Hemlock Woolly Adelgid. Robert M. Jetton, Ph.D. North Carolina State University Department of Forestry & Environmental Resources

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1 Hemlock Woolly Adelgid Robert M. Jetton, Ph.D. North Carolina State University Department of Forestry & Environmental Resources

2 The Hemlocks Genus: Tsuga (Carriere) Family: Pinaceae Slow-growing; Long-lived 800 to 1000 years Shade tolerant Drought susceptible 10 accepted species world-wide World-wide distribution restricted to 3 regions Photo: Kevin Potter Farjon Pinaceae: Drawings and Descriptions of the Genera Tsuga sieboldii Southern Japanese Hemlock

3 Hemlock Distribution and Phylogeny T. ulleungensis Photo: Kevin Potter

4 Geographic Distribution of Eastern & Carolina Hemlock Map: Robert Jetton

5 Eastern Hemlock Silvics Tsuga canadensis Typical habitat: riparian; mesic cove forests, swampy areas Climate: cool, humid Rainfall: mm/year Soils: acidic, moist, very welldrained Elevation: 0 to 1500 m Pinus strobus common associate Large geographic distribution in eastern North America Photo: Kevin Potter Godman & Lancaster Silvics of North America Vol I. USDA Forest Service Ag Hdbk 654.

6 Carolina Hemlock Silvics Tsuga caroliniana Typical habitat: exposed mountain bluffs and dry, rocky ridges Soils: acidic, nutrient poor, dry, sandy, sandy loams, sandy clay loams, with course rocky materials in upper profile. Photo: Robert Jetton Elevation: 600 to 1500 m Small geographic distribution in Southern Appalachian Mountains Photo: Kevin Potter Rare, occurring in a relatively small number of isolated populations Jetton et al For Ecol Mgmt. 255: Photo: Andy Whittier

7 Hemlock Ecological Importance Robert Jetton USDA Forest Service

8 Hemlock Economic Importance northernwoodlands.org whatgrowsthere.com Robert Jetton

9 Hemlock Woolly Adelgid (HWA) Adelges tsugae Hemiptera: Adelgidae World-wide pest of hemlock Native to Asia & Pacific Northwest Exotic invasive in Eastern North America Introduced to Richmond, VA early 1950s. T. sieboldii nursery stock. Maymont Estate Widespread hemlock decline and mortality in eastern US maymont.org

10 Robert Jetton

11 HWA Worldwide Distribution NATIVE EXOTIC Photo: Kevin Potter

12 Hemlock Resistance/Susceptibility to HWA Species Native Range Putative Level of HWA Resistance Tsuga canadensis (L.) Carr Eastern North America no resistance T. caroliniana Engelm. Southern Appalachians no resistance T. heterophylla Sarg. Pacific Northwest moderate resistance T. mertensiana (Bong.) Carr Pacific Northwest moderate resistance T. sieboldii Carr. Southern Japan moderate resistance T. forrestii Downie China moderate resistance T. dumosa (Don.) Eichler Himalayan Mountains moderate resistance T. diversifolia Masters Northern Japan high resistance T. chinensis (Franchet) China high resistance Photo: Kevin Potter

13 HWA Life Cycle Host-alternating between spruce and hemlock in Asia sexual and asexual reproduction Non host-alternating in eastern and western North America secondary host only (hemlocks, Tsuga spp.) lack of susceptible spruce species Photo: Kevin Potter asexual reproduction only Havill & Foottit Ann. Rev. Entomol. 52:

14 HWA Life Cycle 3 generations each year Sistens Overwinter generation (late June-mid March) Progrediens Spring generation (mid March to late June) Sexupare Winged generation that disperses to spruce in Japan This generation is formed in eastern and western North America but no suitable spruce hosts exists Sistens and Progrediens Egg stage 1 st instar nymph = crawler 3 additional nymph instars Adult stage (females only) Photo: Kevin Potter

15 HWA Crawler Only mobile stage Either remains on natal host tree, or is passively dispersed by wind, birds, deer or other animals (including humans) Selects a feeding site within hours after hatching Settles at base of hemlock needles Inserts piercing-sucking mouthparts into xylem ray parenchyma cells of twigs and consumes stored nutrients Insect remains at same feeding site for its entire life Photo: Nathan Havill

16 HWA Feeding Photos: Kelly Oten

17 HWA Feeding Impacts Depletion of stored nutrients Inhibition of new growth production Abortion of vegetative and reproductive buds Premature needle shed (defoliation) Trees experiencing predisposing stress (drought) at time of first infestation can die in as few as 4 years Many trees survive infestation for 10 years or more Improved Tree Health Growing HWA Infestation Density Hemlock Death Spiral Declining HWA Infestation Density Reduced Tree Health

18 HWA Feeding Impacts

19 HWA Distribution in Eastern North America 100% Carolina hemlock 50%+ Eastern hemlock Photo: Kevin Potter

20 Carolina Hemlock Mortality Linville Gorge Photo: Robert Jetton

21 Eastern Hemlock Mortality Shenandoah National Park Hemlock Woolly Adelgid Photo: Robert Jetton

22 Hemlock Woolly Adelgid IPM Toolbox Insecticides soaps, oils, systemics, foliar sprays, soil injections, stem applications high-value trees in ornamental settings, recreation areas Imidacloprid (5 or more years of protection) and Dinotefuran (1 or 2 years of protection) Biological Control predators from the native range of HWA in Asia and the Pacific Northwest Sasajiscymnus sp., Scymnus spp., Laricobius spp., Leucopis sp., Entomopathogens for HWA management in forest settings Host Plant Resistance hybridization of HWA susceptible hemlocks with resistant hemlock species low frequency resistance in generally susceptible species (eastern and Carolina hemlocks surviving infestation) transgenic resistance

23 Hemlock Woolly Adelgid IPM Toolbox Genetic Resource Conservation saving seeds in seed banks and trees in seed orchards that represent the genetic and adaptive variation of the species provide propagules for breeding and restoration efforts hemlock insurance policy Silviculture cultural strategies to improve health of high value trees manipulation of forest stands to reduce HWA susceptibility manipulation of forest stands to promote the next non-hemlock forest type silvicultural strategies to retain or reintroduce a hemlock forest type

24 HWA Info North Carolina Forest Service Forest Health Branch Rob Trickle Kelly Oten Jim Slye Wayne Langston Brian Heath Craig Lawing

25 HWA Info

26 HWA Info

27 HWA Info

28 Questions? Robert Jetton Department of Forestry & Environmental Resources North Carolina State University