hemlocks

Hemlock Pests and Diseases

Hemlock Pests & Diseases

Hemlock Woolly Adelgid (HWA) is a powerful predator of these integral trees, but unfortunately it is not the only serious threat to hemlock ecosystems. Hemlock trees battle a variety of other insect pests, and can be beleaguered by diseases – here are a few of the more formidable.

Threats to Hemlock Trees:

Threats to Hemlock Trees - Dale Luthringer, Cook Forest State Park

Elongate Hemlock Scale

Elongate hemlock scale, a tiny insect with an oval hard cover, or “scale,” is brown or white, and attaches on the undersides of needles seemingly at random.  This pattern is different from HWA, which lines up near where needles are attached to the twig. It sucks out juices, weakening the tree.

The elongate hemlock scale is particularly devastating to hemlocks already affected by HWA or drought, and often arrives after HWA has been found in the area. This “one-two” punch of two invasive insects is extremely difficult to treat, requires a great deal of labor and costly chemicals, and ultimately reduces the numbers of hemlocks that can be saved. 

the Hemlock Looper

The hemlock looper moth (Lambdina fiscellaria), a/k/a the mournful thorn, is a native insect which has “very long pectinations resulting in a conspicuously feathery antenae.” This little bug can severely defoliate hemlock during high population phases, and also damages balsam fir, white spruce, oak, and other hardwoods.

the Spruce Spider Mite

These rapidly-reproducing, warm-weather-loving arachnids use “piercing-sucking mouthparts [to] withdraw sap containing chlorophyll from the needles” of conifers, which don’t recover once damaged.  “Infested needles become mottled and appear yellowish to gray in color,” and are commonly in groups low and on the inside of plants. They’re not terribly easy to kill (use miticide, not insecticide), so read this informative Penn State Extension article if you worry about a spruce spider mite (Oligonychus ununguis) infestation.

the Hemlock Borer

The hemlock borer (Phaenops fulvoguttata, f/k/a Melanophila fulvoguttata) prefers to attack when a hemlock has already been weakened by other pests, disease, or drought.  The best defense against these destructive bugs is maintaining healthy hemlocks.  

Click here for more information on the hemlock borer – USDA Forest Service “Pest Alert,” Aug. 2000.

hemlock borer insect
PA DCNR - Forestry , Bugwood.org

Signs of hemlock borer infestation include:

  • small oval holes in the bark, about 3mm in diameter, [from which] beetles have emerged;
  • larval galleries on the surface of the sapwood, beneath the bark;
  • woodpecker damage may indicate heavy infestation with larvae; and
  • bark chips piled at tree bases indicate the same.

Needle Rust

There are several types of rust affecting hemlocks.  No treatment is usually needed, but you can identify hemlocks infected with needle rust by spotting that “current-season growth is slightly swollen and curled, [and] orange-yellow spores coat the infected tissue.”  

Climate Change Threats

While neither pest nor disease, it’s worth noting here that hemlocks are also intolerant to drought.  Weather patterns of late have shifted, becoming less even and predictable.  Pennsylvania has witnessed several years of long dry periods punctuated by strong storms, the water of which falls too heavily for proper saturation into the soil.  Dry, warm winters benefit the HWA, while weakening the trees.  

The hemlocks of Cook Forest are less impacted than those of the Smoky Mountains primarily due to environmental factors:  the southern environment more strongly favors HWA.  While the southern hemlocks sickened more quickly, northern hemlocks held on while science worked on “vaccinations,” and our occasional cold winters knocked back HWA infestation levels. 

How to help hemlocks

Improve the health of all your trees:

  • plant and encourage a biologically diverse property – trees with unrelated but nearby neighbors are often healthier 
  • invite and protect pollinators, both bird and insect
  • plant natives 
  • insist on local stream and riparian health protections
  • reduce pollution:  gasoline, exhaust, consumer pesticides; minimize lawn
  • monitor your trees for stress or disease, and act early 
  • protect roots from soil compaction (e.g., don’t park or drive  under tree canopies)

The majority of this presentation is courtesy of Dale Luthringer, Environmental Education Specialist, Cook Forest State Park – with thanks for his gracious permission and his time, from the CFC.  

Do you think your hemlock is afflicted by pests or diseases?  For specific questions on hemlock health issues, please contact your DCNR Service Forester, or the PA Bureau of Forestry

Hope for Hemlocks article

hemlocks over Cook Forest Longfellow Bridge

The Cook Forest Conservancy obtained permission from the author to link to this informative article, which summarizes the situation, the current science, and the programs and trials underway in the US to control HWA (hemlock woolly adelgid, an invasive insect) on Eastern Hemlocks, as of late 2020.  Cook Forest State Park is a priority area for HWA treatment, as both an exemplary old-growth area, and a National Natural Landmark – so our trees are in better shape than most.  HWA is currently in the forest, though, and we and all others in hemlock forests must remain informed and vigilant. 

Hope for hemlocks: New tactics found to fight deadly pest

by Ad Crable for the Bay Journal, 23 November 2020

The article bluntly sets forth the magnitude of the threat:

“Without intervention, most trees in natural settings will die,” according to [Pennsylvania’s] latest Eastern Hemlock Conservation Plan.


There still are an estimated 124 million hemlock trees greater than five inches in diameter alive in Pennsylvania. But that’s nearly 13 million fewer than in 2004, and the mortality rate has increased fourfold since 1989.

and emphasizes the importance of Eastern hemlock to hundreds of other species, and its unique and irreplaceable niche in the forest ecosystem.  For example, Hemlock groves provide cooling, filtering, and erosion control along streambanks, and their survival is essential for the survival of native trout, and the other organisms of Pennsylvania’s cold water streams.


The article succinctly covers the current methods of protecting hemlocks, from injecting chemical pesticides into the soil surrounding tree roots, to releasing varieties of beetles and sliver flies that predate on the HWA.  Scientists are studying stands of hemlock which appear resistant to HWA, and working on replicating this characteristic.


Science is working to help the hemlocks find a natural balance – to let the tree adapt to this non-native insect threat, or to bring in predators of HWA to keep its impact on hemlock health manageable – and to keep this valuable and venerable conifer in our forests.  Because, as Donald Eggen, forest health supervisor for the Pennsylvania Bureau of Forestry so aptly states:

When you walk through a hemlock forest, you are experiencing a unique habitat that is only found in a hemlock forest.

HWA in Cook Forest – 2020 Update

Hemlock Woolly Adelgid – it’s a non-native invasive insect that’s a massive threat to the old-growth hemlock trees of Cook Forest, and it’s still here.

Hemlock Woolly Adelgid in Cook Forest State Park - present in 2020

Hemlock Woolly Adelgid in Cook Forest State Park

Hemlock woolly adelgid (HWA) has been consistently treated by state agencies since it was first found in Cook Forest State Park in 2013.  First – the bad news – it’s still here.  The photo above was taken in May 2020, and those white little cotton-like tufts confirm the presence of HWA on hemlock trees within park boundaries. 

The good news: 

  • the infestation is not blanket, but concentrated in small areas; 
  • the Eastern Hemlocks in Cook Forest remain largely healthy;
  • the state is continuing treatment, even in this most uncertain of years — 100,000 inches of trees are scheduled to be treated again in 2020, as soon as rainfall rises the water to levels enabling soil injection

HWA was never going to be a short-lived threat, and it’s important to keep in mind the utter devastation it wrought in the Great Smoky Mountains, where it hit first, and in a warmer climate.  The PA Bureau of Forestry continues to work toward establishing a bio-control for the insect, as exists in places where HWA is native (the Pacific Northwest and Japan).  Until then, regular treatments can keep these hemlocks healthy, and their surrounding ecosystems intact.  Eastern Hemlock is a “keystone” species, and integral for keeping our streams cool and clear, for filtering pollutants, and for and managing storm runoff. 

These tasks become more challenging as our climate cycle changes – we’ve experienced stronger, shorter storms punctuating long dry periods, which means less water is being absorbed into the aquifer.  Western Pennsylvania also had a warm winter, which favors reproduction of HWA – and they reproduce exponentially.

HWA – What can be done by individuals to protect Hemlock trees?

Monitoring is of utmost importance – regularly check the health of the hemlocks in your yard, and stay vigilant when hiking or out on state forest lands.  Since HWA often infects trees from the top down, especially check branches blown off by wind, and the upper canopies of hemlock trees that have recently fallen.

We appreciate your supporting ongoing efforts – both in the state and private sectors – to control HWA.

  • Private landowners seeking assistance for trees they think may be infested can contact the CFC, or their county’s Service Forester.
  • To report infestations found on public land, please email PaForester@pa.gov – it’s ideal if you can provide a GPS location, and a clear photograph of the suspected bugs, as well.

Follow these links to learn more about the importance of eastern hemlock, or the invasive insect threatening it – hemlock woolly adelgid.

Cathedral film at Clarion University

A short documentary on how & why the State Park is protecting the Hemlock trees of Cook Forest from the Hemlock Woolly Adelgid (HWA) – and what it would mean if we lost that battle.  Hemlock is a keystone species, irreplaceable.  Eastern hemlock trees filter sediment and prevent stream bank erosion, and its evergreen boughs are integral for keeping streams cold enough for trout – hemlock streams average ten degrees cooler than waterways without hemlock. 

The film is 22 minutes long, will be followed by a short Q & A session.

At 7 pm, all are welcome to attend a general meeting of the Iron Furnace Chapter #288 of Trout Unlimited, featuring speaker Ryan Borcz, DCNR park manager for Cook Forest & Clear Creek State Parks, discussing an in-progress stream habitat improvement the chapter is orchestrating in Clear Creek.

Both events are in Room 120 of the Grunenwald Science and Technology Center (STC), Clarion University of Pennsylvania – GPS Address: 909 E Wood St. Clarion PA, 16214. Free parking is available slightly downhill & across the street.

Hosted by the Cook Forest Conservancy, Iron Furnace Chapter #288 of Trout Unlimited, & Clarion University – film courtesy of Wild Excellence Films.

Forest Resilience in a Changing Climate

Penn State Forest Stewards series article – written by Jim Finley, Professor Emeritus, Forest Resources Management, Center for Private Forests at Penn State.

So far for most Pennsylvanians, Winter 2020 has been a non-event. Depending on where you live, temperatures are considerably above normal and snowfall below normal. Individual perspectives might lead to interpreting these two statistics as either positive or negative. No snow equals no shoveling. Warm temperatures equal more time outside. Or, no snow equals no sledding or skiing. Warm temperatures equal more ticks.

Thinking more broadly than personal values or needs; Is this winter’s weather a harbinger of a future driven by climate change? If so, how will Pennsylvania’s forests respond?

PA Forest Stewards - Jim Finley on Climate Change 2020

For sure, weather is fickle. Mark Twain purportedly said, “Climate is what we expect, weather is what we get.” It seems something is happening to the climate and, whether you attribute it to human activities or just unexplainable variation, Pennsylvania’s forests are facing challenges.

Forest Resilience in a Changing Climate

Aldo Leopold, a 20th century mid-western conservationist, and author of The Sand County Almanac and many other writings about our relationships to the land and natural systems, was a keen observer of change that others seemed to miss. He wrote, “One of the penalties of an ecological education is that one lives alone in a world of wounds. Much of the damage inflicted on the land is quite invisible to laymen . . . in a community that believes itself well and does not want to be told otherwise.” Simply, he was saying that the more one knows about ecology, the more apparent change is and that many will neither see nor believe that it matters. Many resource professionals as well as laypeople are seeing change in many areas of our environment. As Leopold suggests though, many of these changes and linkages may not be obvious to less than “keen observers.”

Disturbance and change are part of natural systems. Resilience is the ability of a system to recover after disturbance, which determines its ability to persist and function over time. The degree and extent of a disturbance logically affects the capacity of a natural system to recover. For example, in a typical winter, forests often experience damage from wind and ice. Most commonly this is local damage and a few trees experience broken limbs and some trees tip over. The ability of the forest to function across a larger landscape continues unabated – some trees benefit from increased light and growing space from the loss of their neighbors – the forest almost ignores the event.

Citizen Scientist Training

Citizen Science Training 2019-10-02

HWA (Hemlock Woolly Adelgid) kills trees – and it’s here.  Invasive plants such as Japanese barberry and tree of heaven are threatening the regeneration of important species, while providing little to no habitat or food for wildlife.  But, with your help, we can protect our valuable old-growth forest.

Join us for Citizen Scientist training to learn about imapinvasives, a free tool that you can use to track infestations. We’ll also show you how to identify the invasive pests and plants – then you just report back data whenever you’re in the field. Together we can keep our forest healthy!

Wednesday, 2 October 2019 – 6 pm >> add event to your google calendar

This Free event is open to all, and is co-sponsored by the Roger Tory Peterson Institute of Natural History as a project of the Allegheny Forest Health Collaborative.  The Gateway Lodge generously donated meeting space – the address is 14870 PA-36, Cooksburg, PA 16217.  

 

Anthropologie in Cook Forest!

Anthropologie supports the hemlocks of Cook Forest State Park

After shooting their fall lighting catalog along lovely Tom’s Run in Cook Forest State Park, Anthropologie decided to get its charity, Philanthropie, involved in saving the hemlock trees that line the stream & do their own important work – protecting the aquatic residents, cleaning our water, and keeping the forest cool and stable.  They’re under assault from hemlock woolly adelgid (HWA), a tiny invasive insect, and the CFC and many other entities – the Bureau of Forestry, the USFS, and the DCNR – are cooperating to keep these essential trees healthy.

You can help too!  Please consider donating via the link below, through which all funds raised will go to hemlock preservation, including education, monitoring, and active treatments:

Or join the Facebook campaign here: Anthropologie Campaign for Cook Forest Hemlocks

Thank you for your support!

HWA Hemlock Seminar Recap 2019

2019 HWA Seminar recap

A solid group attended this year’s Bureau of Forestry seminar on Hemlock Woolly Adelgid – its life cycle, the dangers it poses and the importance of Eastern (Canadian) Hemlock to our biodiversity, and the currently available treatment options – at the Cook Forest State Park office.  Following the classroom session, we trekked a short distance along beautiful Birch Trail, where Forestry scientists illustrated the soil injection method of tree inoculation, which will protect the treated trees for an estimated seven years. 

Jim Altemus explaining the soil treatment procedure to an attendee

As you may know, many of our ecosystems depend upon hemlock to filter our water and contain our streambanks, shade these streams for trout and the aquatic insects they feed upon, clean our air, and create the singular micro-climate that no other tree can reproduce, and on which many species depend.

You can protect your hemlocks at home:

  • minimize stressors by keeping them watered in droughts and not compacting their soil, and 
  • monitoring them closely for health – watch the crown for thinning, and always check wind-blown limbs for evidence of HWA infestation, as they tend to colonize the top half of the tree.   

View the entire photo gallery here – and please join us next year, as we hope to make the HWA Treatment Seminar an annual event!  The Cook Forest area hemlock are relatively healthy now, and by keeping Pennsylvanians aware and proactive, we can ensure their survival for the good of the woods, waters, and people of the coming decades 🙂

Shagbark Jones admires some hemlocks

a Quick Walk for the Woods – 28 Sept 2019

Cook Forest Hike - 28 Sept 10 am

Before the WIN Wildlife Courier Training, before the hour of relaxing yoga on the lawns along Tom’s Run, before a peaceful lunch in the park – walk with the CFC for a brief tour of the hemlocks and cold-water streams they protect. Saturday, 28 September, 2019,  10: 30 am, meeting at the new Cook Forest State Park office, 100 Route 36, Cooksburg, PA 16217.

No fee or registration required – just bring a water bottle, and your patience 🙂 for the CFC director’s first public tour of the forest.  We’ll try to cover the importance of hemlock, why Cook Forest is the best old-growth stand to protect, and how to help do it.  Our hellbenders, warblers, and the future is counting on us to do so!  

Learn more & let us know you’re attending on the Facebook Event here

then join Soul Blossom Yoga of Erie for a refreshing 60 minutes of Yin Yoga amongst the hemlocks – bring your mat and a water bottle – Donations only, generously collected by Soul Blossom to benefit the CFC 🙂 

 

HWA Treatment Seminar – 14 Sept 2019

2019-09-14 CFC BOF HWA Seminar Cook Forest

HWA kills trees - Protect your Hemlocks!

Learn more about the threat, and how to treat your own trees.  This event is free to all – held at 2 pm on Saturday, 14 September, 2019, at the new Cook Forest State Park office, 100 Route 36, Cooksburg, PA 16217.  It will follow the member’s picnic and history walk hosted by the Woodland Owners of Clarion-Allegheny Valley.

Join specialists on invasive insects from the PA Bureau of Forestry for information on at-home treatment for Hemlock Woolly Adelgid (HWA), including:

  • the importance of helmock
  • the reduced cost of treatment (far less than removing dead trees!)
  • different treatment methods, including:
    • overview of available pesticides;
    • which is best for a given situation; and
    • the best seasons for treatments

followed by an on-site session during which attendees can actually apply the treatment – this single application should protect each target hemlock for seven years!

We’ll be walking along Tom’s Run for the field work – please wear long pants and closed shoes; gloves will be provided.  Attendees may be able to loan equipment from the PA Bureau of Forestry for treating their private hemlock stands – more details at the event. 

Download a printable copy of the event PDF here

HWA Treatment Seminar – 26 Sept 2018

HWA Kills Trees, and it is here, in Northwestern PA

Free HWA Treatment Seminar

Learn more about the threat, and how to treat your own trees.  This event is free to all, but space is limited – RSVP kelly @ cookforestconservancy.org, or via facebook, to join specialists on invasive insects for information on at-home treatment for Hemlock Woolly Adelgid (HWA), including:

  • the importance of helmock
  • the reduced cost of treatment (far less than removing dead trees!)
  • different treatment methods, including:
    • overview of available pesticides, chemical and insect;
    • which is best for a given situation; and
    • the best seasons for treatments

followed by an on-site session during which attendees can actually apply the treatment – this single application will protect each target hemlock for seven years!

RSVP reply will include further details – we’ll be at Shelter #1 off Forest Road (the map should get you close enough to see us!  First right past the park office along Forest Road, before Breezemont and the double turn-offs at the Log Cabin Inn & Longfellow/ Forest Cathedral trailheads).

Download a printable copy of the event PDF here.

Twilight of the Hemlocks & Beeches

Brunch with the author, Tim Palmer
16 September 2018 – Cook Forest

cover of Twilight of the Hemlocks and Beeches by Tim Palmer, a new book published by Penn State University Press.

 

Join the Cook Forest Conservancy for coffee with author Tim Palmer, who’s presenting a slideshow of his lovely photography and research detailing the decline of the Eastern Hemlock and American Beeches, published this month by Penn State University Press — and what we can do to save these stately trees.

This event is free to all who RSVP, though space is limited – please RSVP here:  http://cfc-palmer.rsvpify.com.

“Tim Palmer’s breathtaking photography perfectly captures the magic of Pennsylvania’s state tree, whether seen during a walk through an ancient grove or meandering along many streambanks and waterways in the commonwealth.

His images and prose will inspire us all to work on building resilience for adaptation to the impacts of climate change and to do what we can to save these majestic trees.”

—Cindy Adams Dunn, Secretary, Pennsylvania DCNR

This beautiful hardcover book will be for sale by the author at the event.  Any donations to the Cook Forest Conservancy will directly benefit efforts to preserve the old-growth stands in Cook Forest from the Hemlock Woolly Adelgid.

>> 10 – 11:30 am, Sunday, 16 September, at Pavilion #2 in beautiful Cook Forest State Park, Pennsylvania.  Approx. GPS coordinates = 41°20’50.0″N 79°13’11.2″W

“Cathedral” – documentary screening – 15 Sept

Cathedral: The Fight to Save the Ancient Hemlocks of Cook Forest

Cathedral - Wild Excellence Films - HWA still

Playing at the Sawmill Theatre in Cook Forest State Park at 7 p.m. on Saturday, 15 September.  Tickets are $15, and are available by calling 814-927-6655, or via Eventbrite by following this link.

The documentary tells the story of the hemlock trees of Cook Forest State Park, Pennsylvania, which are under attack by the Hemlock Woolly Adelgid (HWA), a destructive insect that has already killed thousands of trees in the eastern United States. Hemlock Woolly Adelgid was discovered in Cook Forest in 2013.  The little “Larry” beetles (i.e., beetles of the genus Laricobius), shown in the image above, are one of the methods of combatting the invasive HWA — click on the image to view the film’s trailer.

“These magnificent trees are hundreds of years old, and we have to do everything we can to help save them,” said Melissa Rohm, filmmaker on the project. “We hope that Cathedral will raise awareness about what’s happening in Cook Forest and why the hemlocks are so important. We want to inspire people to help.”

Cathedral includes interviews with park staff and is narrated by Old-Growth Forest Network founder Joan Maloof. The film takes the viewer on a journey through the forest in all seasons and shows the important work being done by the Pennsylvania Department of Conservation and Natural Resources and the Pennsylvania Bureau of Forestry.

Interview with Wild Excellence Films by Allegheny Front

Listen to “Filmmakers Highlight Plight of Cook Forest’s Iconic Hemlocks,” an interview with Dave & Melissa Rohm, the team behind Wild Excellence Films‘ documentary on Cook Forest, Cathedral: The Fight to Save the Ancient Hemlocks of Cook Forest. Here’s an excerpt:

Interviewer Kara Holsopple: What would it mean to lose the hemlocks in Cook Forest, to the ecosystem there and also to people?

David Rohm: Cook Forest would be a much different place. If you’ve been to Cook Forest, there’s a sheltering ability that these hemlock trees provide. 120-foot trees, you take away even half of them, and you’re going to see a huge difference. There’s a lot of wildlife. Migrating birds love the forest –way up in the canopies, they’re safe there. They reintroduced fishers there not too long ago. It’s like a mink but a little bigger. To people, Cook Forest means a tremendous amount. They get 500,000 visitors a year who aren’t going to visit if it’s not the same forest.

Please visit the Allegheny Front, via this link, for the full interview and audio.