烟草病害英文资料.docx
- 文档编号:11070367
- 上传时间:2023-02-24
- 格式:DOCX
- 页数:27
- 大小:589.63KB
烟草病害英文资料.docx
《烟草病害英文资料.docx》由会员分享,可在线阅读,更多相关《烟草病害英文资料.docx(27页珍藏版)》请在冰豆网上搜索。
烟草病害英文资料
TobaccoDiseaseInformationNote
BlackShank
TT.A.Melton,PhilipMorrisProfessorandDepartmentExtensionLeader
H.D.Shew,ProfessorofPlantPathology
Introduction
BlackshankisamongthemostdestructiveandwidespreadofalltobaccodiseasesinNorthCarolina.BlackshankfirstappearedintheUnitedStatesin1915andwasfirstreportedinNorthCarolinainForsythCountyin1931.Later,itwasfoundinPittCountyin1938.Currently,blackshank,causingstate-widelossesofapproximately1to2.5%eachyear,canbefoundineveryNorthCarolinacountythatgrowsflue-curedtobacco.Thisdiseaseismostprevalentinpoorly-drainedareaswheretobaccowasplantedthepreviousyear.Blackshankisawarm-weatherdisease,whichisfavoredbytemperaturesrangingfromabout84to90F.Oncesoilinafieldbecomesinfestedwiththeblackshankfungus,itcannotbeeliminated,therefore,thediseasemustbemanagedeveryyearonacontinuingbasis.
Symptoms
Thediseaseischaracterizedbyarapidyellowingandwiltingfollowedbydeathoftheentireplant.Adarkbrowntoblack,somewhatsunken,lesionusuallyappearsonthestalkatornearthegroundlevel.Thislesionoftenextendsupthestalkorshankoftheplantcausingittoturnblack.Stalks,whensplit,usuallyrevealtheblackenedpithseparatedintodiscretedisks.Thisfeatureisofdiagnosticvalueonlywhenusedinconjunctionwithotherobservationsbecausediskingmayoccurduetootherfactors.Infectedplantsmaybescatteredoruniformlydistributedinagivenfield.Rootsandcrownsareusuallydecayed.Onlyrootandcrownsymptomsmaybeobservedinverydryyearsoronresistantvarieties.
CausalAgent
BlackshankiscausedbythefungusPhytophthoraparasiticavar.nicotianawhichlivesinthesoil.Thispathogenbelongstoagroupoffungithatoccurscommonlyinareasofhighsoilmoisture.Thefungusproducesmicroscopicsporeswhichswiminwatersurroundingrootsand/orsoilparticles.Theseswimmingsporesareattractedtotobacco,theironlynaturalhost,byrootexudatesproducedprimarilyatgrowingpointsandwounds.Whereaswoundsarenotrequiredforpenetration,theydofavormorerapiddiseasebuild-up.
Whenthesoilenvironmentisnotsuitableforprotectionandsurvivalofthemotilespores,thefungusformsthick-walled,resistantsporessomeofwhichmaysurviveforyearsduringconditionsunfavorableforthefungus.Onceconditionsarefavorable,theresistantsporesgerminateandmotilesporesareproduced.Duringfavorableconditionsforthefungus,anewgenerationofmotilesporesisproducedevery72hours.
Theblackshankfungusisspreadwheninfestedsoilismovedfromoneplacetoanother.Contaminatedirrigationorrunoffwatermayalsoaidinitsmovementwithinafieldorfromonefieldtoanother.
Althoughrootsarethemostcommonlyaffectedplantparts,occasionallythefungusinfectsleavesandformscircular,yellowish-to-brownlesionsupto3inchesindiameter.Leafinfectionmayoccurasaresultofzoosporesinsplashingwaterorcontactwithinfestedsoil.
Control
CropRotation-Rotationshouldbethefoundationofanyblackshankmanagementprogrambecausethefungusattacksonlytobacco.Leavingthefieldoutoftobaccoforoneormoreyearswillreduce,butnoteliminate,thisfungus.Anycropcanbegrownbetweentobaccocropstoreducethepopulationlevelofthepathogen.
ResistantVarieties-Varietiespossessingvariouslevelsofresistancetoblackshankareavailable;however,theyshouldbeusedaspartofanintegratedapproachincludingcroprotationandotherappropriateculturalpractices.ThelatestissueoftheFlue-CuredTobaccoInformationbulletinlistsvarietiesandtheirresistancelevels.Thisbulletinisavailableinallcountyextensioncenters.
ChemicalControl-Severalsoil-appliedchemicalsarelabeledforblackshankcontrol.Includedarethemulti-purposefumigantsTeloneC-17,Chlor-O-Pic100,andTerr-O-Gas67.However,thesystemicfungicidesRidomilGoldorUltraflourisharethemosteffectivematerialsagainstblackshank.AdditionalinformationonchemicalcontrolcanbeobtainedfromthemostrecentFlue-CuredTobaccoInformationbulletin.
Drainage-Improvingdrainageinpoorlydrainedareasreducesblackshanklossesbymakingthesoilenvironmentlessfavorableforinfection.
Sanitation-Eliminationofthehostbydestroyingstalksandrootsimmediatelyfollowingharvestwillhelpreducepopulationsofthefungusandnematodes,resultinginlessdamageinthenextcrop.
NematodeControl-Controlofroot-knotnematodeshelpstoensuretheeffectivenessofresistantvarietiesandfungicides.Infieldsinfestedwithboththeblackshankfungusandroot-knotnematodes,theeffectivenessofblackshankresistantvarietiesandfungicidesisreducedifthenematodesarenotcontrolled.
BrownSpot
T.A.Melton,PhilipMorrisProfessorandDepartmentExtensionLeader
H.D.Shew,ProfessorofPlantPathology
Introduction
Brownspot,oneofthemostdestructiveleafspotdiseasesontobacco,wasonlyaminorprobleminNorthCarolinauntilthemid-1950's.Fromthattimeuntilthemid-1970's,diseaselossesaveragedabout0.5%peryearinNorthCarolina.Lossesincreasedduringthe1980'sbuthavedecreasedbackto0.5%orless.Becausebrownspotpopulationsbuilduphigherandhigherthroughoutthegrowingseason,andbecauseagingtissueismoresusceptibletothebrownspotfungus,plantsthatremaininthefieldlongerthannormalaremostdamagedbythebrownspotdisease.Otherimportantconditionsthatleadtobrownspotarecontinuoustobaccoculture,frequentrains,andverysensitivevarieties.
Symptoms
Theleafspotscausedbythisfungusappearascircularspots,rangingfrom1/4inchto11/4inchesindiameter,andarefoundprimarilyonthelowerleavesoftheplant.Initially,thesetarget-likespotshaveayelloworyellowish-greenhaloaroundthem.Thefunguscausestheleaftissueintheareaofthespottoageprematurely,whichresultsinayellowhaloaroundthelesion.Eachofthedarkringsinthetargetaremadeofthousandsoftinyspores(seed-likestructures)thatmaybesplashedorblownupintotheupperleaveswhereadditionalspotswilloccur.Asspotsenlargeandcoalesce,deadtissueoftentearsandfallsoutoftheleafmakingtheentireleafraggedandworthless.Lateintheseason,onverysensitivevarieties,spotsmayoccuronsuckers,petiolesandevenonthestalk.Whenstalksandsuckersareinfected,girdlingoftheplantcanoccurandtheplantdies.Thepathogencanalsoactsystemicallyandaffecttheoverallplantmetabolismresultinginprematuredeath.Brownspotmaycontinuetodevelopinthecuringbarnatlowtemperatures.
CausalOrganism
Brownspotiscausedbyanair-bornefungus,Alternariaalternata.Thisfungusoverwintersprimarilyintobaccostalks.Whenspring-timebringswarmweather,sporeproductionbeginsonoldstalksthatarestillexposedontopofthesoil.Thesesporesarethenblownand/orsplashedupontothelowerleavesofthenewplantswheretheygerminateandpenetratetheleavesdirectly.Spotsproducedonthelowerleavesformnewgenerationsofsporesthataresplashedandblownontootherleaves.Eachofthesporesrequiresmoisturetogerminateonatobaccoleaf.Therefore,theleavesmustbewet.Ifdryconditionsexist,sporescannotgerminateandnewspotscannotdevelop.Alternariaalternataisacommonfungusassociatedwithatleast56differentspeciesofplants.However,undernaturalconditionsitrarely,ifever,causesdiseaseinplantsotherthantobacco.Ithasbeenfoundtobeawoundpathogenofcloselyrelatedplantssuchaspeppersandtomatoes.Inotherwords,itcanonlyattackthoseplantsaftertheplantshavebeenwoundedandoneofthesporesofthefunguslandsinthewound.
Management
Brownspotmanagementshouldfitintotheoveralldiseasemanagementprogram.Thegoalistodelaydiseasebuild-up.Rotationwithanothercropwillallowtimeforthetobaccodebristodecaytherefore,leavinglittleornofoodforthebrownspotfungus.Stalkandrootdestructionhelpspreventearlyinfectionbyreducingavailabilityofinoculum.Earlyinfectionmeansfasterbuild-upandgreaterdiseaseseveritybytheendoftheseason.Highnematodelevelsalsoleadtoincreasedbrownspotdamage.Therefore,nematodesshouldbecontrolled.Properlevelsofpotassiumalsoshouldbeavailabletotheplanttoinsurevigorousgrowth.Infectedleavesshouldbeprimedassoonaspossibletoreducethenumberofsporesavailableforpathogenspread.Properplantspacingwilldecreasehumiditiesaroundtheplant,thusdecreasingtheincidenceofbrownspot.Efficientsuckercontrolalsoaidsinreducinglosses.Excessivefertilization,especiallywithnitrogen,mayleadtogreaterlossestobrownspotandshouldbeavoided.Inareaswithahistoryofseverebrownspot,brownspotsensitivevarietiesshouldbeavoided.
ControlofTobaccoMosaicVirusonFlue-CuredTobacco
T.A.Melton,PhilipMorrisProfessorandDepartmentExtensionLeader
Tobaccomosaicvirus(TMV)resultsinlossesinNorthCarolinaofabout1to2percentofthecropbyreducingtheyieldandqualityofflue-curedtobacco.Theidealwaytocontrolmosaicisbytheuseofresistantvarieties,andseveralnewhybrids,whichhaveacceptableyieldandquality,arenowavailable.Strictsanitationproceduresarenecessarytopreventthevirusfrombecomingestablishedinthecropandtopreventspreadofthevirusifeffortstokeepitoutofthecropareunsuccessful.Croprotationhelpstokeeplossesminimalinfieldswheremosaichasoccurred.
Mosaicissocommonthatmosttobaccogr
- 配套讲稿:
如PPT文件的首页显示word图标,表示该PPT已包含配套word讲稿。双击word图标可打开word文档。
- 特殊限制:
部分文档作品中含有的国旗、国徽等图片,仅作为作品整体效果示例展示,禁止商用。设计者仅对作品中独创性部分享有著作权。
- 关 键 词:
- 烟草 病害 英文 资料
![提示](https://static.bdocx.com/images/bang_tan.gif)