Eastern hemlock (Tsuga canadensis) is a large growing, long lived tree found throughout the eastern part of the United States and Canada.  Hemlock prefers northern climates so it tends to be found in cooler “micro-climatic” sites in the southern part of its range such as higher elevations, north facing slopes, or depressed “coves” existing around streams and other wetlands.  In Frederick County most of the native hemlock stands are found in the mountainous areas in the north western part of the county around Mountaindale, Thurmont, Sabillasville, and Emmitsburg.  Many of these hemlock groves exist in and around small streams that contain cold water fisheries such as the native brook trout.

The past 10-15 years have witnessed a general decline of hemlock groves in the county with many areas loosing most of the hemlock overstory.  Much of this decline is the result of infestations of hemlock adelgid (Adelges tsugae) an insect that attaches to the underside of the hemlock needle and sucks the juices from the needle causing the tree to defoliate.  This loss of needles can cause the hemlocks to decline and die within 2-3 years.  Besides the aesthetics of loosing this large stately tree, the loss of hemlocks will adversely affect wildlife that feed or roost in these trees.  It has also been demonstrated  that the loss of hemlock canopy will cause a general rise in water temperatures which can adversely affect brook trout, other trout, and organisms that require cooler water temperatures. 

Due to the important ecological niche that hemlock occupy and their significance to recreation especially the cold water fisheries, a number of hemlock restoration projects have been undertaken throughout its native range.  A similar venture should be considered by the Catoctin Forest Alliance for Frederick County.  Enclosed with this memorandum is an outline that will overview what might be necessary to conduct this project.  If the Catoctin Forest Alliance wishes to consider this project further, I suggest meeting with potential partners to discuss the matter.  In particular, I recommend meeting with Tom Lupp, Regional Manager with the Maryland Department of Agriculture Pest Management Division since Tom can provide much insight into a potential program.

1. Assessment:  An assessment should be made to identify existing or historical stands of hemlock.  We need to know which stands are left, and what sites have the potential to support these stands. This would involve the use of mapping and field surveys.  Some sort of standard should be devised to rate each site. I.e. (amount of hemlock already present, proximity to sensitive areas like trout streams, bogs, recreational areas,  size of the compartment, micro-climatic conditions that would favor a healthy population of hemlock.)
 
2. Planning:  This stage would involve a number of elements to enable CFA to be well prepared for the implementation phase.  Some of these elements would be:
 

   1. Researching other attempts at hemlock restoration to find out what would be the most likely course to ensure success.
   2. Identifying partners and resources: e.g. places to purchase adelgid predators, obtaining hemlock seedlings, pesticides, contractors etc.
   3. Obtaining grants, donations, payments to fund this project.
   4. Prioritizing stands for restoration.
   5. Contacting property owners to participate in the program.
   6. Preparing restoration plans for the individual stands.

3. Implementation: Once we have identified the restoration sites we need to implement restoration measures which could include, forest management practices to promote hemlock growth and development, tree planting activities, adelgid control strategies, etc.

4. Monitoring: Following implementation the site should be monitored to determine how successful the restoration activities were.  This might include determining health, growth and survival of the hemlock, conducting adelgid predator surveys, monitoring for adelgid and other pests, conducting landowner surveys to ascertain participants attitude regarding the program.

5. Preparing final report:  So as to document what was done and how successful we were.  (We might have to place a finite time on this project say 3-5 years.)

 

 
http://images.google.com/images?hl=en&q=hemlock+woolly+adelgid&um=1&ie=UTF-8&ei=cL1VSvTXHOO_twfhk6HhAg&sa=X&oi=image_result_group&ct=title&resnum=4

 

 

 

http://www.invasive.org/hwa 

 

 http://www.nysaes.cornell.edu/ent/biocontrol/predators/pseudoscymnus_tsugae.html

 

http://www.treecareindustry.org/articles/Safety/TCI0708_1.htm

Trunk injection of insecticides 

http://www.arborjet.com/

http://www.mauget.com/index.cfm?PageID=7

Soil injection 

INTRODUCTION AND CULTIVATION OF CHINESE HEMLOCK (TSUGA CHINENSIS) AND ITS RESISTANCE TO HEMLOCK WOOLLY ADELGID (ADELGES TSUGAE)