street
Hartford, CT 06106
Race is On to Eradicate Invasive Water Chestnut Weed
By Lynne Hendricks
Staff Writer

AMESBURY — Even as residents along Lake Gardner grapple with how to control a lake bottom teeming with milfoil, an invasive species threatening to deplete the lake of oxygen and force native species into extinction, another invasive species with even greater ability to overtake the ecosystem has quietly emerged to threaten nearby Lake Attitash.

Members of the Lake Attitash Association were granted an emergency order from the Conservation Commission this week that will allow volunteers to fan out along Attitash's back river region this weekend to pluck a thriving crop of water chestnut while the weed is at a manageable stage of development.

"We are poised to begin an emergency eradication program," said conservation agent John Lopez. "Evidently these plants are just about ready to seed. I issued them an emergency certification to allow them to go in and pull these plants."

Lopez said the group is waiting for the weather to clear before heading out on the lake, and volunteers are needed.

"They have 30 days (per the order)," Lopez said. "They hope to do it as soon as the weather clears. They need to pull these things out this weekend."

If the flowering, floating plants are allowed to drop their seeds, as they typically do between mid-July and the beginning of August, the species could prove catastrophic for the lake environment.

"Water chestnut is highly invasive, and if left alone could take over our lake in a few short years," said LAA representative Katie Karatzas in her petition to the commission. "One acre of water chestnut can produce enough seeds to cover 100 acres the following year,"

The water chestnut, or Trapa natans, is a floating, leaved vine that forms a canopy over the surface of lakes and ponds where it takes root. It can become so dense in such a short period of time that it quickly impedes navigation on the body of water and restricts swimming and recreational fishing.

Instead of being a positive for local fish populations, however, the decomposing plant settles on the bottom of the water and snuffs out native plants that fish populations depend on. Over time, the weed reduces dissolved oxygen levels in the shallow portions of the lake, which further threatens fish populations.

The University of Maine Cooperative Extension reports an outbreak of the weed in Lake Champlain cost $3.7 million to eradicate over a period of 18 years.

"That's why people have to clean off their kayaks and their boats when they go from one water body to another, because it's a real nuisance," Lopez said. "It's rather aggressive."

The weed was found in the back-river section of the lake when the state Department of Conservation and Recreation hosted a weed identification class at the site on July 1. DCR Lakes and Ponds coordinator Jim Straub identified the species and helped Attitash volunteers understand the need for taking immediate action.

"The problem is at a manageable size right now," Karatzas said. "Water chestnut is an annual species, which reproduces only by seed ... . Persistent removal of the plant prior to seed drop can dramatically reduce the population over time. Each year will be less work until the weed is gone. Then we can take a proactive approach and simply monitor the lake a couple times each year."

Those with kayaks and canoes who are interested in helping the effort are urged to contact the Lake Attitash Association by e-mailing katiekaratzas@yahoo.com.

"Our goal is to solicit volunteers to hand pull the weed as seen in the guide to hand pulling water chestnut," wrote Karatzas. "The volunteers will work from kayaks and canoes, dumping to a pontoon boat. The removed weeds will then be transported to a truck and brought to a local composting site."

For more information on water chestnut, visit Http://dnr.wi.gov/invasives/fact/wchestnut.htm.