Conifer die‐back seems to be running rampant again!...Conifer die‐back (cont’d) I believe...

PETER COPPIN Email: pcoppin@tpg.com.au Horticultural Consultant Web: www.petercoppin.com

Coniferdie‐backseemstoberunningrampantagain!AlsoknownasCypresscanker,itiscausedbyaSeiridiumfungus(usuallyS.cardinale),andisoftenaswiftanddeadlydiseasetoarangeofConifers,JunipersandPencilpines.

Thediseaseaffectsthevesselsthatcarryliquidsfromtherootsuptothecanopy,causingasevererestrictionorcessationofsap‐flow.Soaffectedbranchesliterallydieofboththirstandstarvation,andthiscanoccurveryrapidly(adollarforeverytimeI'veheard"itseemedtodieovernight").

InEuropeandpartsoftheU.S.,it'sbelievedthatmostinfectionisspreadbywater‐splash,especiallyduringspringsnowmelts.Whilewater‐splashcanberesponsiblehere,mostinfectionsseemtobecausedbyborers,thoughduringthenineties(andprobablysince)someretailnurserystockwasobservedasbeinginfected.Aswithmanydiseases,stressedtreesaremorelikelytosuccumb(andarealsomoreattractivetopestssuchasborers).Itreallysaddensmethatmanypeoplearetoldthereisnothingyoucandoaboutit,whenexactlytheoppositeistrue.Treatmentwithphosphoricacidischeap,safeandusuallyveryeffectiveiflessthenone‐thirdofthecanopyhasbeenaffected.

Somedotpoints:

• Usuallymostdeathordamageisseeninsummer(whenthereismaximumheatandmoisturestress),butthisseasonI'vewitnessedalotofdamageinlatespringandearlysummer(2011/12).

• Followingonfromthelastpoint,pleaseknow

thatalargernumberofsmallerdeadpatchesinacanopymayactuallybecausedbymites,somakesurethediagnosisisdoneproperlybeforecommencinganytypeoftreatment.

• Onlyinfectedtreesneedtobetreated,and

possiblytheirimmediateneighboursiftreesareplantedingroupsorrows,thoughitissensibletocover‐sprayothertrees(especiallyyoungtrees)onceinthespringwitheitherphosphoricacidorasuitablecoppercompound.

• Youmayreadorbetoldthereisnochemical

treatmentregisteredforthespecifictreatmentofSeiridium.Whiletrueinapedanticway,phosphoricacidandmanycoppercompoundshaveagenericregistrationforuseonornaments,andaren'tconifersornamentals?

• Youmayreadorbetoldthatcontinualdrilling

holesforinjectionweakenstreesandtheycansnapandfalldown.Whatrubbish.Theremayhavebeenaveryslightchancebackwiththedinosaurswhenweusedtodrillanumberof12‐16mmwideholesanduseafunneltopoorininsecticidestotreatborers.Wenowusespecialinjectorsthatonlyneedafew4mmholes.

• Youmayreadorbetoldthatyouhavetotreat

thetreesonceortwiceperyearforever.Totallywrong.Afewtreatmentsoveracoupleofyearsseemstoovercomethediseaseaslongasthetreesarenotbadlystressedfromothercauses.Thenit'samatterofkeepingacloseeyeonthesituationanddofurthertreatmentswhennecessary.

This once would have been a glorious hedge lining the driveway into a semi-rural property in the Swan Valley. Simple, safe and relatively cheap treatments could have saved these trees.

Coniferdie‐back(cont’d)

Ibelieveconifersareanintegralpartofmanyurbanlandscapes,addingadeepergreen,moreformalandattractiveformofevergreentrees.Youcouldsaytheyareoneoftheveryfewnorthernhemispheregroupoftreesgivingusthat'littletasteofEurope'thatmanypeopleseemtowantinmostsouthernstatesofAustralia,nottheleastonthegutlesssandysoilsofPerthandthesouthwestcoastalplain.

Mostspeciestolerateexceptionallyharshclimaticconditionsfromscorchingdrywindsthroughtofrostsandevensnow,andonceestablishedneedlittleornosupplementarywaterings.

Soit’sagreatpitytoseethemdisappearfromourtreescapes.Therearevaryingestimates,butinPerthalonepossibly60%ofsusceptiblespecieshavedied.

Sowhatcanwedoaboutit?Theanswerissomesimpletreatmentscanhaveatleasta90%successrateiflessthanone‐thirdofaparticularspecimen’scanopyhasdiedfromSeiridiuminfection.

Sodon’tlistentothemany‘experts’outtherethattellyouthatit’sawasteoftime–theyeitherhaven’ttreatedtreesproperly,orsomehaven’tevenbeenoutinthefieldandactuallydoneit,andsomesimplywouldn’thaveaclue.

I’vetreatedoradvisedontreatmentsonhundredsofspecimenswithasuccessrateofaround85%,includingthosespecimenswithmuchgreaterthan30%canopydeath.Here’sasummaryofoneofthebestsuccessstoriesI’vebeeninvolvedin:

Thisresidentialpropertyhadawalkwayononeboundaryandlessthanidealneighboursontheadjoiningboundary.TheyhadplantedConifersandJunipersonthesefencelinesthateventuallybecamebeautifulborders/barriers.

Unfortunately,Seiridiumtookholdandsomeofthetreesbegantodiebackandtheyweretoldtherewasnothingtheycoulddo.TheycontactedmesoIvisitedthemandinstigatedatreatmentprogram.

AsInormallysuggesttosavecostsfortheclients,Ishowthemhowtodothetreatmentsthemselves.Becausethesespecimenswere,quote“invaluable’,theclientsdidevenmorethanisnormal.Oneofthespecimenshada60%canopymortality,buttheypersevered(seenextphoto).

Thisspecimenwastreatedanumberoftimesinthefirst3‐4years.Onlyonepreventativeinjectionhasbeendonesince.Thisislivingproofthattreatmentcanbeverysuccessful.

Sohowmuchdoyouvalueyourtrees?Thinkabouthowmuchitwouldcosttoreplacethemwithtreesofthesamesize,orhowlongitwouldtaketogetalternativereplacementspeciestothesamesizeandform.Forthecostofavisitfrommeyoucouldsaveahugeamount.

Verysusceptiblespeciesinclude:(Mostofwhatwecall‘Conifers’areCupressusspporChamaecyparisspportheirhybrids,Cupressocyparisspp).Commonnamesinclude:• Montereycypress• SwanesGolden(andotherselections/cultivars)• CastlewellianGold• NaylorsBlue• Lawsoniaselections/cultivars

Othersusceptiblespeciesinclude:• Pencilpine(Thujaoccidentalis)• Westernredcedar(Thujaplicata)• Junipervirginiana• OtherCupressusspecies:C.arazonica,C.glabra,

C.lusitanica,andC.torlosa

Agreatfact‐sheetoninjectingtreescanbefoundathttp://www.dwg.org.au/files/Phosphite%20Injection%20using%20Chemjet%20Syringes1.pdf©PeterCoppin,23/01/2012Canbereprintedaslongastheauthorisacknowledged.

NOTE:IneedtoacknowledgeCharlesAldous‐Ball,anarboriculturalconsultantwhodidamazinggroundworkonSeiridiumduringtheninetiesandfreelyshareditwithme.

Look at it now!

Seven years after treatment started, this magnificent specimen is now in great condition. Even though it lost its apical growing tip (this often can be terminal), it has again become a healthy tree.