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

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

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 15-400 Dense canopies -stable micro-climate-salamander, fish, aquatic insects -deer wintering

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

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

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

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

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

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

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

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

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

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

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

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

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

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 http://www.invasive.org/hwa/

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

Health Management Plan