EmergencyAuthorisationApplication
fortheuseofAsulam
forthecontrolofbrackenonroughgrazing,moorland,amenitygrassland,
forestryandthehistoricenvironmentin2017.
SupportingInformation
CONTENTS
1. NatureConservation................................................................................................................................2
DesignatedSites.......................................................................................................................................2
Cutting..........................................................................................................................................................4
Requirementsfromconservationagencies..................................................................................4
NaturalEngland...................................................................................................................................4
ScottishNaturalHeritage................................................................................................................4
2. HumanHealthImpacts...........................................................................................................................5
IndirectImpacts.......................................................................................................................................5
TickBorneDiseases...........................................................................................................................5
Recreationalactivitiesandoccupationalgroupsatrisk....................................................5
Tickhostactivity......................................................................................................................................6
Risks...............................................................................................................................................................6
Directrisks.............................................................................................................................................6
Indirectrisks.........................................................................................................................................6
TheQuantockHillsStudy.....................................................................................................................7
Conclusion...................................................................................................................................................9
Newtonrigg,Holywood,DUMFRIESDG20RA
Tel / Fax : 01387 723201
Coordinator:SPRThorpBSc(Hons)CEnvMRICS
E-mail: [email protected]
Web: www.brackencontrol.co.uk
1.
NatureConservation
Author:AlastairBurn,NaturalEngland
DesignatedSites
Bracken can provide an important habitat for specific wildlife species. In some areas,
there are positive associations with species such as fritillary butterflies. Bracken can
provideakeyhabitatforuplandmarginbirds,andinsomehabitatsitisanimportant
component adding to structural diversity, especially in rough grassland on the upland
margins.However,brackenhasseriousnegativeimpactsinsomehabitatsandhereit
requires management. Bracken is often invasive and can dominate other vegetation,
leadingtochangesinlivestockgrazingpatterns(whichmaytheninterferewiththeuse
oflivestockforhabitatmanagementonasite)orout-competinganddirectlossofthe
interestfeatureforwhichawildlifesiteisdesignated.
In England and Wales, 60% of moorland is designated for the quality of vegetation or
theimportanceofthehabitattobreedingbirds(NationalNatureReserves(NNR),Sites
ofSpecialScientificInterest(SSSI),SpecialAreasofConservation(SAC)and/orSpecial
ProtectionAreas(SPA)).Ifthevegetationcommunities,whichoftenformthebasisof
thesedesignations,areinvadedbybrackenandout-competed,ithasanadverseeffect
ontheirconservationstatus.70%ofEnglishgrousemoorsarewithinaNationalPark
orAreaofOutstandingNaturalBeauty(AONB)andoftentheirheathermoorlandisthe
key component of these treasured landscape designations. Allowing heather to be
swampedbybrackencompromisesthesedesignations.Excessivebrackencoverisalso
aconcerninsomelowlandhabitats,suchasheathlands,whicharealsoofnationaland
internationalimportance.
Control of bracken is therefore widely carried out for nature conservation purposes.
Control is a requirement to maintain SSSIs currently achieving or recovering to
favourable condition, and in restoring sites, which are not yet recovering. Bracken
management is therefore anticipated to play a key role in helping to achieve
GovernmentcommitmentstoSSSItargets,andforexampleinEngland,contributingto
achievement of the requirement to restore 200,000 ha of priority habitat by 2020.
Asulamistheonlypartially-selectivetoolavailabletocontrolbrackenonalarge-scale.
To achieve clearance of a particular patch of bracken may require a programme of
treatmentforupto10years.
Brackencancompletelyre-establishitsdominancewithinabout3years,soiftreatment
isnotmaintained,resourcesappliedtocontrolthatbrackenwouldhavebeenwasted;
thecontrolprogrammewouldneedtostartagain.Muchofthecostofsuchprogrammes
is covered by Government and/or European grants / public money and more still is
invested by private individuals. The gains from the large amount of public funds, the
resourceandtheeffortthathasbeeninvestedinbrackencontrolmanagementoverthe
last10yearswillbeputatriskifitisnotpossibletocarryonusingAsulamtomaintain
theselective,follow-uptreatmentsontheseareas.Inaddition,ifthereisadelayinthe
programme,andbrackenisallowedtopartlyorfullyrecoveritsdominance,thenitmay
require more intensive herbicide management to bring the matter under control at a
laterdate.Thiswouldbebothwastefulofresourcesandconflictwithbestpractice.
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BrackencontrolisafrequentmanagementrequirementinSSSImanagementplansand
exists in agri-environment scheme options to facilitate this activity both within and
outsideSSSIs.Conservationagencieswouldgenerallyconsideralternativemethodsto
herbicide use as a first option for bracken control, such as grazing, bruising or other
mechanical control, and this decision process is set out in the revised “Herbicide
Handbook”(Brittetal,20031).However,whereaccessorterrainmakemechanicalor
physical management difficult, dangerous or impossible (mechanical control is
dangerous in MoD sites where ammunition may be a hazard), or where mechanical
control is ineffective or poses a risk to other fragile habitats, ground nesting birds,
reptilesorscheduledmonuments,thenchemicalcontrolistheonlymanagementoption
available.
In order to control bracken a systemic herbicide is needed (to kill the rhizomes).
Asulamhasthissystemicproperty,aswellashavinglessnegativeimpactonnon-target
plants than other effective alternatives, although there is evidence that Asulam can
cause damage to other fern, lower and vascular plant species. The conservation
agencies have supported research into the risks of asulam to non-target plants
(Sheffield et al 20032) and a considerable body of evidence is available in order to
enable judgements of risks through drift or overspray onto non-target areas. Such
evidencehasnotbeensystematicallycollectedforalternativeselectiveherbicideswith
potential for bracken control, although Natural England has been supporting research
intotheefficacyandrisksofcertainpossiblealternativeproducts.Thisevidenceshould
helpinformapproachestobrackenmanagementoverthelongerterm,butwillnotbe
availabletoinformmoreurgentmanagementworkoverthenextfewyears.
Asulam is needed for bracken control on lowland (especially heathland but also other
grassland) SSSIs, many of which are also designated under the EU Habitats and Birds
Directives.Inabilitytouseherbicidesforbrackencontrolwouldrisksignificantareasof
lowland heath returning to unfavourable condition. Large blocks of bracken with a
goodheathlandunder-storeycanbetreatedusingAsulamandsoeffectivelycontrolthe
extentofbrackeninanarea,aslongasfollowuptreatmentsareappliedinsubsequent
years.Glyphosatecannotbeusedinthesamewaywithoutriskofextensivemortalityof
non-targetplantsintheunder-storey
In both the uplands and the lowlands, there are a number of SSSIs where herbicidal
controlofbrackeniscarriedoutforbiodiversityconservationpurposes.Herbicidesare
usedinthepreparationofgroundforestablishmentofwoodlandforbiodiversityandits
useisofmajorimportancefortheprotectionofarchaeologicalsitesmanyofwhichare
scheduled monuments. In both cases it is important to minimise any effects on nontarget plants to maximise re-establishment of ground flora. The extensive use of
Asulam in the uplands for agricultural and sporting purposes has often prevented
brackenbecomingaspecificconservationissueinsuchareas,andinabilityinthefuture
to carry out selective herbicidal control is likely to result in an impact on favourable
habitatconditioninsuchareas.
1Britt.C,MoleA,KirkhamFandTerryA(2003)TheHerbicideHandbook.GuidanceontheUseofHerbicidesonNatureConservation
Sites.EnglishNatureReportundercontractEIT31-04-003.EnglishNature2003.UpdatedbyNaturalEngland2011.
SheffieldE,JohnsM,RumseyFJ,andRowntreeJK(2003)AninvestigationoftheeffectsoflowdosesofAsuloxonnon-targetspecies.
EnglishNaturecontractsEIT20-19-001andEIT30-08-07.Peterborough.EnglishNature.
2
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Ingeneral,aprogrammeofherbicideuseisneededoveranumberofyearstoachieve
completecontrolasbrackenvigourisprogressivelyreducedoveranumberofseasons
of control. This programme is still underway in many SSSIs and under agrienvironmentschemeagreements.Wherecompletionofacontrolprogrammecannotbe
achieved, there is likely to be rapid reversion to bracken dominance and loss of the
gainsmadeinprecedingtreatmentyears.
Cutting
Cutting is often not a practicable alternative to chemical control with a selective
herbicide like Asulam in heather moorland areas. Experiments on the North York
Moorshaveshownthatcuttingcannotachieveclearanceunlessitisdoneatleast3or4
times per growing season, to a very low level below the height of surrounding
vegetation and for at least 3 or 4 years successively. Labour costs make this
impracticableinmanysituations.Itisnotpossibletocutbrackenwithmachinerylow
enoughwithoutriskingdamagetoothervegetationand/orcausingdamagetosurface
peat that can lead to an erosion risk. Furthermore, mechanical cutting may cause
damagetoknownandunknownarchaeologicalinterestpreservedinthepeat.
Requirementsfromconservationagencies
NaturalEngland
Overall, Natural England estimates that some 6,680 ha SSSI (4,730 ha Natura 2000
sites)haverecentlyrequiredherbicideuse,asignificantproportionofwhichhasrelied
on Asulam for bracken control. As examples of the scale of implication for heathland
sites, the majority of the unfavourable Dorset heathland units have a bracken control
requirement and there has been heavy reliance on Asulam in heathland restoration
projects, for example in the Thames Basin Heaths area, where there has been a major
efforttoexpandheathlandfollowingconiferremoval.
On grassland habitats, use is more variable but essential in some cases: e.g. Quantock
common (borderline between upland and lowland grassland) had an asulam bracken
controlregimeon770.6hain2009and152hain2010.Thiswasamajorcontributorto
an improvement in SSSI condition (c.1,500 ha) but this gain in condition is reliant on
followuptreatments.In2012,therewereover7,000haofchemicalbrackenoptions
live across all Higher Level Stewardship (HLS) agreements in England. 2,400 ha of
those were in agreements issued in 2011. This provides an indication of the rough
annualscaleofrequirementtomeetexistingHLSagreementtargets.
ScottishNaturalHeritage
The scale of requirement for Scotland was indicated by the figures for bracken
managementoptionsfundedthroughtheScottishRuralDevelopmentProgramme,asat
January 2011. It should be noted that figures for SSSI and Natura areas are
approximate, and not all may relate to application of asulam to designated sites since
somemayincludeareasofapplicationadjacenttothosesites:
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•
•
•
On SSSIs: 104 cases of the option 'Bracken Management Programme for Habitat
Enhancement' had been approved on fields that overlap SSSI boundaries. This
comprises 155 fields, which overlapped SSSIs to the extent of around 49,191 ha.
OnNatura2000sites: 84 cases had been approved, made up of 128 fields with an
overlap with Natura 2000 sites of around 35,497 ha.
SSSIandNaturacombined: 116 cases had been approved, made up of 175 fields
with an overlap of 58,023ha.
2.
HumanHealthImpacts
Author:ProfessorRoyBrown
IndirectImpacts
TickBorneDiseases
TheenvironmentcreatedbybrackenbedshasbeenshowntofavourSheepTickIxodes
ricinus activity, with up to 70% of all tick activity in heath and dry moorland areas
associatedwithbrackendominatedhabitats.Inadditiontocausingdamagebysimply
suckingbloodfromahost,especiallyifthepuncturesitesbecomeinflamed,tickscarrya
range of Tick Borne Diseases (TBD) which affect humans, mammals and birds. The
mainticktransmitteddiseasesaffectinghumansintheUKareLymeDisease,TickBorne
Fever (Anaplasmosis), Louping Ill, Babesia and infections created by the bacteria
Staphylococcusaureus,althoughseveralotherpathogensaretransmittedandmaycause
problems,especiallyifina‘cocktail’ofTBDstransmittedbyasinglebite.
The number of confirmed reports of Lyme Disease in England, Wales and Scotland
increasedfrom200in1999toalmost1,600in2009,accordingtodatafromtheHealth
Protection Agency and Health Protection Scotland. More recently, Public Health
England estimates that in England & Wales there are now between 2,000 and 3,000
caseseachyear3,althoughitisthoughtthatmanycasesgounreported.
Recreationalactivitiesandoccupationalgroupsatrisk
Brackenisoftenmostextensiveinlowlandheathanddriermoorlandsituations,aswell
as in certain pastures, grass rough grazing and on woodland floors. These areas are
frequentlydesignated,e.g.AreaofOutstandingNaturalBeauty(AONB),NationalParkor
Forest Park, and therefore attract outdoor recreational activities such as walking and
cycleriding.Levelsofrecreationalusemaybehigh,especiallyattimesoftheyearwhen
‘questing ticks’ (those actively searching for a blood feed) are at their most active.
Foresters, farmers/shepherds, gamekeepers, countryside rangers and wardens are at
increasingrisk,aswellasvisitorstoareaswhereticksandTBDareendemic.Reducing
theextentofthebrackenhabitatsprovidesanabilitytoatleastregulateandreducethe
riskoftickbites,andAsulamisthebesttoolforlarge-scale,selectivecontrolofbracken
indifficultterrain.
3
http://goo.gl/mLfPhf - accessed on 31 July 2013
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All moorland is open access for walkers and is criss-crossed by a network of rights of
way,bridleways,bywaysandvariouspermissiveaccessroutesusedbywalkers,horse
riders and mountain bikers. Bracken is a physical barrier to access. Health & safety
advice recommends that anybody passing through stands of bracken in the summer,
whensporulationcouldbetakingplace,shouldwearafacemask.
Allowingbrackentoincreaseitsareaofdominancewillrestrictpublicaccessandpose
anincreasingthreattohumanhealth.
Tickhostactivity
The sheltered environment, created by dense bracken beds, makes them attractive as
resting areas to large herbivores such as sheep and deer (mainly Red Deer).
Unfortunately,theseanimalsarealsothemajorhostsforthefourlifestageSheepTick,
the female of which requires three blood feeds at different life stages to complete her
lifecycleoflayingeggs,whichisnormallyoveratwoorthreeyearperiod.
Risks
Directrisks
Fewpeopleeatbracken,buttherearelocalwatersuppliesthatareaffectedbyitandin
yearswhenthereisheavysporulation,peopleinhalethedust.
The formation of spores depends on conditions and tends to be associated with
excessivedroughtyears.Itishighlyvariableintermsoftimeanddistribution,butthere
seemstobeanunderlyingcycleofbetween8and12years.Whensporulationoccurs,
normally in late July to mid August, the very edges of the pinna (leaf) turn under to
develop and protect the sporulation centres and this gives the impression of early
senescence.
Whilst there is debate over the significance of bracken in situ causing direct health
problems to humans, there is little doubt of its negative impact on farm and wild
mammals,aswellasgroundnestingwildbirdsinparticular.
Therefore,theexistenceofbrackenbeds,whichhaveshowndramaticextensionsdueto
environmentalandmanagementchangesoverthelast80years,isamajorproblemin
animalhealthandwelfareterms.
Indirectrisks
TherehasbeenadramaticincreaseindiagnosedTBDintheUKandmanycasesremain
undiagnosed(althoughfrequently‘blankettreated’),especiallyLymeDiseaseofwhich
thereareatleastthreestrainsinEnglandandScotlandnow.Whilstgreaterawareness
and improved diagnostic methods partly explain the recorded increase, there is an
upward trend as records from three Districts in Somerset where a high standard of
accuratediagnosishasbeeninplacesince1997.
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2003
2005
2007
2008
2009
2010
2011
No.of
Cases
3
5
6
8
11
16
18
20
23
26
191 171 241 262
2016
2001
2014
2000
2013
1999
2012
Year
1997
FrequencyofLymeDisease(Borreliosissensulato)from
SevenGeneralPractitionerSurgeriesinSomerset1997to2014.
293
Notes:
1. The reduction in 2011 and 2012 was due largely to fewer cases being diagnosed in the three practices
associatedwiththeQuantocksarea.Thisisalmostcertainlyaresultofthereductioninthebrackenhabitat.
Unfortunatelylackoffundinghasrestrictedtheleveloffollowupfrom2012onwards,andticknumbersare
increasingagain.
2. Note the general upward trend, reflecting the general increase in infection rates in nymph and adult
femaleticksandthere-establishmentofbrackencoverintheabsenceofproperfollowupsincetheprimary
spray in 2009. Asulox is the only chemical that can be used at the necessary scale in the sensitive
environmentinvolved.
3.Itwaspossibletodoaresurveyin2016andthehighestnumberoflocaldiagnosesevermadehasbeen
recorded.BytheendofSeptember2016,29caseswereconfirmed(plus5othercasesofTickBorneDisease).
The common denominator is extensive bracken cover, frequently on difficult ground.
Whilstthereareseveralalternativemethodstocontrolbrackenonasmallscale,thereis
noalternativetoaerialcontrolforbrackenonroughorsteepground.Theonlychemical
suitable for such control work is Asulam, which also has limited impact on non-target
speciesandhabitats.
ThepotentialimpactofnotbeingabletocontrollargeareasofbrackenusingAsulamis
bestillustratedbyreferencetotheQuantockHillsStudy.
TheQuantockHillsStudy
The combination of providing favourable habitat for tick activity, the attraction of
intermediatehostsandthepatternsofoutdoorrecreationmeanthatextensivebracken
beds often pose an increasing threat to human health. The work carried out on the
Quantock Hills by Brown has shown that the favourable habitat for sheep ticks
increasedbetween1991and2013.
Bracken beds have the potential to support disease vectors and the pathogens
themselves via the reservoir hosts. The changing relationships and increasing risk
factors were reported in this Study in 2008, and this provides a template for what is
happeninginmanyruralareas.
Nearly 22% of the open hill area of the Quantock Hills Area of Outstanding Natural
Beauty was covered in bracken in the early 2000s. The negative impact on habitat,
stockhealthandgrazingwaswellestablishedandbythetimetheincreasinglevelsof
tickactivityandprevalenceoftickbornediseasepathogenswereestablishedin2007,
boththeconservationagenciesandlandmanagerswerekeentoreducethearealostto
brackenandatthesametime,lessenthenegativeeconomicandhealthissuesaswell.
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In2009,almost800haofbrackenencroachedlandwascontrolledbyaerialapplication
ofAsulox®underaHigherLevelStewardship(HLS)SchemewithfundingfromNatural
England.Thisrepresented73%ofthetotalbrackenareaontheopenhillarea.Earlier
trialworkbyBrowninthe1990shaddemonstratedthatthelossoffavourablehabitat
dramaticallyreducedtickactivity.Priortothesprayingin2009,andonanannualbasis
since, the condition of the sprayed area (which is now in a follow up programme to
restrict re-growth) and levels of tick activity have been monitored on 14 fixed sites
along with 4 untreated sites where bracken has not been cleared. The dynamics are
summarisedbelow.
2016
2014
2013
2012
2011
2010
2009
2008
Year
MeanNumberofSheepTicks(Ixodesricinus)/m2
ontheQuantockHillsTrialPlots
A.Areassprayedin2009
Larvae
14.5
15.1
16.81
13.11
2.71
3.12
5.93
6.2
Nymphs
6.3
6.2
0.7
0.2
0.1
0.32
1.03
1.1
Females
3.1
2.9
0.3
0.1
0.05
0.12
0.63
0.3
B.ControlAreasnotsprayedin2009
Larvae
14.6
15.3
15.7
16.1
17.2
17.82
18.63
18.5
Nymphs
6.2
5.9
5.6
4.9
6.1
6.92
7.23
8.2
Females
3.2
3.1
2.9
2.2
3.1
2.92
3.33
4.0
Notes:
1. The increase in larval activity is related to accelerated hatching rates due to changes in the critical
humiditylevelsintheexposedbrackenlitteroncethecanopyhasbeenremoved.Byyear4(2013),reduction
inlarvalactivitywasinsynchronisationwiththenymphandfemalereductionprofiles.
2. The increases are probably due to some areas no longer being followed up properly, but the difference
betweencontrolledanduncontrolledareasremainsstriking.
3.Notethecontrastbetweenthecontrolandtreatedareas.Withinthetreatedareanumbersareincreasing
againduetotherecreationofthedensebrackenhabitatinsomeplaces,butthereisalsoageneralupward
trendinthecontrolareasduetobackgroundfavourableconditions(weatherandhostavailability).
Theresultsshowclearlythatbyyear3,aftercontrol,tickactivityatalllifestageswas
reducedbyatleast60%,andatthistimereductionby90+%wasprojectedbyyear5.
Thisreductionwasnotquitereachedbecauseofsomebrackenhabitatregeneration.
Thisisthefirsttimesuchalarge-scalestudyhasbeencarriedoutandtheresultsshow
very clearly the potential benefits to human health from tick reductions as a result of
bracken control. Currently, only aerially applied Asulox® can deliver the primary and
follow-upcontrolthatisrequired.
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Conclusion
Itishopedthatthere-registrationofAsulaminEuropewillbeachievedinthenextfew
years, but in the interim, to minimise the risk to human health from Tick Borne
Diseases,Asulamshouldremainavailableunderanemergencyauthorisationprocedure
toallowinitiationofnewbrackencontrolschemesandmaintenanceofthosewhichare
alreadyinprogress.
In the short to medium term at least, the maintenance of Asulam, as a large-scale
bracken control agent, is vital in the context of human health, both for occupational
groupsandtoprotectvisitorstoopengroundinthecountrysideandlargerurbanparks.
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