MDA, DNR Working to Protect Maryland’s Premier Hemlock Stand at Swallow Falls State Park from Devastating Pest

OAKLAND, MD (May 11, 2011) – Today, deep in the 300-year old hemlock forests of Maryland, Deputy Secretary of Agriculture Mary Ellen Setting joined forest health inspectors from state and federal departments of agriculture, Maryland Park Service and Maryland Conservation Corps (MCC) members as they began proactively treating the State’s premier hemlock stand at Swallow Falls State Park in Garrett County to protect the trees from the devastating impact of the hemlock woolly adelgid (HWA).

The HWA is a small exotic insect native to Japan, discovered in Virginia in 1951, that has slowly spread along the east coast of the United States resulting in hemlock decline and death. In addition to enhanced surveillance, Maryland Department of Agriculture (MDA), Maryland Park Service and MCC started proactively treating thousands of hemlocks with soil and tree insecticide injections with the goal to ultimately treat 100 percent of the hemlocks in the state park. They will concentrate on first treating the old growth area and entrance to the park and then treat the remaining hemlocks there. This program could take up to five years to complete. The injection suppression technique complements the biocontrol release of predator insects currently underway, which is showing great promise in Maryland.

“I am pleased to witness firsthand the steadfast efforts that Maryland is taking to stop the spread of the hemlock woolly adelgid and the damage it causes to our region’s important hemlock trees and associated ecosystems,” said MDA Deputy Secretary Mary Ellen Setting. “Together with our state, federal and academic partners we are finding innovative ways to protect the environment for generations to come and to help keep Maryland smart, green and growing.

“The virgin hemlocks of Swallow Falls State Park are a natural mecca for 250,000 visitors annually,” said DNR Secretary John Griffin. “We are committed to working in partnership with the MDA to protect this special place, as well as other important hemlock stands throughout Maryland’s public lands.”

“The Maryland Park Service has mobilized all 50 of its Maryland Conservation Corps (MCC) members to support the week-long HWA suppression effort at Swallow Falls State Park,” said Maryland Park Service Superintendent Nita Settina. “MCC members will be literally walking in the footsteps of their predecessors, the Civilian Conservation Corps, which encamped at Swallow Falls State Park on May 14, 1934. Today, MCC members will be working to save the same trees that 77 years ago inspired a generation that restored Maryland’s natural resources and built many of its State Parks.”

Without any natural controls, such as predators or disease, HWA populations often go unchecked, resulting in hemlock decline and death. The hemlock forests of Maryland are part of a unique and often fragile habitat. Hemlocks are usually found growing in riparian areas or in steep cove forests in the northern and western tier counties of Maryland. It is estimated that more than 42,000 acres of such forests exist in Maryland. Of special concern are a number of undisturbed stands of large hemlocks in Garrett County, namely Swallow Falls State Park.  Swallow Falls has the largest population of hemlock trees in Maryland and is the largest virgin hemlock stand in all of Maryland – over 300 years old.  Swallow Falls State Park is 478 acres in size, and contains 37 acres of virgin old growth hemlock forest, which means it has never been cut or logged by anyone.

The hemlock woolly adelgid was found in landscape hemlocks in the Baltimore and metropolitan Washington areas of Maryland in the 1980s and has spread to natural stands across Central Maryland finding its way to Garrett County by 2001.  The hemlock woolly adelgid is most easily recognized by the white “woolly” wax they produce on young hemlock twigs. The “wool” is present all year, but is most abundant and conspicuous during the spring and fall when egg masses are present. Fully grown adults are only about the size of a period on a printed page.

“We are taking a two-pronged approach to control these pests by implementing biocontrol and suppression using insecticides. While the predator beetles are the best long term hope for management of the hemlock woolly adelgid, especially in remote natural stands of hemlock, it is essential we take proactive steps to protect these treasured stands until we can establish a strong population of the biocontrol beetles in the area,” said Bob Tatman, program manager of MDA’s Forest Pest Management Program.”

A bucket truck, supplied by Potomac Edison, assisted entomologists in their inspection of hemlocks in Swallow Falls State Park for signs of HWA infestation.

“We recognized the state could use a little help, so we lifted an experienced lineman into the canopy to snap photos, collect samples, and make observations,” said Jim Fakult, president of FirstEnergy’s Maryland Operations. “We’re pleased to lend park service officials a hand to protect this treasured stand of old-growth forest for Marylanders to enjoy for generations to come.”

The Maryland Departments of Agriculture and Natural Resources have developed a Hemlock Woolly Adelgid Management and Suppression Plan. This plan sets forth management options for HWA on public lands across the State. More than 50 hemlock stands were prioritized. The top 50 prioritized stands were selected as the sites where suppression might be attempted.  Last year MDA started to survey all 50 top priority sites for the HWA. Only publicly-owned sites would be part of this suppression project. Beginning in 1999 with funding and technical support from the USDA Forest Service, MDA evaluated predators for control of HWA, all of which are very small beetles in the same family as “lady bug” beetles familiar to gardeners. Since that time, MDA Forest Pest Management staff have been releasing biocontrol beetles to suppress the hemlock woolly adelgid.

Since 1999, MDA has released three different species (Sasajiscymnus tsugae, Laricobius nigrinus, Scymnus sinuanodulas) totaling 49,358 beetles in 27 locations in Harford, Baltimore, Frederick, Washington, Allegany and Garrett counties. Of the three species released, Laricobius nigrinus has already been established at seven of the 10 release sites.  The other three sites are the most recent release locations and population levels have not met the requirements to be considered established. MDA will continue to release this species and monitor for establishment. Sasajiscymnus tsugae and Scymnus sinuanodulaswere never recovered after release and have been dropped from consideration for bio-control releases in Maryland.

In addition to the biocontrol beetles, MDA has been implementing a suppression program using insecticide since 2004.  To date, MDA has treated 719 trunk injected trees since and more than 4,450 soil injected trees in Baltimore, Frederick, Garrett, Harford, and Washington counties.

MDA is currently undertaking its largest HWA suppression project to date with a goal of treating more than 5,000 trees in Harford, Baltimore, Frederick, Allegany and Garrett counties between spring 2010 and spring 2012.

Additional information about the hemlock woolly adelgid can be found on the following websites:
•    www.mda.state.md.us/plants-pests/forest_pest_mgmt/cooperative_forest_health_program/hwa.php 
•    http://na.fs.fed.us/spfo/pubs/pest_al/hemlock/hwa05.htm
•    www.fs.fed.us/foresthealth/technology/pdfs/FS_hwa.pdf 

For further information, contact Bob Tatman, Maryland Department of Agriculture, Forest Pest Management Program at (410) 841-5922.