1. Decline of Eastern Hemlock due to Hemlock Woolly Adelgid
Sophia DeMaio
April 25, 2007

2. Susceptible Species
Carolina (Tsuga caroliniana) and eastern hemlock (Tsuga canadensis)
Western (T. heterophylla) and mountain hemlock (T.mertensiana) also become invested but do not decline

3. Eastern Hemlock Range: Great Lakes to New England Cool, moist climates
Acidic soils
Very shade tolerant
Long-lived
-But soils vary in texture and drainage-affects rooting
Shade
-late successional-can regen. in gaps
-persists in 5% sunlight for 40 years
-responds well to release after 200 yr supression
Lifespan
-800 or more good sites
-frequent cone producers age
Dense canopies
-stable micro-climate-salamander, fish, aquatic insects
-deer wintering

4. Eastern Hemlock Importance
Economic
Tanning
Lumber
Pulp
Ornamental varieties
Ecological
Dense canopies
Vertical structure
Horizontal structure
Nutrient cycling
Ecological research
Canopy-Microclimate-hab. For deer, salamanders, fish and aquatic insects, prevents spread invasive plants
Vert. Structure-higher stand density, layering, birds
Horizontal-large diam. Snags for foraging and cavity-dwelling birds, mammals, carnivores
Combined effects-important food source, certain spec. highly dependent
Nutrient-slow decomp. Rates
Cultural aspect also very imp.-this is a case where economic concern is not driving research, monitoring and management of a species-people love hemlock because it is beautiful

5. Symptoms Needles dry Turn grayish green or yellow Thinning of foliage
Crown and branch dieback

6. Forest Impacts Tolerant conifer replaced by hardwoods Stand structure
Stand density
Microclimate
Wildlife habitat
Nutrient cycling
Ecosystem research

7. Primary Stress Hemlock woolly adelgid (HWA; Adelges tsugae)
Signs: fuzzy white spots underside of needles, late fall-early summer, crawlers spring and summer
Introduced from southern Japan to NJ->New England->Maine
Limited by T (39F spring generation, -25F winter generation) and vectors
Recent DNA testing shows region of southern Japan with milder winters (lower elevation) that originally thought and suggests HWA on the west coast is not the result of a recent introduction
Hurricane Gloria-1985, Nursery stock-1999, Gerrish Is.-2003, York County towns-2005-York, Kittery, Wells

8. Predisposing factors Warm winters Introduced pest Drought
No time for tree to adapt or predator populations to build
Drought
Low precipitation (especially in summer)
Drought-prone sites (shallow rooting, southern slopes)
Other hemlock stressors

9. Life Cycle Winter generation Eggs hatch mid-summer ~300 per adult
Crawler enter summer dormancy late summer
all adults are female=parthenogenesis)
Only moving and exposed stage
Find feeding sites on twigs
Resume development in October (2,3,4 instar nymphs)
Feed in place
White woolly covering
Spring generation
Eggs hatch early spring (20-75/adult)
Reach adulthood early summer
Some winged adults fly to alternate host (not available so die, but keep populations viable)
Density dependent population growth

10. Mechanisms for disruption
Depletes tree’s starch reserves
Inserts stylet into xylem ray parenchyma
starves to death
allocates E to external new shoots
New growth reinfested

11. Number of -25C events in Sanford, ME
Population control
Early freezing (spring generation)
Cold winters (-25) with little snow (overwintering sistens)
Predation
Native environment
here
Number of -25C events in Sanford, ME
Kathleen S. Shields and Carole A. S-J. Cheah.
USDA Forest Service, Hamden, CT
Connecticut Agricultural Experiment Station, Windsor, CT

12. Inciting factors
Transport of eggs or crawlers to suitable feeding site
Spread by wildlife, human activities, wind
HWA Feeding and reproduction

13. Contributing factors Drought Fungal infection
Other insect pests and diseases
Elongate hemlock scale
Hemlock looper
Spruce spider mite
Hemlock borer
needlerust

14. Control-preemptive Quarantine
Increase hemlock vigor (5 yrs before infestation)
Manage for white pine over hemlock in drought-prone sites
Decrease spread by vectors
Could do another map with vector risk

15. Monitor and Survey Public outreach education Costa protocol
Take a stand
Costa protocol
Especially important for tree of high cultural and ecological but not economic significance

16. Reactive control-Chemical and physical
Horticultural oils
suffocates adelgid
minimal impact other forest trees
widely spaced, manageable height
Stem/root injection
concentrated chemical
Systematic
drilling may further stress tree
Soil injection
Problem near streams
Soil organisms
Harvest vector trees
Salvage
Plant with white pine or other intermediate species on good sites
When apply hort oils?June-Oct. exposed on branch tips

17. Reactive control-biological
Beetles
Sasajiscymnus tsugae
Scymnus
Laricobius nigrinus
Fungi
Beauveria bassiana
Metarhizium anisopliae
Verticillium lecanii
Paecilomyces sp.
Ideal?
Whey-based fungal microfactory
Ideal?
Causes mortality of HWA (not other species)
Range limited to HWA
Tolerant of environment
Synchronized with life cycle

18. Feasibility Ecological Economic Conservation of threatened species
Pesticides for ornamental and vector trees
Risk maps, silvicultural methods and possibly biological controls more feasible forests-even with high conservation value
-preemptive measures most effective in both cases

19. Health Management Plan