全 文 ：AReviewofLeafySpurge,Euphorbiaesula(Euphorbiaceae),
theMostAggressiveInvasiveAlieninNorthAmerica*
MAJin灢Shuang**
(ShanghaiChenshanPlantScienceResearchCenter,ChineseAcademyofSciences,Shanghai201602,China)
Abstract:Leafyspurge(EuphorbiaesulaL.,s.lato.)nativetoEurasiaisoneofthemostnotoriousinvasive
plantinNorthAmerica.Inordertofulyunderstandthecurrentsituationwel,detailsoftaxonomy,biology,
physiology,invasion,damageandloss,aswelasvariouscontrolsofleafyspurgehavebeenreviewedhere,
andconciseprospectsandsummaryarealsodiscussed,withmorethan200referencescitedaswel.
Keywords:Euphorbiaesula;InvasivePlant;NorthAmerica;Review
CLCnumber:Q948暋暋暋暋DocumentCode:A暋暋暋 暋暋ArticleID:0253灢2700(2010)Suppl灡桗桏灢019灢27
Introduction
Leafyspurge(EuphorbiaesulaL.,s.la灢
to.),anativeperennialherbfromEurasia,acci灢
dentintroducednearly180yearsagofrom Eu灢
rope,hasbecomingaseriousandaggressivein灢
vasivealieninthe North America,andcosts
milionsand milionsofloss,especialyinthe
NorthernGreatPlainsofNorthAmerica.
Inordertofulyunderstandthecurrentsi灢
tuationin dealing withthis mostaggressive
plantinNorth America,detailsoftaxonomy,
biology,physiology,invasion,damageandloss,
aswelasvariouscontrolsofleafyspurgehave
beenreviewedinthispaper,especialyinthe
pastmorethantwentyyears,andconcisepros灢
pectsandsummaryarealso discussed,with
morethan200referencescitedaswel.
Taxonomyandclassification
Leafyspurge,Euphorbiaesula L.(Eu灢
phorbiaceae),anativeperennialherbtoEura灢
sia,isveryvariablespeciesinvegetativeandflo灢
ralmorphology,andthishascausedsomeprob灢
lemsinthetaxonomicfield.Taxonomistsdisa灢
greeastowhetherleafyspurgeshouldbeasin灢
glespecies(EuphorbiaesulaL.,sensu.lato.),
oranaggregateoftwoormorespecies,notonly
inEurasia (Geltman,1998;Ma,1997;Rad灢
cliffe灢Smith and Tudin,1968),butalsoin
North America (Dunn and Radcliffe灢Smith,
1980;BiesboerandKoukkari,1992).
Croizat(1945)treated “Euphorbiaesula暠
inNorthAmericawithfourtofivespecies(such
asE灡virgataandmanyothers).RecentlyGelt灢
man (1998)discussedthetaxonomy,ecology
andgeographyofEuphorbiaesulaL.andEu灢
phorbiavirgataWaldst.,& Kit.fromEurope,
andadvocatedtoseparatethemasdifferentspe灢
ciessincethedifferenceofecologicalelements.
暋暋DunnandRadclife灢Smith(1980)usedtwenty灢
eightherbariasheetsofleafyspurgefrom12states
wereexaminedandcomparedwithEuropeanspeci灢
mensmaintainedastheRoyalBotanicalGardens,
Kew,England,andtreatedfivemorphologicaly
separabletaxa:E灡esulas.str.,ors.lato(incl.
E灡androsaemifoliaWild.),E灡virgata(withva灢
rieties:uralensis&orientalis)andE灡xpseudo灢
virgata.Radcliffe灢Smith (1985)madeataxo灢
nomiclistof78taxaunderthebroad ‘leafy
spurge暞inNorthAmerica,withmanyhybrids,
云 南 植 物 研 究暋2010,Suppl灡桗桏:19~45
ActaBotanicaYunnanica暋暋暋暋暋暋暋暋暋暋暋暋暋暋暋暋暋暋暋暋暋暋暋暋暋暋 暋暋暋暋暋暋
*
**
Foundationitems:TheprojectwaspartlysupportedbythePBIofNSF(2007灢2010,ledbyDr.PaulBerry,ANN)andbyNYMF
(2001灢2009,ledbyBrooklynBotanicGarden,BKL)
Authorforcorrespondence;E灢mail:jinshuangma@gmail灡com
especialyfromeastandcentralEurope.Hiskey
waswithonlylengthdiferencebutnothingreality
tobefolowedorusedinpractice,evenhemade
fullistofmostoftheminNorthAmerica.
暋暋Ebkeand McCarty (1983)colectedlive
rootmaterialofleafyspurges(Euphorbiaspp.)
from38locationsacrossnorthernUnitedStates,
southernCanadaandfromonelocationinAus灢
tria.Thesematerialswereestablishedinanurs灢
eryatLincoln,NebraskaalongwithE灡agrarian
and E灡cyparissias.Compared with A.Rad灢
cliffe灢Smithwork,andgotfivemorphologicaly
separabletaxa: E灡xpseudovirgata,E灡esula,
E灡uralensis,E灡agrarianandE灡cyparissias.
Morphometrictechniqueswereusedtoana灢
lyzerelationshipsinleafyspurgeanditsalies
(Cromptonetal灡,1990).Onthebasisofstud灢
ying26 morphologicalcharactersfoundin200
colectionsrepresenting32putativetaxa,theau灢
thorsconcludedthatinNorthAmericaonlyfour
speciesshouldberecognized,namely,E灡agrar灢
ianBied.,E灡cyparissiasL.,E灡esulaL.,and
E灡pseudoesulaSchur.
Inordertosolvethedifficultintaxonomic
problem (Harvey etal灡,1988),the within灢
plant,within灢clone,among灢clone,andamong灢
sitevariationinleafymorphologyandtriterpe灢
noidcontentofthelatexofleafyspurgewere
demonstrated qualitatively and quantitatively,
andtheresultshowsthatlatextriterpenoidpro灢
fileswereusefulindistinguishing E灡lucidax
salicifoliaandE灡salicifoliafromEuropeanE灡es灢
ula,E灡waldsteini,and E灡sequieriana spp灡
seguieriana,andal Montanaaccessionsprevi灢
ouslydescribedfrommorphologicalstudies,and
concludesthatMontanaleafyspurgeandtheEu灢
ropeanE灡esula,E灡waldsteini,andE灡sequier灢
ianabelongtoasingletaxon:E灡esula.
Inshort,mostscientistsfrominvasivebiol灢
ogyfieldtreatedandusedleafyspurgeinNorth
AmericaasEuphorbiaesula(sensu.lato.),i.
e.broadsense,notonlyfromtheorybutalso
frompracticesinceitisveryhardtoseparate
them.However,otherplantnamesarestil
usedtodayinthetaxonomicfieldandinvasive
works.
DistributionandInvasion
ThenativedistributioninEurasiaisvery
wideandalsoverycommonforthemostcoun灢
triesinAsiaandEurope,fromJapantoPortu灢
gal,from PakistantoSweden,from Russiato
ArabianPeninsula.However,itisnotaggres灢
siveintheirhomelandsincevariousnaturalene灢
miesandbalancedecosysteminthenature.It
couldgrowinmostofconditionbothfromnative
andinvasiveareasinAsia,EuropeandNorthA灢
merica,especialyin mixedprairie,cropland,
rangeland,pastures,wildland,open woods,
marginofforests,roadside,evenun灢grazednat灢
uralareas,fromelevationfromsealevelto2500
to3000m.
InNorthAmerica,thefirstspecimencol灢
lectedfrom Newbury,Massachusetts,USA,in
1827,anditwasfoundfrom New Yorkasa
“rareplant暠in1876,from Michiganin1881,
from Huron County,Ontarioin1889,from
Minnesotain1890,fromIowain1899,from
NorthDakotain1909,from Manitobain1911,
fromCaliforniain1916,Saskatchewanin1928,
Albertain1933,andBritishColumbiain1939
(Bestetal灡,1980).Leafyspurgerecognizedin
atleastfourstatesandCanadianprovincesin
1913.However,itfirstlabeledasa“weed暠ina
NewYorkHeraldEditorialin1921,andithas
occupied19statesandseveralCanadianprov灢
incesin North Americaaround1933.During
1949-1950,ithasoccurredinalofsouthprov灢
incesinCanadaexceptNewfoundland.In1970,
itoccupies26statesinUSA;in1979,itoccu灢
pies30states;in1997,itoccupies35statesand
southCanadianprovinces.
Severalfurthersurveyshavebeenmadefor
leafyspurgeinNorthAmericatodeterminethe
extentoftheinfestations,suchas1930s(Han灢
sonandRudd,1933).In1970s,itisfoundin
02暋暋暋暋暋暋暋暋暋暋暋暋 暋暋暋暋暋暋暋云暋南暋植暋物暋研暋究暋暋暋暋暋暋暋暋暋暋暋暋暋暋暋暋增刊桗桏
458countiesin26statesfrom coasttocoast
(Reed,1970;Dunn,1979),especialyitdis灢
ruptsnaturalandagroecosystemsacrossmuchof
theNorthern GreatPlains (Barkosky etal灡,
2000).In1992and1993,thesurveyshowsthat
theleafyspurgehasbeenexpandedintoIowa曚s
26of99counties,andthepopulationsarerapidly
expandingespecialyintheLoessHilsandinthe
northeasternIowa(HuerdandTaylor,1998).
Sofar,thisinvasivealienhasbeenreported
from643countiesin35StatesinUSA (except
southeastUSA,northfromOklahomaandTex灢
astoNorthCarolina,southtoFlorida,accord灢
ingtotheUSDA PlantDatabase,searchedat
July102007),morethan192countiesand10
stateshavebeenaddedsincethelastsurveyin
1979.InCanada,itisoneoftennationalprinci灢
palinvasivealiens (Whiteetal灡,1993),and
widelyspreadinBritishColombia(ntoQuesnel,c.
53N),Alberta(ntoFortSaskatchewan,nesub灢
urbofEdmonton;Moss,1974),Saskatchewan
(nto Maidstone,53灡06N),Manitoba (nto
Gimli,about45minofWinnipeg),Ontario(n
tonearThunderBay),Quebec(ntoSt.Nicho灢
las,Levis Co.),New Brunswick (St.An灢
drews,CharlotteCo.,NBM;Hinds,1986),
PrinceEdwardIsland (York,York Co;Er灢
skine,1960),andNovaScotia(NorthSydney,
CapeBretonCo.;Scoggan,1978).Therecord
in Henderson Corner,Dawson,from Yukon
TerritoryofCanada,isalsoreportedrecently
(Cody,1996).
However,no definitetime oftheleafy
spurgewasintroducedintoNorthAmericainthe
history.Britton (1921)statedthataboutone
hundredyearsago,possiblyevenearlier,the
leafyspurge,nativeofEurope,obtainedafoot灢
holdinEssexCounty,MA;theactualdateof
itsintroductionisnotdefinitelyknown,buta
specimenpreservedintheTorreyHerbariumof
ColumbiaUniversity,depositedatNYBG,was
colectedatNewbury,MA,byWiliamOakesin
1827.Andin1875,itwasantherrecordfrom
Groton,NY,i.e.CayugaFlora.(Source:In灢
vasiveExoticPlantsofCanadaFactSheetNo.
9,June28,2007)
Bysearchedtheliteratures,andthroughthe
correspondence,Dunn (1985)concludedthe
fourmostprobablewaysleafyspurgewasintro灢
ducedintoNorthAmerica:1)asseedspresent
inthesoilofthebalastofcargoshipsfromEu灢
ropeinthe1700sand1800s;2)intheseed
stocksofMennoniteimmigrantstotheprairie
statesfrom Russiainthedecadeof1870to
1880;3)insmoothbromegrassseed (Bromis
inermisL.)thatseedsmenintroducedtoCanada
andthenorthernUnitedStatesfromRussianand
Hungaryforagecrops;and4)probablybyMen灢
nonitessettlinginMinnesotatoimportedmany
bushelsofoatsfrom Russiathatwereprobably
contaminatedwithleafyspurgeseeds(Biesboer
& Koukkari,1992).Andtwomostprobablear灢
easofitsorigin (the UkraineandthePenza
ProvinceintheVolgaValeyofRussia)andthe
twogeneralareasoforigin(RussiaandEurope)
havebeendetermined.
Leafyspurge曚sspreadanddispersalwere
mainlycausedbyhumanactivities (including
farming,logging,husbandry,livestock,travel,
lodging,eventrade,import,seedexchange,as
wel asimmigration),sincetheseedofleafy
spurgecan曚tbecarriedbywind,anditalsovery
hardforanimalsto bringawayfrom parent
plantstoafardistance,andtheycouldbeonly
reachedverylimitedareaafterdehiscencefrom
capsuleatautumn.Thepotentialcarrier,such
as mourning doves (Zenaida macroura L.;
Bakke,1936),andotheranimalsareverylimi灢
ted(Blocksteinetal灡,1987;Waldetal灡,2005),
evensomereportedthatbirds,animalsandeven
watercouldspreadtheseeds(Messersmithet
al灡,1985).
InfectionandDamage
Leafyspurgebecomesaseriouseconomic
andecologicaltreattotheproductivityofagri灢
12增刊桗桏暋 暋MAJin灢Shuang:AReviewofLeafySpurge,Euphorbiaesula(Euphorbiaceae),theMost...暋 暋
culturalandnaturalareas,especialythecattle,
thepredominantlivestockspeciesontheGreat
Plainof North America (Halaweish etal灡,
2002,2003),andreducesrangelandcarryingca灢
pacitybycompetingwithdesirableforagesand
causinginfestedareastobeundesirabletocattle
andwildlife(MasterandNissen,1998).Itises灢
timatedtheleafyspurgehasinfestedabout1606
185acres(650000hm2)inNorthandSouthDa灢
kota,Montana,and Wyoming,andestimated
annualeconomiceffectofinfestationsinthe
four灢stateareaisabout$130 milion (Sel et
al灡,1999).
Potentialeconomicbenefits (i.e.gross
benefits,notincludingthecostofbiologicalcon灢
trol)frombiologicalcontrolofleafyspurgein
thefourstatesregionofMontana,NorthDako灢
ta,SouthDakotaand Wyomingareestimated
(Bangsundetal灡,1999).Biologicalagentswere
predictedtocontrolabout65% oftheregion曚s
leafyspurgeinfestations,about1灡2milionsa灢
cres(497000hm2)bytheyear2025.Directe灢
conomicimpactsfromcontrolwereestimatedto
totalabout$19灡1milionannualy,andsecond灢
aryimpactswereestimatedat$39灡3milions,
foratotalannualeconomicimpactof $58灡4
milions.
Arangelandeconomics modelwasdevel灢
opedtoestimatetheeconomicimpactsofleafy
spurgeinfestationonbothranchersandregional
economicsin North Dakota (Leistritzetal灡,
1992).Leafyspurgeinducedcarryingcapacity
reductionofabout580000animalunitmonths,
orenoughfor77000cows,reducedranchers暞
annualnetincomenearly$9milion.Ranchers
didnotspendanother $14 milionininput
costs,whichreducedregionalbusinessactivity.
Theregionalimpactsareabout$75milionin
reducedbusinessactivityforalsectors.These
impactsonrancherincomesandregionaleco灢
nomicssuggestthepotentialeconomicreturnsof
leafyspurgecontrolcouldbesubstantial.
Abio灢economicmodelwasdevelopedtoes灢
timatetheeconomicimpactsofleafyspurgeon
grazinglandandwildlandinafourstatesregions
(Montana,NorthDakota,SouthDakota,and
Wyoming;Leistritzetal灡,2005).Leafyspurge
infestationongrazinglandwasestimatedtore灢
sultinalossinregionalgrazingcapacitysuffi灢
cienttosupportaherdof90000cows.Directe灢
conomicimpactsonstockgrowers,landowners,
andagribusinessfirmswereestimatedtoexceed
$37milionsannualy,whereassecondaryim灢
pactsthroughouttheregionaleconomytotaled
almost$83milions.Impactsonwildlandwere
smalerbutstilsubstantial.Studyresultsindi灢
catedtheseriousnatureoftheleafyspurgeprob灢
leminthenorthern GreatPlainsregionand
helpedtojustifyenhancedcontrolefforts.
Forageproductionanddisappearancewere
estimatedinfourdensityclassesofleafyspurge
early(LymandKirby,1987).Useofcool灢and
warm灢season graminoids, forbs, and leafy
spurgewasestimatedduringthemiddleandthe
endofeachgrazingseason.Cattleuse20%and
2%oftheherbageinthezeroandlowdensity
infestations,respectively,by mid灢season.Mo灢
derateandhighdensityinfestationwereavoided
untilthemilkylatexinleafyspurgedisappeared
inearlyfal,andherbageavailabilityinzeroand
lowdensityinfestationdeclined.Herbageusein
moderateandhighdensityinfestationsincreased
toanaverageof46% bytheendofthegrazing
seasoncomparedto61%inzeroandlowdensity
infestations.Anannualherbagelossofatleast
35%occurredinpastureinfestedwith50%den灢
sityormoreofleafyspurge.
Thetestshows (Kronbergand Walker,
1993;Kronbergetal灡,2006)thatsinceleafy
spurgeisnotgeneralytoxictotheruminalbac灢
teria,butthatmicrobialactivityintherumen
mayberesponsibleforenhancingleafyspurge
toxicitytocattle.Sheepgrazingisanexcelent
methodforcontrolinglargeinfestationsofleafy
spurge (Lacey etal灡,1984).Althoughthe
sheepwil noeradicatetheweed,withagood
22暋暋暋暋暋暋暋暋暋暋暋暋 暋暋暋暋暋暋暋云暋南暋植暋物暋研暋究暋暋暋暋暋暋暋暋暋暋暋暋暋暋暋暋增刊桗桏
managementsystem,they wil keepitfrom
spreading.Sheepgrazingasaspurgecontrol
toolalsohasadvantagesoverherbicides:ranch灢
ersreceiveahighreturnfortheirinvestment;
environmentalhazardsarereduced;andspurge
canbecontroledininaccessibleareas.
Leafyspurgewasfirstobservedin North
Dakotain1909,andhasspreadrapidlysince.It
isfoundinal53countiesofNorthDakotainthe
mid1980s,andispresentonnearly7percentof
theuntiledlandinthestate(LymandMesser灢
smith,1985a).Lossofhayandbeetcattlepro灢
ductionisestimatedat$7milionannualydue
bothtoreducedforageproductionfromleafy
spurgescompetitionandtocattleavoidinggraz灢
inginleafyspurgeinfestedarea.
TheinfectionofleafyspurgeinManitobaof
Canadawasjustabout7413acres(3000hm2)
in1952,c.113669acres(46000hm2)in1982,
and133436acres(54000hm2)in1995(Har灢
ris,2005).
Aplantpestascomplexandtenaciousas
leafyspurge,infestingnearly2灡5milionacres
(1011714hm2)inNorthAmerica,withacon灢
servative1978economicimpactinthe USof
$10灡5 milion,hasreachedaserious,ifnot
criticallevel(Nobleetal灡,1979).Theproblem
is mostsevereonrangelands,pastures,tree
belts,parks,waterwaysandroadsides.Evenon
cultivatedcropland,whereleafyspurgehasbeen
controled,itcanreducecropyields10% to
100%.Amongthem,Minnesotahashighestin灢
festationat800000acres(c.323748hm2)fol灢
lowedbyNorthDakotaandMontanawith600000
and543000acres(242811&219744hm2),re灢
spectively.TheCanadianproblemisestimated
to becomparableto Nebraska,whereleafy
spurgecurrentlyinfectsatleast321000aces
(129904hm2),76of93counties,thedirect
lossinforagevalueattributedtoleafyspurgehas
beenestimatedatmorethan$2milionannual灢
ly,andestimatesofdirectandindirectlossesex灢
ceed$16milionperyear(Masters,2003).
NorthDakotalegislatureemphasizedleafy
spurgecontrolinthe1981-1983bienniumby
appropriating $500000foracost灢sharepro灢
gram.Also,eachcountywasalowedtoincrea灢
sestaxesby1 miltobeusedexclusivelyfor
leafyspurgecontrol.Thefunding wasdivided
33暶47暶20betweenthestates,countyandland灢
owner,respectively.The1983and1985legisla灢
turesprovidedadditionalbiennialappropriations
of$500000and $600000,respectively,to
continuethecost灢shareprogramthroughthe1986-
1987fiscalyear(LymandMessersmith,1985a).
InManitoba,leafyspurgeisaninvasiveweed
speciesthatthreatensanestimated340000acres
(137593hm2).Thestudyestimatesthatthenete灢
conomicimpactsassociatedwiththeleafyspurgein灢
festationinManitobamaybeapproaching$20mil灢
lionperyear(http://www灡brandonu灡ca/rdi/LSSG/
issues—and—impact灡htm,searchedatJuly13,
2007).Thetotalannualeconomicimpacton
pasturelandisestimatedat$16milion.Anes灢
timated225000acres(91054hm2)ofgrazing
landisinfestedinManitobawithapotentialim灢
pactofareducedherdsizeof16540head.Leafy
spurgecostsManitobansmorethan$5milionper
yearinreducedproducerincome ($1940040
peryear)andreducedproductionexpenditures
($3104044).Potentialsecondaryeconomic
impactsonotherbusinesssectorsareestimated
at$11milionperyear.Additionaly,landval灢
uesarepotentialyreducedbyover$30milion.
Thisbringspotentialpropertytaximplications
forownersofcroplands.Whiletaxesoninfested
acresmayreduce,otherlandswilhavetomake
upthelostrevenue.
InBritishColombia,isolatedpocketsoccur
inthe Thompson,Cariboo,Boundary,East
Kootenay,Nechako,andNorthOkanaganareas
(Poweletal灡,1994).
InSaskatchewan,theleafyspurgeinfectsap灢
proximately20000acres(c.8094hm2)ofpasture
andnativeprairieinadiagonalbeltfromNorthBat灢
tlefordtoEstevan (http://www灡agr灡gov灡sk灡ca/
32增刊桗桏暋 暋MAJin灢Shuang:AReviewofLeafySpurge,Euphorbiaesula(Euphorbiaceae),theMost...暋 暋
docs/environment/Biocon灡asp,BiologicalControlof
LeafySpurge,AgricultureandFood,Saskatche灢
wan,Canada,searchedonJuly13,2007).
Grasslandbirdpopulationsaredeclining,
andinvasiveplantspecies,suchasleafyspurge,
maybecontributingtothesedeclinesbyalter
habitatquality(Scheimanetal灡,2003).
Preventionisbestcontrol,especialyfor
leafyspurge!Infestationsofleafyspurgeshould
beeradicatedwhentheproblemissmal.Itisa
mistaketowaituntilthousandsofhectaresare
infestedunderthemisconceptionthattheweed
canbeeliminatedeconomicalylaterwithherbi灢
cides,grazingmanagementorbiologicalcontrol
methods.Seedproductionandseedlingsestab灢
lishmentcanbeprevented withavailablecon灢
trolsatreasonableapplicationratesand ex灢
pense,butcontrol,onceinfested,wilrequires
repeatedtreatmentsand/oruseofexpensivea灢
gents(AleyandMessersmith,1985).
Theseedsaredispersedafewfeetbydehis灢
cenceofthecapsuleandforlongerdistancesby
birds,butmanisprobablythechiefagentfor
seeddispersal.Theseedsalongwiththefolow灢
ingissuesshouldbeconsidered:inthecrop
seeds,inthehaysandotherfeedfedtothelive灢
stock,withintheculturaltools,machineriesand
otherequipments.Oneleafyspurgeinfestation
inSouthDakotastartedatthespotwhereagrain
threshingmachine,obtainedinIndiana,wasun灢
loadedin1918.Thirtyyearslatertheinfesta灢
tion,coveredover600acres(c.243hm2).Suc灢
cessfulestablishmentoflargenumbersofleafy
spurgeseedlingsinclosedgrasslandsisunlikely;
butwhenthehabitatisdisturbedoropenedin
someway,seedlingsemergeandsurvive.Nu灢
merousrangelandssitesthathavebeen main灢
tainedingoodorexcelentconditionhavenot
beeninvadedbyleafyspurge,eventhoughthe
weedinfestedadjacentcultivatedlandorgrass灢
landthatwasabusedbyovergrazing.Frequent灢
ly,thefirstareasofnativegrasslandtobeinva灢
dedbyleafyspurgearethosethathavebeendis灢
turbed,such asthe mounds around badger
holes.Thisisespecialytrueofearth mounds
nearrocksonwhichbirdsmightperch.
Biology
Leafyspurge,aperennialherb,oneofthe
firstplantsemergesintheearlyspring,asearly
asMarchin mostpartsofNorth America.It
growsalofseasons,fromfloweringtofruiting,
untildeepautumn.Themulti灢branchedinflores灢
cenceisfromtoppartofthestems,andflowe灢
ringfrom MaytoSeptember,andfruitingfrom
JunetolateOctoberorearlyNovember.Poli灢
nationis mainlybyinsects,suchasbumble
bees,honeybeesandants (Fowler,1983).
Eachindividualplantcouldproduce10-50cap灢
sules,eachwith3seeds,whichwildehiscence
aftercapsuleopenedatmature.
Reproductionofleafyspurgeismainlyfrom
seedsandrootsystems(Morrow,1979).How灢
ever,theaggressiveandcolonizingabilityfor
themostpartcanbeattributedtothevigorous
andextensivegrowthoflongroots,whichare
alsocapableofregeneration(Raju,1985),and
containingabundantorganicreserveswhichthe
nitrogenplaysintheover灢winteringstrategyand
regenerativecapacity(CyrandBewley,1989).
Thedevelopmentofanextensiverootsystem
andtheabilityofrootstoproducebudsenable
leafyspurgetoexplorenewhabitatsefficiently
andtocompletewithotherplants.Asingleleafy
spurgeplant,onceestablished,wilinhabitan
acreinapproximately65years (Strohetal灡,
1990).
Cytologicaland cytogeneticstudies were
carriedoutonpopulationsofleafyspurgeandits
aliesprimarilyfrom North Americabutalso
from Europe (Stahevitch etal灡,1988).The
chromosomenumbersweredeterminedfor126
samplesofE灡esula,11ofE灡cyparissias,1of
thehybrid (E灡xpseudoesulaSchur)between
thesetwospecies,and1ofE灡agrarianBieb.Al
plantsofE灡esulawerehexaploid.Ofthetotal,
42暋暋暋暋暋暋暋暋暋暋暋暋 暋暋暋暋暋暋暋云暋南暋植暋物暋研暋究暋暋暋暋暋暋暋暋暋暋暋暋暋暋暋暋增刊桗桏
125leafyspurgeaccessionshadachromosomenum灢
berofn=30;1ofn=25++.E灡cyparissias
wasprimarilytetraploid(2n=20),althoughoc灢
casionaldiploids (n=10)wereencountered.
Tetraploidswerefertile;diploidsweresterile.
Thehybridbetweentwoforegoingspecieshada
chromosomenumberofn=25,indicatingthat
theE灡cyparissiasparentwasatetraploid;meio灢
sisinthehybridwasabnormal.E灡agrariawas
foundtohaveagameticnumberofn=20,
whichisthefirstchromosomenumberdetermi灢
nationforthespecies;meiosiswasnormal.Ar灢
tificialcrossesweremadesuccessfulybetween
31accessionsofleafyspurge.Seedgermination
oftheF1progenyslightlyexceededthatrepor灢
tedfornaturalpopulations,and meiosis was
normal.Polenstainabilitystudiescarriedouton
herbarium material.Stainabilitywas100% for
mostofthesamplesstudied.Extensivepolen
sizepolymorphism wasfound.Itissuggested
thatthisphenomenonsupportsthehypothesis
thatE灡esulaisofalopolyploidorigin.
Chromosomenumbervariabilityandchro灢
mosomemosaicism wererevealedthroughcyto灢
taxonomicstudies (Schultz灢SchaefferandGer灢
hardt,1987,1989).Evidencefromthelitera灢
ture for introgressive hybridization between
E灡esula andE灡cyparissiasaswel as between
E灡virgataandE灡esulawassubstantiated.Chro灢
mosomenumbersin E灡esulawere2n=48to
60,inE灡xpseudovirgata2n=40to64,andin
E灡cyparissias2n=36-41.Compositeideograms
ofE灡cyparissias(2n=4x=40),E灡esula(2n=
6x=60)andE灡xpseudovirgata(2n=6x=60)
seemtoindicatesegmentalalopolyploidyatthe
tetraploid and hexaploid chromosomelevels.
Basedontheirusefulnessasgenome marker
chromosomestheyindicateacloserelationship
betweenE灡esulaandE灡xpseudovirgataaswel
asapossiblecontributionofE灡cyparissiastothe
hybridnatureofE灡xpseudovirgata.
Detailreviewsaboutthebiologyofleafyspurge
couldbefoundinBakke(1936),Bestetal灡 (1980),
Galitz(1994)andMessersmithetal灡 (1985).
Physiology
Thephysiologicaltestshowsthattheleafy
spurgedominanceinagrazedplantcommunity
bytoleratingherbivore morethanneighboring
plants,notbyavoidingherbivore (Olsonand
Walander,1999).Theroleofmatureleavesof
leafyspurgeininhibitionofrootbudgrowthis
alsoreported(Horvath,1999).Mostlargeher灢
bivoresavoidtheinvasive weedleafyspurge,
however,ithashighnutritivevaluebasedon
traditionalmeasuressuchascrudeprotein,fi灢
ber,anddry matterdisappearanceandiscon灢
sumedbysheepandgoats(RobertsandOlson,
1999b)becausethematerialfromun灢defoliated
andpreviouslydefoliatedleafyspurgeshoots,
mixedindifferentproportionswithgrasshay,
adverselyaffectssheeprumenmicrobialactivity
andmassinvitro.Variousstudieshavebeen
conductedtodeterminethebehaviorofleafy
spurgeinaninvasiveconditioninNorthAmerica
(Horvath,1998).Toxicityinfoliar灢andsoil灢
treatedleafyspurgeisalsoreported(Rusnesset
al灡,1998).Polyamines,austinsandorganogen灢
esisinleafyspurgeisalsoreported (Davis,
1997).Therelationshipbetweenunderground
adventitiousbudsofleafyspurgeandsugars,
hormones,andenvironmentisreported (Chao
etal灡,2006).Theseasonexpressionpatterns
andcharacterizationofleafyspurgerootstorage
proteinwasstudiedinordertofindpotentialtar灢
getsforchemicalorbiologicalweedcontrola灢
gents(LusterandFarrel,1996).
Seasonalvariationinnitrogenstoragere灢
servesintherootsofleafyspurgeandresponses
todecapitationanddefoliation(CyrandBewley,
1990).Seasonalfluctuationsofcarbohydrates
andnitrogenouscomponentsintherootsofthe
noxiousperennialleafyspurgearestronglyasso灢
ciated with over灢wintering strategy. Amino
acidsanddistinctsolubleproteinsaccumulate
during fal and remain at elevated levels
52增刊桗桏暋 暋MAJin灢Shuang:AReviewofLeafySpurge,Euphorbiaesula(Euphorbiaceae),theMost...暋 暋
throughoutwinter.Theformationofcarbohy灢
dratereservesinrootswasnotsignificantlyaf灢
fectedbydecapitationofselectivedefoliation;
however,maximumaminoacidandsolublepro灢
teincontentsweremarkedlyreduced.Studieson
organogenesisofleafyspurgeshowsthatal
partsofleafyseedlingscanberegeneratedwhen
isolated(DavisandOlson,1993).Theseeddor灢
mancyisalsoreported(Foley,2004),andthe
resultsshowthattheseedcoat灢imposedseed
dormancy.Variousfieldsaboutleafyspurgein
North America werealsotestedandreported
(HoganandManners,1992).
Aknownlathyraneesterandanewjatro灢
phaneesterhavebeenisolatedfromseedsoftwo
differentstandsofNorthAmericanleafyspurge
(OnwukaemeandRowan,1992).New macro灢
cyclicditerpenoidswasalsoisolated(Liuetal灡,
2002).Fournewjatrophanediterpenoids,esula灢
tinA&B(MannersandWong,1985),DandE
(Guentheretal灡,1998)havebeenisolatedfrom
theroots,andthedichloromethaneextractof
thewhole,undriedplant,respectively.Another
jatrophanediterpene,esuloneCwasalsoisola灢
tedandreported(MannersandDavis,1987).
Culturalcontrol
Thestrictestdefinitionoftheterm“cultural
control暠includespracticesthatcanbeusedon
cultivatedland.Thislimitsthecontrolpractices
topreventive measures,intensivecultivation,
competitivecrops,or a combination ofthe
three.Abroaddefinitionalowsuseofalnon灢
chemicalcontrolpracticesincludinggrazinglive灢
stockandmowing.However,themostpractical
controlmeasuresforuseonlargeinfestationson
cultivatedlandincludecombinationsofcultiva灢
tion,competitivecropsandchemicals (Dersc灢
heidetal灡,1985).
Artificialdefoliationwasconductedonceor
twiceannualyatvariousphonologicalgrowth
statesofleafyspurgetosimulategrazingbyher灢
dedAngoragoats(Kirbyetal灡,1997).Single
defoliationtreatmentdidnotreducetotalleafy
spurgestem densities.Defoliationtwiceina
growingseasonfor4consecutiveyearreduced
totalleafyspurgestem densitiesby55% over
non灢defoliated controls. However,cattle use
wouldlikelybelimitedinthesetreatmentsdue
tothehighdensityofleafyspurgestems.
Reduced灢tilagepracticeshavealowedleafy
spurgetofestcropland.Thereductioninleafy
spurgeinfestationandwinter灢hardinessbyfal
tilage,orherbicidetreatment wasevaluated
(Layand Messersmith,1993).Cultivationre灢
ducedtheleafyspurgerootsystemfasterthan
herbicidetreatmentespecialyatthe15灢to30cm
depth,andcultivatingleafyspurgetwiceeach
falfor3yearsprovidedcompetecontrol.
Severalgrassesarecompetitivewithleafy
spurgeincluding ‘Rebound暞smooth brome,
‘Rodan暞westernwheatgrass,‘Pryor暞slender
wheatgrass,and ‘Manska暞pubescent wheat灢
grass.Cultivatingtwiceeachfalafterharvest
forthreeyearsincroplandcompletelycontrol
leafyspurge.Asuccessfullong灢term manage灢
mentprogramshouldbedesignedforspeciessit灢
uationandshouldincludecombinationsofherbi灢
cides,insects,grazing,and/orseedingcompeti灢
tivespecies (Lym,1998).Anothertestwith
twelve grass genotypes from North Dakota
showsthatthe‘Rebound暞smoothbrome,‘Ro灢
dan暞westernwheatgrass,‘Bozoisky暞Russian
wildrye,and ‘Arthur暞Dahurian wildryewith
betterresults(LymandTober,1998),andthey
reducedleafyspurgestemdensityanaverageof
63% after3yearsinasiltyclaysoilatFargo.
‘Reliant暞intermediatewheatgrassreducedleafy
spurgestemdensityeveryyearfor3years,in灢
cludingan85%reductionthesecondyearafter
planting,andconsistentlyproducedhighherb灢
ageyields.‘Rebound暞and‘Reliant暞intermedi灢
atewheatgrassaveraged72% leafyspurgere灢
duction3yearsafterseedlinginaloamysand
soil at Jamestown. ‘Reliant暞intermediate
wheatgrassand‘Manska暞pubescentwheatgrass
62暋暋暋暋暋暋暋暋暋暋暋暋 暋暋暋暋暋暋暋云暋南暋植暋物暋研暋究暋暋暋暋暋暋暋暋暋暋暋暋暋暋暋暋增刊桗桏
providedthe mostconsistentherbageproduc灢
tion,whichaveragedabout2000kg/hm2annu灢
alyfor3years.
BiologicalControl
Biologicalcontrolofweedsisthedeliberate
useofnaturalenemiestoreducethedensityofa
targetweedtobelowaneconomicthreshold.In
classicalbiologicalcontroloneormoreorgan灢
isms,usualyinsectsorpathogens,fromanoth灢
erpartoftheworldareestablishedontheweed
(Harrisetal灡,1985).Thetestingrepresentsis
veryexpensive,especialyintheinitialstage.
However,itcontrasttoothermethodsofweed
control,oncetheagentisestablishedanddis灢
tributed,thereislittleornocontinuingcost.
Theconflictofinterestshouldbeconsideredand
evaluatedfirst,eventested,beforeanybiologi灢
calagentisclearedandreleased.Sofar,thelist
ofnon灢Americaninsectsthatattachleafyspurge
includes131specieshavebeencolected,anda灢
boutthree灢fourthsofthemthatfeedonrestrict灢
edtothegenusofleafyspurge,includingAph灢
thonaspp.(Coleoptera:Chrysomelidae).The
prospectsareexcelentthatbiologicalcontrol
canreducetheaggressivenessoftheweedon
thesesitesbyestablishingspurgeinsectsand
pathogensfromEuropeandAsia.
Effortstomanageleafyspurgewithbiologi灢
calcontrolbeginin1960s.Andfirstleafyspurge
bio灢controlagentin U灡S. (the Hyles hawk
moth)isreleasedin1964.In1978,Entomolo灢
gistsinitiateasearchforhost灢specificAphthona
spp.inEurope.Thesearchidentifiesfourflea
beetles:A灡cyparissiae,czwalinae,flavaand
nigriscutusforfurtherstudy;alareultimately
importedandreleased.In1985,firstfleabeetle
(A灡flava)released.In1988,USDA灢APHIS
beginsleafyspurgebiologicalcontrolprogram.
In1989,A灡nigriscutis wasapprovedandre灢
leased,and A灡lacertosawasapprovedandre灢
leasedin1993.
Folowingbio灢controlsaredetailedinthisreview:
Pathogen:Fungiandothers
FungirecordedonEuphorbiaspecieshasa
lot,butverylittleefforthasbeendirectedto灢
wardtheiruse(Harrisetal灡,1985).Thecom灢
parisonofmethodsforselectingfungipathogen灢
ictoleafyspurgewasreviewed (Yangetal灡,
1991).
Thehostrangeof Myrothecium errucaria
(Hypocreales:Incertaesedis)isolatedfromleaf灢
yspurgecolectedfromChina,haspotentialasa
mycoherbicide against annual herb (Yang,
1995).LeafyspurgeinoculatedwithMyrotheci灢
um verrucaria had deadtopsorshoots with
blackenedstemsandblackened,curled,orwil灢
tedleaves(YangandJong,1995).Myrotheci灢
um verrucaria did notspread from diseased
plantstohealthyplants,evenwhenthehealthy
plantstouchedthediseasedplantsinthedew
tentfor7days.Fourweekoldoryoungerseed灢
lingsofleafyspurgegrownfromseedswerekil灢
edwithoneinoculation,butrepeatedinocula灢
tionswererequiredtokilolderplants.Pathoge灢
nicitytestson89colectionsofninespeciesof
Euphorbiaandonreedcanarygrass (Phalaris
arundinacea)showedthatthepathogenseverely
infectedalcolectionstested.
Sixmultinucleateandtwobinucleatestrains
ofRhizoctoniaspp.pathogenictotheweedleafy
spurgewerecomparedinaggressiveness(Caesar
etal灡,1993;Caeser,1994).Pathogenicitywas
testedbyinoculatingstemsofleafyspurgeor
plantingrootsorseedsinsoilinfestedwithRhi灢
zoctoniastrains.Theresultsindicatevariationin
aggressivenesstoleafyspurgeandinhostrange
amongstrainsofRhizoctoniaspp.from which
optimumbio灢controlstrainsmaybeselectedfor
appropriateuse.R230,anisolateofRhizoctonia
solanianastomosisgroup5fromleafyspurge,
causedrootandcrownrotsonleafyspurgewhen
inoculatedviasoilin greenhouseexperiments
(Yuenand Masers,1995).Rhizobacteriahave
beenshowntobephytotoxictoleafyspurgein
laboratoryassays.ThefieldshowsthatPseud灢
72增刊桗桏暋 暋MAJin灢Shuang:AReviewofLeafySpurge,Euphorbiaesula(Euphorbiaceae),theMost...暋 暋
omanasfluorescens,deleteriousrhozobacteria,
couldreducerootweightandrootcarbohydrate
contentby20% from testin North Dakota
(Brinkmanetal灡,1999).Toevaluatethepo灢
tentialofRhizobacteriaasbio灢controlagent,the
celculturesandcalustissuesofleafyspurge
weretested(SouissiandKremer,1994).Arap灢
idmicroplatecalusbioassayforassessmentof
rhizobacteriaforbio灢controlofleafyspurgehas
beenreported(SouissiandKremer,1998).Its
rootcolonizationofseedlingsbyrhizobacteriais
alsoreported(Souissietal灡,1997a).Andinter灢
actionofrhizobacteriawithleafyspurgecalus
tissuecelsisalsoreported (Souissietal灡,
1997b).Itisconcludedthatcalustissuemay
provideanexcelentworking modeltoinvesti灢
gatethemodeand/ormechanismofactionofpo灢
tentialbio灢controlagentsontheirhostplants.
LeafyspurgestandsinthePrairieProvinces
inCanada weresurveyedforplantpathogens
duringthegrowingseasonsof1981,1982and
1983 (Mortensen,1984).In mostsitessur灢
veyed,leafyspurgewasdisease灢free.Themost
frequentdiseasesobservedwereleafspotandtop
diebackcausedby Alternariaspp.(Dothideo灢
mycetes:Pleosporales),andaleafspotcaused
by Septoriaguepini (Mycosphaerelaceae).A
potential agent, A灡tenuissima was obtained
fromdiseasedplantoftheleafyspurge(Krupin灢
skyandLorenz,1983),andtheexperimentsfor
A灡anguistiovoideawerealsomade(Yangetal灡,
1990).SeveralfungiwereisolatedofwhichFu灢
sarium spp. (Sordariomycetes:Hypocreales)
werethe mostfrequent.StrainsofFusarium
spp.causingrootdiseaseandcrownrotonleafy
spurgeinnaturalepidemicsandinassociationwith
standdeclines wereidentifiedas F灡oxysporum,
F灡solani,and F灡proliferate. These species
predominated among Fusarium spp.isolated
from stunted and diseased feederroots and
crowns.Theresultindicatesthat Fusarium
spp.capableofcausingdiseaseonleafyspurge
varyastospecies,virulence,andcompatibility
groupandarefoundinanumberofsiteswhere
thistroublesomeperennialweedoccurs(Caesar,
1996).Furtherstudiesonthehostrangewere
conductedingreenhouseusingboth European
andUSstrainsofFusariumspp.pathogenicto
Euphorbiaspp.(Caesaretal灡,1999).
Previousfieldinvestigationsrevealedpatho灢
gen灢insectinteractions ontheroots ofleafy
spurgeleasingto mortality.Thestudyshows
thatthe mosteffectiveconditionforinducing
diseaseandsubsequentmortalityofleafyspurge
includesasynergism betweenplant灢associated
microorganismsandroot灢damaginginsects(Kre灢
meretal灡,2006).Furthermore,theresultsare
valuableforidentifyingsitesforcolectingsoil灢
bornemicroorganismsonweedsintheirnative
rangeforevaluationasbio灢controlagentsintheir
invasiverange.
InsectsControl
GassmannandSchroeder(1995)reviewed
thehistoryandlessensfromleafyspurgeandal灢
liedspeciesinsearchingthebiologicalagentsin
Europeinthepast40yearswithsolidcomments
andresults.Moreinsectspecieswerefoundon
themostcommonandthegeographicalymost
widespreadspurgespeciesandonthoseoccur灢
ringinawiderangeofhabitattypes.Theinsect
familiesmostfrequentlyassociatedwithperenni灢
alspurgesinEuropearethechrysomelids,sesi灢
ids,cecidomyidsandanthomyids.
Biology,ecology,and hostspecificityof
five Aphthonaspeciesfrom Europehasbeen
studied,andalofthemareunivoltineandover灢
winteraslarvae(Gassmannetal灡,1996).The
hostrangeofthesespeciesisrestrictedtospecies
inthesubgenusEsula.Fewthan19of113Eu灢
phorbiaspeciesnativetotheUSappeartobepo灢
tentialhost plans for A灡flava. Release of
A灡flavaweremadeinMontana(1985-1987),
NorthDakota (1985)andIdaho (1986).The
potentialhostplantrangeoftheEuropeanflea
beetle,A灡flava,acandidatebiologicalcontrol
82暋暋暋暋暋暋暋暋暋暋暋暋 暋暋暋暋暋暋暋云暋南暋植暋物暋研暋究暋暋暋暋暋暋暋暋暋暋暋暋暋暋暋暋增刊桗桏
agentforleafyspurgewasalsoevaluated(Pem灢
bertonandRees,1990).A灡chinchihiChenwas
colectedinChinafeedingonleafyspurge,and
studieswereconductedonitshostspecificityin
thelaboratory,usingfieldcolectedadultsand
theirprogeny (Fornasari,1997).Thisspecies
caneffectivelycomplementtheimpactofthe
othernaturalenemiesofleafyspurgeestablished
from EuropeintheUSAandCanada.Thea灢
dultsfeedonleavesandshootsandthelarvae,
whichcausethemaindamagetotheplant,feed
onthehypogenousportionoftheplant,serious灢
lystressingtheplantandpreventingitsvegeta灢
tivespread.Theexperimentsdemonstratedthatit
hasahighlevelofspecificity.Thisfleabeetlecom灢
pleteditslifecycleonlyonleafyspurge.Also,be灢
causeofitsecologicalvalence,A灡chinchihihas
averygoodpotentialasabio灢controlagentin
North America.The black dotflea beetle,
A灡nigriscutis,isveryeffectiveincontrolleafy
spurgefromtheGreatPlaininNorthAmerica
(MicoandShay,2002).InCanada,theintro灢
ducedpopulationofA灡nigriscutisincreasedsig灢
nificantlyin1994and1995,butnotenoughto
damagethehost灢plant(Lesage,1996).Phenolo灢
gymodelsforfirstemergenceofadultA灡nigriscutis
isalsoreported(Leggetal灡,2002).
Acroclitasubsequana(Lepidoptera:Tortri灢
cidae)apossibleagentforbiologicalcontrolof
leafyspurgeinNorthAmericaisalsoreported
(Sobhian,1996). The new description of
Chamaespheciaspp.(Lepidoptera:Sesidae)re灢
centlyfrom Europemaybeanothersourcefor
thebiologicalcontrolonleafyspurgeinNorth
Americabecauseitslarvaehavecouldfeedand
developintherootsofleafyspurge(Tosevskiet
al灡,1996).ThebeetleThamnurguseuphorbiae
(Coleoptera:Scolytidae),whoselarvaefeedin
theinnerstemsofE灡characiasfoundinItaly,
wasselectedasacandidateagentforthebiologi灢
calcontrolofE灡esula灢virgataintheUSA.Its
adaptationtoandsurvivalonseveralE灡esula灢
virgataecotypesfrom North Americajustified
hostrangestudiesconductedinItalyduring1993
-2001 (Campobassoetal灡,2004a,b).Bio灢
nomicalandhost灢rangestudiesofthelacebug,
Oncochilia simplex (Hemiptera: Tinigidae)
weremadeinlaboratories(Pecoraetal灡,1992),
andtheauthorsconcludethatO灡simplexshould
beintroducedasabiologicalcontrolagenta灢
gainstleafyspurgeintheUnitedStates.Thean灢
thomyidfly,Pegomyacourticornis (Diptera:
Anthomyidae),introducedinto Albertafrom
Europe,normalyinducessimplegalsonsub灢
terraneanstems (Gassmannand Shorthouse,
1991;ShorthouseandGassmann,1994).How灢
ever,ithasbeenfoundonhorizontalrootsof
spurges.Tissuesoftherootgalswerecom灢
posedofgal parenchymathathadproliferated
fromfeedingsitesneartheoutsideedgeofsec灢
ondaryxylem.Itisassumedthatsomelarvaein灢
advertentlytunnelbeyondthebaseofstemsinto
therootsandthatsimilargals wil form on
spurges.Dasineurasp.nearcapsulae(Diptera,
Cecidomyidae)wasalsointroducedasacandi灢
dateforbiologicalcontrolofleafyspurgecom灢
plexinNorthAmericasincetherestrictedhost
rangeonleafyspurges(Pecoraetal灡,1989).
Studiesofapopulationofthismidgeassociated
withleafyspurgeindicatesthatthis midgeis
univoltine,andcompleteddevelopmentonlyon
thetestplantsonwhichitoviposited,alinthe
subgenusEsula.
Since1988,theUSDA,PPQ(PlantProtec灢
tionand Quarantine),APHIS (Animaland
PlantHealthInspectionService)hascoordinated
aclassicalbiologicalcontrolimplementationpro灢
gramagainstleafyspurgeintheUSA (Hansen
etal灡,1997).ThroughthisprogramnineEura灢
sianinsectspecieshavebeenimportedandre灢
leasedintheUSA,includingsixspeciesofflea
beetles,Aphthoniaspp.,aroot灢boringmoth,
Chamaespheciahungarica (Lepidoptera:Sesi灢
idae),aroot灢boringbeetle,Obereaerythro灢
cephala(Coleoptera:Cerambycidae),andagal
midge,Spurgia esulae (Diptera:Cecidomyi灢
92增刊桗桏暋 暋MAJin灢Shuang:AReviewofLeafySpurge,Euphorbiaesula(Euphorbiaceae),theMost...暋 暋
idae).Thesespecieshavebeenreleasedin188
countiesin19states.Establishedpopulationsof
atleastoneagentarepresentin148countiesin
18states,whilepopulationsofatleastoneagent
in62countiesin16statesarelargeenoughto
permitcolectionanddistributiontootherleafy
spurge灢infectedareas.Biologicalcontrolagents
havebeenreleasedthroughoutareasoftheUnited
Statesinfectedbyleafyspurge.S灡capitigena,a
kindofinsectfrom Europe,wasalsousedto
controlleafyspurgeinNorthAmerica(Lloydet
al灡,2005a,b;Sobhianetal灡,2000).Another
species,S灡esulaefrom Italy,alsointroduced
basedonthestudiessinceearly1980s,hasbeen
releasedin1985(Pecoraetal灡,1991).
Nonlinear models were usedtoestimate
firstemergenceandpeakabundancedatesfor
A灡lacertosaand A灡nigriscutis(Skinneretal灡,
2006).26fieldsitesweresampledforfleabeetle
abundanceatweeklyintervalsforeightweeksin
threewesternMinnesotacountiesin2000,2001,
and2002.Athree灢papameterWeibulfunction,
fittoobservecumulativeprobabilitydistribu灢
tions,wereusedtopredictaccumulateddegree灢
daystofirstemergence.Modelswerevalidated
withadditionaldatasetsfrom Minnesota,Mon灢
tana,andNorthDakota.Estimateddateofpeak
emergenceprovidedusefulpredictionsofpeake灢
mergenceforMinnesotaandNorthDakota,but
failedtopredictpeakemergencein Montana.
Thevariationinclimateandenvironmentalcon灢
ditionsbetweenMidwesternstatesandMontana
wereresponsiblefordifferingemergencepat灢
terns.Thephenologymodelsshouldbedevel灢
opedregionalytoprovideusefulpredictionsof
peakemergenceforlandmanagers.
Since1993,A灡abdominalis wascolected
fromItalyasacandidateforbiologicalcontrolof
leafy spurgein North America (Fornasari,
1995).Thestudieswereconductedtodetermine
thehostspecificityofA灡abdominalisbothinthe
fieldandinthelaboratory,usingfield灢colected
adultsandtheiroverwinteringprogeny(Forna灢
sariandPecora,1995).A灡abdominalishasfour
ormoregenerationsperyearinItalyandoccu灢
piesa wel灢defined ecologicalniche onleafy
spurge.The main damage bythisagentis
causedbythelarvaefeedingontherootsandthe
undergroundportionsofshootsthroughoutthe
generations ofthis multivoltine flea beetle.
Testswithlarvaeandadults,conductedinthe
laboratoryandinthefield,underno灢choiceand
free灢choiceconditions,demonstratedthatthis
fleabeetlehasahighlevelofspecificity.Inthe
field,underfreechoiceconditions,itattached
anddevelopedonlyonleafyspurge.Thisflea
beetlehasagoodpotentialforbeingeffectivein
humidhabitats,whereotherfleabeetlesprevi灢
ouslyreleaseddidnotperform wel.Theeffect
oftemperatureonembryonicdevelopmentofflea
beetle,A灡abdominais,wasstudied(Fornasari,
1995).Theexperimentaldatagaveadevelop灢
mentalzerobetween12and13degreeC.The
embryoscompletedtheirdevelopmentatcon灢
stanttemperaturesfrom15to38degreeC.De灢
velopmentrequiredfrom32灡6daysat15degree
Ctoonly4daysat35degreeCconstanttemper灢
atures.Thelifehistoryandhostspecificityof
A灡venustulahasbeenfulystudiedandreported
(Gassmann,1996).
Taxonomy,distribution,lifehistoryand
hostplantrelationshipsofthecerambycidOber灢
eaerythrocephala(Coleoptera:Cerambycidae),
anoliphagous,univoltinestem灢androot灢miner
of Euphorbiaspp.arediscussed (Schroeder,
1980).Theresultsoffeedingandovipositiontests
with43plantspeciesin20families,andoflarval
transfertestswith31plantspeciesarepresented,
andshowthatO灡erythrocephalaisrestrictedto
certainspeciesofthegenusEuphorbia,notin灢
cludingtheornamentalspecies E灡pulcherrima
andE灡mili.InEuropethebeetleiswidelydis灢
tributedandlocalyquitedestructive.Itaccepts
thetargetweed,leafyspurge,anddevelopsnor灢
malyonitandthereforeshouldberelatively
easy to establish in the field. The beetle
03暋暋暋暋暋暋暋暋暋暋暋暋 暋暋暋暋暋暋暋云暋南暋植暋物暋研暋究暋暋暋暋暋暋暋暋暋暋暋暋暋暋暋暋增刊桗桏
O灡erythrocephalawasintroducedintoOregon,
Montana,andWyomingbetween1980and1984
(Reesetal灡,1986).Althoughitwasnotrecov灢
eredinOregonandWyoming,itbecameestab灢
lishedattwoofthreereleasesiteinMontanaand
appearstobeacceptingleafyspurgeplantsata
fourth.
Theeffectoftemperatureondevelopmental
ratesofover灢winteredthirdinstarstoadultfor
A灡laceratosa and A灡nigriscutis were made
(Skinneretal灡,2004),andtheresultshows
thatthedifferentclimaticand environmental
conditionsmayhaveplayedarole.InYugoslavi灢
a,theEntomofaunaofleafyspurgewassur灢
veyedbetweenfrom1985to1988,andover32
insectspecieswerefoundbutnotfulystudied
yet(Zlofetal灡,1989).Black(A灡lacertosaand
A灡czwalinae;Kalischuk et al灡,2004)and
brown (A灡nigriscutis)fleabeetlesareamong
the moresuccessfulbiologicalcontrolagents
usedinthecontroland managementofleafy
spurgeonarelativelylargescaleintheNorthern
GreatPlains.Thedetailandfulreporttodocu灢
mentthepopulationdynamicsinresponseto
controlbyblackandbrownfleabeetles,tode灢
terminetheroleofselectedsitecharacteristics
onestablishmentandpersistenceofthebeetles,
andevaluatethegeneralresponseoftheresident
vegetationtocontrolleafyspurgehavebeenre灢
ported(Butleretal灡,2006).InlateJune1998,
about3000insectsofeachspecieswerereleased
intopermanentlymarkedplotsinnorthwestern
SouthDakotaandsoutheasternMontana.Beetle
abundance,density andfoliarcoverofleafy
spurge,andfoliarcoveroftheresidentvegeta灢
tionwereevaluatedeachyearfrom1998through
2004.Blackbeetlesincreasedrapidlyandpeaked
at65% oftheirmeasurablepotentialabundance
within2yearsfolowingreleaseanddominated
alreleaseplotsthroughoutthestudy.Although
populationgrowthcharacteristicsofblackflea
beetleswerehighlyvariable,thesuccessfulpat灢
ternsinreducingthedominanceofleafyspurge
werefairlyconsistent.By2004,foliarcoverof
leafyspurgeonbothreleasedandnon灢release
plotwassignificantlyreducedcomparedtopre灢
releasevalues.Foliarcoverofgrassandgrass灢
likeplantsincreasedconcomitantlywiththere灢
ductioninleafyspurgedominancewhilecoverof
forbsonreleaseandnon灢releaseplotsremained
consistently below non灢infested values. The
temporaldynamicsinlargenaturalareawithbi灢
ologicalcontrolofleafyspurgebyfleabeetles
hasbeenevaluatedinTheodoreRooseveltNa灢
tionalPark,westernNorthDakota(Larsonetal灡,
2004).A灡lacertosaandA灡nigriscutishavebeenre灢
leasedatmorethan1800pointsinthe18600hm2
SouthUnitoftheparkbeginningin1989;most
releaseshaveoccurredsince1994.Theperma灢
nentvegetationplotsthroughouttheinfestedar灢
eaoftheparkanddeterminestemcountsandbi灢
omassofleafyspurgeandabundanceofthetwo
fleabeetlespeciesattheseplotseachyearfrom
1999to2001.Bothbiomassandstemcountsde灢
clinedoverthe3yearsofthestudy.Bothspecies
offleabeetleare wel established withinthe
park,andhaveexpandedintoareaswherethey
werenotreleased.
ThebiologyandhostspecificityofNephop灢
terix divisela (Lepidoptera:Pyralidae) was
studiedtoevaluateitspotentialasanewbiologi灢
calcontrolagent(Cristofaroetal灡,1998).The
useofagromyzidflies(Diptera:Agromyzidae)
tocontrolleafyspurgein North Americaand
prospectsisalsoreported (MartinezandSob灢
hian,1998).Effectofleafyspurgeongrowth
andmortalityofmigratorygrasshoppernymphs
(Orthoptera:Caelifera)arealsoreported(Ro灢
bertsandOlson,1999a).
Refiningtheprocessofselectingspecialist
herbivoresthatareusedasbiologicalcontrola灢
gentstomaximizeeffectsonthetargetscandi灢
minishtherisktonon灢targetspecies.Whileabi灢
oticfactors(e.g.plantdemographyandagent
hostinteractions)havebeenexploredforclues
toimprovethewaywemakeagentselectionde灢
13增刊桗桏暋 暋MAJin灢Shuang:AReviewofLeafySpurge,Euphorbiaesula(Euphorbiaceae),theMost...暋 暋
cisions,recentecologicalresearchindicatesthat
bioticfactorsrelatedtothehabitat(e.g.plant
andsoilnutrientcompositions,andsoilcharac灢
teristics)areimportantpredictorsofinsecther灢
bivorecommunitycomposition(SchwabandRa灢
ghu,2006).
Otherworksininsectcontrolpartarenot
verypositive.Thefeasibilityofusingthespurge
hawkmoth, Hyles euphorbiae (Lepidoptera:
Sphingidae),asabiologicalcontrolagentwase灢
valuatedinNebraska (Forwoodand McCarty,
1980),buttheresultsshowthatthespurge
hawkmothwilnotbecomeavaluablebiological
controlagentforleafyspurge (ReesandFay,
1989).ThetwoEuropeanroot灢boring moths,
ChamaespheciahungaricaandCh灡astatiformis,
twocandidatesforthebiologicalcontrolofleafy
spurgeinNorthAmericawastested(Gassmann
andTosevski,1994).Both,univoltineando灢
verwinterasmaturelarvae,havealowersurviv灢
alrateonleafyspurgethanontheirfieldhosts,
andthusarenotoptimalcandidatesforthebio灢
logicalcontrol.However,therateoflarvalde灢
velopmentandlarvalgrowthonthetargetweed
andonthetowfieldhostsisnearlythesame.
ThebiologyandhostspecificityofOxicestageo灢
graphica(Lepidoptera:Noctuidae)from Roma灢
nia,HungaryandSouthwestern Russian were
alsostudiedtoevaluatethepotentialbiocontrol
agent(Cristofaroetal灡,1994).Theresultsof
no灢choicefeedingtestswithfirstinstarson93
plantspeciesand biotypes,distributedin33
families,show that O灡geographicacompleted
itslifecycle mainlyonplantsofEuphorbia,
subgenusEsula,andoccasionalyfedanddevel灢
opedonspeciesinothersubgeneraofthegenus.
Andstudiesoflateinstarsdidnotshowanyim灢
portantextensionsofthehostrange.
ChemicalControl
Thehistoryandprogresstocontrolleafy
spurgeinchemicalscanbetracedfromtheearly
researchintheUnitedStatesin1930s(Bakker,
1937;Aleyand Messersmith,1985),andin
Canadain1940s (Bestetal灡,1980).Since
then,differentkindsofproductionshavebeen
testedandappliedincontrolofleafyspurges.In
addition,chemicalcontrolofleafy spurgeis
abasedonthenatureoftheinfestation,because
themethodssuggestedandtheherbicidesthat
canbeusedinrangeand pastureland,non灢
croppedareasandcroppedareasdiferconsiderab灢
ly:rangeandpastureland (suchaspicloram),
cropland(suchas2,4灢D),non灢cropland(include
utility,highway,pipelineandrailroadrights灢of灢
way,industrialsites,fencerowandaroundfarm
buildings,withcombinations).
Imazapicappliedwithamethylatedseedoil
adjuvanttendedtoprovidegreaterleafyspurge
controlthanwhenappliedwithothertypesof
adjuvants(MarkleandLym,2001).Theab灢
sorptionandfateofimazapyrinleafyspurgeis
alsoreported(Nissenetal灡,1995).Andresult
shows that Imazapyr phototoxicity to leafy
spurgeappearstoresultfromhighimazapyrab灢
sorption,translocationtounderground meris灢
tematicareas (root and adventitious shoots
buds),andaslowrateofmetabolism.
Fieldresearchwasconductedtodetermine
themosteffectivequincloractreatmentforleafy
spurgecontrol(KuehlandLym,1997).Quin灢
cloracappliedwiththecrop灢oil灢basedadjuvant
Scoilprovidedsimilarleafyspurgecontrolcom灢
paredtoquincloracappliedalone.Quinclorac
plusScoilappliedwithpicloramprovidedbetter
leafyspurgecontrolthanquincloracplusScoila灢
lone.Quincloracabsorption,translocation,me灢
tabolism,andtaxicityinleafyspurgewerealso
evaluatedforthesuitabilityofthisherbicidefor
useinthecontrolofleafyspurge(Lamoureux
andRusness,1995).
Thetestwithimidazolinoneandsulfony灢
lureaweretestedinthefalonrangelandsites
nearAinsworthandColumbus,Nebraska(Stou灢
gaardetal灡,1994).Imidazolinoneandsulfony灢
lureaherbicidecombinationsdid notimprove
23暋暋暋暋暋暋暋暋暋暋暋暋 暋暋暋暋暋暋暋云暋南暋植暋物暋研暋究暋暋暋暋暋暋暋暋暋暋暋暋暋暋暋暋增刊桗桏
leafyspurge control nor affectforage grass
yieldswhencomparedwithherbicidesapplieda灢
lone.Imazapyrandsulfometuronwerethemost
efficacious,providinggreaterthan80% leafy
spurgecontrol9monthsaftertreatment.Ima灢
zethapyrprovided80%controlofleafyspurge9
monthsaftertreatmentwhenappliedtoacoarse
textured,loworganicmattersoil.Incontrast,
leafyspurgecontrolwason15% whenimazetha灢
pyrwasappliedtoafinetexturedsoil.Chlorsul灢
furondidnotcontrolleafyspurge,regardlessof
sitecharacteristics.Andimazapyrreducedpe灢
rennialgrassyieldsbymorethan60%.
Leafyspurgeviableseed productionand
germinationwerereducedby2,4灢Dapplieddur灢
ingflowerdevelopmentandseedformation,in
thefield (Al灢Fenaidetal灡,1993).Theviable
seedproductionwasreducedwhen2,4灢D was
appliedatal growthstagesafterthestartof
flowerbuddevelopment.Leafyspurgeseedger灢
minationwashigheringibberelicacidthanin
waterforseedcolectedfrom untreatedplants
andfromplantstreatedwith2,4灢D7,14and21
daysafterbudinitiation.Thisresearchshows
that2,4灢Dmustbeappliedpriortoflowerbud
developmenttopreventseedproduction.Annual
applicationofpicloramandpicloramplus2,4灢D
andbiannualapplicationof2,4灢Dfor5consecu灢
tiveyearswasevaluatedforleafyspurgecontrol
(LymandMessersmith,1987).Thelaboratory
experimentsforadjuvanteffectsonimazethap灢
ry,2,4灢D and picloram absorption by eafy
spurge wasalsocarried (Thompson etal灡,
1996).Theabsorption,translocation,andme灢
tabolismof14C灢picloramand14C灢2,4灢Dapplied
aloneandtogethertoleafyspurgewasalsoeval灢
uated(LymandMoxness,1989)whichshowit
wilincreasedleafyspurgecontrolwhenthese
herbicidesareappliedtogether.Therelativehu灢
midityafterapplication,sprayadditives,andso灢
lutionpH affectedbothfoliarabsorptionand
translocationof14C灢picloram toleafyspurge
roots(MoxnessandLym,1989).Theabsorp灢
tion,translocation,rootrelease,and metabo灢
lismofimazethapyrbyleafyspurgeweredeter灢
minedundergrowthchambercondition(Nissen
etal灡,1994).Thepicloram metabolism was
studiedinrootedcuttingsandexcisedleavesof
leafyspurge(Frearetal灡,1989).Andvarious
chemicalcontrolsatdifferentplacesindifferent
doseanddifferentconditionstoleafyspurgeas
welastheevaluationshavebeentestedandcar灢
riedindifferentareaamongnorthwestNorthA灢
merica(HeinandMiler,1991;Lym,1992a,b;
Regimbaland Martin,1984,Mastersetal灡,
1994,1998;ThompsonandNissen,1998),in灢
cludingtodeterminecosteffective (Lym and
Messersmith,1985a,1990b;MoomawandMar灢
tin,1990),andsomeevenestablished with
modeltodeterminethebestcontrolofleafy
spurge(LingleandSuttle,1985).
Responseofleafyspurgeclonestochlorsul灢
furon,clopyralid,andglyphosatewerealsore灢
ported(FrankandTworkoski,1994).Clonesof
leafyspurgevariedsignificantlyforalresponses
toeach herbicide.Thedifferentialeffectsof
chlorsulfuron,glyphosate,and clopyralid on
leafy spurge suggest that geneticaly based
differencesmayaccountforthefailureofthe
herbicidestokilalplantswithincolectionloca灢
tionsorbetweencolectionlocations.Theinflu灢
enceofglyphosateonbuddormancyalsorepor灢
ted(Maxweletal灡,1987).
Efficacyandeconomicsofleafyspurgecon灢
trolinpasturewithvariouschemicalswerestud灢
ied(GylingandArnold,1985).Severaltreat灢
mentsresultedinleafyspurgecontrolexceeding
90% meanherbagedry灢weightyieldintreated
plotswas2340kg/hm2,a67%increaseover
untreatedplots.Marginalnetreturnovermar灢
ginalcostfromherbicidetreatmentsrangedfrom
$35to$63/hm2.Treatmentsprovidingsatis灢
factoryleafyspurgecontrolwithminimumeco灢
nomicriskwereannualspringapplicationsof2,
4灢Dat1灡7kg/hm2ordicamba+2,4灢Dat0灡6+
1灡1kg/hm2andthebiannualapplicationof2,4灢
33增刊桗桏暋 暋MAJin灢Shuang:AReviewofLeafySpurge,Euphorbiaesula(Euphorbiaceae),theMost...暋 暋
Dat0灡8kg/hm2.
Leafyspurgecontrolandforageproduction
aftervariousfal灢appliedherbicidetreatmentro灢
tationswereevaluatedinabluegrasspastureand
amixedgrassprairie (Lymand Messersmith,
1985c,1994).Leafyspurgecontrolwithfour
herbicides wasevaluatedatninesitesinsix
GreatPlainsStates,andtheresultsshowthat
sulfometuronalonedidnotcontrolleafyspurge
satisfactorily12monthaftertreatment(Becket
al灡,1993).
ThechemicalcontrolinNorthDakotafrom
1963to1982wasreviewedintwentyyears(Lym
and Messersmith,1985b).Thetemperature
changespriortopicloramapplicationaffectits
activityinleafyspurge(LymandMessersmith,
1990a).Diflufenzopyrisalsoakindofuseful
chemicalseffectivelytocontrolofleafyspurge
(LymandDeibert,2005).
GrazingControl
Grazingexperimenttocontrolleafyspurge
wasalsostartedin1930swithsheep (Bakke,
1937).UseofAngoragoatsisanothertoola灢
vailabletolandmanagerstomanageleafyspurge
infestationsintheNorthernPlains(Kirbyetal灡,
1997).Angoragoatshavebeensuggestedasbio灢
logicalcontrolagentsforleafyspurge,especialy
inenvironmentalysensitiveorlimitedaccessar灢
eas.Dietarypreferencesanddietarynutritive
contentofherdedAngoragoatswereevaluated
overatwo灢yearperiodinNorthDakota.Rela灢
tivepreferencesofforages wereevaluatedby
comparingbotanicalcompositionofdietsasde灢
terminedby microhistologicalanalysisoffecal
samplestoforageavailabilityinthefield.Leafy
spurgeandshrubscomprisedthelargestper灢
centageofgoatdietsthroughouteachgrazing
season.Goatspreferredleafyspurgeandshrubs
atal thetimesandavoided mostcool灢season
grassspecies.Thenutritionalrequirementsof
Angoragoatsnursingkidsweremetthroughout
thegrazingseason.
The germinability and viability ofleafy
spurgeseedsfolowingingestionbysheepand
goatswereevaluated(Laceyetal灡,1992).The
resultsindicatethatsheepandgoatsareeffective
biologicaltoolsforreducing spread ofleafy
spurgeseeds(Landgrafetal灡,1984;Olsonand
Walander,1998;Olsonetal灡,1996),butnot
finaltooltoerasedfromroot(Masters,2003).
ComprehensiveControl:
Nosingleagentorherbicidecouldcontrol
suchkindofaggressiveinvasiveplant,andvari灢
oustreatmentandcombination wil greatin灢
creasetheeffectincontrolingspreadanddensi灢
ty,andfinalyremovedit.
IntegratedPestManagement(IPM),ade灢
sirableapproachtotheselection,integration,
anduseof(pestcontrol)methodsonthebasis
oftheiranticipatedeconomic,ecological,and
sociologicalconsequenceshasbeenformedsince
1980s(AlenandBath,1980;Watson,1985).
IPMforleafyspurgehasbeenevaluatedasinva灢
siveplantasTheodoreRooseveltNationalPark,
North Dakota (Larson etal灡,2007).The
effectsofherbicidesonleafyspurgeabundance
andon dynamicsofflea beetles (Aphthona
spp.)usedtocontrolleafyspurgewereevalua灢
tedoverthreefieldseasonsfolowingherbicide
application.Theresultsuggeststhatthemost
effectivecomponentofIPMforleafyspurgeat
theexperiencesiteisbiologicalcontrol,andal
herbicideeffectswereshort灢lived.
Thecombinationoffleabeetlesandherbi灢
cidecanincreaseleafyspurgecontrolwhencom灢
paredwitheither methodsusedalone (Lym,
1998;LymandNelson,2002;NelsonandLym,
2003).Thecombinationtreatmentwas most
successfulwhenusedwithestablishedfleabee灢
tlespopulations,whichcouldsavetheexpensive
from30-50percentwiththecombinationtreat灢
mentcomparedwithherbicidesalone.Dicamba,
2,4灢D,glyphosate,andpicloramhavecommon灢
lybeen usedtocontrolleafyspurge (Lym,
43暋暋暋暋暋暋暋暋暋暋暋暋 暋暋暋暋暋暋暋云暋南暋植暋物暋研暋究暋暋暋暋暋暋暋暋暋暋暋暋暋暋暋暋增刊桗桏
1989).Teninsectspeciesforleafyspurgehave
beenreleasedin North Dakota,andthe most
successfulhavebeenthefleabeetles,A灡nigris灢
cutis, A灡czwalinae,and A灡lacertosa. The
leafyspurgegal midge (Spurgiaesulae)has
beenmostsuccessfulnearwoodedareas.Herbi灢
cidescombinedwitheithertheleafyspurgeflea
beetlesorgal midgehascontroledleafyspurge
betterthaneithermethodusedalone.Grazing
withsheeporgoatsisacost灢effectivemethodfor
controlingleafyspurgetopgrowthinlargein灢
festations.Thegrazingcombinedwithfal灢applied
picloramplus2,4灢Dreducedleafyspurgedensity
morerapidlyandmaintainedcontrollongerthanei灢
thermethodusedalone(Lym,1998).
Biologicalcontrolisanalternativetochemi灢
calcontrolforleafyspurge,especialyalongrail灢
roadright灢of灢ways (Lym and Nelson,2000).
Re灢vegetatingleafyspurgeinfectedrangeland
withnativetalgrasswasalsoconducted(Mas灢
tersandNissen,1998).Thefourexperiments
wereconducted withimazapyr,sulfometuron
andincombinationbyglyphosatetoapplyto
leafyspurgeatdifferentdosesanddifferentsea灢
sons.Leafyspurgeyieldswereusualyreduced
inareaswheretalgrassyields weregreatest.
AnothertestwascarriedinCrookCounty,Wyo灢
ming,todeterminethepotentialofelevengrass
speciestocompetewithleafyspurgeasanalter灢
nativetorepetitiveherbicidetreatments,andthe
resultshowsthat ‘Bozoisky暞Russian wildrye
and ‘Luna暞pubescentwheatgrassarethe most
promiseforsuccessfulcompetition(Ferreletal灡,
1998).
Aninvasiveweedcanoccupyavarietyof
environmentsandecologicalnichesandgeneraly
nosinglecontrolmethodcanbesuedacrossal
areastheweedisfound(Lym,2006).Biological
controlagentsintegratedwithothermethodscan
increaseand/orimprovesite灢specificweedcon灢
trol,butsuchcombinatorialapproacheshavenot
beenwidelyutilized.Thesuccessfulleafyspurge
controlprogramprovidesexamplesforfuturein灢
tegrated weedprogramsthatutilizebiological
controlagentswithtraditionalmethods.Weed
controlmethodscanbeusedseparately,suchas
whentheleafyspurgegal midge(Spurgiaesu灢
lae)reducedseedproductionin woodedareas
whileherbicidespreventedfurtherspreadoutside
thetreeline.Traditionalmethodsalsocanbe
useddirectlywithbiologicalcontrolagents.In灢
corporationof Aphthonaspp.withherbicides
hasresultedinmorerapidandcompletecontrol
thaneithermethodusedalone.Also,theinsect
populationoftenincreasedrapidlyfolowingher灢
bicidetreatment,especialyinareaswhereAph灢
thonaspp.wereestablishedforseveralyearsbut
hadbeenineffective.IncorporationofAhthona
spp.withsheeporgoatsgrazinghasresultedin
alargedeclineinleafyspurgeproductionthan
insectsaloneandinweeddensitythangrazinga灢
lone.Controledburnscanaidestablishmentof
biologicalcontrolagentsin marginalysuitable
environments,buttimingofthefiremustbeco灢
ordinatedtotheinsect曚slife灢cycletoensuresur灢
vival.Integrationofbiologicalcontrolagents
withre灢vegetationprogramsrequiredtheagent
tobethelastmethodintroducedbecausethecul灢
tivationandherbicidetreatmentsnecessaryto
establishdesirablegrassesandforbswerede灢
structivetotheinsect.
ProspectsandSummary
Survey
Withspreadofleafyspurgeandawareness
inNorthAmerica,thesurveyofcurrentinfec灢
tionareahasbecomingahugechalenge,espe灢
cialyforthoseremoteareas wherecommon
methodcan曚tbeaccessedforhumanbeings.Use
ofremotesensingfordetectingand mapping
leafyspurgehasrevealedbroadprospecttomo灢
nitorthespreadordeclineofleafyspurgere灢
cently(Everittetal灡,1995),whichcouldbe
usedforconstructingdistributionandabundance
mapswithsatelitehyperspectraldataforlarger
regionalareas(WiliamsandHunt,2003).Hy灢
53增刊桗桏暋 暋MAJin灢Shuang:AReviewofLeafySpurge,Euphorbiaesula(Euphorbiaceae),theMost...暋 暋
perspectraldataprocessingforrepeatdetection
ofsmalinfestationswasalsoreported(Glennet
al灡,2005).Plantcanopyreflectance measure灢
mentsshowedthatleafyspurgehadhighervisi灢
ble(0灡63-0灡69mu/m)reflectancethanseveral
associatedplantspecies.Theconspicuousyelow
bractsofleafyspurgegaveitdistinctyelow灢
greenandpinkimagesonconversionalcolorand
color灢infraredaerialphotographs,respectively.
Leafyspurgealsocouldbedistinguishedoncon灢
ventionalcolorvideoimagery whereithada
goldenyelowimageresponse.Quantitativedata
obtainedfrom digitized videoimagesshowed
thatleafyspurgehadstatisticalydifferentdigit灢
alvaluesfromthoseofassociatedvegetationand
soil.Computeranalysesofvideoimagesshowed
thatlightreflectedfromleafyspurgepopulations
couldbequantifiedfromassociatedvegetation.
Theimageanalysistoseparateleafyspurgefrom
otherplantspeciesandobjectsisalsoreported
(Birdsaletal灡,1997).Thespectralcharacteris灢
ticsofleafyspurgeisfulydiscussedwithdetail
(Huntetal灡,2004),andthespecialcharacteris灢
ticsareimportantforconstructingawel灢docu灢
mentedspectrallibrarythatcouldbeusedwith
hyperspectralremotesensing (Hunt etal灡,
2004).
Classicalmonitoringtechniques,whichoften
involveextensivegroundsurveyefforts,can曚tbe
aidedbythesynopticnatureofremotelysensed
imagery.Theresearch addressesthe use of
SpaceImaging曚s4灢m multispectralIkonosima灢
geryforthesurveyanddetectionofleafyspurge
infestations(Casadyetal灡,2005).Surveydata
werecolectedatasiteinwesternNorthDakota
andusedtoproducesupervisedclassificationsof
leafyspurgeinfestationswithIkonosimagery.
Finaly,individualpatchesofleafyspurgewere
analyzedtodeterminetheminimum patchsize
andpercentcoverthatweredetectablewithsu灢
pervisedclassificationofIkonosimagery.Multi灢
dateimageryprovidedincreasedaccuracy,but
improvementwasnotconsistentlysignificant.
Leafyspurgeinfestationsof <30% coverand
200sq.mwerenotreliablydetected.
Management
Weedpopulation modelscan serveasa
frameworktoorganizeweedbiologyinformation
andtodevelopweedcontrolstrategies.Models
helptoidentifyinformationgaps,tosetresearch
priorities,todevelophypothesespertinentto
weedpopulationregulation,andtosuggestcon灢
trolstrategies(Maxweletal灡,1988).Apopu灢
lationsimulationmodelofleafyspurgewasused
todemonstratetheapplicabilityofpopulation
modelstoweedscience.Sensitivityanalysisof
anexistingleafymodelindicatedthattransition
frombasalbudstovegetativeshoots,survivalof
vegetativeshoots,andsurvivalofbasalbuds
overwinterwereimportanttransitionparame灢
tersinfluencingpopulationgrowthofthisweed
species.Fourcontrolstrategiesweresimulated
andwerecomparedtofieldstudiestoshowthe
predictiveandmanagementpotentialofthemod灢
elingapproach.
TheEcologicalAreawideManagement(TEAM)
ofleafyspurgeprogram wasdevelopedtofocus
researchandcontroleffortsonasingleweed,
anddemonstratetheeffectivenessofacoordina灢
ted,biologicalybased,IPM (Andersonetal灡,
2003).Thiswasaccomplishedthroughpartner灢
shipsandteamworkthatclearlydemonstrated
theadvantagesofthebiologicalybasedIPMap灢
proach.However,thesuccessofregionalweed
control programs horizontaly across several
statesandprovincesalsorequiresaverticalinte灢
grationofseveralsectorsofsociety.Awareness
andeducationaretheessentialelementsofverti灢
calintegration.Therefore,asubstantialeffort
wasmadetoproduceawidevarietyofinforma灢
tionproductsspecificalydesignedtoeducatedif灢
ferentsegmentsofsociety.Thelandmanagers
andagencydecisionmarkershaveseenthepo灢
tentialofusingtheTEAMapproachtoacceler灢
atetheregionalcontrolofleafyspurge.Theex灢
amplesetbytheTEAMorganizationandpartic灢
63暋暋暋暋暋暋暋暋暋暋暋暋 暋暋暋暋暋暋暋云暋南暋植暋物暋研暋究暋暋暋暋暋暋暋暋暋暋暋暋暋暋暋暋增刊桗桏
ipantsisviewedasamodelforfutureweed灢con灢
trolefforts.Thesurveytoevaluaterespondent曚s
perspectivesof managerial,institutional,and
socialfactorsfromlocalranchers,decisionmak灢
ersandpubliclandmanagersinNorthandSouth
Dakota,MontanaandWyomingshowsthatthe
financialconstraintsmaybeaddressedthrough
cost灢shareprogramseither offeredlocaly or
throughstateagencies,anditisfolowedbyalack
ofknowledgetoworkwithvariouscontrols(Selet
al灡,1999),evenfirecontrol(Masters,2003).
ProposalforTEAMLeafySpurgearea灢wide
programsubmittedin1996,andTEAM Leafy
SpurgeisselectedastheUSDA灢ARS曚sfirstare灢
a灢wideIPM program.The USDA灢APHISis
namedasaco灢managerofthe5灢yearprogram
with$4灡5mfrom1997,andofficialyfinished
in2002.TEAM Leafy Spurgepublishesthe
“BiologicalControlof Leafy Spurge暠hand灢
book.Morethan14000copiesaredistributedto
endusersin16statesandseveralCanadianpro灢
vincesduringitsfirstsixweeksofpublication.
In2001,TEAMLeafySpurgeisfeaturedonthe
BBC曚s“EarthReport暠,adocumentary灢styleen灢
vironmentalnewsprogram.Theepisode,“Alien
Invaders暠,isbroadcastin220countriestoapos灢
sibleaudienceof167milionviewers.Distribu灢
tionoftheTEAMLeafySpurge“BiologicalCon灢
trolofLeafySpurge暠handbookhits30000.
“IPM InformationSeries/BiologicalControlof
LeafySpurgeCD暠includesanarratedPower灢
Pointpresentation,thebio灢controlmanual,cata灢
logsofphotos,informativeprofilesofbio灢control
agents,and miscelaneousresources. “Purge
Spurge:LeafySpurgeDatabase暠CD灢ROM.
LeafySpurgeNews,publishedbyAgricul灢
turalExperimentStation,NorthDakotaState
University Extension Service, North Dakota
StateUniversity,Fargo,NorthDakota,issemi灢
annualnewsletter (basicaly)publishedsince
1979,anditisalsothebestnewsletterinNorth
Americaregardingthesinglefightforleafy
spurgeintheworld,butfinalydeceasedinOc灢
tober2005.Someofitscontentsfrom1996are
available(http://www灡team灡ars灡usda灡gov/v2/
publications/leafyspurgenews灡html)withTEAM
ofARS,USDA.
MolecularApproach
Themoleculartoolfrombiologicalfieldre灢
centlydefinitelyopensanewfieldincontroling
leafyspurgeinthefuture.Evensometestsand
reportshavebeenmade,however,itisstila
longwaytogobeforethepowerfulwaycouldbe
foundandapplied,especialyinsuchlargelyin灢
fectionareainNorthAmerica.
Thelevelsofinter灢andintra灢populationge灢
neticvariationweredeterminedinfiveNorthA灢
mericapopulationsofleafyspurgeusingchloro灢
plastDNA(cpDNA)RELPsandRAPDmarkers
(Roweetal灡,1997),andtheresultshowsthat
thehighdegreeofgeneticvariabilityinNorthA灢
mericanleafyspurgesuggestspossiblemultiple
introductionsora high degree ofvariability
withinleafyspurgepopulationsinits native
range.Thegeneticvariationandrelatednessa灢
mongselectionsofNorthAmericanandEurasian
leafyspurge wasalso made (Nissen etal灡,
1992),andtheresultshowsthattheAmerican
accessionsareclosedrelatedeachotherandto
theRussianleafyspurgeaccession.
Effectofleafyspurgegenotypeonfeeding
damageandreproductionofAphthonaspp.is
tested,andthegenotypedoesaffectfeedingbut
notegglayingby Aphthonaspp.adults(Lym
andCarlson,2002).However,thegenotypeaf灢
fectsgal midge(Spurgiaesulae)establishment
(Lym etal灡,1996),whichwasintroducedin
NorthDakota(LymandCarlson1994).
Using molecularreportshowed (Horvath
andOlson,1998)thatmorethan16geneshave
beenidentified,thataredifferentialyexpressed
inundergroundbudsofleafyspurgeduringdor灢
mancybreakandgrowthinitiation(Horvathand
Anderson,2002).Adetailedexpressionanalysis
ofthesegeneswilalowthemtobegroupedby
theirresponsestovarioussignalsknowntoplay
73增刊桗桏暋 暋MAJin灢Shuang:AReviewofLeafySpurge,Euphorbiaesula(Euphorbiaceae),theMost...暋 暋
aroleincontrolofundergroundbudgrowth.
Thisinformationwilbeusedtoidentifykeycis灢
actingelementsinvolvedintheregulationof
thesegenes,andsuchinformation onsignal
transductionprocessesmaybeusedfordevelo灢
pingnewweedcontrolstrategiesbytheidentifi灢
cationofnoveltargetpathwaysanddevelopment
ofDNA灢basedherbicides.Agenomicandnear
fullengthcDNAcloneforaD灢classcyclingene
fromtheleafyspurgehasbeenisolated (Hor灢
vathetal灡,2005).TwosubtractivecDNAli灢
brariesweredevelopedtostudygenesassociated
withbuddormancy(reverselibrary)andinitia灢
tionofshootgrowth(forwardlibrary)inleafy
spurge(Jiaetal灡,2006).Andtheanalysisof
buddormancyinthemolecularmethodisalso
tested(Horvathetal灡,2002,2005).
WorkshopandSymposium
Sinceearly1980s,thefighttoleafyspurge
bothlocalyandnationalyhavebeenlargelybe灢
gan,andthevariousworkshopandsymposium
werehold,andvariouskindsofpublicationsand
comprehensive serious monograph were also
published.Andamongthem,folowingshould
benotomittedhere.
NorthCentralWeedControlConferenceRe灢
searchReportpublishedbyNorthCentralWeed
ControlConferencein1980,withvariouspubli灢
cations,suchasthevariabilityofleafspurgein
theUnitedStates(37:48-51).LeafySpurge,
MonographSeriousoftheWeedScienceSociety
ofAmerica,editedbyAlanK.Watson(1985).
LeafySpurgeSymposiumProceedings,Lincoln,
Nebraska,July22-24,1994:Taxonomyand
biology(4:3-7).Proceedings:LeafySpurge
StrategicPlanningWorkshop,Dickinson,North
Dakota,March29-30,1994.Thispublication
includevariousreview,suchasbiology(p.57-
62),
Thecoordinatedregionalresearcheffortbe灢
ganwiththeLeafySpurgeSymposium,June26
and27,1979,Bismarck,ND.About125educa灢
tors,scientists,landmanagers,farmers,ranch灢
ers,legislators,andconcernedcitizensattended
thesymposium (Messersmith,1989).Oneout灢
comeoftheplan wasapprovedbytheGreat
PlainAgriculturalCouncilofaresearchcommit灢
tee,GPC灢14LeafySpurgeControlintheGreat
Plains,asarecognizedorganizationtofacilitate
programcoordination.ThefirstGPC灢14 meet灢
ingwasheldinJune1981,Fargo,andannual
meetingshavebeensincethen:1982inBozem灢
an,MT,1983inSundance,WY,1984inDick灢
inson,ND,1985inBozeman,MT,1986inRiv灢
erton,WY,1987inFargo,ND,1988inRapid
City,SD,1989inBozemanMT,1994inBozem灢
an,MT,1995inFargo,ND,1996inBrandon,
Manitoba,1997inGilette,WY,1999&2001
inMedora,ND,and2004heldattheSocietyfor
RangeManagement(SRM)57thannualmeeting
January24-30,2004inSaltLakeCity,Utah.
Whatcanleafyspurgeteachusaboutman灢
agementofnoxiousweedingeneral?Sevenim灢
portantlessonsemerge(Cox,1998):1)noxious
weedshavebeenwithusfordecades,andthere
istimetodevelopsuccessfulandsustainable
managementstrategies;2)afocusonelimina灢
tingthecauseofweedproblemsisimperative,
sothatwecreatelong灢termsolutions;3)biolog灢
icalcontrolisausefulandcost灢effectivetech灢
nique;4)managementtechniquesneedtoin灢
cludetoolstoreduceseedpopulations;5)en灢
couragementofdesirablevegetationiscrucial;
6)propertimingcanmaximizetheeffectiveness
of non灢chemicalcontrols;and 7)techniques
mustbeappropriateforthetreatmentsite.
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54增刊桗桏暋 暋MAJin灢Shuang:AReviewofLeafySpurge,Euphorbiaesula(Euphorbiaceae),theMost...暋 暋