Tag Archives: eastern hemlock

Cool Science, Flora & Fauna, Research

Big Hopes for Little “Army” in Parks’ Fight against Hemlock Invaders

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As the third most common tree in New York, hemlocks fill our forests and are found in many New York State Parks. Located along hiking trails, streams, gorges, campsites, and lake shores, the evergreens can live to be hundreds of years old, providing vital ecosystem services and supporting unique habitats.

In addition to providing homes and food for many forest creatures, hemlocks also keep fresh water resources cool and clean by moderating water temperature and acting as a natural filtration system along streams. Since hemlocks are such a critical component of eastern forests, they are known as a “foundation species.”

Hemlocks in New York have been under attack by an invasive forest insect pest that originated from southern Japan, the hemlock woolly adelgid (HWA), which after being found in Virginia in the 1950s has spread to kill untold millions of hemlocks from Georgia to Maine.

Hemlock Woolly Adelgid infestation in the Eastern U.S. (U.S. Forest Service)

Adelgids are tiny insects that insert piercing-sucking mouthparts into hemlock twigs, causing damage to woody tissue that inhibits water and nutrients from reaching emerging hemlock buds. This limits the growth of new twigs and eventually kills the tree.

First detected in New York in the 1980s, the insects have spread through the Hudson Valley, Catskills, Southern Tier and Finger Lakes regions. Infested hemlocks can be found at state parks including Harriman, Minnewaska, Taughannock Falls, Watkins Glen, Letchworth, and Allegany.

At about 6/100ths of an inch long, the flightless adelgids are hard to spot, but in the winter through early summer leave distinctive white “woolly” egg masses on hemlock twigs. In an infestation, developing buds are killed first, then in a few years, the weakened tree loses its needles and dies.

Left, a dead hemlock after being killed by HWA. Right, a healthy tree.
A map of New York State towns and counties where HWA had been found in the Hudson Valley, Capital Region, and Southern Tier by 2017. The HWA has yet to move into the Adirondacks or the Tug Hill Plateau. (State Department of Environmental Conservation)

The threat posed by HWA is dire, especially since the state’s ecosystems lack natural controls _ known as biocontrols _ such as predators or tree resistance that could fend off some infestations and avert widespread hemlock destruction.

Currently, insecticide treatments are our only sure option for saving trees, but trees must be treated on an individual basis, so it can be costly or impractical to treat large swaths of hemlocks. In parks with thousands of trees and important or rare ecosystems to protect, biocontrol is the only solution to counter a pest like HWA.

But biocontrol against the invading adelgid may be on the way. It is the form of a small dark beetle and a small silvery fly, nicknamed “Little Lari” (Laricobius nigrinus) and “Little Leuc” (Leucopis spp.), respectively, by researchers at the New York State Hemlock Initiative at Cornell University.

Led by forest entomologist Mark Whitmore, the program operates a biocontrol lab researching the introduction of HWA predators throughout New York, hoping to protect hemlock trees by slowing the spread of adelgids into new areas.

The NYSHI collects these predators in the Pacific Northwest where HWA is native and has many predators controlling population growth so the hemlocks are not damaged. The collected beetles and flies are shipped to the quarantine facility at Cornell  to be certain none of the western adelgids are accidentally introduced into New York with the predators.

Knowing where to release these “good bugs” can be a challenge, but we are helped in this by State Parks staff, who provide critical data from ground surveys to find emerging infestations, assess potential biocontrol sites, and monitor for whether the biocontrol insects are thriving and growing in their new homes.

Read this post in the State Parks blog by Abigail Pierson, state Parks Forest Health Specialist, to learn how crews search for and document the presence of HWA.

Since 2009, the Cornell initiative has released more than 4,500 Laricobius beetles in State Parks including Harriman in Rockland County, Letchworth in Wyoming County, Mine Kill in Schoharie County, and Taughannock Falls, Buttermilk Falls, and Robert H. Treman in Tompkins County. Additionally, parks staff at Minnewaska State Park Preserve in Ulster County helped survey for Laricobius beetle establishment, and mapped hemlocks to help identify hemlocks stands and prioritize HWA surveys in the park. 

Since 2015, when Leucopis silver fly releases began, researchers have released more than 3,300 flies at several state park sites including Taughannock Falls and Buttermilk Falls state parks in Tompkins County.

“Little Lari” (Laricobius nigrinus) (New York State Hemlock Initiative)
“Little Leuc” (Leucopis spp.) (New York State Hemlock Initiative)

While there has been no evidence of the biocontrol bugs suppressing HWA populations on a large scale, it takes time for predator populations to build. There has been recovery of Laricobius beetles at some sites, indicating establishment. By continuing to release more “Little Laris” and “Little Leucs” to bolster those established populations, we will be able to build on that initial success.

The list of parks that have reported HWA infestations is growing, especially in the Capital Region. Thacher State Park in the Capital Region reported adelgid infestations in 2017 and while insecticide treatments reduced the local problem, the insects continue to threaten the Adirondacks, which so far remains uninfested.

In State Parks, preventing dead trees from injuring park visitors or damaging park infrastructure including campsites and trails is crucial. Additionally, preventing the loss of a critical foundation tree species in forest habitats is another major priority.

Park visitors can play an active role in slowing the spread of the adelgid in New York by keeping an eye on hemlocks. Reporting any infestations that you find provides researchers and land managers with invaluable data for improving our management efforts.

How You Can Help

If you believe you have found HWA:

  • Take pictures of the infestation signs (include something for scale such as a coin or ruler).
  • Note the location (intersecting roads, landmarks or GPS coordinates).
  • Fill out the hemlock woolly adelgid survey form.
  • Email report and photos to Department of Environmental Conservation Forest Health foresthealth@dec.ny.gov or call the Forest Health Information Line at 1-866-640-0652.
  • Contact your local Partnership for Regional Invasive Species Management (PRISM) by visiting http://www.nyis.info/.
  • Report the infestation at iMapInvasives.
  • Slow the spread of HWA in our forests by cleaning equipment or gear after it has been near an infestation, and by leaving infested material where it was found.

The New York State Hemlock Initiative has produced a variety of educational videos on the threat posed to hemlocks by the HWA.

Cover Photo: A hemlock branch showing the woolly white egg masses of Hemlock Woolly Adelgid. (New York State Department of Environmental Conservation)

Post by Charlotte Malmborg, Education and Outreach Technician, New York State Hemlock Initiative, Cornell University Dept. of Natural Resources

Flora & Fauna

Winter Tree Identification Part II: Evergreen Trees

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Evergreen means these trees keep their “leaves” throughout the winter. Though we may call them pine needles, they are actually very skinny leaves that serve the same function as the leaves on a deciduous tree. Identifying evergreens during the winter months is almost the same as in spring and summer, with the added advantage of having mature pine cones.  Growth pattern, bark, cones, needle shape and number are used to identify the different species. Let’s learn how you can identify red pine, white pine, and eastern hemlock.

Last time we learned that leaves attached at the stem from the node. This is the same for evergreen trees, except these trees can have multiple needles attached to the stem in a bundle or sheath. This helps identify species since they differ by the number of needles they have per bundle.
See the example below:

Needles per cluster 2
This red pine has two needles per bundle.

 

Now we are ready to learn some tree species!

We will start with white pine. First let’s look at the bark and growth pattern:

WHITE PINE

White Pine LS Final 2

White pine usually grows straight and tall with horizontal, upturned branches. The tree has a uniformly full foliage appearance. The bark is a light gray in color with shallow ridges.  White pines can be found in well drained soils and are native throughout the state.

Now we will look at the characteristics of the twig and cone. There is a pencil in each picture for size reference:

White Pine LS 1

White pine has 5 needles per bundle. The needles and stem are flexible and slender. The cone is long and narrow and about 3 to 8 inches in length. Needles are light green in color.

RED PINE

Red Pine Tree LS Final

Red pine is a tall, straight growing tree with horizontal or dropping branches. The foliage looks clumpy, instead of uniformly full like white pine.  The bark can have a reddish coloring and is flaky/ scaly. This tree grows in well drained areas; such as rocky or sandy habitat. Red pines are native to a small area of the state, but are often planted around reservoirs or in parks.

Red Pine LS

Red pine has two long needles per bundle. The needles and stem are thick, unlike white pine. The needles are dark green and stiff – they break in half easily. The cone is short and round; usually about 1.5 to 3 inches in length.

EASTERN HEMLOCK

Hemlock LS Final

Eastern hemlock has a tall straight growth pattern. The branches grow horizontally. The foliage is more of a yellowish green in color compared to white pine. In this picture there are white pine trees in the left background for comparison. The bark is scaly when young, becoming ridged with age. The trunk is reddish-brown in color. These trees grow in shady-moist habitat, often along streams, on slopes or at higher elevations. Eastern Hemlocks are native to NY.

Hemlock LS 5

Hemlock does not have bundles of needles, just one short needle per node. The needles are yellow-green in color and are soft and flexible. The underside of the needle is whitish. The cone is small and round, under an inch in length. The twig is thin and flexible.

Learn more about winter tree identification by reading the Winter Tree Identification Part I: Deciduous Trees and Winter Greens blogs.

Post and photos by Lilly Schelling.