Pest: Major Pests

Emerald Ash Borer

  • Scientific name: Agrilus planipennis
  • Tree species affected: Ash species (Fraxinus spp.)
  • TN counties under quarantine (39):Anderson, Bradley, Campbell, Carter, Claiborne, Clay, Cocke, Davidson, Blount, Fentress, Grainger, Greene, Hamblen, Hamilton, Hancock, Hawkins, Jackson, Jefferson, Johnson, Knox, Loudon, Macon, McMinn, Meigs, Monroe, Morgan, Overton, Pickett, Polk, Putnam, Rhea, Roane, Scott, Sevier, Smith, Sullivan, Unicoi, Union and Washington Counties.
  • Current regulations: Federal and State
  • Basic summary: Invasive species from Asia. First discovered in Michigan 15 to 20 years ago. It has spread to 15 states as well as parts of Canada. It was first discovered in TN in 2010. Once a tree is infested, mortality will occur within three years. Treatment and biological controls are being developed and will become available in the future.
  • Primary pathways: Firewood, logs, green wood products

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Southern Pine Beetle

  • Scientific name: Dendroctonus frontalia Zimmerman
  • Tree species affected: Loblolly (Pinus taeda), shortleaf (Pinus echinata), pitch (Pinus rigida), and Virginia (Pinus virginiana)
  • TN counties with known occurrences: Various counties statewide
  • Current regulations: No
  • Basic summary: Native to United States, the southern pine beetle is widespread and destructive when populations peak. The beetles are attracted to stressed trees and can cause individual tree or large scale mortality. Mortality is caused by structural damage from beetle behavior as well as the introduction of the bluestain fungus.  Proper forest management and vigilance are best methods of control.
  • Primary pathways: green logs, beetle flight

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Hemlock Woolly Adelgid

  • Scientific name: Adelges tsugae
  • Tree species affected: eastern hemlock (Tsuga Canadensis) and Carolina hemlock (Tsuga carolinian)
  • TN counties with known occurrences: Anderson, Bledsoe, Blount, Campbell, Carter, Claiborne, Cocke, Cumberland, Fentress, Franklin, Grainger, Greene, Grundy, Hamblen, Hamilton, Hancock, Hawkins, Jefferson, Johnson, Knox, Loudon, Marion, McMinn, Monroe, Morgan, Pickett, Polk, Putnam, Rhea, Roane, Scott, Sequatchie, Sevier, Sullivan, Unicoi, Union and Washington.
  • Current regulations: No (some other states regulate)
  • Basic summary: Invasive species from Asia, the hemlock woolly adelgid was discovered in Virginia in 1951. It has spread to 17 states from Maine to Georgia. It was first noted in Tennessee in 2002 and has been spreading from east to west at a rate of 15-20 miles per year. Once a tree is infested, mortality will occur within 3 to 15 years. Treatment and biological controls are currently available.
  • Primary pathways: Birds & animals, firewood, logs

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Gypsy Moth

  • Scientific name: Lymantria dispar
  • Tree species affected: Most oaks (Quercus spp.) and many other hardwoods
  • TN counties affected: Various counties statewide
  • Current regulations: Federal
  • Basic summary: Native to Europe, Asia, and northern Africa, the gypsy moth was introduced into the US in 1869. It has become established in the northeast and is spreading toward TN at a rate of seven miles per year. The gypsy moth is a major defoliator of several different hardwood species and poses a major threat to TN. Trapping and treatment programs have been in place since the 1970’s and have prevented the gypsy moth from becoming established in TN.
  • Primary pathways: firewood, campers, vehicles, common outdoor household articles.

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Oak Decline

  • Scientific name: none
  • Tree species affected: Oaks (Quercus spp.)
  • TN counties affected: counties within the western Highland Rim and the Cumberland Plateau
  • Current regulations: No
  • Basic summary: Oak decline has been periodically noted over the past 100 years. It is the gradual weakening and crown dieback of oak trees due to several environmental factors. Death ultimately occurs. Proper forest management and vigilance are the best methods of control.
  • Primary pathways: soil, insects, disease

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Dogwood Anthracnose

  • Scientific name: Discula destructive
  • Tree species affected: Flowering dogwoods (Cornus florida)
  • TN counties affected: Higher elevations in east TN
  • Current regulations: No
  • Basic summary: First reported in the northern US 25 years ago and is moving south. Unknown origin. The fungus develops tan spot with purple rims on the leaves. As the fungus moves up the stem and into the crown, it will cause elliptical cankers on twigs and trunks. Keeping dogwoods healthy during periods of stress is the best control.
  • Primary pathways: infected transplants or nursery stock

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Thousand Cankers Disease and Walnut Twig Beetle

  • Scientific name: Thousand cankers disease: Geosmithia morbida; walnut twig beetle: Pityophthorus juglandis
  • Tree species affected: black walnut (Juglans nigra)
  • TN counties with known occurrences: Anderson, Blount, Jefferson, Knox, Loudon, Morgan, Rhea, Sevier, and Union.
  • Current regulations: State
  • Basic summary: The origin of the thousand canker disease is unknown at this point. The walnut twig beetle is native to western United States and was first discovered in TN in 2010. The beetle carries the thousand canker disease as it tunnels through the bark.  Once the tree shows signs of decline, mortality occurs in 2 to 3 years. Treatment and biological controls are being developed.
  • Primary pathways: firewood, logs, green wood products

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Black Turpentine Beetle

  • Scientific name: Dendroctonus terebrans
  • Tree species affected: Loblolly (Pinus taeda), shortleaf (Pinus echinata), pitch (Pinus rigida), and Virginia (Pinus virginiana), and other yellow pine.
  • TN counties with known occurrences: Various counties statewide
  • Current regulations: No
  • Basic summary: Native to United States the black turpentine beetle is the largest of the pine beetles. The beetles are likely to be found living in trees that have been previously infested by other pine beetles. They may cause individual tree or large scale mortality. Mortality is caused by structural damage from beetle behavior as well as the introduction of the bluestain fungus.  Proper forest management and vigilance are best methods of control.
  • Primary pathways: green logs, beetle flight

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The Nature Conservancy
  • Department of Agriculture  |  
  • Ellington Agricultural Center  |  
  • 440 Hogan Road  |  
  • Nashville, TN 37220  |  
  • (615) 837-5520  |  
  • Protect.TNForests@tn.gov