Biology And Management Of Beech Bark Disease
Extension Bulletin E-2746 Reprinted March 2005Biology and Managementof Beech Bark DiseaseMichigan’s Newest Exotic Forest PestDeborah G. McCulloughAssociate professor of forest entomologyDept. of Entomology and Dept. of ForestryMichigan State UniversityEast Lansing, Mich.byRobert L. HeydForest health specialistForest Management DivisionMichigan Dept. of Natural ResourcesMarquette, Mich.Joseph G. O’BrienForest pathologistUSDA Forest ServiceNortheastern Area Stateand Private ForestrySt. Paul, Minn.Managing beech bark disease inMichigan will be challenging. Boththe scale insects and the fungal sporescan be transported in the wind.Eventually beech scale and beech barkdisease will affect beech treesBeech bark disease is one of thelatest exotic pest problems toplague Michigan forests. Beechbark disease refers to a complex thatconsists of a sap-feeding scale insectand at least two species of Nectriafungi. Beech bark disease begins whenAmerican beech (Fagus grandifolia)becomes infested with beech scale(Cryptococcus fagisuga Lind)( Cryptococcus fagi Baer.). The tinyscale insects, found on the tree trunkand branches, feed on sap in the innerbark. White wax covers the bodies ofthroughout Michigan. The goal of thisbulletin is to help you understand thebiology and impacts of this new pestand potential management options.Distribution: Beech scale wasaccidentally introduced into NovaScotia in 1890 on ornamental beechimported from Europe. By the early1930s, the scale and associated Nectriafungi were found throughout thethe scales. When trees are heavilyinfested, they appear to be covered bywhite wool. Minute wounds andMaritime Provinces in eastern CanadaBeech bark disease begins when beech scaleinjuries caused by the scale insectsand in localized areas of Maine. Muchinfests a tree.eventually enable the Nectria fungus toof New England and parts of New Yorkenter the tree. Nectria kills areas ofwere affected by 1960, and the diseasewoody tissue, sometimes creating cankers on the tree stemhad expanded into northeastern Pennsylvania by 1975.and large branches. If enough tissue is killed, the tree will beBeech bark disease has continued to spread through muchgirdled and die. Other trees may linger for several years,of Quebec, northern Pennsylvania and, most recently,eventually succumbing to Nectria or other pathogens. Somenortheastern West Virginia. Localized infestations of beechinfected trees will break off in heavy winds — a conditionscale have also been found in Virginia, North Carolina,called “beech snap.” Dense thickets of root sprouts areTennessee, Ohio and Ontario.common after trees die or break.MICHIGAN STATEU N I V E R S I T YEXTENSION
2Beech scale and beech bark disease were discovered inMichigan in 2000. To date, affected beech trees have beenfound in several counties in the northwestern LowerPeninsula and in areas of the eastern Upper Peninsula. Asdetection efforts continue, other infested areas will likely befound.Beech ScaleBeech scales are yellow, soft-bodied insects that are 0.5 to1.0 mm long as adults. They feed on American andEuropean (Fagus sylvatica) beech trees. Adult scales arelegless and wingless and have only rudimentary antennae.Several glands secrete the white, wooly wax that coverstheir bodies. Scales reproduce by parthenogenesis, whichmeans that all beech scales are females and no matingoccurs. This form of reproduction enables scale populationsto build rapidly when suitable hosts are present.Life cycle: Beech scale has one generation per year. Adultslay pale yellow eggs on the bark in midsummer, then die.Eggs are attached end-to-end in strings of four to seven eggs.Eggs hatch from late summer until early winter. Theimmature scales that hatch from eggs are called crawlers ornymphs. Unlike adults, crawlers have functional antennaeAn immature beech scale.and legs and can move about. When a crawler finds asuitable location on a host tree, it forces its long, tubelikestylet into the bark and begins to suck sap from the tree.Once a crawler begins to feed, it will molt to the secondstage. Second-stage crawlers have no legs and are immobile.They produce the white wax that eventually covers theirbodies. Second-stage crawlers overwinter and molt to theadult stage the following spring.Mortality factors: Crawlers that fall from trees or arewashed off during heavy rains in late summer and autumnusually die. Severely cold winter temperatures (i.e., –35degrees F) that persist for at least a few days may kill someoverwintering crawlers, but others will be insulated by snowor protected by moss. A small twice-stabbed ladybird beetle,Chilocorus stigma (Say), feeds on this scale and is commonin Michigan. Though this predator will reduce scalenumbers on some trees, it cannot control an infestation.Spread: When eggs hatch, crawlers may remain under thebody of the adult or move to other areas of the same tree.Some of the wingless crawlers are blown to other trees.A small number of crawlers may be carried for longdistances in air streams above forest canopies. Birdsprobably transport crawlers short distances and perhaps longBeech bark scales secrete a white waxy coveringthat looks like wool.distances during migratory flights. In addition, the beechscale infestations in Michigan, West Virginia and Ohio allcentered on campgrounds or scenic areas, suggesting that
3humans likely play a role in moving scales long distances.For example, transporting infested beech firewood betweenmidsummer and early winter could allow mobile, first-stagecrawlers to infest new areas.Symptoms of scale infestation: Crawlers prefer tocolonize areas of the tree where the bark is rough. Newlyinfested trees usually have the first small spots or patches of“white wool” onthe trunk aroundareas of roughbark. Infestationsoften start near oldbranch stubs,under largebranches, orsometimes beneathmosses or certainlichens. As thescale populationbuilds, the entiretrunk and largebranches of thetree may becovered with whitewool.Peritheciea of Nectria ochroleuca are light-colored.Virginia and Ontario, Canada. The asexual form of N.ochroleuca (Gliocladium roseum) has also been found onbeech trees in Michigan.Beech scales first become establishedon rough areas of the bark, such asold branch stubs.Both the native and exotic fungi produce fruiting bodiescalled perithecia. Perithecia of N. galligena and N. coccineavar. faginata are tiny and bright red and occur in clusters onliving or dead bark. Perithecia of N. ochroleuca are lighter incolor — usually salmon or pink. Each perithecium is filledwith sacs of spores. These spores are the sexual stage of thefungi. Spores are released from perithecia in the fall and canbe carried in the wind. On some infected trees, peritheciaare abundant, causing large areas of the bark to appear red.In Michigan and some other areas, however, perithecia canbe difficult to find.NectriaFungiThree species of Nectria fungi are associated with beechbark disease in North America. Nectria galligena is a nativepathogen that causes perennial cankers on many hardwoodspecies. It rarely affects beech, however, unless beech scaleis present. Another species, Nectria coccinea var. faginata, isan exotic pathogen that was introduced from Europe. Often,the native Nectria species is the first to invade trees infestedby beech scale, followed by the exotic Nectria species. Athird Nectria species, N. ochroleuca, has been found inassociation with beech bark disease in Pennsylvania, WestPerithecia of the exotic pathogen Nectria coccinea are bright red.
4All three Nectria species can also form spores by an asexualprocess. Small, white or pink cushions of these asexualspores sometimes burst through the bark before peritheciaappear. The asexual spores can be found from midsummerthrough fall and can be mistaken for small colonies of thebeech scale. These spores are also wind disseminated.Trees dying from Nectria infection usually have a distinctappearance when viewed from a distance. Leaves thatemerge in spring do not mature and crowns appear thin orraggedy. Leaves remain on the trees but become yellowishlater in the summer.Symptoms of Nectria infection: Tarry spots are often anearly symptom of trees infected by Nectria. Tarry spots occurwhen a brownish fluid oozes from a dead spot on the trunk.Perithecia sometimes form around the tarry spots. Otherinjuries, however, can also cause tarry spots to form.Typically only the bark and inner bark are killed by theNectria fungi, but occasionally dead areas may extend into thesapwood when the cankers are infected by other fungi. TheNectria fungi may infect localized areas on the tree, causinglinear strips of bark to die along the tree trunk or branches.If larger or more numerous areas are infected, the tree may beFoliage of infected trees appears yellowish.girdled and killed. If the fungus invades only narrow strips ofbark on vigorous trees, callus tissue often forms and the barkbecomes rough. Sometimes the tree is able to wall off thesecankers if they are small. If beech scale numbers are high,however, Nectria often spreads or coalesces rapidly and is notlikely to be restricted by callus formation. Scales cannotsurvive on tissue that has been killed by the fungus. A strip ofscale-free bark running down an otherwise infested tree oftenStages of Beech BarkDisease InvasionBeech bark disease develops in three stages identified as theAdvancing Front, the Killing Front and the AftermathForest.indicates where bark has died.The Advancing Front refers to stands where trees areinfested with beech scale but not yet infected by Nectria.Estimates from northeastern forests suggest that beech scaleand the Advancing Front spread at roughly 6 miles per year.Stands can be infested with beech scale for several yearsbefore Nectria infection is widespread, particularly when theinfestation is a long distance from other affected areas.The Killing Front refers to stands where beech scalepopulations are high and Nectria infection is abundant. Treemortality is heavy within the killing front.The Aftermath Forest refers to stands that haveTarry spots can indicate Nectria infection.experienced the first wave of beech mortality. These standstypically have lower populations of beech scale than
5previous stages. Residual beech trees in the AftermathForest are mostly defective and declining. Some large treesremain — many of these large trees simply escaped scaleinfestation or Nectria infection, but some are at leastpartially resistant.Impact of Beech Bark DiseaseOther insects and fungal pathogens can invade wood killedby beech bark disease. These organisms can increase theseverity of defects initiated by beech bark disease. Ambrosiabeetles often bore into dead sapwood, and their galleriesweaken areas of the tree. Many trees that are partiallygirdled by Nectria and/or those with ambrosia beetlegalleries are broken by high winds. This breakage is called“beech snap.” Live trees with areas of dead tissue are alsoinvaded by other fungi, including Hypoxylon and Armillaria.Tree mortality — Though high populations of beechscale can weaken a tree, beech bark disease and mortality donot occur until Nectria invades infested trees. This usuallyhappens 3 to 6 years after scalesinitially infest an area. It can takelonger, however, if the area is a longdistance from other beeches infectedwith Nectria or if the amount ofNectria inoculum in the area is low.Once Nectria invasion begins, thelargest trees and trees with heavyscale infestations (usually roughbarked trees) are most likely to bekilled.Young beech trees that escape or regenerate after the firstwave of mortality can be colonized by a second scale insect(Xylococculus betulae [Perg.] Morrison). This scale can causerough areas to form on the stemthat are attractive to the beechscale, which then leads to Nectriainfection.Older trees that have decayed orbroken crowns before beech barkdisease invades a stand are often thefirst to succumb to beech barkdisease. Severe drought orconsecutive years of severedefoliation have also beenassociated with massive invasion byNectria.The first wave of beech bark diseasein northern Pennsylvania forestskilled roughly 50 percent of thebeech trees larger than 10 inches indiameter at breast height (dbh).Another 25 percent of the trees livedbut were infected by Nectria. Thesetrees were weak, grew slowly and hadpatches of dead tissue. Theremaining 25 percent of the treesWildlife — Beech provides foodDead beech trees provide wildlife habitat.either escaped scale infestation or Nectria infection or are atleast somewhat resistant. In Maine forests, where beechbark disease has been present for more than 60 years, mostlarge-diameter beech trees have been killed. Trees thatescaped heavy scale infestation often remained alive butwere highly defective.and habitat for more than 40species of birds and mammals. Manyanimals feed on beech nuts in thefall and winter, including blackbears, gray squirrels, chipmunks,turkeys and deer. Trees begin toproduce substantial numbers of nuts at about age 40. By age60, large nut crops are produced every 2 to 8 years. Thishard mast is especially important in northern forests whereoak and hickory are rare. Branching characteristics of beechtrees make them attractive to raptors for perches, andseveral species of hawks prefer to nest in beech trees.Standing beech trees that have some decay are used for
6nesting, roosting or insect foraging by a variety of birds,ranging from pileated woodpeckers to nuthatches. Pinemartens, fishers and other mammals use cavities in beechtrees for shelter or dens.Effects of beech bark disease on wildlife will depend on thedensity and size of beech trees in a stand and the availabilityof alternative hard mast producers such as oak, hickory orhazel. Large, open-grown wolf trees and trees with decay areoften most valuable to wildlife and will be highly vulnerableto beech bark disease. Trees that diefrom beech bark disease will providehabitat for some wildlife species for anumber of years, either as standingdead trees or as coarse woody debris.Over the long term, however, thenumber of large beech trees willdecrease.Regeneration and beechthickets — In Maine, forestersfound that one long-term result ofbeech bark disease was a shift inspecies composition — toward anincreased number of beech stems. Thisresulted from heavy root sproutingsuperficial. Trees with raised lesions or blocky bark(indicating that Nectria was walled off) had little or nowood defect. Most defects were removed with the bark slabat the sawmill. Sunken lesions could cause defects overtime, usually because of bark inclusions buried in wood.Defects associated with sunken bark lesions generallyaffected lumber grade rather than volume. Trees that wereheavily infested by scale and had large patches of dead barkhad extensive wood defects or, more typically, died.Resistance to BeechBark DiseaseStudies in northeastern states haveshown that some American beechtrees are resistant to beech barkdisease. In stands where beech scaleinfestation is generally heavy, insectfree trees are occasionally observed.Even in stands that have beenaffected by beech bark disease foryears, trees that are free of insectsand disease can be found. Trials haveshown that roughly 1 percent ofafter beech trees were cut (forAmerican beech is truly resistant topresalvage or salvage) or killed bybeech scale and beech bark disease.beech bark disease. In the northeast,Other trees are partially resistant andforesters refer to this denseare colonized by only a few scales.An example of beech snap.regeneration as “beech thickets.”Resistance probably involves barkBeech thickets are often impenetrable, exclude regenerationstructure and chemistry that make certain trees unsuitableof other species and have little value for wildlife. Sproutsas hosts for the beech scale.that develop from parent trees that were killed by beechbark disease will also be susceptible to the disease. If rootIn eastern states where beech usually develops from rootsprouts from susceptible trees are allowed to grow, the longsprouts, resistant trees tend to occur in groups and areterm susceptibility of stands to beech bark disease willgenetically related. However, beech may regenerate fromincrease.seeds more often in Michigan and other areas in the westernWood defects — Research in New York stands that wereaffected by beech bark disease for at least 10 years showedthat most external defects associated with the disease wereportion of its range than in eastern areas. This could meanthat resistance might exist at a slightly higher rate than ineastern states. This also suggests that resistant trees are aslikely to be scattered through a stand as to occur in clumps.
7More experience with beech bark disease in Michigan willbe needed to confirm these patterns. Efforts to identify andselect resistant and partially resistant trees will be a criticalpart of reducing the long-term vulnerability of beech tobeech bark disease.Managing Beech Bark DiseaseFactors that affect development of beech bark diseaseinclude species composition and density of stands, and thesize, age and vigor of trees within a stand.Selecting a proper management strategy depends on thedisease status of the stand, as well as your managementobjectives. Management guidelines are presented here forstands that are (1) not yet infested by beech scale, (2)within the Advancing Front, (3) within the Killing Frontand (4) in the Aftermath Forest. If your stand is withinroughly 6 miles of a stand that is affected by beech scale orbeech bark disease, treat the stand as if it were part of theAdvancing Front.Stands Free of Beech ScaleIf your stand is beyond the Advancing Front, consider thepotential vulnerability of the stand when you develop plansfor thinning, harvesting or other silvicultural activities.Stands that are dominated by beech (i.e., 50 percent ormore basal area) will be highly vulnerable to damage,especially if large or decayed trees are abundant. On theother hand, if beech is a minor component of the overstory,effects on the stand will be less severe. Managementguidelines are presented separately for these situations.function as a selective thinning. Growth of other specieswill typically increase in response to increased availability oflight, water or nutrients, especially in well-stocked stands(i.e., basal area of at least 90 ft2/acre). Beech thickets arenot likely to be a severe problem in well-stocked standsbecause most root sprouts will be outcompeted by otherspecies. Mortality of scattered large beech trees may increasethe habitat available for birds, mammals and other wildlife.If beech is a major component of the overstory:If beech accounts for more than 40 to 50 percent of thebasal area in a stand, effects of beech bark disease may besevere. Preventive management can reduce thesusceptibility of the stand to the eventual beech scaleinvasion and reduce the vulnerability of the stand to beechbark disease. Appropriate actions will depend on theexisting condition of the stand, the management objectivesfor the stand and the proximity of the stand to theAdvancing Front.Consider reducing the amount of overstory beech presentin the stand. It is not necessary or desirable to eliminatebeech from a stand. However, increasing tree speciesdiversity provides more management options and mayreduce rates of beech scale reproduction and spread. Beechis relatively shade tolerant and often is outcompeted byother species in large canopy gaps where the ground isexposed to sunlight during much of the day. Birch, blackcherry, red maple or other shade-intolerant species will growfaster and overtop beech reproduction. Beech is avoided bybrowsing deer, however, and browsing may decreasesuccessful regeneration of more favored species in areas withhigh deer numbers. Leaving large snag or den trees toenhance wildlife habitat does not significantly increase therisk of tree loss from beech bark disea
Managing beech bark disease in Michigan will be challenging. Both the scale insects and the fungal spores can be transported in the wind. Eventually beech scale and beech bark disease will affect beech trees throughout Michigan. The goal of this bulletin is to help you understand the biology and impacts of this new pest and potential management .
Reference Code Appch Speed Knots Wingspan Feet Length Feet Tail Height Feet Maximum Takeoff Lbs Beech Bonanza B36TC A-I 75 37.8 27.5 8.6 3,850 Beech Bonanza F33A A-I 70 33.5 26.7 8.2 3,400 Beech Bonanza V35B A-I 70 33.5 26.4 6.6 3,400 Beech Duchess 76 A-I 76 38.0 29.0 9.5 3,900 Beech Duke B60 B-I 98 39.2 33.8 12.3 6,775 Beech E18S A-II 87 49.7 .File Size: 2MB
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6. Defendant Beech-Nut Nutrition Corporation is a foreign corporation with its headquarters in Amsterdam, New York. Beech-Nut manufactures, markets, and sells Beech-Nut baby food products throughout California and the United States. JURISDICTION AND VENUE 7. This Court has subject matter jurisdiction over this action pursuant to the Class
on the trunks of beech trees as a result of repeated climbing by bears to access beech nuts; these stands are referred to as bear scarred beech (BSB). Currently it is unknown if wind turbine development within these stands will displace black bears from foraging within beech stands adjacent to areas cleared for wind energy projects.
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SOME ASPECTS OF THE ECOLOGY OF CTRIA ON BEECH David onsdale and Christine sherriff3 Abstract. --Observrttions of the mycoflora of beech hark infested with Crptococacs fagisuga suggested that Neotria coccinea can colonise sites on and in the outer tissues, and
ment is the density of beech to treat. Areas with more than 400 to 500 stems per acre9 should be considered for broadcast foliar applications. Brush saw cutting and other individual stem treatments usually are most cost-efficient in areas with a lower density of under-story beech. Sapling-siz
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