Southern Perspective

The official blog of the Southern Group of State Foresters

Nathan Hoover

The War on Invasive Species in Tennessee

March 18th, 2016
Forest Health Forester
Tennessee Department of Agriculture - Division of Forestry

EABKnoxCo.TNinfestation_Aug102010_0022.jpgMarching along, the rattling of paulownia seeds drew my eyes to the forest edge where the red maples stood in bloom. Working in forest health, unavoidably I soon began to think of efforts to control the spread of Asian longhorned beetles in Ohio and the potential loss of their preferred host species currently blooming on the Cumberland Plateau. I next dwelled on the black walnut and considered potential for wide spread mortality caused by thousand cankers disease, EAB Infestation Knox Co.the result of a combined effect of walnut twig beetle and the fungus Geosmithia morbida. Frantically, my thoughts panned along to the sassafras thinking on the potential spread of laurel wilt disease, a fungus Raffaelea lauricola vectored by the redbay ambrosia beetle from the Southeast. Then there were the oaks; red, chestnut and white! Gypsy moth, which has defoliated approximately a million acres since 1980, looms adjacent to the Tennessee border in the northeast. As I neared the steepening hollow, the grey ghosts of hemlocks attacked by hemlock woolly adelgid (HWA) entered view and instead I followed the drumming of a woodpecker into the upland. I pushed past the bush honeysuckle and privet, over the Japanese honeysuckle, tripped over an old blighted chestnut stump, and around the multi-flora rose. The ash, infested with emerald ash borer (EAB), stood blonded and bright, the bark fletched away in the search for larvae. As I scanned the forest, the ash stood out like candlesticks where the woodpeckers had left their mark. Another thought stood out in mind – we’ve got work to do!

Invasive Species Strike a Major Blow to Tennessee Forests

Introduced from outside of the natural ecosystem and free from predation, invasive species characteristically propagate rapidly and in large number. Impacts to the ecosystem are broad and sometimes species specific. They include mortality of hosts, decreased value, arrested succession, decreased biodiversity and altered ecosystem cycling mechanisms. The Tennessee Exotic Plant and Pest Council estimated the cost of managing invasive plants alone to be $2.6 million in Tennessee. Other species may hold an even bigger economic punch, such as gypsy moth, which has dramatic impacts on host species while at outbreak levels. The Iowa Department of Natural Resources estimated $551 million in annualized losses to wood businesses and $4.1 billion in lost community services if the state where infested with gypsy moth. On a similar scale, impacts from EAB on the national forest industry have also been estimated in the billions. In Tennessee, we estimate that 271 million ash trees, amounting to $11 billion value, could potentially become infested with the emerald ash borer.

12_2gypsymothandeggmass_JPG.jpgPreventing the spread of Invasive Species

Prevention is the number one tool a land manager has in the fight against invasive species. Quarantines and/or active monitoring are prevention strategies utilized in Tennessee. There are 47 counties quarantined for EAB under state and federal quarantine, 37 counties are monitored for infestations of HWA, and 28 counties are under state regulation for thousand cankers disease. Fortunately, no current outbreaks of gypsy moth are occurring in the state. Movement of wood products outside of quarantined or otherwise regulated areas must meet official standards established regulatory bodies. A more bottom-up approach to preventing the spread of pests via the Don’t Move Firewood campaign has focused on promoting the use of local or treated firewood. Following the ban of outside firewood by the Great Smokey Mountain National Park in 2015, Tennessee state parks are exploring a similar option. To support the purchase of pest free or local wood, has been developed which provides campers with a continually updated list of firewood vendors nationwide.

Striking back at Invasive Species

The second most important to tool for land managers is early detection and rapid response. Tennessee annually traps for gypsy moth, EAB and sudden oak death and surveys the spread of HWA. While large scale treatment for EAB is impractical, many property owners and land managers have committed to annual treatment of select trees and removal of future potential safety hazards. Several agencies also actively release parasitic wasps of EAB as biological control measures. Biological control is also effectively used in the control of HWA, primarily through the release of several species of predator beetle, by federal, state, and private efforts. Organizations, such as the Tennessee Hemlock Conservation Partnership, have rallied around such efforts and promote cooperation between government, private, and commercial parties. In fact, just last year, TDF partnered with the Kentucky Division of Forestry to establish the HWA Strike Team to actively treat hemlock, cooperate in the release of predator beetles, and facilitate private land owners workshops. So far, the team has treated over 225 acres and 3700 trees. A great accomplishment!

0743_40459AM.JPGA Farewell to Invasive Species

The people, programs and partnerships connected with these efforts highlight the pressing problems and, more importantly, the solutions for management of invasive species in the southeast. As a new member of our community, I have been impressed by the capability and commitment of those involved in managing our southeastern forests. In the spirit of Winston Churchill – we shall fight in the forests and parks; we shall fight in the urban areas and on private lands; we shall never surrender!

To learn more about forest health and threats in Tennessee, visit us at

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