The capacity of the southern Appalachian region to provide extensive and diverse resource values is seriously compromised by unhealthy forest conditions. Poor health jeopardizes the underlying ecosystems that support timber, wildlife, fisheries, water, and scenic resources. A variety of insects, diseases, and other stressors have had pervasive impacts on the structure and composition of Southern Appalachian forests and threaten forest health in this region. Introduced, invasive species have changed the character of these ecosystems in unintended (and often disastrous) ways. Increased human populations, both within and near these upland ecosystems, threaten their health from overuse, water and air pollution, and urban development. The forest health section of the encyclopedia highlights many of the important species and factors which influence the health of our forests.

Forest Insects

Conifer Insects

• Southern Pine Beetle
• Hemlock Woolly Adelgid
• Balsam Wooly Adelgid

Hardwood Insects

• Gypsy Moth
• Red Oak Borer

Forest Diseases

• Chestnut Blight
• Dogwood Anthracnose
• Dutch Elm Disease
• Beech Bark Disease
• Oak Decline
• Butternut Canker

Nonnative Invasive Species

Nonnative Invasive Plants

• Kudzu
• Japanese Honeysuckle
• Oriental Bittersweet
• Purple Loosestrife
• Lespedeza
• Japanese stiltgrass
• Privet
• Mimosa
• Garlic Mustard

Nonnative Invasive Insects and Pathogens

• Asian Longhorned Beetle
• Emerald Ash Borer
• Sudden Oak Death

Invasive Plant Control

Air Quality

Southern Appalachian trees are hosts for a variety of insects. Although most insects are vital to maintaining ecosystem functions, several species have been introduced from Europe and Asia and, due to a lack of natural endemic controls, have threatened the survival of several southern tree populations. Factors such as fire supression, drought, and air pollution also influence periodical outbreaks of native insects causing tree mortality. The damage by insect pests impact forest by stressing and killing trees which can lead to increased fire risks, reduction in wildife habitat, loss of timber resources, endangerment of rare species, loss of biodiversity, and promotion of invasive plants from increases in disturbance and light availability to the understory environment. The encyclopedia highlights some of the major pests and potential threats to forest health in the southern Appalachians.

Conifer Insects
Southern Pine Beetle Dendroctonus frontalis	Native to the United States, this beetle is a major pests of pines (Pinus spp) in the southeastern United States. It constructs galleries in the inner bark of trees, girdling and killing the tree.
Hemlock Woolly Adelgid Adelges tsugae	An exotic insect that has seriously threatened the health and sustainability of hemlocks in the eastern United States. They feed upon the nutrients of the young twigs by piercing the bark near the base of needles.
Balsam Woolly AdelgidAdelges piceae	Introduced around 1900 from Europe, this insect is well established in the southern Appalachians where it is the major pest of Fraser fir (Abies fraseri). Feeding causes the Fraser fir to produce abnormal wood cells, leading to difficultly in translocating water and nutrients.
Hardwood Insects
Gypsy MothLymantria dispar	This moth is an exotic insect introduced from Europe in the mid 1800s. It is a major pest of hardwoods (especially oaks, Quercus spp.) in the northeast. It is currently expanding its range south through the Appalachians. The caterpillars of this species feed upon the leaves of trees, defoliating, stressing, and eventually killing them.
Red Oak BorerEnaphalodes rufulus	This native longhorned beetle is a major pest of red oaks throughout the eastern United States. The larva bore into the wood, damaging but rarely killing trees. Damage caused by this insect causes defects in and degrades lumber, resulting in millions of dollars worth of losses.
Asian Longhorned BeetleAnoplophora glabripennis	This species was introduced into the United States sometime around 1990. It has been found in many nurseries but, as yet, escaped populations have been found only in New York, Illinois, and New Jersey. This insect bores into and feeds upon a variety of hardwood trees, including maples, elms, birches, willows, and poplars. The potential threat to the southern Appalachians is uncertain.
Emerald Ash BorerAgrilus planipennis	This insect is a newly introduced species (found in 2002) from Asia and populations have been found in southern Michigan, Ohio, and Indiana. Maryland has also reported an infested tree nursery. Larvae feed on the phloem and sapwood of ash species (Fraxinus spp.) girdling and killing the trees. Ash trees throughout the southern Appalachians are potentially at risk.

The southern pine beetle (Dendroctonus frontalis Zimmermann) is native to the southern Appalachians and feeds upon pines (Pinus spp.), often leading to large amounts of tree mortality. The recorded history of outbreaks in the eastern United States dates back to the late 1700s. Southern pine beetle biology includes the release of phermones which can attract many indiviudals leading to mass attacks on trees. Characteristics of the adult beetles or the galleries can be used for identification.

Successful control relies on the ability to recognize susceptible stands and survey for new outbreaks. Several silvicultural treatments are recommended to help reduce losses in infested stands. When dealing with multiple infestations, it is important to set control priorities and act quickly.

• History
• Biology
• Identification
• Control
• Recognizing Susceptible Stands
• Survey and Detection
• Silvicultural Treatments to Reduce Losses in Existing Stands
• Setting Control Priorities for the Southern Pine Beetle

The southern pine beetle (Dendroctonus frontalis Zimmermann) is a serious pest of pines in the southern United States, Mexico, and Central America. The southern pine beetle (SPB) kills conifers by boring under the bark and destroying the cambium layer of the tree. Trees are often mass attacked by thousands of individual southern pine beetles. Because populations can build rapidly to outbreak levels, large numbers of trees can be killed and forested ecosystems seriously affected. Infested areas may range from ten trees to several thousand acres. Large areas are often killed before land managers are aware of the beetles presence. The SPB can be found from northern Nicaragua to the United States, Maryland to Arizona. The most contiguous populations occur in the southern states especially in the range of shortleaf pine.  Most species of conifers are susceptible to attack during intense outbreaks. In the southern Appalachians, shortleaf, Virginia, pitch, table mountain, and eastern white pine are attacked (Price 1994).  Homogeneous pine stands are more susceptible than those mixed with hardwood and pine. Outbreaks in Tennessee, North Carolina, South Carolina, Virginia, and Georgia were recorded as early as the late 1700s and early 1800s. Beginning in the 1960s outbreaks were systematically surveyed and recorded. The worst southern pine beetle outbreak in the southern Appalachians since the 1960s occurred between in 1973 and 1976 (SAMAB 1996).  Based on the data collected since 1960, over 36.6 million cords of pine pulp and saw timber worth over $901 million dollars was destroyed.

SPB populations vary widely between years and are cyclic in nature, normally peaking in magnitude on roughly an eleven to fifteen year cycle.  Contact your local state or national forest service or local cooperative extension service county office for current SPB population information.

Southern Pine Beetle Galleries

Southern pine beetle infestations often begin on damaged or severely stressed trees. Odors emitted by trees struck by lightning, damaged by storms, mechanically injured by construction or harvesting equipment, or severely stressed by heavy pruning attract bark beetles from surrounding areas.

Colonizing bark beetles attack living trees and emit specialized chemicals called pheromones. These pheromones combine with volatiles released from the host tree to "call" in large numbers of beetles that "mass attack" a tree. The female begins constructing a gallery and is joined by a male. Both males and females "reemerge" or leave the host to infest another tree. During peak attack, there may be several thousand beetles involved in the attack on a tree.

Healthy trees respond to beetle attacks by exuding copious amounts of pitch or sap. The pitch and sap may exude from the entrance holes and harden on the bark surface to form pitch or resin tubes that are characteristically sized and shaped. This defensive response of the attacked tree can sometimes "pitch-out" the attacking beetles (Douce 1993).

Southern Pine Beetle Adults

The adult southern pine beetle is 2 to 4 millimeters in length, has a rounded abdomen and is brownish-black in color. Males have a frontal groove on top of the head, while the females possess a broad elevated ridge called a mycangium on the anterior pronotum. Both males and females are capable fliers. Larvae are wrinkled, yellowish-white, legless grubs with prominent heads and stout, dark mandibles. Mature larvae are about 7 mm long.

Dependent upon temperatures, the beetles complete their life cycle -egg, larva, pupa, and adult- in 35 to 60 days, generally from April to September in the southern Appalachians. As many as seven generations (broods) may be produced annually, but in the northern extremities of its range (North Carolina, Virginia, and Maryland) as few as three generations may occur.

Southern Pine Beetle
Galleries

After mating, the female excavates the characteristic S- or serpentine-shape gallery and lays eggs along both lateral walls of the gallery. Eggs are deposited singly in discrete cavities (egg niches). SPB galleries normally contain one pair of adults. Eggs hatch in two to nine days and the larvae enter the cambium layer, then the inner bark, enlarging their galleries as they grow. When mature, larvae bore to the outer dead bark, create a cell and pupate. Generally, emerging adults leave the host tree and aggregate on an adjacent tree or leave the area to find a suitable new host tree. Trees from which the brood has emerged are covered with large numbers of small (~1/16 inch in diameter) emergence holes. Adult emergence may continue for an extended period of time.

Southern Pine Bark Beetle
Pitch Tubes

SPB attacks normally occur on open trunks of trees from the base to the crown, usually attacking first at mid-trunk or in the lower crown. Large numbers of beetle adults and/or larvae girdle the tree by feeding under the bark on the phloem tissues. Besides their feeding, these bark beetles carry blue stain fungi on their bodies. Once introduced into a tree, these fungi colonize the sapwood and disrupt the flow of water to the tree crown, killing the tree. These fungi usually also cause ?blue-staining? of the sapwood which can decrease the salvage value of the wood. It is believed that action of the blue-stain fungi make nutrients more readily available to the beetles and/or that the beetles feed on the fungi.

Bark beetle attacks can be recognized by the presence of boring dust, pitch tubes on the outside of the bark, characteristic galleries under the bark, and beetle adults and larvae in the inner bark.

The presence of "pitch tubes" on the bark of trees is one of the best ways to identify bark beetle attack. However, pitch tubes may not form on stressed trees. Instead, attacks are indicated by the presence of brown boring dust. On severely weakened trees, brown boring dust accumulated in bark crevices or on spider webs is often the only visible sign of early attack (Douce 1993).

If SPB are infesting the trees, there are several management schemes available to help reduce the severity of the attack (Douce 1993).

Chemical Applications

Southern Pine Beetle salvage operation

There are currently no effective chemicals registered for use in commercial pine stands. There is an effective restricted use chemical registered for use in ornamental trees. Contact your local county extension office for use information. Chemical applications for bark beetle control usually are not practical, cost effective, or environmentally wise when large numbers of trees are involved.

Salvage Removal

Southern Pine Beetle cut and leave treatment

This is usually only feasible when a relatively large volume of wood is available and makes the operation cost effective for a logger. Prompt action is necessary to prevent significant degradation of the wood, to allow for some economic return, and to prevent further expansion of the bark beetle infestation. The first step is to remove a 50-100 foot (at least one tree height) buffer strip of green non-infested trees around the most recently attacked trees. Second, remove newly attacked trees and any trees containing beetle brood. Next, remove older standing trees from which the brood has already emerged.

Cut and Leave

This is best used for controlling small spots (10-50 trees) when salvage is not practical or cost effective. Fell attacked trees and a border of healthy trees toward the center of the beetle spot. It may be necessary to cut limbs on the underside of the felled trees to ensure that the tree trunks are lying on the ground. It is believed that the increase in mortality caused by the high temperatures on the bark of the trees, increased humidity on the underside of the trunks, and increased predation may combine with the disruption of emergence and attack patterns to lessen further infestation of standing trees. Cut-and-leave is practical, relatively inexpensive, and requires minimal manpower, equipment and training. Unfortunately, the owner/manager realizes no cost recovery.

Cut and Spray

Ths is no longer a viable option since there are no effective registered chemicals available for this use.

Pile and Burn

Trees with live brood are felled, piled, and burned. A distinct disadvantage to this technique is the need for heavy equipment to pile the trees so they can be burned. Infestations in pre-commercial stands can be controlled by knocking down all the trees and burning. Additionally, due to smoke and fire use restrictions, this may not be a viable control option for you.

Behavioral Modifying Techniques

In recent years, there was much work done on the development of SPB control tactics that utilized the various chemicals the beetles (or their natural enemies) use to orient, attack, or disperse their populations. To date, these projects have met with limited success and it is often very difficult to locate the needed behavior modifying chemicals and individuals sufficiently trained to successfully apply them.

Fusiform Rust

Across the South, pine stands which are susceptible to southern pine beetle (SPB) infestations are usually dense, older, slower-growing stands on poorly drained sites or those growing on severely eroded sites of poor quality. However, younger stands also may be at risk. Generally SPB susceptible stands have one or more of these characteristics:

• High stand densities
• A large proportion of pine sawtimber
• Declining radial growth
• A high (>=28 percent) clay content in surface and subsurface soils in Piedmont sites
• Slopes exceed 10 percent
• Poorly drained soils and low-lying areas in Coastal Plain sites
• High percentage of shortleaf, pitch and/or loblolly pine in the stand
• Presence of annosus root rot, fusiform rust, littleleaf disease

Annosum Root Rot

Littleleaf Disease

Survey and Detection

Aerial Survey

For many owners, on-site inspections for determinations of SPB hazard may be most practical. Evaluating stands of similar ages, stocking levels, and on similar sites can help pinpoint potential outbreaks. Information from management plans and inventory or timber cruises also is valuable. Pay particular attention to well-stocked and over-stocked stands nearing thinning age or those which are past optimum thinning age and are beginning to experience reduced growth. Other hazard sites are stands on poorly-drained or eroded clay soils and those on steep slopes. Factors leading to tree stress and to possible outbreaks include:

• Prolonged moisture or drought stress in trees, or prolonged flooding.
• Slow tree growth common to overstocked and over-mature stands.
• Sites having poor internal drainage or low soil fertility.
• Diseased and storm-damaged stands.
• Excessive damage to residual stand when cutting or doing other work (more likely to lead to black turpentine beetle or Ips beetle attacks).

During outbreak conditions, rapid assessment can be made from aerial surveys and by ground checking previously identified hazard stands.

Southern pine beetle outbreak spot1

Southern pine beetle outbreak spot2

Southern pine beetle outbreak spot3

Good stand management offers the cheapest, most practical, and longest lasting means of preventing SPB infestations, especially where beetle epidemics occur frequently. Recommended practices are:

• To reduce stand susceptibility and damage from southern pine beetle, periodically reduce stand density to increase or maintain tree vigor.
• Southern pine beetle infestations are often associated with poor tree vigor. Tree vigor is related to site, tree, stand, and environmental conditions.
• Poor tree vigor is usually associated with densely stocked stands and declining or slow radial growth.
• Other factors that affect vigor include age, species composition, soil texture, and type, drainage patterns, and stand disturbances associated with cultural practices.
• Thinning, especially of weak, less vigorous trees in lower crown classes, that are susceptible to southern pine beetle attack, reduces competition and enhances the vigor of residual trees.
• Thinning to reduce southern pine beetle hazard is recommended when stand basal area approaches 120 square feet/acre or when live crown ratios of dominant and co-dominant trees drop to about 40 percent.
• Thinning stands back to 60 to 90 square feet/acre basal area reduces the risk of attacks and may also help to slow infestation expansion (spot growth) if an attack does occur.
• For greater effectiveness, thinning should be conducted in winter when the beetle is least active.
• Any thinning strategy to reduce the risk of southern pine beetle attack should be compatible with management goals and consider such things as site and stand factors, equipment, seasonality, market price for small diameter trees, and product objective. Management of other potential hazard (e.g., fusiform rust, annosus root rot, Ips spp., and black turpentine beetle) that might conflict with recommendations for southern pine beetle must also enter into the decision-making process.

Timing of the First Thinning

Precommercial thinning

• Precommercial thinning is probably justified in dense, natural stands and in plantations established by direct seeding or supplemented with natural regeneration from surrounding stands if there are 1,500 or more well-spaced seedlings per acre.
  

  Precommercial Thinning1
  

  Precommercial Thinning2
  
  
• The first thinning often is performed as soon as the seedlings are well established, usually between ages 2 and 5, before they have experienced severe intraspecific competition and while they still are small enough to permit thinning with relatively light equipment such as a rotary mower or light chopper.
  

  Precommercial Thinning3
  

  Precommercial Thinning4
  
  
• If stocking is fairly uniform, seedlings can be removed in strips. Where stocking is extremely high, cross stripping can be used to further reduce seedling numbers. The best response appears to be obtained with a residual stocking of 500 to 750 trees/acre.
  

  Precommercial Thinning5
  

  Precommercial Thinning6
  
  

Commercial thinning

• First commercial thinnings should be made just prior to overcrowding, reduced diameter growth, and heavy mortality and before the live crown ratio is reduced to below 35 percent of total height.
  

  Commercial Thinning1
  
  
• The beginning of suppression-caused mortality in 4- to 5-inch-diameter trees serves as a good signal for a first thinning in most stands. Generally this occurs at 13 to 18 years.
  

  Commercial Thinning2
  
  
• Thinning guidelines for southern pines frequently suggest removing 30 to 45 percent of the stand basal area.
• The percentage of the basal area to be left tends to increase with increasing site quality because of greater productive capacity. Residual basal areas range from 60 to 90 square feet/acre and tend to be lower on poor than on good sites.

  Commercial Thinning3

  Commercial Thinning4

  Commercial Thinning5

All southern pine beetle spots (groups of infested trees) do not have the same control priority. The following guidelines should help you set priorities for controlling individual spots.

A. Classify the infested trees according to the stage of attack shown below.

Stage of Attack
Symptom	Stage 1 Fresh attacks	Stage 2 Developing broods	Stage 3 Vacated trees
Foliage	Green	Green; fade to yellow before beetles emerge	Red; needles falling
Pitch tubes	Soft; white to light pink	Hardened; white	Hard; yellow; crumble easily
Checkered beetles	Adults crawling on the bark	Larvae in SPB galleries; pink or red; 1/2 inch long	Larvae and pupae are purple; occur in pockets in the outer bark
Bark	Tight; hard to remove	Loose; peels easily	Very loose; easily removed
Color of wood surface	white, except close to new adult galleries	Light brown with blue or black sections	Dark brown to black; may have sawyer galleries
Exit holes	----	May appear where parent beetles left the tree	Numerous; associated with brood adult emergence
Ambrosia beetle dust	----	White; begins to appear around the base of trees	Abundant at the base of trees

B. Collect spot expansion data:

1. Walk completely around the spot and look for stage 1 trees, which indicate the area of most recent beetle activity. Areas with stage 1 pines are called "Active Heads." Check to see if the spot is expanding in more than one direction. Large spots can have more than one "active head."
2. Determine the number of stage 1 and 2 trees. For large spots that have more than 50 trees, it is not necessary to examine each tree. Just walk the boundaries and estimate the number of these trees in the spot.
3. From a location about 20 feet (6 m) in front of the active head(s), determine the pine basal area (a measure of stand density) in square feet per acre. A 10-factor prism is useful for this purpose.
4. Note whether most trees in the spot are pulpwood (less than 9 inches in diameter) (23 cm) or sawtimber size (more than 9 inches in diameter).
5. If only stage 3 trees are present, control is not necessary.
6. Determine the control priority for the spot. See C, below.

C. Guide to southern pine beetle control priorities (May through October):

	Key to spot growth	Your spots classification	Risk-rating points
A.	Stage 1 trees (fresh attacks)	absent present	0 30
B.	Stage 1 (fresh attacks) and Stage 2 trees (developing brood)	1 to 10 11 to 10 21 to 50 more that 50	0 10 20 40
C.	Pine basal area (ft2/acre) or stand density at active head or heads	less than 80 (low density) 80 to 120 (medium density) more than 120 (high density)	0 10 20
D.	Stand class by average d.b.h. (in inches)	pulpwood (9 inches or less) sawtimber (more than 9 inches)	0 10

Add up the risk rating points that apply to your spot: Score Control priority 70 to 100 High 40 to 60 Medium 0 to 30 Low

Identification

Hemlock woolly adelgid infestation

Hemlock wooly adelgids (Adelges tsugae) are small insects (1 to 2 mm long). The adelgid itself is not visible to the naked eye, but the white, woolly secretion that protects the adelgid and its eggs is visible and indicates an infestation. The adelgids feed on the new shoot growth and the white woolly masses are visible on the underside of young twigs.

Hosts

Within the southern Appalachians, hemlock woolly adelgids are serious pests of the two species of hemlock native to the eastern United States, eastern hemlock (Tsuga canadensis) and Carolina hemlock (T. caroliniana). In the western United States, hemlock woolly adelgid is a minor pest of western hemlock (T. heterophylla) and mountain hemlock (T. mertasiana).

Impacts

Hemlock woolly adelgid damage

The adelgids feed on young twigs by inserting their stylet-like mouth parts through the bark near the base of needles. Fluid from the tissues of the inner bark and phloem are extracted. Once the hemlocks are infested their foliage is discolored to a gray-green color. The needles dessicate and fall prematurely. Regeneration of needles and buds is inhibited and the crown thins, becoming increasingly more transparent (Rhea 1996). Foliage loss and dieback of major limbs become visible in 2 to 4 years (Cheah and others 2004). Complete defoliation and tree mortality occurs generally within 5 years of initial infestation.

Eastern hemlock is an ecologically important tree in the southern Appalachians. Hemlock forests are unique ecosystems that provide habitat for a wealth of rare plants and animals. Eastern hemlocks are late succesional trees that, if left undisturbed, will dominate stands (McClure and others 2001).

Hemlock woolly adelgid seriously threatens the existence of these two native species of hemlocks in the southern Appalachians. The potential negative impacts are great and include loss of an important ecosystem, decrease in habitat for many rare plants and animals, increased fire risks, and loss of tourism revenues.

According to Rhea (1996), the southern Appalachians hemlocks are the preferred habitats for many animals such as:

Salamanders

• Cow Knob salamander (Plethodon punctatus)
• Shenandoah salamander (Plethodon shenandoah)

Birds

• Blackburnian warbler (Dendrocia fusca)
• Veery (Catharus fuscesens)
• Black-throated blue warbler (Dendrocia caerulescens)
• Black-throated green warbler (Dendrocia virens)
• Dark-eyed junco (Junco hyemalis)

Mammals

• Southern red-backed vole (Clethrionomys gapperi)
• Woodland jumping mouse (Napaeozapus insignis)
• Smoky shrew (Sorex fumeus)
• Red Squirrel (Tamiasciurus hudsonicus)

In addition, shade produced from hemlock forests maintain the cool temperatures necessary for the native brook trout (Salvelinus fontinalis) to survive in southern Appalachian streams. Hemlocks are very important aesthetically to the southern Appalachians as well. Tourism is a major source of income within the southern Appalachians and hemlocks provide beautiful settings for picnic areas, hiking trails, and aesthetic views.

History and Distribution

Hemlock woolly adelgid is a minor pest in its native range of Asia (Japan, India, Nepal, southwestern China, and Taiwan). Within its native range, it feeds upon several species of hemlocks which are not seriously affected by the feeding (The western United States species of hemlock, T. heterophylla and T. mertasiana, also display this resistance). Hemlock woolly adelgid was introduced into the western United States in the 1920s. It was first found in the eastern United States in 1951 near Richmond, Virginia (Rhea 1994). Infested nursery stock from Asia is believed to be the avenue of introduction. It quickly established itself in the wild where it began to slowly spread. Currently hemlock woolly adelgid can be found in hemlock forests from Maine to Georgia. In the southern Appalachians, it can be found from northeast Georgia, north along the border of Tennessee and North Carolina into central Virginia. It is believed to be spreading at a rate of approximately 10 miles per year (Cheah and others 2004). The eggs and ?crawler? stage adelgids are spread wind, birds, mammals, as well as humans. Hemlock wooly adelgid is likely to spread to and infest the entire range of eastern and Carolina hemlock.

Biology

In North America, hemlock woolly adelgid reproduction is by females only (parthenogenetic). Two generations are produced each year. One, the sistens, is wingless, hatches in late spring, overwinters, and survives about nine months. The other, the progrediens, hatches in early spring, is comprised of both wingless and winged (sexupara) offspring, and survives for about three months. Sexupara fly from hemlock in search of a species of spruce (Picea) on which to deposit eggs. However, a suitable species of spruce is not present in North America, so this portion of the population dies before sexual reproduction occurs (Cheah and others 2004).

Control

Individual trees can be protected from infestations of hemlock woolly adelgid either by treating them with an insecticidal soap or by injecting the trunk or soil with chemical insecticides. This is easily done in an ornamental setting but treating stands of hemlocks rapidly becomes too costly and time-consuming for practical use. Recently, a biological control program for hemlock woolly adelgid was initiated. In 1992, explorations for natural enemies within the hemlock woolly adelgid?s native range began (Cheah and others 2004). Several species were found that potentially could be used for biological control. The most promising of these was Sasajiscymnus tsugae, a beetle from Japan. In 1995, S. tsugae was released into infested forests in Connecticut. In 1999, releases were initiated in the southern Appalachians as well as other portions of the hemlock woolly adelgid?s range. S. tsugae has shown great potential to affect adelgid populations but with varying results depending upon adelgid population size and climatic conditions (Cheah and others 2004). Several other insects are currently being evaluated for potential use as biological control agents.

Hemlock woolly adelgid control

Hemlock woolly adelgid biological control

Balsam woolly adelgid stand mortality

The balsam woolly adelgid (Adelges piceae), a native of Europe, was first located in the southern Appalachians in 1957 on Mount Mitchell, North Carolina. It has became the major pest of Fraser fir (Abies fraserii) in the southern Appalachians. Fraser fir is an endemic southern Appalachian tree and the only fir native to the southeastern United States. Fraser fir occurs in the high elevation spruce-fir ecosystem,which is rare in the southern Appalachians (SAMAB 1996). The balsam woolly adelgid has spread throughout the entire range of Fraser fir and now threatens the existence of a rare tree and its unique ecosystem. In addition, Fraser fir in an important species for Christmas tree producers. Balsam woolly adelgid infestations can severly impact Christmas tree plantations via tree damage and cost of control efforts (USDA Forest Service 1989).

Balsam woolly adelgid immature "crawler" stage

The balsam woolly adelgid is a small (< 1 mm in length), wingless insect. Adults are black to purplish in color and roundish in shape. They are not easily visible to the naked eye. However, a noticable white woolly mass covers the adults and their eggs, making infestations easily visible. These woolly masses appear as white dots along the trunk, limbs and buds of infested trees (USDA Forest Service 1989). Within America, the entire population is female and reproduction occurs via unfertilized eggs. Adults lay up to 100 eggs. Two to four generations are produced each year. The mobile immature stage, called crawlers, are orange in color with small legs and black eyes. The eggs and crawlers are dispersed mainly by wind but also can be dispersed by birds, mammals, and humans.

Balsam woolly adelgid damage - gouting

When feeding, the adelgids inject salivary compounds into the boles of Fraser firs, stimulating the growth of abnormal xylem cells. These cells, called roholz cells, are wider than normal and red in color (SAMAB 1996). The roholz cells interfere with the trees ability to transfer water, causing increased stress. Most species of fir display a response to this infestation, thus reducing the stress. However, Fraser firs usually do not display this response. Initial signs of damage from infestations include gouting of twigs and buds and twig dieback (USDA Forest Service 1989). A heavily infested tree may die within 2 to 7 years after infestation.

Balsam woolly adelgid infestation

Chemical control of balsam woolly adelgid is very expensive and time consuming. Ornamental trees or Christmas tree plantations can use chemical control to lessen the impact but it is not feasible in forested settings (USDA Forest Service 1989). Other control efforts have been initiated with little result. Currently, Fraser fir remain at great risk from balsam woolly adelgid infestations.

Gypsy moths are serious pests of hardwoods in the northeastern United States.  It primarily feeds on oaks, which are dominant in many areas of the southern Appalachians.  Research, surveying, and control projects are underway investigating how to slow the spread and minimize the impact of this exotic insect.

Select one of the following pages to learn more about Gypsy Moths:

• History
• Identification
• Biology
• Host and Impacts
• Management and Silvicultural Options 

History

Gypsy Moth Quarantine Area

The gypsy moth (Lymantria dispar Linnaeus) is native to most of temperate Europe and Asia. The gypsy moth was first introduced into North America near Boston, Massachusetts in the mid-1860s when a French scientist brought egg masses from France for the purpose of crossing the species with the silkworm. Some of these larvae escaped and established a local population in the native vegetation. The scientist alerted US authorities about this accidental introduction but no action was taken at that time to eradicate it. About 10 years later, the first outbreaks began in the neighborhood around this site and in 1890 the state and federal government began their attempts to eradicate the gypsy moth. These attempts ultimately failed and since that time, the range of gypsy moth has continued to spread by both natural methods and by man-enhanced transport of eggs and pupae to new areas. By the 1980s, the leading edge of the infestation reached the northern bounds of the southern Appalachians. Between 1984 and 1994, more than 4 million acres in Virginia and more than 1 million acres in West Virginia were defoliated due to gypsy moth (SAMAB 1996). Several small infestations, likely resulting from long-distance transport by humans, have been detected and eradicated throughout the southern Appalachians. The gypsy moths North American range now includes all of the northeastern US, portions of the southeast (including Virginia, West Virginia and North Carolina), parts of the midwest, and portions of eastern Canada.

Gypsy Moth Aerial Spraying

Over the last 30 years, several millions of acres of forest land have been aerially sprayed with pesticides in order to suppress outbreak gypsy moth populations. Though some areas are treated by private companies under contract with land owners, most areas are sprayed under joint programs of state governments and the USDA Forest Service. Since the gypsy moth is a federally regulated pest, there is a federal quarantine that regulates movement of articles from infested areas to uninfested areas. There are also regulations aimed at preventing/reducing spread of the pest. The USDA, state and local governments have and continue to jointly participate in programs to locate and eradicate new gypsy moth populations in currently uninfested areas. Most of these projects focus on populations of European origin, but recently several Asian-origin populations have been discovered and eradicated in the US and Canada. Your local extension service can provide more detailed information about programs in your area.

Gypsy moth adults

The gypsy moth, Lymantria dispar (Linnaeus), goes through four stages of development?egg, larva (caterpillar), pupa (cocoon), and adult (moth). Male moths have tan-to-brown wings marked with dark, wavy bands and a wing span of about 1.5-inches (38mm). Females are larger than males with a wing span of 2 to 2.5 inches (50-63mm) and have a white- to cream-colored body and wings with distinctive black wing markings. The abdomen of the female is clothed in yellowish hairs, and is so large and heavy that she is unable to fly. Males have plumose or feathery antennae, while the female antennae are thin.

Gypsy moth larva

The grayish, hairy caterpillars are easy to identify when about half-grown or larger by the five pair of blue followed by six pair of red dots along the back of the body. Mature caterpillars are from 1.5 to 2.5 inches (38-63mm) long. The head of the larva has yellow markings and the body is dusky or sooty-colored and hairy. The pupa is reddish brown with a sprinkling of reddish hairs. The gypsy moth over winters in the egg stage. (Coulson and Witter 1984, Doane and McManus 1981, USDA Forest Service 1989, USDA APHIS PPQ 1999)

Gypsy moth female
with egg mass

Gypsy moths have one generation per year. Adults emerge in mid-late summer. The females, unable to fly, crawl a short distance from the pupal case and emit a chemical (pheromone) that disperses through the air. Male gypsy moths are good flyers. Use of a pheromone trail helps locate a receptive female with which to mate. After mating, the females lay their eggs in oval masses from 100?1,000 eggs per mass and cover them with buff-colored hairs from their abdomens. The vast majority of eggs are laid on the trunks and limbs of trees, but some are laid in other places including under stones, inside hollow stumps and trees, under stones and even on buildings, on and under vehicles, picnic tables, doghouses, and other items stored out-of-doors. The winter is spent in the egg stage. The eggs hatch as the host leaves begin to unfold in the spring, usually in late April-to-May depending upon location.

Gypsy Moth Larvae

After hatching, young larvae crawl from the egg masses and move toward the tops of the trees and may begin to feed. However if they are on an unfavorable host or are disturbed, they often spin-down on silken threads and are picked up and transported by the wind (?balloon?) to other locations (SAMAB 1996). In woodland situations, larvae may go through several windblown dispersals before settling down to feed. Although some larvae may be carried for long distances by the wind, most spread results in massive redistribution of the population within relatively local areas. After dispersing, larvae begin feeding when they encounter acceptable food plants. If they land on unfavorable hosts or if the host leaves are not yet unfurled, they can usually sustain themselves by feeding on tree buds and on many understory plants or shrubs until they are able to move and find suitable host leaves (Doane and McManus 1981). During early stages, the larvae feed mostly at night and may move down the tree to sheltered places during daylight hours. Older larvae may feed almost continuously. If the larvae exhaust their local food supply they may move, in mass, to search out other food sources. Mature larvae seek out protected places and pupate. The pupal stage lasts from 10 days up to 2 weeks.

Asian Gypsy Moth

The adults do not feed and are very short-lived (2-4 days). The dispersal of the gypsy moth is greatly aided by the inadvertent transport of egg masses and pupae on cargo, vehicles, and outdoor articles that are moved by man from one location to another. In the last few years, there have been several accidental introductions and subsequent releases of Asian-origin populations into North America and Europe. Asian?origin individuals appear to mate freely with the European strain and since females of these Asian strains are capable of flight, there is considerable concern that Asian gypsy moth could very quickly spread throughout North America.

Hosts

Gypsy moth defoliation

Gypsy moths are known to feed on more than 500 species of plants, principally broad-leafed trees and shrubs. In the eastern U.S., the gypsy moths favorite trees include apple, speckled alder, basswood, gray and river birch, hawthorn oak, poplar, and willow (Ghent 1994). Less desired but still attacked are black, yellow, and paper birch, cherry, cottonwood, elm, blackgum, hickory, hornbeam, larch, maple and sassafras. Older gypsy moth larvae devour the foliage of several species that younger larvae normally avoid, such as hemlock, southern white cedar, and the pines and spruces native to the East. The gypsy moth avoids ash, balsam fir, butternut, black walnut, catalpa, red cedar, flowering dogwood, American holly, locust, sycamore, yellow or tulip poplar, and shrubs such as mountain laurel, rhododendron, and arborvitae.

Impacts and Ecological Effects

Gypsy Moth Frass

Gypsy moth impacts people in many ways. In the process of feeding on trees, they generate copious fecal material (frass) that is deposited over the forest floor and everything on it including picnic tables, cars and other outdoor articles. During heavy population densities, there can be millions of larvae crawling over everything. In addition to these feeding and population-related impacts, gypsy moths possess numerous easily-broken body hairs that many people are moderately-to-severely allergic to if they come in contact with them. Additionally, the loss of tree leaves and the impact of this feeding and leaf loss impacts wildlife and subsequent use of the outdoors by people.

Gypsy moth stand damage

Gypsy moth populations are typically eruptive in North America; in any forest stand, densities may fluctuate from near 1 egg mass per ha to over 1,000 per ha. During gypsy moth outbreaks, feeding by caterpillars may remove much, if not all foliage from trees. This defoliation represents another form of stress (in addition to drought, soil compaction, etc.) that affects a trees physiology and may ultimately result in tree death. When defoliation levels are high, hardwood trees will "refoliate" after early season defoliation by producing a second flush of leaves. The defoliation, and subsequent refoliation, weakens the tree and lowers its susceptibility to secondary agents such as the secondary oak pest shoestring root rot fungus Armillara spp. and the two-lined chestnut borer Agrilus bilineatus. These agents attack weakened oaks and are usually the direct causes of mortality. At minimum, defoliation will result in a slight decline in radial grown and tree vigor. Healthy trees can usually withstand several years of 50% or more defoliation before any dieback occurs (Ghent 1994). However, extensive mortality of oaks can occur following two or more consecutive years of defoliation in some cases. Much less frequently, mortality can occur following only one year of defoliation if some other predisposing condition exists, for example severe drought conditions. The mortality associated with gypsy moth outbreaks can profoundly affect the composition of forests and successional trends (Liebhold 2003).

Gypsy moth defoliation

Despite over 100 years of presence in North America, researchers are still at a loss to explain and predict the extent of changes in forest vegetation likely to take place as a result of gypsy moth disturbance. Oaks (Quercus spp.) are often the dominant tree species in an area and serve as host trees for gypsy moth and many other insect species that are important food chain items for many birds and other animals. Yet the acorns the oaks produce are also an important food for many wildlife species. The loss of dominant oak species in the forests will also severely impact the economic value of the forest but will also affect hunting, fishing and other wildlife and outdoor recreational activities.

Because the gypsy moth has many undesirable effects on trees and forests, efforts are made to manage the problem. Suppression, natural enemies, biological control, and silviculture are stategies used to manage established gypsy moth populations. Eradication and Slow the Spread are stategies used to prevent or postpone the establishment of gypsy moth populations in portions of the country where it currently does not exist.

Suppression

Gypsy Moth Aerial Spraying

Most of the negative impacts associated with the gypsy moth occur at high densities. Therefore, a common approach to gypsy moth populations is the direct suppression of populations in order to minimize these effects. These efforts are sometimes carried out by individual homeowners using ground applications of pesticides to individual trees, aerial application of pesticides by private contractors, or aerial applications of pesticides in cooperative state/federal programs (Liebhold 2003). Materials used in these treatments include the chemical pesticide "Dimilin" or the biological pesticides Bacillus thuriengensis and "Gypchek," a formulation of the naturally occurring gypsy moth virus (Liebhold 2003). In 1998, a fungal pathogen, Entomophaga maimaiga, was first recorded from gypsy moth larvae in Connecticut. By 2001, this fungus was causing death of larva in gypsy moth populations in 10 states and in southern Ontario, Canada, and extensive epizootics in the Northeast. The fungus is currently found in most states where the gypsy moth is established. Fungus-killed larvae are commonly seen attached to tree trunks and appear similar to virus-killed larvae (Liebhold 2003).

Natural Enemies and Biological Control

Gypsy Moth Predators

A variety of natural agents are known to kill gypsy moths in nature. These agents include over 20 insect parasitoids and predators that were introduced over the last 100 years from Asia and Europe. Small mammals are perhaps the most important gypsy moth predator, especially at low population densities. Birds are also known to prey on gypsy moths but at least in North America this does not substantially affect populations. A nucleopolyhedrosis virus usually causes the collapse of outbreak populations and recently an entomopathogenic fungus species has caused considerable mortality of populations in North America. Some effort is also underway to develop methods to increase the effectiveness of natural enemies that are already established.

Silviculture

The gypsy moth can have substantial effects on the growth and survival of forest trees. One approach to managing this problem is to use silvicultural methods to reduce the susceptibility (defoliation potential) and vulnerability (tree mortality) of forests to the gypsy moth. This can be accomplished by selectively cutting host trees preferred by the gypsy moth and/or cutting trees that are in poor condition and likely to die following defoliation (McManus and others 1989).

Eradication

In states that currently do not have established gypsy moth populations, grids of pheromone traps are used to detect new, isolated populations. These populations are usually the result of the accidental introduction of gypsy moth life stages on articles such as recreational equipment, fire wood, or nursery material. Pheromone traps are very sensitive methods for detecting gypsy moth populations even when they exist at such low densities that egg masses or caterpillars may not be found. When males are trapped for several years at the same location, this is evidence of a reproducing population. In these cases, an effort is usually made by state and federal agencies to eradicate (totally eliminate) this infestation. Eradication methods vary, but sometimes include spraying with chemical or biological pesticides, mating disruption, or mass trapping.

Slow the Spread

Gypsy moth populations in North America are slowly expanding their range. Because it may take many years before the gypsy moth range spreads to include all of North America, there is logic in attempting to slow the rate of spread into uninfested areas. Doing so will reduce gypsy moth impacts in those areas. Currently, the USDA Forest Service is undertaking a major effort to slow gypsy moth spread. Scientists believe that it is impossible to stop gypsy moth spread but evidence to date indicates that it is possible to reduce the rate of spread by 50% or more. This is accomplished by using grids of pheromone traps along the expanding front to detect isolated colonies. These colonies are then suppressed or eradicated using environmentally benign methods. More information about this method can be found at the Slow the Spread Project.

Research

The gypsy moth has been intensively studied over the last 100 years in North America. Currently there are numerous groups around the country investigating various aspects of the biology, ecology, and management of the gypsy moth. This work is funded by the USDA Forest Service, USDA Agricultural Research Service, USDA Cooperative State Research Service, USDA Animal and Plant Health and Inspection Service, and numerous state and private universities (Liebhold 2003).

Red oak borer adult

The red oak borer, Enaphalodes rufulus, is a native pest of oaks (Quercus) throughout the eastern United States. While infestations usually do not lead to tree mortality, the wood is often severely damaged resulting in degraded timber and a loss of lumber value (USDA Forest Service 1989).

Adult red oak borers are mostly nocturnal and are active in mid to late summer. They are large light-brown longhorned beetles, 1 to 1 ? inches in length (Solomon 1995). Female antennae are about as long as the body and male antennae are up to twice as long as the body. Larvae are thick and white with dark mandibles.

Red oak borer larva

Red oak borers have a two-year life cycle (Donley and Acciavatti 1980). Adults emerge in mid-summer to mate and lay eggs. Eggs are laid in bark depressions, under lichen patches, or under vines on the bark?s surface. The newly hatched larvae burrow under the bark to feed upon the vascular tissue. Larvae overwinter within the tree. During the next season the larvae begin feeding upon the wood of trees, creating large mines. Pupation occurs early in the following season. New adults emerge in mid-summer through large exit holes. Throughout the southern Appalachians, adult emergence is synchronized to occur in odd-number years (Donley and Acciavatti 1980). Evidence of infestations include fine frass, discolored bark patches, oozing sap, and exit holes (Solomon 1995).

Red oak borer damage

Red oak borers infest many different species of oaks in the eastern United States. Red oaks tend to be more susceptible than white oaks with the most common hosts being northern red oak (Q. rubra), black oak (Q. velutina), and scarlet oak (Q. coccinea), located commonly throughout the southern Appalachians (Solomon 1995). Woodpeckers feed heavily upon larvae, often reducing larval numbers by as much as 40% (Donley and Acciavatti 1980).

Red oak borer damaged stand

Since red oak borer infestations are a natural part of the ecosystem and rarely lead to tree mortality, the ecological damage to the southern Appalachians is minimal. However, the large mines created within the wood of many oaks do affect the economic value.

Nonnative invasive species, also called invasive exotic species or biopollutants, are important threats to forest health in the southern Appalachians. Invasive plants (kudzu, privet, Japanese honeysuckle), invasive insects, (European gypsy moth, hemlock wooly adelgid), and invasive pathogens (chestnut blight, Dutch elm disease, dogwood anthracnose) have become established in the region; they are affecting watershed integrity and sustainability, biological diversity, economics, and human health and safety.

Introduction and Spread of Nonnative Species

As many as 50,000 nonnative species are estimated to have been introduced; of these, at least 4,500 are established. Approximately 675 species in the United States cause severe economic or environmental harm. Of 370 identified nonnative invasive species of insects in the United States, 17 are highly invasive to forests and have caused or could cause serious environmental and economic impacts. On National Forest System rangelands, 6 to 7 million acres are infested with noxious weeds and invasive plants. Infestations are increasing at an estimated rate of 8% to 14% per year. Estimates of the economic losses due to nonnative invasive species are as high as $125 billion per year (USDA Forest Service 2000).

The unintentional introduction of nonnative invasive species into the United States is a byproduct of travel, immigration, and global commerce. Invasive species may enter:

• In timber, produce, seeds, or nursery stock.

• In wood used for packing crates. The Asian gypsy moth and the Formosan termite were introduced in this manner.

• In freight via railway cars, tractors, aircraft, automobiles, bicycles, ships, and other vehicles.

• In ballast water dumped from ships.

• On hiking boots, camping equipment, and lawn furniture.

• In or on soil.

Although State and Federal plant quarantine laws slowed the rate of introduction of insect pests and plant pathogens after 1912, rates have been higher throughout the 20th century than in the preceding one (USDA Forest Service 2000). Once introduced, the domestic spread of invasive species occurs naturally, and often with (intentional or unintentional) human assistance. Once in a new environment, a nonnative invasive organism may simply die; it may become established with little noticeable effect; or it may become established and spread, often with devastating environmental and economic results. Populations of many nonnative invasive species expand rapidly upon reaching new habitats where the competitors, predators, pathogens, and parasites that formerly kept them in check are no longer present. Without natural enemies to limit reproduction and spread, some nonnative species grow, adapt, multiply, and disperse to unmanageable levels over time (SAMAB 1996).

Negative impacts of invasive species

Established nonnative species become harmful by destabilizing existing ecosystems. Deforestation or conversion of tree species or both may occur. Riparian forests may be altered, causing deterioration of water quality and wildlife habitat. Fire danger may increase. Habitats of indigenous species may be modified and degraded. In fact, nonnative invasive species are the second largest cause of decline in 42% of the threatened and endangered species listed today. Only habitat destruction is a greater cause of loss or decline for native species (SAMAB 1996).

• Invasive species control describes basic strategies available for solving exotic species problems.

Exotic plant species have been introduced into the southern Appalachians since the beginning of European settlement of the region. Many of these introductions have posed no problems, remaining essentially within the boundaries of human cultivation. Some, however, have escaped and spread, displacing native vegetation, causing ecological disturbance and, in some cases, causing economic loss or impairing land use (SAMAB 1996).

Most Invasive Plant Species in the Southern Appalachians

The Southern Appalachian Man and Biosphere formed the Southern Appalachian Native Plant and Invasive Species Initiative to increase understanding and awareness of invasive plants in the southern Appalachians. As a part of this initiative, an Invasive Plants Assessment is being conducted to determine the extent and impact of invasive plants in the southern Appalachians. One of the initial results of this assessment is to identify the most problematic invasive plants on public land of the region. SAMAB queried 41 state, federal, and nongovernmental agencies about nonnative species. Although a total of 263 plant species were reported as invasive within the region, most agencies reported a particular set of "dirty dozen" species which posed their greatest ongoing and potential management headaches (Table: Frequently Reported Invasive Plant Species on Public Land in the Southern Appalachians).

Kudzu Pueraria montana (Lour.) Merr.	A fast-growing Asian vine that covers some 7 million acres of land (an area larger than Vermont) in the southeastern United States. Prior to 1953, the plant was widely grown as livestock forage and as a means of controlling erosion. Park crews have largely contained the spread of kudzu in the Smoky Mountain National Park and they continue to monitor 116 sites and treat them as needed.
Japanese honeysuckle Lonicera japonica Thunb.	A woody vine introduced for erosion control, wildlife cover, and as an ornamental. It forms ground-covering mats and dense infestations of tree-climbing vines in forest margins, rights of way, and other open spaces. Its persistent green leaves photosynthesize in winter, increasing its ability to dominate native plants.
Oriental bittersweet Celastrus orbiculatus Thunb.	A vine that has infested many of the cooler parts of the Southeast, primarily forestland in the Appalachian Mountains. It is a serious threat to native plant communities due to its high reproductive rate and rapid growth. As a climbing vine, it damages or kills native plants by girdling and shading. It can also hybridize with American bittersweet, leading to the natives loss of genetic integrity. Oriental bittersweet is native to Japan, Korea, and China.
Purple loosestrife Lythrum salicaria L.	A flowering plant introduced during the 1800s. It is found in all of the 48 contintiguous states. It chokes wetlands, replacing native shoreline vegetation.
Lespedeza Lespedeza spp.	Several species of these shrubs have become significant pests in forests and forest openings. Their dense leafy growth shades out all competitors. They are still being planted in some areas either as wildlife food or as soil rehabilitating (nitrogen fixing) plants. Seeds from these plants are spread by birds and new plants thrive under moderate to dense overstory cover, making them extremely difficult to control.
Japanese stiltgrass (Nepalese browntop) Microstegium vimineum (Trin.) A. Camus	This grass is pervasive in disturbed lowlands. It can rapidly replace native ground cover in moist, fertile areas. At present, there is no efficient means of controlling Japanese stiltgrass over a large area, and the plant will continue to gain ground until new treatments are developed.
Privet Ligustrum spp.	Several species of privet are native to Europe, Asia, and North Africa, have been planted widely in this region as a hedge. Birds and other wildlife spread the seeds far and wide. Once it is established, privet can form dense thickets which displace native plants. Crews spend up to 550 work hours each year digging and spraying privet thickets in the Great Smoky Mountain National Park alone.
Mimosa Albizia julibrissin Durazz.	This medium-sized tree is a continual problem along some roadsides and streams in the southern Appalachians. It seeds prolifically and resprouts quickly when cut. Mimosa seeds may remain viable for 50 years or more. The tree is native to Asia and was introduced to this country in 1745. Smoky Mountian park crews have spent up to 600 work hours per year controlling mimosa.
Garlic mustard Alliaria petiolata (Bieb.) Cavara & Grande	This ground layer plant can tolerate shade, making it especially threatening to the Appalachians densely forested environments. When introduced to disturbed areas or streamsides, it can completely dominate the ground layer within 10 years. It can also move from disturbed roadsides or trailsides to undisturbed forest. Garlic mustard is native to Europe. It can be controlled with prescribed fire as well as by applying herbicides, cutting, and hand pulling.

A more extensive list of nonnative invasive plantsin the eastern United States can be found at www.invasive.org, maintained by The University of Georgia, the USDA APHIS PPQ and the USDA Forest Service Forest Health Technology Enterprise Team. This site contains a synthesis of recent publications by the USDA Forest Service, National Park Service, US Fish and Wildlife Service, USDA APHIS PPQ, and the Southeast Exotic Pest Plant Council. It covers identification characteristics, distribution, and control options for 97 tree, shrub, vine, grass, fern, forb, and aquatic plant species that are invading the eastern United States. For each species, a menu of control options is presented, including mechanical treatments, specific herbicide prescriptions, and, for selected species, recent advances in biological control.

Kudzu leaf

Kudzu is a climbing deciduous vine capable of reach lengths of over 100 feet. The stems can grow to 4 inches in diameter and the large semi-woody roots can reach depths of 3 to 16 feet (Miller 2003). Kudzu is easily identified when it grows in a large dense mat of vines, its usual growth form, often totally covering other vegetation, structures, or land. It has three-parted leaves with large broad leaflets, up to 4 inches wide. Purple flowers with yellow centers occur is small clusters. Flowering occurs in June and July.

Farmstead infested with kudzu

Kudzu is native to Asia and was first introduced into America in 1876 at the Philadelphia Centennial Exposition (Swearingen and others 2002). It was widely planted throughout the eastern United States in an attempt to control erosion. Currently it can be found at low elevations throughout much of the southern Appalachians. Kudzu?s preferred habitat is open, disturbed areas such as roads, right-of-ways, forest edges, and old fields. It is an aggressive invader capable of growing over 1 foot a day in prime conditions. If left unchecked, kudzu can grow over, smother, and kill all other vegetation including trees. A common site in the southern Appalachians is a hillside or old farmstead that has been completely covered by kudzu, with only the shapes of the trees and buildings remaining visible. For more information and control recommendations, click here.

Japanese Honeysuckle Flowers

Japanese honeysuckle is an evergreen to semi-evergreen vine that can be found either trailing or climbing to heights of over 80 feet. It has opposite, oval shaped leaves that are 1 to 2.5 inches long. Showy, fragrant, tubular flowers that are whitish-pink to yellow in color and small green berries that turn black when ripened make this plant easily identifiable any time of the year.

Japanese honeysuckle, Lonicera japonica, was introduced to the United States for erosion control before 1860. Most honeysuckle occurs in the Piedmont, where it is found in greatest abundance is in abandoned cropland, or rolling uplands with loamy, well-drained soils (Craver 1982).

Large "impenetrable" mats occur in some areas (Stransky 1984). It competes with young timber in 10 percent of forest land from Georgia to Maryland.

Japanese Honeysuckle Infestation

From a practical viewpoint, Japanese honeysuckle cannot be eradicated. However, it can be controlled by shading. Increasing the percent of tree stocking has an effect on density, but not occurrence, of honeysuckle. In a study conducted near Nacogdoches, Texas, Japanese honeysuckle grown in an open field was nearly 8 times more prolific than honeysuckle grown beneath a forest of shortleaf (Pinus echinata) and loblolly pine (P. taeda) (Hall and Alcaniz 1968). Stem length per plant for open-field honeysuckle was 8,369 cm and 1,009 cm beneath trees. Therefore, clearcutting should be used with caution in some areas and, instead, group and single-tree selection cuts might be used to assure control by shading. Both mechanical and chemical means have been used to control honeysuckle. Herbicide treatments appear to be more effective than mechanical suppression. Among successful mechanical methods during site regeneration are brush-hogging and planting seedlings or disking with natural regeneration (McLemore 1984, Giles 2001).

Although Japanese honeysuckle is considered to be a forest pest, it does offer some benefits. It is eaten by at least 14 wildlife species and is favored in some areas by deer. In a study of seasonal nutrient quality and digestibility of Japanese honeysuckle, it was found that seasonal variations in nutrient quality and metabolic usefulness of leaves and twigs are closely associated with plant growth and tissue maturation. During rapid spring growth, leaves and twigs are most succulent and their dry matter fractionare highest in nutrition and digestibility. During the summer, as twig growth slows, fiber deposition increases in maturing tissues and quality and digestibility decline. Twigs express this decline to a greater degree than leaves. Throughout the year, leaves generally have high nutrient content and are more digestibile than twigs (Giles 2001). Japanese honeysuckle is also valued for erosion control and its aesthetic qualities. For more information and control recommendations, click here.

Oriental bittersweet foliage

Oriental bittersweet is a deciduous, climbing, woody vine that can grow to lengths of 60 ft (Miller 2003). The alternate, elliptical leaves are light green in color. Small, inconspicuous, axillary flowers give way to round green fruit. The fruits ripen and split to reveal showy scarlet berries in winter. The bark is dark gray to brown and smooth when young but flaking and becoming striated on older stems. It closely resembles American bittersweet (Celastrus scandens) but can be distinguished because American bittersweet has flowers and fruits in terminals rather than axillary along the stem (Miller 2003).

Oriental bittersweet vine

Oriental bittersweet was introduced from China around 1860 as an ornamental (Swearingen and others 2002). It is commonly found through the southern Appalachians in old house sites, fields, and road edges. Some shade tolerance allows it to also grow in open forests.

Oriental bittersweet berries

Oriental bittersweets prolific vine growth allows it to grow around trees and girdle them. It also can completely cover other vegetation and shade, out-compete and kill even large trees. It can be dispersed widely and quickly due to the berreis being eaten and spread by birds.

Oriental bittersweet has also been shown to hybridize with American bittersweet, potentially leading to a loss of genetic identity. For more information and control recommendations please click here.

Purple loosestrife flowers

Purple Loosestrife is a tall, perennial forb that can grow up to 10 feet in height. It is easily distinguished by abundant, showy spikes of purple flowers that occur at the tops of the plants (Swearingen and others 2002). Flowering occurs from summer into early fall. The opposite or whorled leaves are dark-green and lance-shaped with heart-shaped bases. The stems are semi-woody, somewhat four-sided, and slightly hairy. Plants often have many stems arising from the same rootstock. Purple loosestrife is a serious invader of many types of wetlands in the southern Appalachians, including wet meadows, river and stream banks, lake shores, and ditches (Swearingen and others 2002). It can quickly form dense stands that displace native vegetation. It is found sporadically throughout the southern Appalachians and is found in 47 of the 48 continental states. Purple loosestrife can spread very rapidly due to its prolific seed production; one plant can produce as many as 2-3 million seeds per year. The seeds are readily dispersed by wind and water. Purple loosestrife is native to Europe and Asia. It was first introduced into America in the early 1800s for ornamental and medicinal purposes. It has also been used as a nectar plant for bee-keeping. Until recently purple loosestrife was still being widely sold in nurseries. Some states now prohibit the sale and distribution of this plant. For more information and control recommendations click here.

Purple loosestrife infestation

Recently, a biological control program has been initiated for the control of purple loosestrife (Blossey 2002). Beginning in 1992, four species of insects have been released throughout the range of purple loosestrife in an attempt to aid control efforts. The species released were:

• Hylobius transversovittatus, a root-mining weevil
• Galerucella calmariensis, a leaf-feeding beetle
• Galerucella pusilla, a leaf-feeding beetle
• Nanophyes marmoratus, a flower-feeding weevil

All of the four species have established viable populations in the United States. In some local infestations, the biomass of purple loosestrife was reduced by as much as 95%. For more information about the biological control of purple loosestrife click here.

Purple loosestrife biological control agents

Shrubby lespedeza flowers

Two species of lespedeza are serious invasive species; Chinese or sericea lespedeza (L. cuneata) and shrubby or bicolor lespedeza (L. bicolor). Chinese lespedeza is an upright semi-woody forb, 3 to 6 feet in height with one to many slender stems (Swearingen and others 2002). Shrubby lespedeza is very similar but usually displays more branching and is 3 to 10 feet in height (Miller 2003). Both species have alternate, abundant, three-parted leaves. Chinese lespedeza leaflets are slender and .4 to .8 inches long whereas shrubby lespedeza leaflets are more elliptical to oval and 1-2 inches long. Flowers are small and whitish-yellow (Chinese) or purple (shrubby).

Native to Asia and introduced into the Unites States in the late 1800s, the lespedezas have been widely planted for wildlife habitat, erosion control, and mine reclamation (Miller 2003).

They are currently found throughout the most of the southern Appalachians. Shrubby lespedeza has been widely planted as cover for quail habitat. Chinese lespedeza has been widely planted for erosion control and can be found adjacent to many roads in the southern Appalachians. Chinese lespedeza has also been included in seed mixes for mine reclamation sites. It quickly dominated reclamation plantings, reducing the biodiversity and wildlife potential of those sites.

Lespedezas are extremely aggressive invaders of open areas. Dense monocultural thickets are formed due to their ability to sprout from root crowns and high seed productivity. They out compete native vegetation and once established are very difficult to remove due to the seed bank, which can remain viable for decades. For more information and control recommendations please click here.

Chinese lespedeza flowers

Chinese lespedeza infestation

Japanese stiltgrass foliage

Japanese stiltgrass, also called Nepalese browntop, is a delicate, sprawling, annual grass that is 1/2 to 3 feet in height (Miller 2003). Alternate leaves are short, flat, and lance-shaped and are pale green with off-center veins. Stems are often multi-branched. Flowers are in delicate spikes that emerge from slender tips. Seeds are prolific and can persist into winter.

Japanese stiltgrass infestation

Nepalese browntop is native to Asia and was accidentally introduced into America sometime around 1920. It has previously been used as packing material for porcelain, possibly explaining its accidental introduction (Swearingen and others 2002). It has little current use and is not intentionally planted. It is found throughout the southern Appalachians along streams at lower elevations. Most commonly an invader of forested floodplains, Nepalese browntop is also found in ditches, forest edges, fields, and trails.