Tag Archives: Invasive Species

What to do with a Thousand Acres of Swallow-wort?

With 80-foot cliffs overlooking eastern Lake Ontario, 14 miles of hiking trails, a dog park, a state-of-the-art playground, a residential cottage that sleeps eight, and a globally rare ecosystem, Robert G. Wehle State Park is a gem.

This striking landscape also has a military history of helping to defend the country. Between 1895 and 1947 before it was a park, the U.S. military used this property as training grounds. The park includes remnants of the Stony Point Rifle Range, where soldiers trained for combat, as well as shoreline concrete observer posts where spotters oversaw aerial gunnery target practice.

In 1963, the U.S. Army sold this land to Louis Wehle, founder of the post-Prohibition Genesee brewery, and Thomas Nagle, a Rochester car dealer. In succeeding years, Wehle and his son, Robert, maintained the property as a cattle farm, game preserve, and rural retreat for raising of internationally-renowned hunting dogs . After Robert Wehle’s death in 2002, the state Department of Environmental Conservation acquired the land, later passing it State Parks to establish as Robert G. Wehle State Park in 2003.

Click on this slideshow below for scenery at the park:

But visitors to this park may notice something else beyond its beauty _ large areas overrun by a strange, twining vine that seems to grow everywhere that is not mowed lawn, leaving few if any other plants surviving. Before his death, Robert Wehle was trying, with limited success, to control this invasive plant, known as pale swallow-wort (Vincetoxicum rossicum).

Now, decades after it was used to help train soldiers, this park is again on the front lines of a new mission: To be part of a campaign to learn whether a small moth found in Europe and Asia can help fight this invading perennial plant, which has spread throughout the eastern U.S. and Canada.

Pale swallow-wort at the entrance to Robert G. Wehle State Park in Jefferson County. The plant has begun to turn yellow at the end of the summer.


But first, what is this aggressive interloper that drives out other plants wherever it spreads?

Also given the ominous name of “dog-strangling vine,” pale swallow-wort is a native of Ukraine that was introduced to North America in the mid- to late-1800s as an ornamental vine in herbariums and greenhouses. Once here, it began expanding into old fields, pastures, and woodland understories. Pale swallow-wort wipes out native plants in its path due to its vast root system, immense seed production and seed dispersal method (seeds look similar to milkweed seeds and can float far away in the wind), and the production of allelochemicals that inhibit growth of other nearby plants and protect it from grazing animals. Whitetail deer, which will eat most plants, avoid it.

Pale swallow-wort also poses a threat to New York’s population of native Monarch butterflies, which require milkweed to reproduce. Monarchs are known to confuse swallow-wort with milkweed and lay their eggs on it. Due to the chemical composition of swallow-wort, Monarch larvae that feed on the plant usually don’t survive.

All of these traits combine to create the ‘perfect’ invasive species and a land manager’s worst nightmare. So, what has been done and what is still being done to control this tenacious weed?

Robert Wehle noticed this plant on his property, according to anecdotal accounts. The cattle herds that he kept could have suppressed the plant’s invasion in pastures through grazing and trampling.  Wehle also utilized fire management to maintain some fields, which could have held swallow-wort at bay temporarily. Records also indicate he tried chemical herbicides to control swallow-wort infestation. This suggests that, like subsequent scientific studies conducted have shown, that Wehle found grazing and burning were not effective control techniques. 

After the land became a State Park, grazing, burning, and chemicals were no longer done.  Instead, staff began mowing areas around the entrance, maintenance shop, parking lots, rental compound, and trails frequently, which cuts back swallow-wort before it matures enough to produce seeds. But only so much mowing could be done on a 1,100-acre property.

Where mowing stops at Robert G. Wehle State Park, pale swalow-wort often begins.
Pale swallow-wort along trails in the park, above and below. The plant turns yellow in the fall.
The flowers of pale swallow-wort.

A plan to address this issue was adopted in 2010 by State Parks, in cooperation with the state Department of Environmental Conservation. The first step was to raise public awareness of the problem. Interpretive signage was installed at most trailheads throughout the park to inform visitors. Boot brush stations were placed at the entrance/exit to the park for patrons to clean off their footwear to limit the spread of swallow-wort and its seeds off the property . The feathery seeds can easily stick to shoes, clothing and even the fur of dogs being walked.

That same year, State Parks hired an excavation company to carry out an experiment that may show promise for restoring degraded portions of Wehle’s globally rare Alvar ecosystem. Alvar is a grass- and sedge-dominated community, with scattered shrubs and sometimes trees. The community occurs on broad, flat expanses of calcareous bedrock, like limestone or dolostone, covered by a thin veneer of mineral soil.

Using a skid steer in selected areas, crews scraped away soil containing swallow-wort roots from limestone bedrock. Once most of the soil was gone, swallow-wort could not take root on bare rock. The areaa was then reseeded with native species. Other native plants showed up on their own, freed from the smothering competition from the swallow-wort. But these efforts could not be used everywhere in the park.

An area of the park reclaimed from pale swallow-wort by scraping off soil and later reseeding it with native plants.
In addition to the Lake Ontario and St. Lawrence regions, pale swallow-wort is found in other areas of the state, including the Finger Lakes and Hudson Valley. (Photo credit – New York State Invasive Species Information, http://nyis.info/)

Where does the moth come into this ongoing effort? For the last two years, Parks and its partners at Cornell University, SUNY College of Environmental Science and Forestry (ESF), Wells College, SUNY Cortland, and the University of Rhode Island have been using Robert G. Wehle State Park to study the viability of Hypena opulenta moths to suppress this invader.

This approach – the use of a natural enemy to deal with an invasive species – is known as biocontrol. In order to ensure that a new introduced species will not negatively impact other plants and animals, the effects must be extensively studied before any widespread use or release can be permitted. It cannot be overstated how extensively biocontrols are scrutinized before potential approval for release. Study can continue for years or even decades. Only after research confirms there will be little or little to no impacts to native species will federal regulators approve the biocontrol to be released.

In this case, the U.S. Department of Agriculture (USDA) in 2017 approved the release of the moths for field testing as biocontrol for pale swallow-wort. After the moths lay eggs on the swallow-wort, the larvae that later emerge eat the plant’s leaves.

For the last two seasons, Hypena moths were placed in cages in areas of swallow-wort at Robert G. Wehle State Park, as well on as nearby Grenadier Island in Lake Ontario off Cape Vincent. The cages ensured that the moths would be confined to the test areas.

Results from 2020 showed promise as one cage showed 100 percent defoliation of swallow-wort within four weeks by the caterpillars. Preliminary results from this year were not as successful. However, this is all part of the scientific process as the battle against the invasive continues with Robert G. Wehle State Park playing its part.

A Hypena opulenta moth inside the mesh cage over a patch of pale swallow-wort. The moth will lay its eggs on the plants.
After eggs hatch, the emerging caterpillars begin eating the plant leaves.
After four weeks, the caterpillars have eaten all the leaves in this cage. (All photos above credited to the St. Lawrence Eastern Lake Ontario Partnership for Regional Invasive Species Management.)

Hopefully one day we can say the tide is turning. Eradication is likely not possible, but containment could give native plants a better chance at a peaceful co-existence. If you visit the park, remember: Use the bootbrushes and check your clothes! Don’t inadvertently spread the ‘perfect invasive.’


Cover Shot – A pale swallow-wort infestation at Robert G. Wehle State Park. All photos NYS Parks unless otherwise credited.

Post by Pete Zimmer, Stewardship Specialist, Mid-State Capital District/Thousand Islands Region, NYS Parks



Resources


Learn more about the biocontrol project from the report below by the St. Lawrence Eastern Lake Ontario Partnership for Regional Invasive Species Management:

More information is also available from the New York State Invasive Species Research Institute.


The 2013 report by the U.S. Department of Agriculture also describes early efforts to contain pale swallow-wort.

Get Out, Darned Spot!

Some of you may have heard about New York’s newest worst pest: The Spotted Lanternfly. This little critter is ransacking our crops, destroying property, annoying park visitors, and generally making everything sticky and gross.

An artistic image of an adult Spotted Lanternfly (SLF) is the top of this article. We are asking for volunteers like you to look for and report any SLF and its favorite Tree-of-Heaven (TOH) plant using the invasive species tracking software iMap either online or on the mobile app.

What is the Spotted Lanternfly (SLF)?

The Spotted Lanternfly (Lycorma delicatula), is an invasive species from parts of China, India, Vietnam and Taiwan, which feeds on more than 70 different plants (especially the invasive Tree-of-Heaven).

The invasive Tree-of-Heaven, a favorite of the Spotted Lanternfly, is present in much of New York State (Photo Credit – New York State Floral Atlas, National Forest Service)
The leaves and flowers of the Tree-of-Heaven (Photo credit – University of Georgia/Bugwood.org)

As an unintended consequence of global trade, the insect  likely reached North America due to inadvertently hitching a ride in cargo shipping containers in the Far East. First reported in Pennsylvania in 2014, SLF has spread to neighboring states when people accidentally move stowaway egg masses to new locations.

Such international shipping has helped spread many invasives species, and national governments have been slow to recognize and address the issue.

Why do we need to “Stop the Spot?”

According to a Penn State study at the College of Agricultural Science, if not contained, damage caused by SLF is estimated to cost “at least $324 million annually and cause the loss of about 2,800 jobs” in Pennsylvania alone.

Spotted Lanternflies feed upon fruit trees, grapevines and hops (which hurts fruit, wine and beer production, an important and growing industry in the Finger Lakes and other areas of New York State), and our beautiful hardwood trees. At the same time, they secrete a sticky honeydew which creates a sooty mold that damages property.

The honeydew and mold also attract stinging insects such as wasps and bees, creating an overall unpleasant atmosphere. No one wants to do outdoor activities when everything is covered in sugary bug poop.

A representation of the Spotted Lanternfly during its lifecycle. A winged adult SLF is center. The insect as it appears with black and white markings after hatching during May and June is to the right. As the insect matures, it changes from black to mainly red, usually during July through September, as shown to the left. It assumes it adult, winged form in late summer, and lays its eggs in the fall, starting the cycle again. (Artwork by Juliet Linzmeier, Student Conservation Association member, Invasive Species Unit, NYS Parks)

            Where is it?

It could be right by you this year! Here is our most up-to-date map of known SLF infestations. Your reports of sightings could change the way this map looks!

On this map, currently infested counties are highlighted blue, while isolated sightings are represented by a red dot. Note that Ithaca County, in the heart of Finger Lakes wine country, is currently listed as infested. However, since infestation in New York State is not yet widespread, there is still time for us all to take important and effective action to mitigate the spread of SPF.

How do we “Stop the Spot?”

Remember these three steps: Report. Inspect. Destroy.

  • REPORT sightings of SLF
    • Download the iMapInvasives Mobile app or go online. You’ll be adding directly into our database.
    • Be sure to take pictures at any life stage (egg masses, larvae, adult insect or groups of infestations) with an item like a ruler or coin for scale.
    • Include the location: address or GPS coordinates (simply enable your location tracking when using the iMap app).
    • Adopt a square!: Consider signing up for a grid square near you to keep us regularly updated about special high-priority locations. 
    • Prefer E-mail? Send your info to SpottedLanternfly@agriculture.ny.gov
    • Eggs are laid on hard surfaces and may be covered or uncovered.
  • INSPECT your gear for stowaways and egg masses
    • Check your car, equipment, and materials when coming from infested areas (certain counties in Delaware, New Jersey, Pennsylvania, Virginia, and Maryland).
    • Egg masses can sometimes resemble mud, and these hitchhikers will hide in your car’s bumper, hood, etc.
  • DESTROY 
    • For every single SLF you kill, you prevent potentially hundreds of plant-sucking critters from draining our economy next year.
    • Look for the different stages throughout the year. Right now in May, focus your search for the nymphs: The first instar nymph is approximately ¼” long and black with white spots, and occasionally mistaken for a tick. Second and third instar nymphs are also black with white spots, but the fourth instar nymph takes on a red coloration with white spots and can be up to ¾”. Fourth instar nymphs molt and become adults approximately 1 inch in length.
    • If egg masses are found, scrap off and destroy them by putting them into doubled bags with alcohol/hand sanitizer, or by smashing/burning them. Honestly, get as dramatic as you want.
The lifecycle of the Spotted Lanternfly, which should be hatching out from its overwintering eggs during May and June. (Photo Credit – Cornell University/NY Integrated Pest Management)

How we manage SLF

While preventative measures are always best, the sooner a new infestation is found, the better chance we have of managing the situation. Our Park’s staff use a combination of strategies to manage SLF, some of which get quite creative…

  • Sticky bands and circle traps on trees will catch some nymphs and adults but are mostly useful for helping us monitor SLF whereabouts.
  • Bio-controls (predators, parasitoids, and insect-killing fungus) are in the works to help control SLF long-term but aren’t happening yet.
  • We’ll also create “trap trees” where we’ll cut most of the invasive Tree of Heaven, then inject a pesticide into the remaining tree. This kills any SLF that take a drink (like how flea treatments on your dog will kill any flea that takes a bite!).
  • Scraping egg masses and destroying them reduces next year’s population.
  • Be aware of look-alikes as seen in this poster

Even with these strategies, we need all the help we can get to stop these spots! Help us by killing SLF at all life stages.

Destroy their egg masses!

Stomp black/red nymphs!

Squish the flying adults!

And then tell us about it when you do.

There’s even a new app specifically for squishing SLF called Squishr which aims to make the hunt into a fun competition for the whole family (especially kids)!

Researchers need as much time as possible to investigate the best possible methods for managing SLF before they damage our resources even worse, so reporting new infestations makes a huge difference!

Through a collective effort of reporting, destroying, and inspecting for stowaways, we can combat the spread of the Spotted Lanternfly. 

For more information, go to Spotted Lanternfly – NYS Dept. of Environmental Conservation


Cover shot – An adult Spotted Lanternfly. Artwork by Juliet Linzmeier.

Post by Juliet Linzmeier, Student Conservation Association member, Invasive Species Unit, NYS Parks

Wasp Warriors Aid Parks Against Insect Invaders

If you haven’t noticed, New York’s ash trees have been struggling lately. Over the last few years, they have been rapidly dying due to a little iridescently green insect: the emerald ash borer (EAB).

An invasive beetle native to parts of Asia and Russia, EAB was first discovered in New York in Cattaraugus County in 2009. It has since spread to 55 of New York’s 62 counties, decimating once thriving ash populations.

Since its discovery in southeast Michigan in 2002, EAB has spread into 35 states and the District of Columbia, killing tens of millions of ash trees in their wake.

EAB is widespread in the eastern U.S. as show in this USDA map. Each red dot represents an infested county and the blue line is a federal quarantine zone.

Emerald ash borers lay eggs between bark layers and in bark crevices on ash trees. Upon hatching, the larvae burrow through the bark and begin to feed on the tree’s living parts: the phloem and sapwood. The larval feeding creates galleries, which cut off the movement of nutrients throughout the tree. Eventually, as the infestation grows, the tree’s system of nutrient transport ceases to function, and the tree slowly starves and dies.

EAB larvae create S-shaped “galleries” where they feed just beneath the bark of an infested ash tree. Use the slider bar to explore the damage in this tree.

Ash trees are important for so many reasons. They provide cool shade in the summer heat, provide habitat for wildlife, and are a valuable source of timber and firewood. When large ash die, however, they can pose serious safety risks. Dead and dying trees often bring down powerlines along the road and cause blackouts.

In addition, many trails, campgrounds, parking lots and playgrounds are surrounded by ash that, once infested, become hazard trees that require removal. Parks’ staff must constantly monitor public use areas for the presence of dying trees that may pose a risk to patrons.

The fight to conserve ash has been an uphill battle. While pesticide treatments work, they only last a year or two before reapplication is necessary and also are too expensive to use everywhere. Statewide quarantines and public education have helped slow the spread, but these little beetles can fly over a mile and lay up to 200 eggs in a lifetime, making containment difficult.

This chart shows the lifecycle of the EAB. (Photo credit – Cornell University)
State Parks staff at Jacques Cartier State Park peel back bark from an infested ash tree to reveal the EAB damage. (Photo credit- Aaron Hemminway, NYS Parks biologist)

You may be thinking “what can be done?!” Well with National Invasive Species Awareness Week coming May 17-23, an update from State Parks is timely.

Luckily, we may finally have a cost-effective, sustainable, and chemical-free solution to the problem. For the second year in a row, the state Office of Parks, Recreation and Historic Preservation and the U.S. Department of Agriculture (USDA) are partnering to release three species of predatory wasps – known ecologically as biological controls or parasitoids – to battle EAB in select state parks.

These tiny warriors are heavily studied little predators from the EAB’s home countries which prey only on these beetles and pose no risk to our native ecosystem. (And don’t worry. These wasps don’t sting and are no threat to people).

The females of these species attack ash borers in the early stages of their life cycle. These three wasps were chosen because they each have slightly different ways of tackling EAB, making them a more effective as a group.

Here, let’s meet our winged team.

Tetrastichus planipennisi

Tetrastichus planipennisi females lay eggs inside of EAB larvae, where the parasitoid larvae grow and eventually kill their host. They are used to protect smaller ash trees in particular, and they originate in China.


Oobius agrili

Oobius agrili lay eggs inside EAB eggs, where the parasitic wasp larvae hatch, grow, and kill the host EAB egg. These wasps are all female, so they reproduce asexually. They also originate in China.


Spathius galinae

Spathius galinae lay eggs outside of EAB larvae; when they hatch, Spathius feed on the EAB larvae, killing it. These wasps are best at helping larger ash trees, and are collected in the Russian Far East.


Last year, 11 State Parks received about 40,000 Tetrastichus wasps: Rockland Lake in Rockland County; Harriman and Bear Mountain in Rockland and Orange counties; Minekill in Schoharie County; Beaver Island and Buckhorn Island in Erie County; Clay Pit Ponds in Staten Island; Lakeside Beach in Orleans County; Golden Hill in Niagara County; Southwick Beach in Jefferson County; and Point Au Roche in Clinton County.

Starting this month, Jacques Cartier State Park in St. Lawrence County and Ganondagan State Historic Site in Ontario County will be added to that list. All three wasp species will be deployed, with an expected total of more than 50,000 wasps. All the wasps used are reared in a lab in Michigan, where they are shipped to New York and other states where USDA is coordinating its EAB biocontrol program.

For the wasps to be successful here, they need to find the beetle in its early life stages. In New York, the emerald ash borer generally begins to lay eggs in the summer; however, many larvae overwinter inside of ash trees, and are thus readily available as food for the parasitoids in the spring.

Parks staff introduces the wasps into infested ash trees through three methods:


  • Ash bolts are small sections of ash (think small ash logs slightly larger than cans of soup) that house mature parasitoid larvae. They are attached to infested ash trees using twine or zip ties. When the larvae mature, they leave the bolts and find EAB larvae to feed on within the ash stand.
Ash bolts are attached to infested trees with zip ties or twine, and are marked with flagging so they can be easily found. Please don’t disturb or tamper with the bolts if you come across them!

  • Plastic cups containing adult parasitoids arrive on-site ready for distribution. The cups simply need to be opened, inverted and tapped gently against the trunks of infested trees.
Adult parasitoids arrive in plastic cups, ready for release.
  • Oobinators are used less frequently and only for the delivery of Oobius agrili. They are small, plastic pill bottles with a screen over the open end that can be attached to trees with zip ties or twine. They contain a sheet of paper with parasitized EAB eggs. Once mature, Oobius will hatch and escape through the screen.
Oobinators are hung upside down, to allow mature parasitoids to escape. Photo credit: USDA

While out exploring NYS Parks, you may see these “ash bolts” or “Oobinators” attached to trees. They are often marked with flagging for easy identification. While it may be tempting to try to get a closer look at these woodland wasp homes, it is important to let the parasitoids grow and feed uninterrupted,  to give them the best possible chance of survival.

While parasitoid releases may be new to New York State Parks, USDA has been conducting releases throughout the country for several years. Subsequent studies indicate that that wasps are surviving and are feeding on the EAB.

Studies have also shown that the Tetrastichus wasps in particular can eliminate up to 85 percent of EAB larvae in ash saplings. (Duane et al., 2017)

These are promising results which suggest if parasitoid wasps can be reared in abundance, they may offer crucial protection to the next generation of ash trees. It is important to keep in mind, however, that success will not happen overnight. Wasps need to find enough EAB to build up their populations to sustainable levels and it takes time to see results, even if wasp populations are doing well. Parasitoids also will most likely not save most larger ash, but they can help manage EAB populations so smaller ash trees can have a chance grow and hopefully reproduce.

Parks is thrilled to partner with USDA in this important endeavor to protect our forests. You also can join in the effort by reporting emerald ash borer sightings or suspected damage to the iMapInvasives website or smartphone app. There is also a USDA online reporting form here.

Also, help stem the spread of EAB and other invasive forest pests by following state regulations that control the movement of untreated firewood, which can carry these invasive hitchhikers.

  • Untreated firewood may not be imported into NY from any other state or country.
  • Untreated firewood grown in NY may not be transported more than 50 miles (linear distance) from its source or origin unless it has been heat-treated to 71° C (160° F) for 75 minutes.
  • When transporting firewood, the following documentation is required:
    • If transporting untreated firewood cut for personal use (i.e. not for sale) you must fill out a Self-Issued Certificate of Origin (PDF).
    • If purchasing and transporting untreated firewood, it must have a receipt or label that identifies the firewood source. NOTE! Source is sometimes, but not always, the same as where it was purchased. Consumers need to use the source to determine how far the firewood may be transported.
    • If purchasing and transporting heat-treated firewood, it must have a receipt or label that says, “New York Approved Heat-Treated Firewood/Pest Free”. This is the producers’ declaration that the firewood meets New York’s heat-treatment requirements. Most “kiln-drying” processes meet the standard, but not all, so it is important to look for the appropriate label. Heat-treated firewood may be moved unrestricted.

Find out if your destination is within the 50-mile movement limit by using this interactive map from the state Department of Environmental Conservation.

Finally, if you encounter evidence of biocontrol release sites while out on State Parks trails, know that you are in the presence of these wasp warriors, engaged in a battle to save our beloved ash trees.

Above, Parks staff hang ash bolts and record release data used by USDA to measure the effectiveness of the project to combat the Emerald Ash Borer.


Cover shot – Emerald Ash Borer (Original Artwork – Juliet Linzmeier, Student Conservation Association member with NYS Parks) All other photo credited to NYS Parks unless otherwise noted.

Post by Sarah Travalio, Terrestrial Invasive Species and Biocontrol Coordinator, New York State Parks


Here are other easy tips that can make a big difference in helping stop the spread of all invasives:

  1. Clean, drain, and dry your watercraft and gear thoroughly to stop the spread of aquatic organisms.
  2. Plant only non-invasive plants in your garden, or even better, plant native plants. You can use the New York Flora Atlas to check which plants are native to New York.
  3. Clean your boots or your bike tires at the trailhead after hitting the trail – seeds of invasive plants can get stuck on your boots, clothes, or tires. You don’t want invasives in your yard or your other favorite hiking spots.
  4. Get involved – volunteer to help protect your local natural areas, join your local PRISM (Partnership for Regional Invasive Species Management) to stay informed, or become a citizen scientist by using iMapInvasives to report infestations of invasive species right from your smartphone.

Interested in taking a deep dive into research on the parasitoid battle against the EAB? Check out these scientific studies:

Jian J. Duan, Leah S. Bauer, Roy G. Van Driesche, Emerald ash borer biocontrol in ash saplings: The potential for early stage recovery of North American ash trees, Forest Ecology and Management, Volume 394, 2017, Pages 64-72, ISSN 0378-1127, https://doi.org/10.1016/j.foreco.2017.03.024.

Duan, Jian J., Leah S. Bauer, Kristopher J. Abell, Michael D. Ulyshen, and Roy G. Van Driesche. “Population dynamics of an invasive forest insect and associated natural enemies in the aftermath of invasion: implications for biological control.” Journal of Applied Ecology 52, no. 5 (2015): 1246-1254. https://doi.org/10.1111/1365-2664.12485

Jian J Duan, Roy G Van Driesche, Ryan S Crandall, Jonathan M Schmude, Claire E Rutledge, Benjamin H Slager, Juli R Gould, Joseph S Elkinton, Establishment and Early Impact of Spathius galinae (Hymenoptera: Braconidae) on Emerald Ash Borer (Coleoptera: Buprestidae) in the Northeastern United States, Journal of Economic Entomology, Volume 112, Issue 5, October 2019, Pages 2121–2130, https://doi.org/10.1093/jee/toz159


Targeting a Watery Invader at Lake Taghkanic

Thanks to a “hands-on” kayak mission against invasive water chestnut this summer at Lake Taghkanic State Park, this popular lake ought to be clearer of these aquatic invaders for next paddling season.

And timing is critical in dealing with water chestnuts, floating plants which can rapidly spread to create dense patches that can clog a lake, damage the native ecosystem and make it hard for canoeists and kayakers to paddle.

Water chestnut (Trapa natans) is one of the several Aquatic Invasive Species (AIS) that are monitored in hopes of reducing abundances in state waterbodies. Widespread in the state, water chestnut is now found in 43 counties.

The aquatic invasive water chestnut can be found in 43 countries across the state. Counties shaded green are known to be infested. (Photo Credit – NYS Department of Environmental Conservation)

Invasive species, like water chestnuts, are organisms that are non-native to an area, typically causing harm to human health, the economy, and the environment. If left unchecked, AIS can spread quickly from one body of water to another, threatening biodiversity and potentially impeding recreational opportunities.

The key to battling the an infestation discovered this season at Lake Taghkanic in Columbia County was to remove hundreds of plants before going to seed. Water chestnuts are annuals, and thus must reseed themselves each year to propagate.

Anyone who has been out along a shoreline and came across a strong, spiny, star-shaped brown nut-like “fruit” or seed pods has found a water chestnut nut. Bearing four sharp spines or points, each nut contains a single seed that can produce 10 to 15 stems.

Anchored to the water bottom, the plants have submerged, feathery brownish leaves on stems that can grow up to 15 feet long. On the water’s surface, these stems come to an end with a floating rosette, or circular arrangement of leaves. The leaves are triangular shaped with toothed edges.

These clusters can float on the surface due to buoyancy bladders connected to the leaf stems, forming dense floating mats that can be nearly impenetrable. Each rosette produces about 20 of the hard nut-like fruits in the late summer and early fall which, after dropping from the plant to the water bottom, lay in sediment over the winter to sprout in the spring

You can imagine the concern when water chestnut showed up in Lake Taghkanic State Park, a park focused on boating, swimming, water sports and beach activities. Controlling water chestnut at the park was vital to support these recreational opportunities as well as the native fauna of the lake, including one rare species known there.

Due to the fast-growing nature of water chestnut, it is important to control newly introduced infestations as soon as possible, also known as “early detection, rapid response” (EDRR). If left unchecked, patches of water chestnuts can spread prolifically.

A map of Lake Taghkanic, showing the area of water chestnut infestation highlighted in green. (Photo Credit – NYS Parks)


Water chestnut is an invasive species of high concern for many waterbodies in New York State, having potential ecological, economic and health impacts. The plant can form dense mats on the water’s surface, greatly impacting the organisms below. These layered mats can block sun and oxygen from submerged plants, resulting in a die back of native species and fish populations. Recreation is also inhibited by dense patches of water chestnuts, making it difficult to swim, boat, kayak, or fish. The spiny nuts often drift to shore, creating an additional hazard for pets and people to step on.

Effective control of water chestnut depends largely on preventing seed formation. By manually removing the plants in mid-summer before mature seeds can drop, managers can halt such potential reproduction.

At Lake Taghkanic, staff from the Office of Parks, Recreation and Historical Preservation, state Department of Environmental Protection, and Capital Region Partnership for Regional Invasive Species Management (PRISM) worked to rapidly respond to the infestation. This team of ten individuals were well-versed in the control of invasive species, and several team members had prior experience manually removing water chestnut.

Held July 16, the pull was led by Matt Brincka (NYS Parks Invasive Biologist), with other participants including Falon Neske (NYS Parks), Lindsey DeLuna (NYS Parks), Lauren Gallagher (NYS Parks), Rebecca Ferry (NYS Parks), Kristopher Williams (Capital Region PRISM), Lauren Mercier (PRISM), Lauren Henderson (PRISM), Steven Pearson (DEC), and Catherine McGlynn (DEC).

The team navigated to the water chestnut infestation in kayaks, maintaining social distancing and wearing face coverings when necessary. When manually pulling water chestnut plants, it’s important to reach as far down the stem as possible to pull the root system from the bottom sediment.

At Lake Taghkanic, water chestnut was mixed in among lily pads, presenting a challenge to pulling by hand from kayaks. (Photo credit – NYS DEC)

Once pulled, the water chestnuts were collected in garbage bags, drained, and weighed. Within a day, more than 100 pounds, or from 300 to 400 plants were removed! The information was recorded for upload to iMapInvasives so that the infestation of water chestnuts can be tracked.

Afterward, the team also surveyed the 3.7 mile lakeshore to ensure there were no other visible water chestnuts. Parks staff developed a control plan that will include monitoring and hand-pulling at Lake Taghkanic annually in order to deplete the seed bank (seeds can remain viable for several years at the bottom) and keep the problem at bay.

Over the years, NY State Parks has organized and participated in several invasive species pulls, additionally having a seasonally staffed AIS Strike Team and Boat Steward program. Reader more about these programs in the posts below.

Selkirk Shores State Park has been one focus area for State Parks staff in efforts to control a water chestnut infestation. In 2015, about 240 bags of water chestnut were removed there, visibly reducing the biomass by 40 percent. During the 2016 season, another 12.5 tons were pulled out. This removal resulted in a decrease in abundance of water chestnut during from 2017 through this year, further maintaining the value of this State Park.

Prompt invasive species responses, such as water chestnut pulls, work towards ensuring recreational enjoyment and preserving natural ecosystems in our parks. Early detections of invasive species are often reported by patrons.

The next paddling season may be months away, but remember: If you believe you have found a new population of an invasive species at a State Park, tell a park staff member or reporting it in iMapInvasives will ensure that swift eradication action is taken.

Protecting Our Waterways

You may have seen them in a park near you, these super heroes and heroines in disguise. Since 2008, New York State Parks have deployed Invasive Species Strike Teams. These Strike Teams conduct invasive species surveys and manually remove non-native invasive plants in areas of significance. The goal is to protect native plant and animal … Continue reading Protecting Our Waterways

Cover shot: Members of the removal team spread out in kayaks on Lake Taghkanic.

Post by Lauren Gallagher, State Parks Water Quality Unit

Parks Won’t Let Invasive Species Get Its Goat

Invasive plant species are a huge problem in modern conservation at our State Parks. These plants can overrun areas and if left unchecked, push out our native species, disrupt natural systems, and negatively impact human activities.

Controlling large infestations is challenging, and sometimes requires using chemical herbicides, which can come with unforeseen costs and undesirable consequences.

But there can be another way that is easier on the environment. To deal with invasive plants at Heckscher State Park on Long Island, we are experimenting with a greener and much cuter alternative – a small army of hungry and quite friendly invasive plant-eating goats.

A little goat can be a big eater of invasive plants. Goats can eat up to a quarter of their body weight each day.

The goats came from Green Goats, a company from Rhinebeck in Dutchess County that for more than a decade has hired out its goats to combat these invaders at various public parks. Their herd has traveled to seven states, as far away as West Virginia and as close by as Riverside Park and Fort Wadsworth in New York City.

Last year at Heckscher, we released goats into a fenced-in, five-acre site overtaken by an invasive plant called Chinese Silvergrass (Miscanthus sinensis). The goal is for the goats to eat the silvergrass so there will be room for our native plants to again take hold. The goats also have been eating other invasives, including Japanese honeysuckle (Lonicera japonica), common reed (Phragmites australis), and Japanese angelica tree (Aralia elata).

Chinese Silvergrass (Photo credit Western New York PRISM)
The hungry herd takes on the Chinese Silvergrass.

However, since goats will eat pretty much everything, we did not want them to eat the handful of native shrubs left in the enclosure, including eastern baccharis (Baccharis halimifolia), highbush blueberry (Vaccinium corymbosum), and common elder (Sambucus canadensis). So, we put up fences around these native plants to protect them so that when the goats leave, these shrubs will be able to spread into cleared areas.

Last year, we had a bit of a late start and only received the goats in September, but by the end of the growing season in October, we had 70 goats moving and eating through the area. When the goats left for the season, there was significant thinning of the silvergrass and quite a few individual plants were eaten down to the ground. The goats also ate a lot of the Japanese honeysuckle and, surprisingly, killed several angelica trees by eating their bark. The bark and leaves of the angelica tree are covered in many sharp thorns and spines to dissuade herbivores from eating it, but that didn’t stop the goats, who happily stripped the bark right off the invasive trees!

This year, our goats arrived in June and as of this month, we have 61 goats working in the area with more on the way. We have used a drone to fly over the site to track their progress, and expect to do another flight shortly.

A goat stretches for its meal of Silvergrass.

A hungry goat can eat up to 25 percent of its body weight each day, said Larry Cihanek, owner of Green Goats with his wife, Ann. An adult goat can weigh between 140 to 180 pounds, so that works out to up to 45 pounds of invasive plants a day. For our herd at Heckscher, that is up to 2,700 pounds of plant invaders being eaten every day!

And the goat “droppings” are a good source of nutrients for the soil as well.

“Using goats like this is like mowing your lawn over and over,” said Cihanek. “You keep the goats on site for a season, and they keep eating as the plants continue trying to regrow. But the goats keep eating the new growth and eventually they starve the roots bit by bit, and the plants will die.”

Ann and Larry Cihanek, owners of Green Goats in Rhinebeck, Dutchess County. They have about 200 goats in their herd. (Photo courtesy of Green Goats)

The Cihaneks now have about 200 goats in their herd, with nearly all the animals being donated by former owners who had been using them for milking, for show purposes, or as pets.

“Eight years is about the maximum for milking, but goats can live for 12 to 14 years. So, this is their second career with us,” he said. “Our goats are living the American Dream: They eat for a living.”

In addition to helping project the environment, the goats are also a good way to draw more people into the park. “In some of our past projects, we have seen that attendance at a park can go up by about 20 percent after the goats come in,” said Cihanek.

Officials at Riverside Park in New York City even held a celebration after the goats finished working there this summer, making the goats the stars of a $1,000-a-ticket fundraiser at a lawn party in August. More than 800 people showed up and there was a contest to vote for the most popular goat, with the winner being Massey, who was presented with a medal and an elaborate bouquet of weeds.

Riverside Park President & CEO Dan Garodnick honors Massey at the winner of the public “Vote the G.O.A.T” contest in August. (Photo by Riverside Park Conservancy)

If you would like to see the goats in action, they are staying through October in the eastern section of Heckscher State Park, to the north of the cottages. The Long Island Greenbelt Trail briefly passes a section of the enclosure when it turns westward.

If you see goats with numbered collars, these are the goats that were honored at Riverside Park.

The goats are quite friendly and like being petted. But please, stay outside the fence and do not feed the goats. They are already surrounded by all the food they need!

A Parks visitor encounter with one of the Green Goats.

All photographs by New York State Parks unless otherwise credited.


Post by Yuriy Litvinenko, New York State Parks Regional Biologist for Long Island