Archives for category: Invasive Plants

a photo of a shrub rose with green leaves, a brown stem and small white rose flowers, this is an invasive plant in the Hudson Valley NY

Multiflora rose, one of several invasive plants in the Hudson Valley

Stop the Spread: Help us “Bust” Invasive Plants!

 Kingston, NY – Please help us “bust” the cycle of invasive plant invaders!  Cornell Cooperative Extension of Ulster County (CCEUC) will be holding two short recruitment events for the Blockbuster Citizen-Science Program on June 13 from 12:30-1:00pm and 5:30-6:00pm at our office, 232 Plaza Road in Kingston.  You will learn how you can help CCEUC and the NYS DEC to survey for the presence of invasive plants in the Hudson Valley this summer.  Please RSVP to Dona at 845-340-3990 ext. 335

Training for the survey will begin in early July, several dates and locations will be offered.  After the training you will pick a 5 km x 5 km block in your area and survey it for invasive plants.  You will select the species that you feel comfortable identifying, so you do not have to be a plant expert to participate. As a Blockbuster Volunteer you will be part of a region-wide team of volunteers who will help us find and identify key invasive species and find areas that are free of invaders. Data collected will help scientists and natural resource managers direct their efforts most effectively. This program is part of the Lower Hudson Partnership for Regional Invasive Species Management’s (PRISM) efforts to stop the spread of invasive species in the lower Hudson Valley.

To become a volunteer, or if you are interested but cannot attend the recruitment events on June 13, contact Dona Crawford at 845-340-3990 ext. 335 or

For information about Cornell Cooperative Extension of Ulster County’s community programs and events go to  Stay connected to CCEUC-friend us on Facebook and follow us on Twitter.

Cornell Cooperative Extension of Ulster County provides equal program and employment opportunities.  Please contact the program office at 845-340-3990 if you have any special needs.

The second week in July is New York Invasive Species Awareness Week

  • Events
  • Identifying Invasive species
  • Education
  • Advice
  • Resources and contacts

Click here for more information

Green foliage of a Barberry Shrub in summer showing detail of leaves and bright 'apple' green color of foliage

Barberry Shrub, a garden escapee, grows in woodland areas



Japanese Knotweed shoots in April.

Japanese Knotweed shoots in the spring

Japanese Knotweed Fallopia japonica is growing well in the Hudson Valley. Too well – it’s everywhere, including people’s gardens. It forms large stands, preventing all other plants from growing and eliminating habitat for wildlife.

Japanese Knotweed shoots.

Spring shoots

If it’s growing on your property, remove it as soon as possible before it becomes a  large clump which is much harder deal with.

Japanese knotweed stems.

The semi-woody stem is hollow


  • A herbaceous perennial that can grow over 5′ tall with stems 2″ wide.
  • Hollow stems look a little like bamboo.
  • In spring the shoots are a reddish color
  • The green stems have enlarged leaf nodes and may have red spots
  • The green leaves are alternate, 6″ long, 3-4″ wide and broadly ovate
  • In August, the flowers are greenish-white panicles in the axils of the leaves
  • In the fall the foliage dies back, leaving the dead woody stems standing
Clumps of Japanese Knotweed in April.

Clumps of Japanese Knotweed in late spring


Barbara Bravo an experienced Hudson Valley gardener, Garden Coach and Master Gardener, recommends these steps for removing the plant.

  • Mowing or cutting to ground. To be effective, continue all season.
  • Use heavy black plastic sheets to smother plants
  • For large stands, the best method is to cut stems off at about 3′ high just below a stem node – use a squirt bottle and fill the hollow stem up ¼ of the way with 25 % Glyphosate (Use Rodeo if in a wetland or near water). Follow all instructions on the product label exactly to avoid contamination and over-use of chemicals.
  • In all cases, dispose of cut stems properly – the plant can resprout from stem or root pieces that are left on the ground.
  • Do not put the plant on a compost heap because it is possible to spread the plant when applying compost
  • Put the plant in a sealed bag in your trash can for garbage removal.
  • Complete removal may take several years, inspect the area often for regrowth and continue the removal process if needed.
  • Alternately, hire a professional Invasive Plant Removal company
Japanese Knotweed flowers in August.

Japanese Knotweed flowers in August

Japanese Knotweed dried flowers in November.

In the fall the foliage and flowers die back

Japanese Knotweed stem in October

Woody stem in the fall

How does this plant spread?

  • This plant has a horizontal, underground plant stem (rhizome) that produces a shoot and root system for a new plant. This rhizome can grow under surfaces such as concrete, bricks etc. until it finds a space to start a new plant.
  • It is also spread by seed
Japanese Knotweed sprouting in November.

New plants sprouting from rhizomes. These new plants are growing in October!

How did this plant arrive in the Hudson Valley?

Japanese Knotweed is native to Japan, China, Korea, and Taiwan and was brought to America in the late 1800s as a garden plant. It now grows wild because it can grow in a variety of soils, in sun or part shade and thrives in this climate.

Japanese Knotweed stems in October.

Japanese Knotweed stems in October

Japanese Knotweed in October. Hudson

Foliage has died back, leaving the dead stems.

Preventing the spread of Japanese Knotweed

In her excellent lecture about invasive plants in the Hudson Valley, Barbara Bravo explained “Gardeners are the first line of defense against invasive plants, if you see a plant that is thriving and you do not recognize it, do some research to identify the plant. If necessary, remove it”

Need some help with this plant?

Contact your local Cornell Cooperative Extension Office

Contact Barbara Bravo at Enter the Garden

For help identifying a plant, post a picture on the Plant Identification Facebook page

Foragers of wild plants can find recipes for eating Japanese Knotweed here

For professional plant removal, contact Poison Ivy Patrol, this business uses non-chemical removal methods

Oriental Bittersweet berries. Source:

Oriental Bittersweet berries are often used for fall decorations.

Last weekend I noticed the orange berries of Oriental Bittersweet are everywhere, beside roads, in yards and in the treetops.

Oriental Bittersweet vine with berries at the top of a tree. Source:

The berries are visible in the treetops in fall and winter

I learnt about Oriental Bittersweet at a presentation by Barbara Bravo  called “Invasive Plants in the Hudson Valley”. (An ‘invasive’ is a plant or tree that is not indigenous to the US and is an aggressive grower which adversely affects the natural ecosystem).

There are two types of Bittersweet vine in the US; the Oriental Bittersweet (Celastrus orbiculata) which was introduced in the 1860s from China, Japan and Korea and the American Bittersweet (Celastrus scandens).

Oriental Bittersweet smothering a tree. Source:

Oriental Bittersweet smothering a tree.

Oriental Bittersweet is an invasive vine growing 66′ tall which crowds out other plants and trees, including American Bittersweet. The woody vine wraps around trees and kills them, while the weight of the vine can smother and topple mature trees. It is more vigorous than the American Bittersweet and spreads by underground roots and from berries which are eaten and dispersed by birds and mammals.

Oriental Bittersweet, woody stems girdling the trunk of a sapling. Source:

Woody stems girdling the trunk of a sapling.

Oriental Bittersweet stems. Source:

Oriental Bittersweet stems

Oriental Bittersweet can be removed by cutting back the vines and digging up the roots. Or a systemic herbicide can be used (glyphosate or triclopyr); cut the stem about 1″ above the ground and apply the herbicide to the stem, always follow directions on the label. Make sure no berries are left behind and burn or dispose of them in the trash.

Oriental Bittersweet foliage. Source:

Oriental Bittersweet foliage

Oriental Bittersweet berries encased in yellow husks. Source:

The berries are encased in yellow husks before they ripen in the fall

American Bittersweet is rare in the wild but is available from nurseries. It grows 30′ high, is not invasive and is much more manageable. It looks slightly different than Oriental Bittersweet. Identification; the leaves have a pointed tip, the berries are a darker red and are in clusters at the ends of stems that extend beyond the leaves. For advice and help identifying American Bittersweet, contact your local Cornell Cooperative Extension.

Sources of American Bittersweet vines:

For professional removal of all invasive plants, contact Poison Ivy Patrol, they use non-chemical removal methods

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