PRINCIPLES PLANT PATH
PRINCIPLES PLANT PATH PLP 3343
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This 0 page Class Notes was uploaded by Ms. Mina Leuschke on Sunday November 1, 2015. The Class Notes belongs to PLP 3343 at Oklahoma State University taught by Stephen Marek in Fall. Since its upload, it has received 37 views. For similar materials see /class/232867/plp-3343-oklahoma-state-university in Pathology at Oklahoma State University.
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Date Created: 11/01/15
Lecture 6 Disease Management ENVIRONMENT THE DISEASE TRIANGLE Physical Environment Survival and dissemination of pathogen Host response n39 J Biological Environment positive or negative organisms PLANT DISEASE qu gffggt In39 weakmac is Emma Disease Control vs Management Control Management Goal zero disease Goal reduced disease Qualitative Quantitative assessment assessment Disease present Amount present yes or no Eliminate prevent or exclude disease Reality impractical or impossible Disease progress over time Maintain disease below acceptable thresholds More practical Disease management strategy A total management plan integrating one or more principles of disease mgt 7 disease mgr practices within economic and environmental limits Most effective strategies address multiple parameters of Disease Triangle and Disease P ramid Host pathogen environment time But again costsandbenefits must be assessed Crop Income vs Control Costs Control Coets Money Max yield amp min costs Income Amountof Disease Constraints on crop production Levels f Absolute Genetic Potential Attainable Environment Affordable Economics Actual Pes si Diseases Other hazards 9quot Traditional Principles of Plant Disease Management Exclusion prevent or avoid the introduction of Inoculum Eradication eliminate destroy or inactivate the Inoculum Host Resistance utilize cultivars that are resistant to or tolerant of infection Modification of Cultural Practices alter environment to be less favorable to disease ProtectionTherapy prevent infection or cure plants that are already Infected by means of a chemical or some other barrier to infection lnoculu t present 2 Eradication Inocul ossible Inocul ommon 3 Host Resistance Pathog ndemic 4 Modified Cultural Practices High dis pressure 5 ProtectionTherapy 1 Exclusion evading inoculum A Avoidance plant when or where a pathogen inoculum is ineffective or absent eg planting date desert seed production B Quarantine prevent introduction of a pathogen inoculum to an area US Plant Quarantine Act 1912 Inspection and interception export g import Clean starting materials Certified diseasefree seed or cuttings Clean soilmixes greenhouse Clean water well water vs surface water Tools and machinery cleaned of infested soil or other inocula Plant Quarantines Agencies I Agriculture39s Beagle Brig d l gm 4 y 7 1 at 1 51 NW in I h CEHtIIE ftme um mm gnmrremm liar fur it 115 A I M we 7710th Eur m 1 1 Hill all room M115quot 3amp4 l he rmmn mun ml 3 1r r 2 1 a l 2 Eradication Reducing Inoculum Especially effective for moncyclic diseases dependent on primary inoculum A Roguing removal and disposal of whole infected plants eg DED trees B Crop Sanitation removal and disposal of infected plant parts and debris Pruning out diseased branches Deeptillageplowingunder of crop debris Sclerotial pathogens Remove resting structures residing in debris Peach mummies pine cones apple leaves and fruit 2 Eradication Reducing Inoculum Ti 2 Eradication continued C Treating propagative materials Hot water treatments of seeds bulbs cutting or rootstocks D Decontamination of soil and water Soil fumigation solarization pasteurization kills soilborne fungi and nematodes Water treatments UV ozone chlorination C rs DF 0 W 212 Heattcvlerant weed seeds 200 and viruses 90 s 180 Most weed seeds bacteria most 80 plantpathogenic viruses most insects 7o 160 Most plantpathogenic bacteria and fungi worms slugs ceniipedes 60 W 140 50 V 120 Oomycetes nematodes some fungi 2 Eradication Reducing Inoculum of seedborne diseases Hot water treatment of seed 39 Extension Fact Sheet 2 Eradication Reducing Inoculum Soil solarization 3 Host Resistance Resistant varietiesscions and rootstocks Traditional Breeding Centers of origin centers of diversity of crop species source of resistance genes Genetically modified organisms GMOs Only virusresistance currently marketed Cultivar mixtures disrupt monoculture Induced or Systemically Acquired Resistance SAR Crossprotection with avirulent or hypovirulent pathogens Plant activators reducedrisk pesticides Actigard chemical Messenger protein Production of protective compounds amp proteins Phytoalexins Types of Plant Resistance Vertical Resistance Vertical Resistance 100 Monogenic single R g 3 7 gene 40 i a 7 Hypersensitive response 50 22 7 7 gene U 0 1 2 3 1213 23123 Pathogen Race racespecific Horizontal Resistance Polygenic many genes Reduced disease field resistance Horizontal Resistance Resistance n u 039 quot J racenonspeclflc n 1 2 3121323133 Pathogen R aoe Host Resistance deploying multilines tttytt 5 R rr HEALTHY DISEASE A lElicitor present lElicitor present Receptor present Receptor absent resistance incompatible susceptible compatible DISEASE DISEASE a Elicitor lost Elicitor lost Receptor present Receptor absent susceptible compatible susceptible compatible Example Tomato Resistance Genes V Verticillium Wilt NET WT WAL MART F Fusarium Wilt 100mg BME 97 FF Fusarium Wilt Races 1 and 2 N Nematodes T Tobacco Mosaic Virus L Septoria Leaf Spot Asc Alternaria ST Stemphylium BSK Bacterial speck Pto BSP Bacterial spot Rxc Most are Stable But can breakdown when new races of pathogens evolve Resistance GeneMediated Disease Resistance Recognition TMV induced Hypersensitive Eggnne Response HR tobacco HR in barle to owder mildew Systemic Acquured A pm y Resistance SAR iquot Systemic Acquired Resistance SAR Nonspecific induced resistance Induced by 1 Pathogenic challenge 2 Chemical signals Salicylic acid 39 ACTIGQQQE Costs to plant 1 Reduced yield in absence of disease 2 Suppressed insectwound response 4 Cultural Practices to Manage Plant Diseases A Removal of alternate or alternative weedy hosts and volunteers Rusts facultatives virus 8 vector reservoirs B Crop Rotation reduce soilborne inoculum Fallow or suppressive nonhost C Reduce favorability of environment to disease humidity increase plant spacing amp air movement evens fans careful watering hand water drip irrigate avoid overhead improve soil drainage Increase light Reflective mulches gt reduced virus vectors D Maintain optimal crop nutrition Judicious fertilization avoid excessive N a succulence a powdery mildews amp rusts E Refri erated stora e and transport plants nursery stock and foods rults amp vegetables 4 Cultural Practices Weedy g reservoirs Cornsoybean rotation 5 ProtectionTherapy Preventing Infection or Curing Plant Disease A Protective chemical materials Applied before infection occurs Contact fun icides bactericides and nematICIdes 970 Sulfur PCNB captan chlorothalonil maneb Agrimycin streptomycin copper Methyl isothiocyanates dichloropropene B Therapeutic chemical materials Applied after infection has occurred curative absorbed into plant locally or systemically kills internal pathogens fungicides and bacterICIdes MoA s Fungal cytoskeleton sterol biosynthesis mitochondrial resplratlon eg benzidazoles triazoles strobilurins carboximides 5 ProtectionTherapy Preventing Infection or Curing Plant Disease C Biological control Application of antagonistic or parasitic organisms against pathogen Composts D Physical barriers applied to plants waxesfilms applied to fruits lmpregnated with chemical agents 1O r i 5 ProtectionTherapy 7 Disease Management Articles more on class webpage Biocontrol httpwwwapsnetorgonlinefeaturebiocontroItophtml Fungicides jpjapsnetorqeducationIntroPIantPathTopicsfunqicidesdefaulthtm Fungicide Resistance Mgt Seed Treatments ttpapsnetorqeducationAdvancedPlantPathTopicsSeedTreatment tophtm Cultivar Mixtures for disease management jpapsnetorqeducationAdvancedPlantPathTopicscuItivarmixtures tophtm Disease Management and Epidemiology ttpapsnetorqeducationAdvancedPlantPathTopicsEpidemioloqyM anagementStrategieshtm ENVIRONMENT Cultural amp Management Practices 1 Water proper amount amp application etc 2 Soil fertility pH drainage etc 3 Temp amp Light greenhouse canopy density mulch etc PATHOGEN HOST 1 Quarantine Exclusion 1 ProtectionTherapy 2 Eradication 2 Genetic resistance 3 Inoculum reduction 3 Nutrition 4 Vector control 4 Planting Date 11 Insect Vectors of Plant Disease Pathogens 11242008 Pathogen Gr39oups Insect Transmission Moves pathogen from source to healthy plant Specific relationship not a syringe on wings 11242008 Vector Taxa Ephemeroptera Odonata Orthoptera Embioptera Dictyoptera Hymenoptera Diptera Why are these such Coleoptera Homoptera r Hemiptera good vectors Thysanoptera H ete r0 pte ra Lepidoptera Collembola Anoplura Neuroptera Siphonaptera Trichoptera Mecoptera Strepsiptera Anoplura Mallophaga Isoptera Tr39ue bugs Heter39opter39a Very large insects Few vector39 species described Some stink bugs are known to transmit tr39ypanosomatids The squash bug tr39ansmits cucur39bit yellow vine agent a bacterium 11242008 Leafhoppers Family Cicadelliae Bulle r or wedgeshaped insecTs Triangular head Rows of spines on me ra rhoracic legs Three feeding sTra regies phloem x lem or lacera re and f ush feeders Aphids Family Aphididae Sof rbodied insecTs Cornicles and long anfennae Phloem feeders Par rhenogenic Most important group fransmiffing plant viruses Psyllids Family Psyllidae Also called barklice Superficially resemble leafhoppers Phloem feeders Nonvirus vecfors Be r rer known as phy roplasma vecfors New disease in The US Crime Greening HiHliiii villuliii ullm lAilllgt i 11242008 Wh i reflies Family A leyrodidae 39 Minufe while insects Immal ur es sessile 39 Phloem mesophyll feeders 39 Very impor fanf as vecfors of geminiviruses Hemip rer39a True bugs Leafhoppers Plan i39hopper s Aphids Whi reflies Who do They all have in common A Ii r rle insec r anaTomy Usefu ferms RosTr um Labium STyleTs Salivary canal Food canal 1 1242008 Piercing sucking mouThpar39Ts S ryle rs s rr39awl ike s ruc rur39es no r unlike a Two way hyper der m c needle Four s ryle rs Two mandibular ou rside Two maxillary inside Maxillary s ryle rs n rer lock To form rwo canals food canal sal ivar y canal Many pathogens are retained INSIDE The body meaning Tha r They must c r39cula re Through The body before inocula l ion To The next plan l39 Open cir cula ror y sys rem Hemocoel Hemolymph n a o a n m 1 m Memo 0 too 00 o l l H l Transmission Acquisition uptake of pathogen and interaction with vector tissues Latent period amount of time required before pathogen can be inoculated to a new plant Inoculationdeposition of pathogen into plant host 11242008 Modes of Transmission retention site and time Nonpersistent stylet tips Semipersistent stylets foregut Circulative moves through the body retained in lymph Propagative moves through body retained in hemolymph and other tissues multiplies in d Transovarial Transmission passed on to offspring s Noncirculative stylets foregut multiplies bacterial Three behaviors required for pathogen transmission Location of specific plant tissues Sucking taking up plant cell contents Salivation spitting up viruses or bacteria that have migrated to the salivary glands Hemipterans display a high degree of behavioral plasticity Epidermis Carrots Mesophyll Lettuce Xylem Rice Phloem Enchilada 11242008 Electrical Penetration Graph a novel way to study pathogen transmission processes mun Iu mpvu pm ll com lolll I circuu open p qua STRI F CHAEI E iiili REccn as ELECTRONIC MDNlTOR Nonpersistant virus transmission A model of aphid probing Fl u m m mu W inlercellularsheathsalivaliun inlracellularpdsalwatmn mlraceilularE1salivauon Wlt llhwm mim 11242008 ForeguTborne nonpersisTenT and SemipersisTenT Transmission NonpersisTenT SemipersisTenT ReTained gt 24 hr ReTained up To 48 hr ReTenTion siTe sTyleT ReTenTion siTe Tips ThroughouT foreguT InsecT salivaTes and InsecT exTravasaTes dislodges virions aTTached To The food canal opening vomiTs and pushes virions ouT of The food canal Tobacco eTch virus poTyvirus ForeguTborne TransmiTTed by aphids Acquired from infecTed epidermis Tissue Virus aTTaches To inside of The food canal Modes of Transmission CirculaTive usually acquired in minuTes laTenT period several hrs To days inoculaTion in minuTes reTenTion Time days To weeks To life of vecTor siTe of reTenTion hemocoel reTained afTer39 molT aphid leafhopper whiTefly vecTors Barley Yellow Dwarf Lu reovirus 11242008 Barley Yellow Dwarf Virus V rions ngesTed from infecTed phloem hindguT info The hemocoel MigraTe To salivary glands EnTer accessory salivary gland leueg pond EjecTed wiTh saliva info 7 ll lquot l l l l i 39 phloem i Ni L hioeiio 70 so 0 0 o a V rions pass Through guT and are TranslocaTed across The Modes of Transmission Propaga rive acquisi rion in minu res la ren r period several days To weeks inocula rion in minu res re ren rion rime weeks To life of vec ror si re of re ren rion hemocoel in rernal organs re rained af rer mol r mul riplies in vec ror some viruses are Transovarially Transmi r red ver rical aphid leafhopper plan rhopper rhrips vec rors Corn s run r spir39oplasma 11242008 Spir oplasma movemen39r in The body of leafhopper39 vecfor39 D maid39539 Salivary Midgul gland D maids and CSS dis rr39 bu rion before and after The domes rica rion of maize 1O 11242008 Non circulative Single example Bacterium X yela fas d osa Xylemlimited Transmitted by xylemfeeding insects Retention site foregu r Lost af rer39 mol ring Retained for39 life if acquired by adults Pier39ce39s Disease of Grapes Noncirculative FIerce s Disease at Grape in United States X ylella fastidiosa Xylemlimited bacterium Sharpshooter vectors Glassywinged sharpshooter invasive species Polyphagous Rselected species Can feed on woody tissue Pierce s now a major threat to the wine industry Bacterial leaf scorch Citrus variegated chlorosis 11 Quick Review What insects are important plant pathogen vectors What is a foregutborne virus Probing activity can be studied by 7 at is a circulative virus What are the three stages of transmission Whydoes it take so long for a propagative pathogen to be transmitted after acquisition 11242008 PLP 3343 Principles of Plant Pathology LAB PERIOD 3 Field Trip to the Plant Pathology Farm Wednesday September 3 2008 Objectives 1 Check your isolation plates from last time 2 Observe multiple diseases in the eld think about and be able to answer the following questions for each disease a What are the pathogens causing diseases F B N V b What are the speci c disease symptoms 0 How are the pathogens disseminated d How speci c pathogens survive season to season e How the disease is managed 3 If you miss any information please consult your course textbook Agrios or APS Compendia Collect at least 3 different specimens in your ziplock bags a Label the bag clearly with your name and lab section number and specimen b These will be moistincubated to induce sporulation of fungal pathogens 0 On Wednesday September 10 you will examine your moistincubated specimens microscopically for any diagnostic features and draw pictures ofwhat you see A Stop 1 North side of Plant Pathology Farm Pepper Plot Bacterial spot caused by Xanthomonas campestn39s pv vesicaton39a and Southern Blight caused by Sclerotium rolfsii What are the symptoms Signs What weather conditions favor these diseases What part of the plant is affected What kind of pathogen causes each disease Bacterial spot Southern blight How are these diseases managed Bacterial spot Southern blight Dutch Elm Disease caused by Ophiostoma ulmi syn Ceratocystis ulmi What are the symptoms What parts ofthe plant is affected What are the earliest symptoms and how does this progress to the eventual death of the tree What kind of pathogen causes this disease How is this pathogen disseminated What is its vector How is this disease managed Slime Flux or Wet Wood of Mulberry and Elm What is slime ux What factors favor this problem What kind of organisms cause slime ux How is this problem managed CedarApple Rust caused by Gymnosporangiumjunipe virginianae What are the symptoms What host plants are required for completion ofthis rust s life cycle What kind of pathogen causes this disease How is this pathogen disseminated to each ofthe hosts How does this pathogen survive season to season How is this disease managed on each host Stop 2 Fungicide trial on turf plots at OBGA Dollar spot caused by Sclerotinia homoeocarpa What are the symptoms Signs s bentgrass a warmseason C4 or coolseason C3 grass What environmental and host conditions favor dollar spot Brown patch caused by Rhizoctonia solani s bentgrass a warmseason C4 or coolseason C3 grass s tall fescue a season C4 or coolseason C3 grass What environmental and host conditions favor brown patch Dothistroma needle blight caused of Mugo pine by Mycosphaerela pini What are the symptoms Signs Another name for the disease What kind of pathogen causes this disease How is this disease managed Stop 3 OBGA Crabapples and rose plantings Apple scab of crabapples caused by Ventun39a inaequalis What are the symptoms Signs What kind of pathogen causes this disease What is the primary inoculum for this disease How is this disease managed Black spot of rose caused by Diplocarpon rosae What are the symptoms Signs What kind of pathogen causes this disease Where does the pathogen ovenNinter How is this disease managed Stop 4 OBGA Garden Powdery mildew of zinnias and coreopsis caused by Goovinomyces cichoracearum What are the symptoms Signs What tissue is infected What kind of pathogen causes this disease How is this disease managed Fire blight on asian pears caused by Erwinia amylovora What are the symptoms Signs What kind of pathogen causes this disease How is the pathogen disseminated How is this disease managed Bitter rot of apple caused by GlomereIa cingulata What are the symptoms Signs What tissue is infected What kind of pathogen causes this disease How does this pathogen overwinter How is this disease managed Fly speck ofapple caused by Schizothyrium pomi What are the symptoms Signs What tissue is infected What kind of pathogen causes this disease How is this disease managed Stop 5 Plant Pathology Peanut Field at Sangre Rd and Hwy 51 Peanut Early and Late Leaf spots caused by Cercospora sp or Cercospon39dium sp What are the symptoms How can you tell them apart What kind of pathogen causes this disease What conditions favor disease development Pathogen dissemination How is this disease managed Peanut Southern blight caused by Sclerotium rolfsii and Sclerotinia blight white mold caused by Sclerotinia minor What are the initial and later symptoms What are the signs What kind of pathogen causes this disease How do you distinguish these two diseases and pathogens from one another Southern blight Sclerotinia blight What conditions favor disease development Pathogen dissemination How is this disease managed Nodules Rhizobium on peanuts Pathogen Function Leaf mosaicvariegationinjury Is this a disease What trait should it possess if it s really a disease What is it Morning glory white rust caused by Coleospon39um ipomoeae What are the disease symptoms Signs ofthe pathogen What kind of pathogen causes this disease What is the alternate host How does this pathogen ovenNinter PLP Farm Pecan scab Cedahapp e Rust Dutch Elm Disease SHmeHuxorwet wood afmu berry A fa fa eafspots Cucurbits powderydeew Peppersibacter39m eafspot outhem nght Leafspots Waterme ons AsparagusCercosporabH ht HerbicidedamagedJacabarke ms Hart Farm Brown Patch Cedarrhawthommst P39mes rDiplodiaSphaeropswsmpbhght rDothistromaneedJeng t Crabapmeapme groverappxescab B ackspotof ruse Zmniasand Coreops srpowdew deew erenghtofAswan pear Bitterrot anthracnose ofapme FWSpECk orapme mack rot Ofgrape Peanut eld spat erotxma ngthhxtemu d gh Leafmosaicvariegatmnimury thte rust ofmommgg ory Plant Disease Diagnostics Working with a Diagnostic Lab Sample Collection Packing amp Shipping Soil Sampling The Diagnostic Process Overview of Diagnostic Process Tools in the Lab Digital Diagnostics Sample Submission Collecting Plant Samples Collect several plant specimens showing various stages of disease development Select plants that are still alive Collect the entire plant whenever possible Plants should be dug not pulled to keep the roots intact Sample Submission Plant sample packaging First wrap roots of plant in plastic bag so that they do not dry out If the plant is already potted then it can be left in the pot for shipping Sample Submission Plant sample packaging Second wrap entire sample in plant bags Sample Submission Collecting Appropriate Sample Unhealthy er 1 f a Healthy Dead Sample Submission Collecting Appropriate Sample A O v Sample Submission Collecting Appropriate Sample i e root rot cannot be diagnosed by leaf sample Sample Submission Collecting Soil Samples for Nematode Analysis Take several soil samples in an area showing possible nematode damage Collect the soil at a depth where the root concentration is the greatest 112 inches Mix the samples from the area Remove a single 1 pint sample for nematode analysis The Diagnostic Process Receive sample The Diagnostic Process Record problem history it c l l 3 The Diagnostic Process Observe symptoms Blight Root rot Leaf spot Scorch Wilt etc history The Diagnostic Process Consult references Publications Perso nal knowledge Web references history The Diagnostic Process A working list of amp possible l causes 4 gt Formulate hypothesis of diagnosis 39 necord history The Diagnostic Process Test specimen for suspect disease v 139 g Formuiate hypothesis Record Observe 7 Consuit refs A history The Diagnostic Process Lieutenant Clouseau Footprints Car Tag DNA Fingerprints w Witnesses Credit Card records The Diagnostic Process Lieutenant Clouseau Plant detective Culture Molecular Footprints Car Tag tOOS DNA Fingerprints Light MOiSt J microscopy Incubation Witnesses Credit Card records The Diagnostic Process Culturing the pathogenic agent Bacteria The Diagnostic Process Culturing the pathogenic agent 0 iFungi EEV II o The Diagnostic Process Culturing the pathogenic agent Bacteria gt PcR DNA ident cation The Diagnostic Process Light Microscopy Cultures Plant tissues Nematodes The Diagnostic Process Moist Incubation The Diagnostic Process Molecular Tools The Diagnostic Process cm gq39wmmmp lt gu iihuma Duierauve Extension SEWKE r mquot lllluu in m In M Inquot prism 5i raw intuitmm edui 39 iii Gra m cell v quotKEIQLLTJJ maul we envelope 0 Gram cell envelope Gram Stain 7 positive Crystal Kl Violet mordant EtOH safranmo I lt2 ll Clavibacter Gram and any other for Gram reaction httpbioloqvclcucedulfankhauserlLabsl MicrobioloqvGram StainGram stainhtm KOH Test Rapid Gram Stain On a glass slidc suspcnu colony of a Gram Clavibacter and Gram other in a drop of 3 KOH careful this is caustic with a toothpick Slow lift the toothpick from the suspension Mucus string Gram negative No string Gram positive 39 Conidia gt 39 39 x s i 39 5 Conidiophme i M I r Gvervn39intering mycelium Overwintering deismthecia Mynelioid appendages Young and mycelium debtothecium FIG URE 1 1 5 0 Disease cycle ol powdery mildew of roses caused by Spham39otiam panama Iquot Sp r0532 Resistance Infection Host Recognition Invasion Penetration Colonization GrowthReproduction Attachment n Disease Cycle of Pathogen or I s i I 7 i S m tom Inoculation Infection Cycl e Deyeloppment Dissemination Dissemination Of Secondary lnoculum Production of primary inoculum overwintering stage Dormant period The Disease Cycle lnoculum Any part of a pathogen capable of being disseminated and causing an infection Host recognition gt InvaSion Penetration Colonization A h G m w Inoculation arrival of quotquot Infection rifle 20 Infection We otppafhogen inoculum at host magmaticquot l Attachment adhesmn to Symptom Dissemination development of pathogen primary mammmm Productionpf Penetration actual ingress inoculum OVerseasumng stage into host tissues Active or Dormant period passive Infection establishment of pathogen within host plant Colonization Inter and intracellular growth The Disease Cycle Symptom development after incubation period internal and external 39 r quot disease expression H t recognsition gt Invasion Pathoqen reproduction Penetration Colonization 39 propagules asexual or A h G h d L lmct mam 39n e l39g rginvilcidjcriiogr sexual Infection y W i i Dissemination airborne Inocu39a im Dissemination Sympiom rain splash water insects oipathogen Jdevebpmem farm machinery etc secondary inoculum I Primary Production of inoculum overseasoning Seasonal Carr OVel39 stage overwinterin or Dormant period 9 FIGURE 22 oversummering in soil Stages in dcvcliipiiicni ii a disease cycle and tin ll39l fuctiuii cycle Bracken indicate substages oi infection structures Fungal Attachment Adhesive mucilage 1 Maqnaporthe grisea Blumeria graminis conidia conidia rice blast powdery mildew Bacterial Attachment Pili Pilus singular Polar attachment Fungal Penetration Super cial Spore my celium Spore Subcuticuiarmycelium Spore Gerr r tube gt A h Direct with appressorium A penerrarion peg PP and inrirateilular mysellum Ilelv Direct penenar on Directintercellular mytelium with he ustoria Gumtinn Directimercellular my39celium Penetration through natural openings Peneuarion through natural wounds Through natural cracks between Fungus kills and macerates Through wounds main and lateral roots cells ahead of its advante FIG U RE 2 5 Methods of penetration and invasion by fungi Active Penetration by Fungi Mechanical force and enzymatic digestion Plasmodiophora brassicae clubroot of crucifers Active Penetration Appressoria 912an Mm Penetration egs Passive penetration through stomata Leaf rust germ tubes grovving perpendicular to grass cells 2 searching for stomata a 3 Sp re cyStS Bacterial Penetration All Passive Mrrt riiinde Through stoma Through wound Through hydathadc Badl fid il39l HECIBF and thruth nectarthode FIGURE 2 Methods of penetration and invastun by Dil 39f 39iil Hickeyl 7 i Nematode penetration active and passive Direct penetration Direct penetration Penetration through stoma Ectoparasitic nematode Endoparasitic nematode Endoparasitic nematode FIGURE 210 Methods of penetration and invasion by nematodes Hm I e Vectors Inoculation amp Penetration Viruses fastidious prokaryotes some fungi amp nematodes Infection and Colonization I 1397 I biOfi CELL WALL 1 2 5 0 as 0 as a quot V A I 715 J W Fungal Haustorlum we O Virus spread through plasmodesmata l v Im site giant cells Infected Cell Healthy Cell Repllcase Protein Infection amp Colonization Vasculature Fungus in xylem a Virus particles in xylem Dissemination 4t e e 7 Rain splashed equipment Airborne fungal spores fungi amp bacteria Dissemination Wind 39 my Airborne x Vedors mgrttn i zcdrty 1 gt if f I l a m m intertwinintutrn I m nui llrrti Y Ailuia quotr tum mitt1 u was near rlGUIii 2739s in thequot em nt t5 nti martin Increasing Distances on plant through fields across regions over continents Root extension e andslurm blowan on the African desert has blanketed undreds of thousands of square miles of the eeen wllha densecluu a mass ve nature cl this first seen in this SeaWIFS These stnrrns arid the rising warm eet er an above the Alrlcan deserte and then a Caribbean w a services to Issue air pollution eierts as was reeerttiy in Rice Recent studies by the USGShllpiica r e sgsgnvt alricanidust e linked the decline at the coral reeis In the Caribbean is the Increasing ironueney and intensity or Saharan Dust events Additionally other studies suggest that Seneiinn Duet may play a role in determining the irequency a intensity cl hurrlcanes iarmed in the eastern Atisntic Ocean t IwahIrdwarldnrgwo hlmli Prevteett b the SeeWiFs Fm ecl Nits Gsrc and OREIMAGE Seedborne pathogens known to be dispersed on or in soybeans Alternaria spp Ascochyta soaecola Cephalosporlum gregatum Colletotrichum truncatum Cortlclurrr solanl Diaporthe phaseolorum Glomerella glycine 0U D E Macrophoma mame Hilum Macrophomlna phaseoli Melanopsichium mlssouriense esta Nematospora spp Phytcphthora megasperma Pleosphaerulina sojlcola Rhlzoctonia leguminicola Sclerotinla sclerotlorum INSIDE virus ringspot virus mosaic virus virus oryne ac errurn spp Pseudomonas glycine Pseudomonas tabaci Ralstonia solanacearum Xanthomonas phaseoli Fungi Bacteria Viruses Pathogen Survival Dormant propagules Spores sclerotia chlamydospores Inactive In buds bark seeds etc Quiescent vegetative forms In vectors In vectors As parasites In alternative hosts As epiphytes on living hosts As saprophytes 4 I In decomposing tissues Pathogen Survival Fnritrng bodies Bacteria e V A u Baneria Spores Mycelrum l 7ected 4 roots 1 nub On or in soil 0n perennial plants Spores or Mycelium or Scierotia mycelium acteria bacteria or bacteria 3 i i t t E aquot 7 V r a On or in seed On or in vegetative propagative organs On or in insects Survival periods in the field Months bacteria fungal spores Years chlamydospores oospores Decades sclerotia Fungal Resting Structures Chlamydospores Sclerotia iniection and colonization infection and colonization survival d secon ary IH eCtIO n inocuilum 39 court survwal disoer ai of 39 secon airy Pamquot inoculum IHOCUI UITI dispersal of primary inoculum dlspgrsam 0f Inoculum primary inoculum K39mwiuv lV39Hh JIULo Physiology of Plant Diseases PLP 5724 Hostpathogen interactions Genetics CH 4 Pathogen weapons CH5 Host defenses CH 6 Wlll mum v39lii lltnu i 1 ulmmh I 39II inl iLI IIIquot Inmh nl nm IhnIlu x i in in mmmn m M m r n H II uluu mumnv Inulu anqli ht 39IAIIH quot KH39yIH4L t g1139KIJ I dlVA LI Virus Disease Symptoms PLP 3343 PLP 3343 VIRUS DISEASES Some typical examples of different types of virus disease symptoms color photos posted on Class Website Be familiar with and be able to recognize the different types of symptoms illustrated refer to lecture notes for important information on the biology and management of these and other diseases caused by plant pathogenic viruses 7m giam mgz I 39 Eai mig hm scrape quot TMNMPVV 71 5 r91 v V r gt 4 v 39 39 39 W 139 y I A39 39 quot Typical mosaic symptom Bean mosaic virus Bean yellow mosaic virus Typical mosaic symptom 21 39 4Leaf cririkli gj nddfgtortion a a Zucchini yellows vir39 jp quot quot i squash t k 7 239 if t quot F n eaF39 m OSaicgf Pumpki ma aic vi p s 391 quot33 Leaf shoestringing sym ptom Cucumber mosaic virus In tomato Mosaic Wheat Soilborne wheat mosaic virus spotting TSWV on peanut quot P4 y af x 39 Leaf distortion distinct quot iquot 4 I IPquot 4 J v gt 3 r i 3 r t I I Large chlorotic areas in field where viruliferous mite vectors moved in from infected weeds and volunteer wheat around field V Color breaking in flower petals Petunia virus Diseased Healthy u r r Greening end blistering of f L fruit surface CMM in pumpkin i Greening and blistering of fruit Sig CMV in yeliow squash Tomato spotted wilt virus Fruit distortion and chlorotic spotting Pitting of fruit surface Pear stony pit virus 1 I Barley yellow dwarf leaf symptoms red and yellow discoloration Zr 1 A MIv4wvh WP u In 2 a h an Wyn L s i 4 v f x u H nu A m I I I u V J J 1 F at s m n l r i u i r 1 Pv Jar Nm m a i s Infection foci in field II39US Barley Yellow Dwarf V Net blotch 0a kleaf mosaic S m V H W 0 9 0 p S 0 t a T 39 Broad host range and symptoms Tulip breaking virus Ornamental Viruses Albutilon Mosaic Virus Normal flower Fasciation Flattening of the stem and distortion of meristems Can be caused by viruses phytoplasmas somatic mutations or physiological injuries Today in Lab Dia nosis of Viral Diseases Rubinoculate tobacco plants 1 Prepare sap from healthy and infected leaves 2 Rub each with celite on tobacco leaves Resistant cv Xanthi NN Susceptible cv Xanthi nn Use immunostrip to detect TMV Understand ELISA and PCR diagnosis of viruses Molecular Plant Virology study viral movement cheese lam 1 q Eaaker gt e Leaves ground in Strained Inlecled sap Inlened sap pkked up bufferwirh pestlE weaned sap on ngers gauze pad g ass mdbru5leu V rrusvinfeued Veung diseased Diseased leaves plan have zullened and bully or d water plam In marlar Coxyledons Sun or ugh I I Systemk Pumary V SYMPIONS V 0 133 E 4 21 7 Cmyledons pumary 1eaves nlecxed sap rubbed an heahhy Inaculaeed planls lnaculaled Luca lesions or regular leaves avedusled planu w n ersgauze pad mun in same cases pwams Rep In mm abrasive powdev 555 red brushe c be mused with gleenhnuse m if devslnp m 0 av waxerimmediately gromhchambu FIGURE 1415 Typical slaps in mechnmczlurszptransmission ofpantnruscs Vim taken in by Virai nucleic acid Virai nucleic acid repiiraies iii wounded ell ireedirom coal eii Some move to adiacent prot ein eiisihraughpiasmodesmara War in pirioemvira nurieic arid or Wei nucieir acid or virus Virai nucleic acid multipiiesin new air and virusisrarried withthephmo rearhesphieemvessel spreadsioadjaterrlceiis Someoitheeariy synrhaieihroughouiihepiant through piasmodesmata formed nucieir acid is coated with protein oi parenchyrnaceiir and iormsvirus FIGUREMH Mechanicai39 quot39 A latrigesinriie vremirriirriisiirinnnivjmgesimplants Abrasive powders used to inoculate plant viruses Carborundum silicon carbide SiC m diatomaceous earth Experimental Modes of Transmission 39 W imunis Hmmmmnn i wm m A noummuw h Virus Diagnosis Differential Hosts Indicator host plants Systemic hosts Local lesion hosts Typical panel Tobacco N tabacum Nicotiana benthiamiana Chenopodium quinoa C amaranticolor Gomphrena globosum Cucurbits Datura sp Pepper Tomato Virus Diagnosis Immunochemical Serological Antibodies and antiserum detect viral proteins Polyclonal vs Monoclonal m Ouchterlony immunodiffusion assay Advantage Simple Disadvantage Large amounts of antibodies required insensitive nonspecific cross reactions Enz meLinked lmmunoSorbant Assa ELISA Advantage Sensitive conserves antibodies quantitative viral titer Disadvantages nonspecific cross reactions possible expensive equipment lmmunostrips Advantages sensitive simple fast fieldtesting possible Disadvantages nonspecific cross reaction possible ngunm Reuczmz Apr mumuvmuluV V Qdd S Li duff A H V J K gig q v I p Lf kf Agdia Immunostrips Fast antibodybased method Virus Diagnosis PCR now most commonly used Polymerase Chain 5 Reaction PCR i i RNA viruses Reverse n Transcriptase Rnstep RT PCR ssRNA 5 cDNAT a9 PCR DNA viruses amplify directly Primers are extremely specific 39 Sometimes too specific Most sensitive detection technique Disadvantage PCR Thermocyclers are expensive 4000 news was 2 mug mum PCR cDNA template Eviral ssRNA Taq DNA polymerase DNAdependent Thermotolerant 32 35x cycles 2quot 235 34 billion 39Ei lmm molecules mu39 m ul m Ilnmlr PRIMERS l l mm mm mm ssDNA oligos Complementary E to specific sequence Must use pairs to amplify DNA Studying plant virus movement Difficult and tedious using destructive assays by PCR or ELISA Nondestructive live imaging of a visible reporter gene is ideal Engineering a plant virus to fluoresce Potato virus X PVX expressing green fluorescent protein GFP wild type PVX w The Nobel Prize in Chemistry 2008 quotfor the discavery39 and develapment of the green fluorescent protein GFPquot 1 1 I l Osamu Shmomura Ah Mann Che e 13 oft1e prZe 13 oft1e prZe USA Marme Bo1ogca1 WoodSHoe MA USA CoUmbaUnverSy Boston UnverSty Medca New York N USA c 00 Massachusetts MA USA b 1928 m Kyoto Japan b 1947 RogerY Ta en 13 oft1e prZe UnverSty of Cahfoma San De 0 CA USA Howard Hughes Medca m5 Ute b 1952 QNobelprizeorg What is fluorescence Visible Liht Spectrum Ultraviolet lnlrared gt 400 700 500 son Figure 1 anE39PHQUI Nanomerers Shorter higher energy wavelength of light excites a fluorophore which emits a longer lower energy wavelength of light excite blue a emit reen absorb blue a fluoresce reen Excitation and Emission Spectral Pro les n u smug smrL Am nun angina 2 2 7 Fluuvuceuc a Emlsulqn 3 Figure L r s eclral my son sou we no 400 Wavelength Nanumelersj Jablouski Energy Diagrams Hm mg and munquot les Lowesl Singlet Exclle Slile C s iarhlren s runs on E 39L39Si n r m39se r an rare 3 Enemy 3 p x n r Ground sure is Fluomsc rice ospnomcrnce Delayed Flam Fiunmscenre Studying plant virus movement with GFP OBSERVE 1 PVXGFPinoculated Nicotiana benthamiana universal suscept 2 uninoculated normal N benthamiana 3 transgenic G M0 N benthamiana engineer to express GFP Long wave ultraviolet UV light required to excite GFP GFP fluoresces GREEN wherever the virus PVX is replicating healthy green tissues fluoresce RED due to f chlorophyll excited by UV j Permits direct nakedeye observations of viral movement in planta chlorophyll b Cauliflower Mosaic Virus Helper protein P2GFP Binds to tip of aphid s stylet SiteSpecific Disease Advisories and Decision Support Systems Traditional Definitions CI39mat statistical summary of atmospheric environmental conditions temperature precipitation etc typical fora given locationquot Weather actual atmospheric conditions prevailing at a given site and timequot AMS Definitions Climate The slowly varying aspects of the atmosphere hydrosphere Iand surface system quot Trendsprediction Weather The state of the atmosphere mainly with respect to its effects upon life and human activities As distinguished from climate weather consists of the shortterm minutes to days variations in the atmosphere Popularly weather is thought of in terms of temgrature humidig precipitation cloudiness visibility and mquot Realtime observation Macroclimate Stu L 1min ma m W MagiEV at a 2001 I Pm m n Scale 300km Global 0 pidemiological importance helps us determine where specific epidemics can occur eg Southern stem rot oGeo h to atholo and com arative epidemiology comparison of epidemic severity eg Stripe rust of winter wheat Mesoclimate Memscale 50 km quot MagiEV at a 2001 PsnfDs Scale 50km Regional oImportant in forecasting and adjusting forecasts based on geograp y oImportant for sitespeci c disease visories Microclimate rim l w MagiEV 225 2001 PantD Scale 1km or less Local Plant oWeather factors that influence local epidemics oTypically the scale that epidemiologists measure oImportant in sitespeci c disease advisories and precision agriculture Sitespecific disease advisories Disease Advisory Requirements 1 Reliable o Epidemiologically based 0 Adequately tested 2 Disease must be important but sporadic Availability of management strategies imperative 0 Chemicals 5 Disease Advisory Requirements 4 Simple Appropriate monitoring and communication sstems Cost effective High value crops Multipurpose applicability 9quot ooxipx Road Blocks to Adoption Equipment Monitoring and scouting cosm Inconveniei i bWNH Riakpreferring Other patnogenspesm to consider 6 Reairtimeimpiementatim oi The Situation halyard 2001 mm National Networks Trends Toward Sitespecific 101024 rule in Grape Downy Mildew 10 mm min rainfall 10 C Soil Wetness period 3 24 hr Automated Weather Stations AWS Drawbacks Expensive but cost always decreasing Seasonal calibration require Sensor inconsistenciesinadequacies Regular maintenance Sensor replacement Equipment maneuverability issues Time 005 Transfer of data can be difficult Not predictive Solution Large area specific Mesascale networks ex Mesonet Modeled sitespecific weather M Icrosc Modificatim and interpolation of existing Weather Station data Adjustment using mammal and Ebsevved ah nusuhai mudds Ju tment uses dullal Elam data 29 Wars mmntains at Local scale 5 6 km2 Can be generated as an mime service Limitations ma good as coverage oflhe W8 A etWOrk Leaf Wemess most limited variable to estimate in plant pathological svstems m o a u g Q 8 m m 1 mltlng 7 t Ukulny Upmzawit Uxule 5m sensmvmes vavv was AWSS W unvainei pasmne Uncurrectable Situation alwavs improving Wltl l technologvl Sitespecific microclimate models for special situations Decision Support Systems DSS Integrates and Drgamzes 3 types Bf nfurmatmn reqmreu fur prnduttmn demsmns 5M quotm mm 07 2002 Mm DSS Spectrum Prnductmn gmde Smumg Equatmnsmnde s Expert cems S mp e Fncused LBW Camp 2x Integrated East LBW Tech ngh East ngh Tech Semen S terspem DSS Delivery Mechanisms UShR REGIONAL LOCAL u n PanmFR I Expert DSS Systems Advantagea Can ntegrate management of manv dwseases Swtenapecw c Dwsadvantages ngh deve opment cost Commeth dwscourages use Grower expectatwons too hwgh DSS Must Do s Expert vahdatwon necessarv Conswder the audwence Swmp e dehverv Keep t 5wmp e stupwd we Con tant commumcat on and re nement U1 A u N H Appropnate use don39t use to answer wnat t can39t do Not a S ver Met 0 Market Droper v Use agwcu tura agenEexperts D39tfarm testng u Be sure the DSS addreSSeS rea Wor d concema m Rename and ef uent we of tne essence Cupotcottee we 1 W Travws Lecture 24 Viruses and Viroids part 2 o Virus Disease and Vector Management Specific Diseases o Tobacco Mosaic Tobamoyirus TMV o Barley Yellow Dwarf Luteoyirus BYDV o Tomato Spotted Wilt Tospoyirus TSWV o Viroids 11192008 Virus Disease Management NO CHEMICAL CONTROLS incurable Exclusion Clean seed and planting materials quarantines inspections Eradication high value crops Heat treatment of propagative materials mother plants Rogue of infected plants Genetic Resistance Natural resistance genes from wild relatives Transgenic resistance Coat proteinmediated Silencing of overexpressed genes doublestranded RNA recognized by host Cultural focused on control or avoidance of vectors Planting date destroy virus reservoirs volunteer amp weedy hosts screen greenhouse insecticidenematicide reflective mulch Host Genetic Resistance Virus proteins are recognized by host resistance genes Results in hypersensitive response HR local lesion host Rgenes introgressed from wild relatives by traditional breeding Center of diversity 111 92008 Example Tomato Resistance Genes am am 9 hi I la 5 V Verticillium Wilt F Fusarium Wilt FF Fusarium Wilt Races 1 and 2 N Nematodes 391 l 1quot1391271117 l vl L Septoria Leaf Spot Asc Alternaria ST Stemphylium BSK Bacterial speck Pto BSP Bacterial spot Rxc Most are Stable 7 V But can breakdown when new 112E955 Rimmimm races of pathogens evolve 7 10mmrm 63mm 761 97 Transgenic Resistance viral genes engineered into plants Papaya Ringspot Virus Hawaii Cucurbit Viruses CMV WMV2 ZYMV Potato Viruses PLRV PVY African Cassava Mosaic Virus staple crop coat protein and replrcase y MVFin cassava 11192008 Transgenic resistance success against Papaya Ringspot Virus PRSV t l awaiian papaya field 1992 Coat protein CP from mild strain of PRSV constitutiver expressed in transgenic papaya Transgenic papaya resistant to infection even with heavy inoculum pressure Vector Transmission I H Persistent Circulative n uences39 Moves inside vector 39 Speed Of acqu39s39tlon gutahemocoelasalivary Latent perIod before glands transmission Nonpersistent Styletborne or Semipersistent Foregutborne Noncirculative Persistent Propagative Replicates inside vector Gut gt hemocoel a salivary glands Few transovarial hemocoelaovaries Vector Management lnsect Vector Transmission Nonpersistent Styletborne Viruses Difficult to manage viruses through vectors Transmission too fast single probing Must deter or exclude prior to probing Host Resistance necessary Semipersistent amp Persistent Vector management can reduce virus spread 11192008 Aphid Management Preventative Strateqies prevent virus acquisition and transmission by aphids Prevent vector aphids from landing repellents mulches Prevent aphids from probing insecticides feeding deterrents fleece nets Prevent probing aphids from transmitting viruses n neralo Prevent landing aphids from settling alarm pheromone Direct Strategies to reduce the population density of vector aphids insecticides insect natural enemies Reflective Mulches Deter and repel vectors uh onquot A I Thrips tosovi Specific Viral Diseases Tobacco mosaic tobamovirus TMV Barley yellow dwarf luteovirus BYDV Tomato spotted wilt tospovirus TSWV Viroids 11192008 Tobacco mosaic tobamoirus TMV Rigid rod ssRNA 6400 bases long Transmission mechanical humans Early infection most severe Seed borne externally Hosts Tobacco Tomato other solanaceous Management 1 Resistant varieties Ngene in tobacco Tm2 gene in tomato Sanitation Hand washes equipment Seeds treated with TSP or bleach Flotation 2 years to eliminate infected roots Roguing infected plants Other TMV Management Strategies 11192008 Barley yellow dwarf Iuteorirus BYDV Iuteus yellow Isometric ssRNA virusg multiple strains Transmission 20 Aphid spp not mechanical Persistent circulative Acquisition period 12 24 hours Latent period 1 4 days gutahemocoelasalivary glands Transmission gt4 hours Virus phloemlimited in plant host Low titer slow replicating Symptoms high light cool temps 1518 C Early infection more severe Older plants more resistant Host Range cereal and many other grasses B I ghhllim Gennmrcm ngMAl ngNM ngNA39i i early gene y ssRNA prududs expressed o released to begin mlecllonpmcess i39 a V nascent viriuns l acqursmon by leedlng aphldlvetlur 39 1 com lexlarmatlu assembly gtVmg m A replicatianalnew anfsyn39ihesrsofrL 5 39 39 b quotquot mlHen 1h ssRNA m erw comp emeritary stran lt alate wrnged aphid WW 9 P g long distance spread 51 I 01 a 5311 39 lzlagane 49 alga r synthesis at subgenomic W BYDV Symptoms BYDV Management Accurate diagnosis Virustolerant amp aphid resistant varieties Plant wheat m aphid activity late autumn or early spring balance with feeding cattle OK Control weedy grass by EL39SA hosts reservoirs 39 susceptible Grzing wheat inOK BYDV vs spring forage Aphid monitoring numbers migration viruliterous insecticide timing time planting Tomato spotted wilt tospovirus TSWV Genome Three ssRNA s LMS ambisense circular 17400 nt Membrane envelope of host origin buds from ost ce Studded with viral glycoproteins GPs Replicase prepackaged in virions Vector Thrips Transmission Persistent propagative Only acquired by larvae Viruliterous adults but NOT transovarially transmitted Wide Host Range gt650 host spp esp solanaceous composites amp legumes Enveloped virion Packaged with replicase 11192008 11192008 UGA1243053 ISympiom expression larval eclosion 1st Inslar Only larva larvae can N acquire virus 2nd ins1ar larva Dispersal q lnoculalion amp I ovlpcsiilun by adulls J Prepupa Thrips larvae pupa adults k 5w Pupaisrages 31513an l 390 Difficult insecticidesNOT 3 quot3 RBSiStance useful Plant clean material Monitor and rogue Greenhouses exclude thrips Reflective mulches Transgenic resistance not available commercially TSWV Manaqement Viroids Smallest infectious agent of plants Circular dsRNA 350 bases No coat protein Transmission Mechanical Pollen and seed Vegetative propagation Chewing insects Management Exclusion clean planting material Roguing Sanitation clean tools amp equipment 11192008 Potato Spindle Tuber Viroid 393 Citrus PSTVd Exocortis Viroid CEVd trifoliate v m a n mattritiumsuf mmjm gw mm rt l 139 N a n Coconut cadang cadang viroid CCCVd important die 10 yrs 10 1162008 OE ya 1 my eeimm mammmwmi m Worldwide the most destructive of all plant parasitic nematodes b tropig39a l 0 Wmmrm m mmmm em mmwmmmwmmmmqm teammatede Lifecvcle e deposited into an egg mass inside a gelat mms p1 duced by the female 011 the gall surface or partly l in robt o wm gmmmmmm o WWWW mmmmma daysmgg ksm mymmm 1162008 0 Penetration of the root epidermis can be intracellular or intercellular The 12 secrete 011101111lS from their esophageal glands into plant cells to tonn 39 int 6 am M gf wefgmm 39wwlsy mammals 0 mmmmzmmmmm The most important species of Meloidogyne reproduce by parthenngenes s 7 progeny 7 riiictles are few in number o 9 Al 1162008 Late 11 stage larvae leading an giunl cells Rum begins In farm gun 11 Sing larvae Muquot mmmdes Mule leaves 700 391 Stage larvae invade mullet and cause rurmauon uf glam cells hrr 7 4 gtr vvae Mack rowers x 5m guns appem 38 an recently miecled reels Emerging Egg Sag mlecl new O if navel at firm 1 ii a Isl molt 23223 Female lays eggs into egg sac 01 gulls may carloin many eggrlnymg females and new inleclmns FIGURE 156 Disease Cycle of root knot caused by nematodes of the genus Melaidagyne The cyst nematodes are characterized by the tanning 0f the mature NematOdeb female body wall after death R00tkn0t 0 ngne Spp forms a protectwepaekage e nclosrng the eggs amyzzmmny ewm mmhemwm o Vaw mm mmmmefmwmag m m em Wilt meayplhalamms xy aplh w mm ngm we g W me am om warm camel G 3 Jamar3mm V umm 1 c 91 o LVN leaheem mgem 1mij 1162008 v m entervanwhe W 0 ootl o me mem m Eggs in egg Inass outside the body generally hatch innnediately as embryos mature and are the next generation 111 the same season 0 a H 39 I I owmmm minis mp M m A mm L mm tag 223 O PathotypesRaces The continuous use of resistant crop cultivars has selected for populationsof species that do not differ morphologically but ditter physiolo39g cally and attac different hosts SCN INFESTATION Soybean Cyst Nematode Update 2005 Nematodes Rootknot Me loia ogyne spp Wit Ewmmmms wm as II 59696 larva intodes root In Stage male and female and causes iormutlon of syncytin Iawae feeding an syncytia 51 3390 quot IO 43quot 39 as W k 39 39 33 a 3 31 Sktuge larvae a a we young roots Syncytla of male J w W begins to degenerate J 397 W Females al varlous stages of development attached to root 7 11 Stage tojva free in 5b HStage larvae attack roots Male eaves loot I39 11 Stage larvae emerge from cyst luvva Iris 5 11 Stage eggs ins n c at ilk 1 Syncytiu b 5ng to degenerate 7 FIGURE 15 9 Disease cycle of the soybean cyst nematode Helerodora glycines 1162008 0 O This group may be considered as the third most eccnlomically important genera of plant parasitic nematodes because of their World Wide distribution tropical and ten 1o1 tes amm mmamm endo arr thnf hs Lifecycle 0 J2 hatch from e g gs often within infected plant tissue but often thewhole life dlb m teeammftatmam wma dismissal mammals 101 dbamm malls in Miss GEM beimg fmmed Um et leomttimmmmm o so mmmyeawmoedbya wmmwm mmwmmhymmmmmmhm 1162008 Affected plant tissues become discolored dark red to brown color 0 it atre eihl nd 390 ally in the r aim my materialism Lesion nematodes multiply in roots and can reach numbers up to 10003 000 nematodes gm root pg Romsyscem of quot H R f r Adul39s healthy plam I le iquot39 about 4 to 8 Weeks long but is dependent Nemmdelpen ms auditenrperature quot quot y quot roofdecy Some nemmodes x JLurvue and adults atlack mm leave me lesion and attack other 7 39 1 r0015 duced rout rsyslem and lesions an moi of Infected plunt 2nd moquot V r I V W 39 3 Nematodes re rodube quot N and migrate wgthin V li me root 1 J i I 39 V r I J Nematodes leave 3 decaying roots and attack new mots Qt mot O 9 I i c I Edgs are laid or E gadget mgrbe 1 14quot 3quot a e no reeusedrin soi Isa par Iuns killed 39 Invaded cor ica hebrrgmmroo lestomm mms s 5 39 Egg m y retire X It is one of two nematodes that are unique in that they are vectored by 39 NematOdCS insects and feed on both plant cells and associated fungi in host trees Rootknot Melr392idr392gyne spp Originally reported to be the causal agent of quotpine wiltquot jdisease 0 eaemmee meemsemeem hm 39 er 9 3 2 WMEmimfmg lmml m m m 0 AlmhmmwteU whweverUscpmmdodheWeemmm WMEmegefheme m 1162008 Lifecycle The pihewood nematodes are vectored bV Ceramb quotid beetles Mmzmzvlmmus and thus have a life cy e Close 1 le 0 the beetle ociated with the life The nematodes feed both on plant cells and k 7 Eventually the entire tree becomes L swlored w tetL and dies 11t cells and wm males I c lu 1erlarv3e migrate to the chambers of beetles tlnt ave led md over 1ntered in the nne tree molt to become fourth e 1d enter the respir tor Enter the Spiracles of young beetle adults as they emerge An average of 15000 70000 danerlim39ae o 39 1 dnlt beetle t the feeding an eV Lt ret b ule moved to healthy trees b 39 run of the beetle 1162008 Nematudu eave baztles and ants Sawyer beetles Veedlng mums feed unvouw mmgs Smut Prmnphaguus Phase mantrteeding phase Bark beetles made and transmit mngl Egglavins Reesrmv cm umbsr Mycuphagnus Fhaa tungtrteet m mass SawEv aette Nematndesveed larvae develop on Mm tn um Vlan ngum at lnterantlans Mme pinswnnd nemaluda mh sawsr bssuss and bark beetles m cause pms wiit disease derawn with permission oft Nichan um ng eld at al 1954 Nematology Lecture 1 Outline Plant Pathology 3343 Oklahoma State University Fall 2008 Plant Pathogenic Nematodes An Introduction Introduction nematodes pseudoceolomates Types of nematodes freeliving nematodes animal parasites plantparasitic nematodes Brief history of nematology Needham sugar beet nematode H eterodera schachtii Dif cult parasites to work with for a few reasons Nematode anatomy cuticle stylet median bulb nerve ring salivary glands intestine reproductive organs Nematode life cycle ve general lifecycle stages for plantparasitic nematodes Movement and spread Local Long distance Feeding habit Ectoparasites S e dentary Migratory Endoparasites S e dentary Migratory Host plant symptoms Above ground symptoms Below ground symptoms Control and management Interactions and vectors plant Viruses Fungi Ledure Exzm 2 New mama 1 range m a1 mm winuxhnanlammunl mam s E E New mm 5 7 range 93 as mm m mn Wm mum Lecture 16 Basidiomycete Rots Basidiomycete Rots Mycelia Steriliaquot Rhizoctonia Diseases Sclero Wood R Armillaria Root Rot and Parasitic Plants Parasitic Plants Dodder Mistletoe Dwan Mistletoe Witchweed tium Diseases ots White Rots Rots Brown Basidiomycota SEPTA Mushroom s Polypores Gastroids Jelly Fungi dolipore Ascomycota Ustilaginales Rusts Urediniales pulleywheel I simple D 1 Review of Morpholo V wquot l W Dolipore septum I39 AL I I Melospores basldlosp borne on basidia ores Clamp connection at septum Taxonomyof Causal F Class Agaricomycetes Order Cantharellales Anamorphs Rhizoctonia spp Multinucleateteleomorphs Thanatephorusamp Waitea Binucleateteleomorph Ceratobasidium Order Atheliales Anamor h Sclerotium rolfsii Teleomorph Athelia rolfsii Southern Blightquot OrderAgaricales gilled mushroomsquot Armillaria spp Armillaria root rots Order Polyporales polypores Wood Rotters Ganoderma Heterobasidion Chrondrostereum Fomitopsis Schizophyllum Tramenes Phellinus Laetiporus Pleurotus ungi sclerotia Rhizoctonia Diseases Mycelia Sterilia no 5 ores r Rightangled branch cells uniform hyphae r Sclerotia undifferentiated no specific layers Numerous anamorphic species with numerous teleomor hs r Rhizoctonia solani Thanatephorus cucumeris a R zeae Waitea circinata r R oryzae w ci inata r R oryzaesatilae Ceratobasidium oryzaesatilae r cerealis c cereale Differentiating Rhizoctonia s p r Multinucleate ThanatephorusWaitea or Binucleate Ceratobasidium r Anastomosis groups AIS1234 10 multinucleate AGA a c s binucleate am 39 Sclerotial cells Rightangled Hg lr WE u t r 4 v related or in the same V anastomosis group AGquot 1 WW mm W mmmmm mm m u monaxmm rumsm m a m m m ol mm mm mm Wm M varwan mm mm H ML may Rhizoctonia Diseases Susceptible Tissues Seedling or Senescent Dampingoff Turf Canker Brown Patch CSG Crown rot 7 R solam39AG1 Agglregate sheath spot 39 Large Pamh W59 amp s eath blight r R solaniAG 22 Web blight 39 Leaf amp Sheath Spot Bottom rot CSGWSG r R ory ea i i 39quot t Yellow Patch cse arge Sp 7 R cerealis E n a r 1 3 a 39 CSG coolseason grass 39 PDd 7 WSG warmseason grass A n a m lt m m u 9 Wm mum w W mm N 1 5m hmwg i 0039 H mm mm m MZmumuvmemuawvwmunn mwam 1mmsz 1 d DamnngH W m D EYSZETWI7LTCZIT 1ch um mun u w mmmuwmm mm MAMAmm mum Rhizoctonia Diseases Disease Management Cultural Reduce moisture leafwetness period Morning irrigation only improve drainage Increase airflow and sunlight Avoid excess nitrogen Greenhouse soil sterilization Crop rotation if prac ical Clean planting materials Chemical contact and systemic Seed treatments stop damping off Soil drenches Foliar sprays with forecasting m m iseases Sclerotium rolfsii teleomorph Athelia rolfsii Southern Blight damping off of seedlings stem canker crown blight bulb amp tuber rots Over 500 plants attacked peanut tomato potato cereals apple Fruit crown and roots rots Girdles stem wilting death Pathogenesis cell walldegrading enzymes and oxalic acid Warm humid climates favor disease 3035 C gt95RH Produces numerous sclerotia Survival structure overwintering Dissemination water soil plants Clamp 739 connecfion SCIEIDHUM Sclerotium Diseases Disease Management Cultural Exclusion clean equipment soil planting materials seed SanitationRoguing infected plants Deep tillage of crop debris amp sclerotia Organic matter amendments ammonia Crop rotation dicottocorn or other monocot Chemical Soil fumigation MeBr and treatment PCNB Foliar systemic and contact fungicides Sclerotium vs Sclerotinia Only dicots Armillaria Root Rot Order Agaricales Gilled mushroom fruiting body basidioma honey mushroomsquot in the fall amp winter Attacks mostly woody perennials Orchards planted in formerly forested soils Forest trees conifers and hardwoods different Armillaria spp Symptoms Basal canker butt rot decayed roots Whiterotted wood lignincellulose degraded 39 ingy Signs mushrooms rhizomorphs mycelial fans under bar m A in Mushrooms Armillaria Root Rot Disease Management Cultural Si 2 in infested soils Sanitation removal of infected roots and stumps Avoid stressing trees Trenching around infected trees Chemical Soil fumigation chloropicrin MeBr banned Fungicides directly applied to infected roots W 0 r D Mostly Polypores Order Polyporales Two general forms of decay White rats white stringy decay Both lignin and cellulose are degraded Lignin degradlrrg enzymes bleach fibers white Brawn rats brawn cubical decay Only cellulose is degraded 39gnin remains phenolics tan Both com promises structural integrity of trees and lumber Blaw aver in the wind Some Ascomycetes rot wood too Cankerfungi Xylaria Hypoxolon Eutypa etc New quotmam la vrdu llm mduww Parasitic Plants General Characteristics Kingdam Embryaphyta Land Plants Repraduce as see s c plants Occur in at least 19 different families sm biatraphic haustaria r Hemiparasites photosynthetic obtain waterand minerals from host xylem facultative can be independent 7 Holoparasites nonphotosynthetic obtain waterminerals and photosynthatesrrom host xylem and phloem obligate Mutable parasitic plants 7 OK state ower Mistletoe Pnoradendron serotinum 7 Indian paintbrush Castilleja spp r Rafflesia spp form largest flowers 7 Indian pipe Monotropa spp e Parasitize myconhiza Systematics of Parasitic Plants amp Fungi i mum 51mm EUKARYOTA E 2 B 3 PROKARYOTA 7 7 so am apislhnkanls mlrlnponull Animals Nematudesamplnsems Myxugastridae e Slime Maids Mymiammm Prutuzua Email a as im v wimopiiiiu W whlwawylcs I Stramenuplles tiiim ltlanivmnl Piasmudiuphunds e parasitic slime mulds Wigwam mim Parasitic Plants Dodders Cuscuta spp Mistletoes Phoradendron spp Dwarf Mistletoes Arceuthobium spp Witchweed Striga spp Parasitic Plants Dodders Cuscuta spp Holoparasite lacks chlorophyll Transmits viruses and phytoplasmas Seed can contaminate alfalfa seed Certi ed dadder free Management clean seed and roguing Young may 7 a mli gge r inargxgziztgiszimsaiw I W 99 q Wammmm m Witmg 5m ails m m m m HGUNE 1372 m AldunldnddrrHimmlthunuplanzmzhMaliale True or Leafy Mistletoe Phoradendron spp Cause serious economic losses but not as severe as Dwarf Mistletoe Obligate hemiparasite the seeds and deposit them elsew ere Management Pruning diseased nches Periodic removal of Mistletoe s ems Oklahoma State Flower Dwarf Mistletoe Arceuthobium spp Costly to Forestry Holoparasite Management Roguing Fires Thinning by modeling Highvalue trees Herbicides ethephon Pruning mm H l m m H A Witchweed Striga spp Major problem in Africa Asia amp Australia Not a major problem in US except 5 counties of South Carolina Dustlike seed dormant lt10 years Obligate hemiparasite Management Exclusion Ethylene injection Ethylene injectiun 4 1quot re a 39 cm Lab Today Review Lab Exam Smuts and Bunt video Rust Video Basidiomycete Rots PLP 33435343 Principles of Plant Pathology Outline of Lecture 13 Some important diseases caused by Ascomycetes part 2 Fall 2008 1 Vascular Wilts continued Dutch Elm Disease 2 Root and stem rots herbaceous plants 3 Stem and trunk cankers woody perennials 4 Toxigenic disease cereals Vascular Wilts continued Dutch Elm Disease Origins lst described in Origin Introduced to US on what Hosts Ulmus spp Lethal wilt Symptoms o o o o Pathogen Anamorph Conidiomata Teleomorph Ascomata Dissemination o o 0 Disease Cycle Vectors Treetotree Pathogenesis Disseminated stages 0 0 Host tree response Disease Management 1 a 2 a 3 a b 4 a b Root and Stem Decays Takeall of Cereals and Turf Diseases Small grains Turf Pathogen Varieties Conducive Environment Soil pH Soil moisture Susceptible Hosts 0 0 Symptoms Cereals o O Disease Cycle Primary inoculum Gaeumannomyces gramim39s varieties var triticz39 var avenae var gramim39s Disease Management 0 Fungicides o Turf o Cereals 0 Biological control Sclerotinia Blights synonymous diseases 0 S sclerotiorum 7 attacks most dicots Conducive environment Disease symptoms Survival structures Disease Cycle Primary inoculum o o Ascomata Disease Management Vegetables amp Peanuts 0 Cultural o Exclusion o o o 0 Resistance 0 Chemicals Turf dollar spot 0 Fertilization 0 Water 0 Stem and Trunk Cankers Hosts Tolerance Susceptibility Pathogens Economic Hosts 0 Disease Cycle Primary Inocula o o Penetration 7 Dissemination Disease Management Toxigenic Diseases of Cereals and Grasses Fusarium Head Blight Scab of Cereals Epidemic Conducive environment and timing Primary inoculum o 0 Symptoms o spikelets o kernels Signs 0 Teleomorph I o Anamorph I Mycotoxins o o o Mycotoxicoses o o O 0 Disease Management 0 0 Cultural I Ergot of Cereals and Grasses 0 Pathogen genus 0 Conducive Environment 0 0 Disease Cycle 0 Primary inoculum 0 Secondary inoculum I Sugary matrix I Anamorphic genus 0 Mycotoxicosis 7 Names 0 Cause 0 Symptoms o Epidemiology 0 History 0 Livestock o Pharmacology 0 Disease Management 0 Clean seed 0 o O Lecture 17 The Rusts Phylum Basidiomycota Order Pucciniales Uredinales Rusts Overview General Life Cycles 5 Spores Macrocyclic demicyclic or microcyclic Autoecious one host or Heteroecious two M hosts Important Diseases Wheat Rusts CedarApple Rust Pine Rusts Soybean Rust Basidiomycetes Systematics based on DNA and morphology SEPTA Mushrooms Polypores Gastroids Jelly Fungi BaSidiOmyCOta SmutsBunts dolipore Ustilaginomycotina Rusts Pucciniales pulleywheel Ascomycota simple Smuts and Rusts Ustilaginales and Urediniales Basidiabasidiospores borne by thickwalled melanized resting spores teliospores Viable for 2 10 years w telios ore 390 basndlum 10142008 History of Rusts Ancient Times Romans 300 BC500 AD Roman writer Pliny described plant diseases and cereal rust management practices Recommended the festival Robigalia to appease Robigus amp Robigo god amp goddess of I rust April 25 Pllnyihe Elder 2379 Roglgo altar found at asti lioncelli And early planting to g avoid late season rusts History of Rusts Economic Period M Ward 18808 Coffee Rust in Ceylon epidemiology protectants British switched to tea Biffen 1905 1st plant breeding for resistance wheat rust Rgenes Mendelian FIG 41 The stage in the life of an eudophytic fungus at which it is vulnerable to chemic tnc 200 Marshall Ward 1882 Rusts General Characteristics Biotrophic Obligate Parasites Probably every plant hosts 13 rusts Basidiomycota Lack clamp connections at all stages Very economically important 10142008 Rust Spores 1n haploid nn dikaryon 2n diploid Q NI39 I39states Q 39 structures 1 Basidiospores1n Basidia 2 Spermatia 1 n 2 Spermagonia 39 pycnia 3 Aeci spores nn 3 Aecia 4 Ureolniospores nn 4 Uredinia uredia 5 Teliospores nn a 2n 5 Telia 1 01 42008 Rust Life Cycle Classifications Spore Stages Macrocyclic all five spore types Demicyclic lacks urediniospores Microcyclic only teliospores and basidiospores Hosts Heteroecious rusts require two hosts to complete life cycle alternate hosts Autoecious rusts complete life cycles on he host Rust Diseases Cereal Rusts Stem rust leaf rust and stripe rust Cedarapple rust White pine blister rust Soybean Rust Cereal Rusts Stem or Black Rust Puccinia graminis f sp tritici Leaf Rust P triticina most important in Oklahoma Stripe Rust Yellow Rust P striiformis Cool moist regions of US eg Pacific NW Disease Management Genetic Resistance Eradicate alternate hosts 10142008 Leaf rust Stem rust Stem Rust of Wheat Puccinia graminis fsp triti Spore stages formed UredialTelial host Wheat Triticum aestivunfi T SpermatialAecial host Barberry Berberis sp lnfectivitv of spores Basidiospores gt barberry Aeciospores gt wheat Urediniospores gt wheat 1 t it quot t 3 39 39 l 39 w quott um I39 39 5 39 J39 39 55 if quotm 39 J 3 w 321 a r Wt 10142008 P graminis SpermatialAecial Host Barberry Adaxial upper side Abaxial under side Insectvectored sermatia in honeydew exuding from spermagonia Barberry Eradication Program Slates Cooperating In me Barberry Eradicallon Program 1 or Comm 039 Siam Rush 19181 41 NATIONAL RUST BUSTERS CLUB Lz fj JOIN Now 39 a mum mum m m Munher 1 huhatrvwlhn my mum mmwm mum u s Yuan mm cum In um Numw 1 IxupMIIn dung mun m Indlllw 1 01 42008 The Puccinia Pathway Movement of urediniospores I Vt39illdbumu rum spuns Eradication of barberry restricted pathogen population diversity to asexual reproduction Slowed emergence of new races CedarApple Rust Gymnosporangium juniperivirginianae Spermatialaecial host Apple Economic damage defoliation and fruit infections TelialBasidial host Juniper cedars Overwinters in galls gttelial horns in spring Provides primary inoculum basidiospores Windborne lt 5 km Management Eradicate cedars good luck preventative fungicides on apples Partially resistant apples Demicyclic No uredinia FlGURElI 138 FIGURE 11737 L39dAY applu rust caused by Gynmospomugmm pmrppnungiumm IA Cedar appivs rm duccd on Mar mp H Cedar apples dcvclop 1111 horns that produce and rahm isxdioporu lhsidmspom iMcct Jpph mm to uni run W and cause spms m dcvclop Phnlngmph L Uurteiy quotIf A And Bl E wwd I39loridn Dcpnmnvm ni Agricuhuw Forumy Divismn and 1C and 1 ml inulLy Unn ursn of MassachusmsJ 1 01 42008 Telial horns on cedar galls White Pine Blister Rust Cronartium ribicola SpermatialAecial Host white pine Aecial galls girdle pine branches and stems Overwinters in pine windborne aeciospores infect Ribes UrediniaITelial Host gooseberry Ribes Produces pineinfecting basidiospores on telial columns Management Eradication of Ribes Breeding for genetic resistance in Pine 10142008 Amuse my mummy lvlmmg lowe39 min oi Rimquot ml 39d Urzdmmvex Uredmm on lcwev lumlud Rims leaves Sldl L7 hes leal mom We mum Wampum are sprung summer Mumpbrea mm mm M mm wrme gooseberry manymlluuwnMSSU mm Mymmm Wand Eammpoms Wm a n mm mm 39 k llama g 99le S Mummy mm quotMm mummy M l yummy toss SeamI olwmm pine mm with Jean Al Sperma um wm nlnn I I 9 spam mg W Ba a 0195 as n 9 we vinenzedtthvmxgh stamau uummtnhlll 49m 47 47 t m ellum lJmmemm Medium um ms MKth cl lame needle Spermagaml mama zmmnimm 039 Muslim hianrhm lm wme pme bunzh we mm 1 ummel mowing mm mm W MM 21 5mm me rly beginning 14 mu Mt inle ien FIG URE 11142 mm swlc l Mm pine bllsrrr m mused by Cmmmmm nlm39nlll Spermatia and resinosis Canker Urediniospores in uredinia Cronartium ribicola on currant Ribes spp Telial columns 10142008 Asian Soybean Rust Phakopsora pachyrhiza Formerly on the APHIS select agents list Introduced by hurricanes in 2004 Disease Management Resistant germplasm under development Numerous fungicides given Section 18 exemptions Timely spraying critical if rust present and conditions conducive Must intensively monitor fields Lookalike foliar diseases make early diagnosis difficult httpwwwsbrusanet Season Early Mid Adaxial side of leaf Abaxial side of leaf 10142008 Asian Soybean Rust Phakopsora pachyrhiza Life cycle Urediniospores repeating asexual TeliosporesaBasidiospores noninfectious to soybean Alternate host unknown Can cause premature defoliation amp yield loss lf infects early in season High humidity favors Lowlying humid fields Early maturing varieties early canopy closure Alternative Hosts Kudzu Pueraria Crotalaria Desmodium Erythrina Pachyrhizus Phaseolus Vigna So far few losses but spreading Comparison Smuts vs Rusts Trait SMUTS RUSTS Parasitism Facultative biotroph Obligate biotroph Saprobic 1N yeast in vitro Both Biotrophic in Nature Economic importance Less important Extremely Important Secondary repeating No secondary spores Prolific secondary spores most cycles important inoculum Host range Limited to Angiosperms WIDE Ferns Gymnosperms and Angiosperms Disease Cycles Autoecious complete cycle Autoecious and Heteroecious on one host two hosts to complete cycle Host Tissues infected Meristematic or actively Most aerial tissues growing Disease management Genetic Resistance Genetic Resistance Fungicides Fungicides seed treatments eradicate alternate hosts Basidiospores Variable number 4 on sterigmata ballistospores not discharged Clamp connections common absent 10 Lecture 22 Disease Forecasting 11132008 Disease Forecasting Disease Forecasts are predictions about the probable occurrence or non occurrence of plant disease at economically important levels Preferred term Disease warning Types of Disease Warnings Disease Advisory A warning that conditions favorable for a disease outbreak to have occurred 11132008 Types of Disease Warnings Disease forecast A warning that conditions favorable that disease outbreaks are about to occur Examples of Disease Advisory Outputs Report of disease in area extension publications farm radio or TV etc Severity of event low medium high Recommendations Sprayno spray Plant resistant varieties Purpose of Disease Warning Systems Make a decision about disease control Is there even a threat for disease Make disease control more efficient when is the most critical period for applying a disease control measure Disease Warning Systems Help Control Costs Direct costs incurred by the farmer Cost of nontarget effects eg PPE required Indirect costs incurred by everyone else Environmental impacts Re ulato consequences Fungicide resistance 11132008 Requirements for Implementing a Disease Warning System Reliable based on sound data field tested 2 Disease important but sporadic inoculum spatially sporadic environment not always favorable 3 Simple only a few input variables are needed 4 Effective disease management available equipment chemicals resistant cultivars 5 Appropriate assay monitoring and communication systems are available 6 Cost effective balance costbenefitrisk Most advisories are conservative by design Constraints to Adoption of Forecasting Systems Costs of monitoring scouting system maintenance Inconvenient more labor or equipment may be needed Grower attitudes toward risk Presence of other pests Fungicide may control minor problems ex Spra to control black rot of grape also control other diseases Combination vs single treatment sprays Pecan insecticide sprays are often combined with fungicide sprays Approaches to Developing a Disease Warning System Fundamental based on experimental data biological approach eg growth chamber studies laboratory studies etc Empirical based on analyses of current and historical data correlationstatistical approach 11132008 Warning systems can be based on 1 Prediction from amount or efficiency of initial inoculum Components of Basic Infection Lateth Period I I la Infection primary Symptom Propagules WOW inoculum Appearance formdisseminated d ssemm m ooridary 09 metal um iricupauori Period irirecuous Period Disease Triangle Environment Warning systems can be based on 1 Prediction from amount or efficiency of initial inoculum 2 Prediction from rate of increase in secondary cycles efficacy of secondary inoculum Components of Basic Infection Latent Period 11132008 Propagul e irifecuori primary Symptom Propagules inoculum Appearance formdisseminated d ssemm m ooridary 09 metal um iricupauori Period lnfecuous Period Disease Triangle 11132008 Warning systems can be based on 1 Prediction from amount or efficiency of initial inoculum 2 Prediction from rate of increase in secondary cycles efficacy of secondary inoculum 3 Prediction from initial secondary increase Amount or efficacy of initial inoculum used for Diseases with one cycle per season monocyclic Diseases with several cycles polycyclic but slow in progress Polycyclic disease with low dispersal ex Nematodes Diseases in which the pathogen does not overseason in target location Example Forecast based on initial inoculum or initial disease a Indirect assessment of initial inoculum Stewarts wilt of corn Envinia stewartii 11132008 Stevens 1934 If mean temp for Dec Jan Feb gt33 F then the disease was severe if lt 30 F then the disease was mild Due to effect of winter temperatures on populations of the corn flea beetle Example Direct Assessment of Initial inoculum o Nematode advisory programs first developed in the 1950 s and 1960 s in Europe 0 USA CJ Nusbaum KR Barker NCSU o Experimentation large databases experience of invesigators were used to establish relations between nematode population levels and yield loss Nematode assay services probably the most common warning system worldwide SemiAutomatic Elutriator 11132008 A report With Recommendations Example Long Distance Transport of Initial Inoculum Pathogen overwinters outside crop production area Epidemics can be explosive but occur infrequently Arrival of inoculum via long distance transport initiates the epidemic Tobacco blue mold CE Main J Davis Recently extended to downy mildew in cucurbits 6 Holmes 11132008 Initial Inoculum Introduced from a distant Source Considers Likely sources of inoculum Weather patterns that could bring 39noculum into an area Likelihood that infection will occur in area if inoculum is presen Downy Mildew Disease Locations Warning Systems based on disease increase in secondary cycles Application Polycyclic diseases with at least limited dispersal Diseases tend to be ubiquitous but speedseverity of the epidemic depends on weather during the season 11132008 Disease Increase in Secondary Cycles Assume that inoculum is present in sufficient amounts to cause an epidemic Population assays scouting or history can be used if this assumption doesn t hold Since warning occurs during the season the usual action is to apply a fungicide Role of Environment Multiple Variables Moisture Relative humidity leaf wetness Often hoursday or consecutive hours Rainfall events andor amount Soil moisture Temperature min max average Air Soil 11132008 Role of Environment Fundamental lgori wm a well defined set of instructions Models describing effect of environment on infection sporula on etc Computer simulation Empirical ori w Multiple regression Computer simualtion Temperature and Moisture Algorithms Depending dn tne disease can act as an Dnfo sWiten andpi as an aeeeleiatdi OrvOff sWiten Example ddes nut develup abuve pi Deluw a eeitain teinpeiatdie Disease ddes nut develup unless a eeitain ndinpei uf nadis uf leaf wetness deedi Acceleraturexamples Disease develups faster pi sluwer dependingdn teinpeiatdie as lung as tne ininnndin lw pendd is ieaened Disease develups faster pi sluwer dependingdn tne ndinpei uf lw nadis as lung as tnese nadis new at a favurable teinpeiatdie Fundamental Example39 Pecan Scab Advisory Pecan scab Cladnsporium Earyigenum Overwintering Inoculum Twig infections 11132008 Spomlallon by CIdasparlum umgenum 11132008 Ratings of Leaves and Fruits HorsquBmmn culx Fm Mesonet sum pm as nmwmm mum Red Rivquot I994 I Susan Plar of RH Ccrrdntinn de Rim 1994 Disease Progress Curves Developed 11132008 Regression and Correlation Analyses Pearson Correlation of Red River 1994 disease and weather t Correlations using combinations of temperature and RH ranges Movinginterval series with T 2 211C and RH z 90 for all sites Correlations for all sites and years and combining years for each site Summary 1 Mesonet stations could be used to monitor weather for predicting disease locally The highest correlated wea wer combi nation was hours in which Ta Z11and RH a 90 The time interval that temperature and N w relauve in subsequent disease development was1428 days prior to the end of a rating period Assumptions Afourteen day protection period following fungicide applications Final disease on fruits not to exceed a rating of 3 on HorsfallBarratt rating scale ie lt 25 area 11132008 The Scab Hour scab hour an hour during which temperature gt 70 F and relative humidity gt 90 The prediction Pecan scab will develop in 7 14 days once a threshold level of scabhours has accumulated unless intervention by fungicides occurs 11132008 Action Thresholds Thresholds were derived for the two levels of susceptibility measured in the field studies from the Best Fit equations for the correlations between disease rating increase and accumulation of scab hours Highly Susceptible Cultivar Burkett y scab hours x rating increase a bx y 357 479x The Thresholds 39 Highly susceptible cultivars 10 scab hours 39 Moderately susceptible 20 scab hours Natives low susceptibility 3O scab hours 16 The Outputs Accumulated scab hours for last fourteen unprotected days Daily scab hours for last 28 days Information on fungicides rates and on cultivar susceptibility Accumulation of scab hours predicted for the following three days 9 3 11132008 A SiteSpecific Output Using the Scab Advisory in the Real World For Natives use to decide if and when to make 1st and 2nd Cover sprays For Susceptible Cultivars use to decide if prepollination spray is needed and when to apply cover sprays For Both Try to use the forecasts for your spraying interpretations Empirical Example Sclerotinia blight of Peanut 11132008 Empirical Example Sclerotinia blight of Peanut Rating 12 rJu1027rSep x20 5 E15 x 510 u E 5 None g 0 Perry 0 2 4 e 8 10 12 Weather modeling using SkyBit Detailed weather data is collected by the National Weather Service NOAA FAA military and others This data can be used to model weather between stations Modifications are made for specific sites based on elevation topography proximity to bodies of water etc Information is specific for sites distant from a rea wea wer stauon 6 X6 mi a Materials and Methods 11132008 Parameters Tested Fweday mavirg average Nean Air Temperature Naxymum Relative Humidity Nean Leaf Wetness Magtltimum Sail Temperature 5 Nean Precipilalmn Magtltimum LeafWELnes Nean Relative Humidity Mmimum Air Temperature Nean WetTemperature Mvmmum Relative Humidity Mean Sail Temperature Mvmmum SmlTemperaLurE Tutal Precipmilmn Magtltimum Air Temperature Huurs Bf Leaf Wetness Principal Components Analysis Eisnvi lies at the cnnelalinn mahix and peninem Eienueetan mmmm PNpurum amen new mmm math mm mm WETmi manna zznzsxons nzszs my mumPm mmm mmm mm mm pman mmm mmm mam nynx new mama nmnnm mm mm mama mmm nnm U w 51 mmm nnzwwm nuns mmm mama mam nnnwxnsz mm mm nnnzmns mum 7 mm nnnnisiw mm a m seeaaawwe mm mm mm A1r Temperature 7R2 050 Soil Temperature 39CV 3975 VSS Remduai 749 Relative Humidity VPRESS 075 Sale 0 02 WRHquot 1 014 MNSTV 0 025 MNST Rsquare amp Regression Analyses 71 independent omenanon 7340177 0 s70 awn 003 RHLn 01751171159 WATo 7 WRHL1232 MNATo 0 045 0mm 0 290 0mm 7 0 002 mlinia Him Dials Index 5mm 1 450 M17000 Residual Plot 06 05 O 04 03 o 239 2 02 3 up 8 o o o u t 3 o v o 0 o 8 39 0 H 31 01 39 02 0 04 011 08 1 02 2 30quot c 03 39 o 04 39 39 t 05 Predicted Value 11132008 unuli ve man mm on Accounting for Resistance Plt0 0001111 0 172 CV 55 174 mu Xenon vuniddeinninami mu Xenon mid1e Intellile gt61 mm mamm x y n nxsx n as an luniddeixuuenliblei vn267x nus 2O Cummalw mm human as Accounting for Resistance Human mean I mmmmn I I I I 39 o x 39 I 39 I I 39 39 11132008 The Advisory Daemne gm spm nzsmzm mnmls mm s2 Ih CD39xx CD39xmu n m mama 39 5quotquot939quot 7mmquot 15 nnsmnn r hmm I 22 1 Yulm n 39 1w mmp m 1 zys Sumnerml sl 39l Zlhmluh mum 31ml N spm 21 Lecture 5 Economic and Social Impacts of Plant Disease Crop yield losses quantity and product damage qualit Restricted production andor plant use Loss of natural resources Direct toxic effects livestock and human Costs of controlling diseases Increased costs to consumers Social and political impacts Human exacerbation of plant diseases WNP P PPN A brief history of Plant Pathology 1 Crop yield losses quantity and product damage quality Quantit volume Crop losses in USA 199039s 39 20 lost lnsectsamp Pests 10 20 lost Weeds 10 20 lost Producer losses result in higher costs to processors and consumers supplyand demand effect Annual Yield Losses to Diseases 10 com 12 wheat 16 potatoes 12 cotton 1 Crop yield losses quantity and product damage quality Quality direct losses due to reduced aesthetic appeal to s increased spoilage in storage reduced nutritional value al as it ma impact domestic or international trade restrictions export limitations Quality Losses depend on commodity Low consumer tolerance Fruits amp vegetables up to 50 lost postharvest Ornamentals turl uncertain easily billionssyr Quarantine trade barriers mestic urseries crown all amp sudden oak death International ergot ol cereals Karnal bunt olwheat 2 Restricted production or plant use either before or after the presence of a disease in the area Before a disease occurs environment is highly favorable to disease SOdo not plant the crop in that area Examples bean seed production in semi Pacific NW rMANAGEMENT PRACTICE CERTIFIED CLEAN SEED wine grapes in SE states due to prevalence of Pierce s disease and its insect vectors 2 Restricted production or plant use either before or after the presence of a disease in the area W Pathogen widespread in area Growing the crop or trees not possible economically OR only after costly management practices Replanting trees alter root disease soil inlestation by the pathogen eg banana wilt Central America m disease USA Europe Chestnut blight USA Cotton root rot TX Collee rust Alrica SEAsia Central America Coconut palm yellows Alrica SE Asia Caribbean Canary palm wilt currently S CA 3 Loss of Natural Resources Loss of dominant native trees due to introduced diseases Chestnut Blight N America 1904 44 now endemic Cryphonectria parasitica Jarrah Eucalyptus DieBack W Australia 9 0 Christmas and pasture beetles Dutch Elm Disease Eur amp N Am 1930 Ophiostoma ulmi O novo ulmi Pitch Canker of Monterey Pine W N Am 1986 Fusarium circinatum Sudden Oak Death W N Am 1995 Phytophthora ramorum Chest l nut Blight 19041944 41 r Plant Quarantine Act 1912 National law restricting importation of all kinds of plants Imported plants distributed only after a waiting period and careful inspection for pathogens and insect pests Passed as a direct consequence of chestnut blight Chestnut planting at Tulsa Zoo 9504 4 Toxic Effects on Livestock and Mycotoxins compounds produced by fungi poisonous to humans or animals Aspergillus toxins Aflatoxin peanuts soybeans corn cottonseed milkfrom cows fed contaminated grains carcinogenic Ochratoxins sterigmatocystin tremorigenic toxin Fusarium toxins cereal grains Trichothecenes T2 toxin vomitoxin diacetoxyscirpenol Zearalenone fumonisins Penicillium toxins cereal grains apples Patulin rubratoxin citrinin The only mycotoxins on CDC s Ust of Select Agents with bioterrorism potential httpwwwcdcgovodsapldocssalistpdf 4 Direct Toxic Effects on Livestock and Humans Ergot of rye Historical significance 1000 1950 s Ergot alkaloids toxicosis hon fire or St Anthony s fire not contagious afflicted rural poor Symptoms hallucinations vasoconstriction gangrene amputations abortion Cure avoid rye products eat white bread Cold winters amp cool wet springs favored Witchcraft French Revolution failed military campaigns Potatoes replaced rye as staple 1700 s Horses and cattle severely affected Fescue amp ryegrass related fungal endophytes Medical uses midwifery and migraines Ergo Allmlallll ls II 56 AVER v A i 7 11 J Sign la l K Ergot of Rye St Anthony of Padua quotPI quotJ mm mm min wu G d h t quot rass en 0P V o quot 5 y 39 39 Ergotism I j of cattle 39 39 Gangrene Aflatoxin fluorescence under blacklight Earworm feding increases Aperg m s ASPergiIIUS infectiOquot 0f Peanuts Penicillium wet core of apple patulin 5 Costs of Controlling 6 Indirect Costs to Plant Diseases consumers Cultural evasive control H39gher pr39CeS 00d ber ornamentals measure Breeding of new disease resistant varieties Chemicals and their application Implementing measures for protection of environmental quality including water Human health effects amp their treatment field workers Negative effects on environmental quality chemical pesticides weed control Costs of disease control on public lands and in the public interest n5 of US Dollars Billie Pesticide Expenditures l Fungicides Insecticides 1 Herbicides U S Dollarsha Eagt1 Lauri East Reslof 399 America Europa world l lt r l7 7 H I l 1950 1970 1980 1990 1999 Years Fl G U R E 1 14 Estimated average expenditures in US dollars on 39 39 i fungicides lDSCCEIL ILlCS and llcrbncrdcs per hectare of arululc land 11 me principal Farming regions of the world in I990 Dam from FAQ 1993 7 Social and Political Impacts of Plant Diseases Historical Epidemics Maize failure amp collapse of Mayan civilization 800 AD virus Irish potato famine 1840s late blight 1 million died 15 million emigrated N Am Diseases of European grapevines 1845 1878 powdery mildew Phylloxera and downy mildew British teacoffee drinkers 18605 coffee rust Great Bengal famine 19405 rice brown spot fungal 2 million died Southern Corn Leaf Blight 1970 1 billion lost Citrus Canker 1910 1980519905 present eradication amp destruction of FL citrus trees 7 Social and Political Impacts of Plant Diseases Widespread malnutrition limited food mainly developing countries Dependent on vulnerable staples Rice or cassava or potato International political problems political quarantines Karnal bunt US excludes Mexican wheat dwarf bunt China excludes US wheat fire blight Europe and Japan excluded S pome fruits 8 Human Exacerbation of Contributions to Plant Diseases Movement of diseased plants seed or infested propagative material into diseasefree areas Import healthy cropsplants highly susceptible to endemic pathogens Extensive monoculture Decreased genetic diversity few varieties preferred germplasm not preserved Cultural practices favoring disease or pathogen dissemination such as irrigation tillage over fertilization Manmade pollutants 03 802 N02 Natural vs Agricultural Plant Communities Ag favors disease Natural Agricultural Genotypes Diverse Uniform Age structure Mixed Uniform Distribution Dispersed Crowded Nutrient status Often low High Coevolution span Long Short History of Plant Pathology Ancient Times 650 500 MYA Fossil fungi found on fossil plants 8500 BCAgriculturein Mesopotamia cuneiform tablets 5000 BC bible mentions blasting blighting rusts mildews and smuts as plagues from God 300 BC Greek Theophrastus writes about plants and plant diseases 1st botanist History of Plant Pathology Ancient Times Romans 300 BC500 AD Roman writer Pliny describes plant diseases and cereal rust management practices Recommends the festival Robigalia to appease Robigus amp Robigo god amp goddess of rust April 25 And early planting to avoid late season rusts L W 7 l L j lilacgr 39 quot 33553 c7 Pliny the Elder 237 79 Robigo altar found at Castiglioncelli History of Plant Pathology Descriptive Period 1577 Aztec Codex Corn smut images Disease g food 1600 s Europe 1St microscopes used spontaneous generation still touted M 97v 2 Rose rust Phragmidium teliospores by Robert Hooke 1655 History of Plant Pathology Classification Period 0 1700s1850s Hints at fungal causes Linnaeus Latin binomial classification of organisms including plant diseases Linn us 17071778 Fabricius Essays on plant diseases Autogeneticists claim fungi the result of NOT the cause of disease blame internal causes Fabricius 17451808 History of Plant Pathology PrePathogenetic Period 1750s early 1800s external causes 88 W690 Q 3 e1 6 a a Tillet 17508 K Bunted seeds gave J 91 M 0 rise to bunted plants Limebrine seed 9amp9 6 treatments prevented J bunt 39 Prevost 1800s fquot m W8 6 0 b u S g i n FIG 8 The germination ofBunt spores in water x zoog grrigglazhigzlggvm 1807 with moisture Copper is antifungal History of Plant Pathology Pathogenetic Period Birth of a Sfcience o Pasteur 1860s amp Koch 18703 Germ theory of disease 0 Berkeley 1846 Fungal hypothesis of late blight deBary 1860s Proved fungus Phytoph thora infestans caused late blight Kiihn 1858 Published 1St Plant Pathology text History of Plant Pathology Economic Period Disease Control Millardet 1885 1st fungicide grape downy mildew Bordeaux Mixture CuSO4CaCO3 M Ward 18808 Coffee rust in Ceylon epidemiology protectants Biffen 1905 1st plant breeding for resistance wheat rust IS vulne M life of a rable to chemical arshall Ward 1882 n endophytic History of Plant Pathology Bacteria Nematodes amp Viruses Bacteria Burrill 1879 fire blight caused by bacterium 1st bacterial plant disease Erwin F Smith 18831907 lD d bacteria pathogens causing cucumber wilt bacterial wilt and crown gall Debated Europeans and proved bacteria were plant pathogens Nematodes Needham 1743 1st description of Anguina Kiihn amp Schact 18505 Ditylenchus and Heterodera Kiihn 18805 chemical soil treatments Viruses Mayer 18805 amp Ivanowski 18905 transmission of Tobacco Mosaic Virus TMV Beijerinck 1898 contagious living fluid TMVfiltrate 1st virus Stanley 1935 crystallized TMV amp won Nobel Prize REVIEW from PREQUIZ question 1 More realistic Anatomy at the Animal Cell quot scale Mitochondria Prokaryotic Cell Structure Micro laments Y Plasma a Membrane Cytoplasmic Membrane 7 Envelope y Go 9 Apparatus f Ruugtl Endoplasmic agella Reticulum Smooth 39 Endoplasmic Figure 1 Reucumm Ribasomes Figure 1 Eukaryotic Cell Prokaryotic Cell REVIEW from PREQUIZ questions 2 amp 3 Plant Cell eukaryotic Leaf REVIEW from PREQUIZ questions 4 monocof wheat dicot cotton soybean Fungi Bean Rm 2 39 1 s t m d a d M ale Yeast molds amp mushrooms REVIEW from PREQUIZ questions 5 amp 6 Photosynthesis 60026H20 i CBH1ZO6602 Chlorophyll Xylem Carries water amp minerals from roots to leaves PLANT PATHOLOGY SOME ESSENTIAL DEFINITIONS AND CONCEPTS PLANT PATHOLOGY The study of the nature cause and control or management of plant disease DISEASE abnormal functioning of an organism continuous injurious irritation by a pathogen or environmental factors leading to the malfunctioning of the host s cells and tissues resulting in development of symptoms DISEASES BIOTIC DISEASES Caused by a living organism Le a pathogen Infectious Transmissible ABIOTIC DISEASES or DISORDERS Caused by an injurious physical chemical environmental factors Noninfectious Nontransmissible HOST Disease PATHOG EN ENVIRONMENT The Disease Triangle 1 Susceptible host 2 Virulent pathogen 3 Conducive environment RULE all three must be present for disease to occur mm synmuiud mmquot and humans yams Raquwn and mm mm Dmmmaud u Trinwlriunn mwnmm um manulaamt k M mm mm Wham rIsuRE M smmn mpmscnunun 1 m but luncnom m J pm Llcm and u m was of mmmnm mm mm mmquot mm tamed h sum mum rum of n nnr Wm HOST A plant or plant species capable of being infected by a pathogen Susceptible lacking ability to resist infection y a given pathogen resulting in disease Resistant capable of impeding infection by a given pathogen thereby reducing disease development quantitative infected to some degree NONHOST lmmune cannot be infected by a given pathogen no apparent disease GENERAL RULE Most plants are immune to most pathogens Leaf Rust Resistance in Rye 4 n 1 L A r miu ck g nifn 7 1 INT 397 u v w l t oul 6 Wu Fi PATHOGEN Organism usually a microorganism microbe capable of inciting a disease while obtaining nutrition from the host plant Each pathogen has particular host range Pathogenicitv qualitative basal capability to cause disease YES pathogenic or NO nonpathogenic Virulence quantitative degree of pathogenicity of a particular pathogen Highly virulent moderately virulent avirulent genetic GENERAL RULE Most pathogens are nonpathogenic on most host plants The Plant Pathogens gt 1 Replicative particles o Virusnucleicacid j proteins o ViroidcircularRNA 2 Prokaryoies no nuclei o MollicuieswaIIIess o Bacteriawalled 3 Eukaryoies nuclei o Proiisis o Oomyceies o Fungi o Nematodesround worms animals x o Parasitic plants quot E in uinrinn in u pinni ceii iincn uu muiinniu uni pruinnnn an not mu in nude nui iiuinu niii ii cciis in nu nieiinnviiux nu u it PATHOGEN Host ranqe the range of plants on which an organism particularly a parasite feeds Specificity of host range BROAD Classes eg monocots vs dicots Families eg cucurbits night shades grasses Genera eg Solanum T riticum Secale Species eg Solanum tuberosum vs S nigrum Cultivars Tomato cv Glamour vs Rio Grande SPECIFIC Genotypes Rio Grande 768 vs Rio Grande 76R NAMING PLANT PATHOGENS STANDARD PRACTICES Scientific names are italicized or underlined pathogens usually only have scientific names except viruses eg Fusarium oxysporum f sp ycopersici eg tomato L ycospersicon esculentum For best accuracy scientific names include authorities names abbreviations once eg Fusarium oxysporum SchlechtendFr f sp ycopersici Sacc WC Snyder amp HN Hans eg tomato L ycospersicon esculentum Mill The pathogen s genus is not italicized included in the disease name eg Disease Fusarium wilt of tomato Conducive Environments Ty ically favor pathogen and disfavor predlspose host Water Excessive humidity water logging hypoxia Deficient drought Light Excessive sunburn Deficient shading etiolation legginess Soil Excessive mineral toxicity pH metals Deficient mineral nutrients texture Temperature Warm or Cool NAMING PLANT DISEASES Common Names of plant diseases includes Name of the host Characteristic symptom Sometimes name of the pathogen Standardized list of common disease names httpwwwapsnetorqonlinecommon eg Southern blight of tomato caused by Sclerotium rolfsii eg Fusarium wilt of tomato caused by Fusarium oxysporum f sp chopersici race 1 eg Gray mold or Botrytis blight caused by Botrytis cmerea PLANT DISEASES vs PATHOGENS STANDARD PRACTICES DISEASE is the interaction of a virulent pathogen with a susceptible host in a conducive environment ie the disease triangle eg Fusarium wilt is the disease NOT the pathogen genus NOT italicized eg Fusarium oxysporum is the pathogen NOT the disease italicized Describing Plant Diseases Symptoms vs Signs SYMPTOMS External and internal reactions or alterations of the host plant due to disease SIGNS Directly observable pathogen its parts or products seen on the host plant Fungi bacteria nematodes parasitic plants Never viruses visible only with electron microscope Mimime 7 i SWIM m nm mm WKM FIGURE 1Z Edmumic dingmn of ha mpcs and 622 Mm glam parhngm in Malian to 6 NM ML Barwrin mnlhcm and prmuzuu ure nu 390de m nude Mcd Mng pm Us SYMPTOMS Necrotic dead cells M bast dampingoff Chlorosis Flagging flaccid blight defoliation wilt watersoaking yellows blotch dieback Exudations canker leaf spot Bleeding gummosis rot lodge resinosis scald mummy Abnormal Color scorch needle cast Albino mosaic shothoe phloem necrosis breakflower break soft rot ringspot chlorosis mottle ringspot stem pitting Stippling yellows wilt mm witches broom edema gallknottumor rugosity clubroot callus enation leafroll russet wart curl epinasty phyllody scab leaf curl dwarfing fasciation rosette stunting SIGNS Sporulation Rust Smut Powdery mildew Downy mildew Mushrooms Fungal mycelium rhizomorphs smoke ring Bacterial oozestreaming Parasitic plants Nematode egg masses Symptom or sign Symptom or Sign Symptom or Sign Symptom or Sign Symptom or Sign Symptom or Sign Symptom or Sign Symptom or Sign mm synmuiud mmquot and humans yams Raquwn and mm mm Dmmmaud u Trinwlriunn mwnmm um manulaamt k M mm mm Wham rIsuRE M smmn mpmscnunun 1 m but luncnom m J pm Llcm and u m was of mmmnm mm mm mmquot mm tamed h sum mum rum of n nnr Wm Plant Pathogenic Prokaryotes Mollicutes and Bacteria Selected Important Diseases Mollicute Diseases Stunts and Yellows Bacterial Diseases Leaf amp Fruit Spots amp Blights Twig amp Stem Diebacks amp Cankers Vascular Wilts Soft Rots Mollicute Diseases anm Asker yeuaws Peach Xdlsease Peach yeuows App e rubbery wand Pear dedinc 1 Elm yEHuws Eivus stubborn Cum 5mm FIGURE 1253 Symptoms caused Ivy mallicums D diseased plant H mm plant Mollicute Diseases Wallless with my a single cell membrane Intracellular Live inside host cells Phloem cells or insect vectors Insect vectors leafhoppers Systemicall infect insect host before transmissib e to plant host Two Genera Spiroplasma helical culturable stunting and declines Ph toplasma round elongate NOT cu turable Yellows and declines Until 19703 thought to be viral diseases Insen needs new annua m pErEnnial plams does noryer smrr pal ogen incubarign Fenod when parnagen 39rs pvesem m vary g ands 597 m 3192 number ew Wants Pathogen is ingested in gur lummJaler passes mm 53 hemolymph muscles g ands ek 39 r r In erred mm 7 a K lnsectvectov feeds on vein cfmfecxed planr Vactnvleedmg on leaf of hea hy plam Heatrhy insecr veuor feeds on recermy infened plam and charm pathogen Palhogen spyeadsabng verns inm new leaf Parhogen egmymplasmm Venus overwrmer Pathogen spreads overwintevs in ees shrubs or as eggs or adults on sysremrrauy hmugh perennial herbaceous ham hosrs av gvound vernsofplarrr Spiroplasma Diseases fried egg j colonies Corn Stunt S kunkelii Citrus Stubborn Disease S citri Phytoplasma Diseases Aster Yellows quot 41x Yellowingdwarfing witches broom abnormal sterile flowers virescence amp phyHody Disease Management eradicate weedy reservoirs spray leafhoppers partial resistance Aster Yellows in alfalfa causing witches broom mawbaaer Fasuauon Canker and mm mm D Xamhomonas Simpromyces Poms scab Soil m cfsweal puma FIGURE 124 The most mpormnt gcnera cf plant pathogenic bacteria and the kinds of sympmm rlvcy must Bacterial Spots and Blights Mostly Pseudomonas syringae and Xanthomonas campestris pathovars Disease Management Resistant varieties Bacteriafree seed grown in arid irrigated regions Crop rotation 3 yrs Cu and Mn sprays when dry A circular yellowish green halo surrounds each lesion Bacteria landing on wetleaves multiply in lime water or gunation drops w Bacteria penetrating leaf I thm 5 omata and Bacteria multiply and spread intercellularly WOUTI S Affected tissues in center of each lesion collapse and die Bacteria in guttation water are sucked in through hydathodes Young seedlings may be killed Infected young leaves develop a wet re Leaf with numerous infections and coalescence Wild re bacteria overwinter in soil debris and on tobacco seeds Killed areas of heavily infected leaves may fall off in wet weather Wildfire lesions on capsules Tobacco lant infected with wildfire Fl G U R E 1 2 1 0 Disease cycle of a bacterial leaf blight eg wildfire of tobacco or soybeans caused by Pseudomonas syringae pv tabaci at various stages of development Wildfire of tobacco and soybean a Pseudomonas syringae pv quot 4 tabaci quot L 439 39 Minor disease of soybean Management Resistant varieties of tobacco available ultraviolet Fluorescent Pseudomonads r x u v Common blight of bean Xc pv phaseoli 3 i F 3 If WV Spot Xc pv vesicator Testing pepper variety for resistance to Xcv Infiltrated section of leaf undergoes a hypersensitive reaction HR Indicates vertical resistance gene present Rgene recognizes bacteria resulting in HR Twig amp Stem Dieback amp Canker Fire Blight Erwinia amylovora Pear more susceptible than apple Overwinters in cankers Disease Management Pruning 10 below lesion margin with cleaned shears pruned branches removed and burned Cu and antibiotic sprays during favorable weather based on forecast models Partially resistant varieties Bacteria penetrate flowers through nectarthodes and leaves through wounds or stomataBacteria multiply and spread intercellularly Infected owers shrivel Bees carry q bacteria to flowers i K I v i 5 The fireblight bacterium Infection spreads to other flowersltwigs r39 and leaves lntercellular multiplication and t prea of bacteria in bark Direct Infection of young twigs Bacteria in exudate 39 39 are disseminated by insects and rain Cankers enlarge and girdle branch Of stem 1 Cells of infected bark a tissue collapse Bacteria overwinter in margins of old Formation of new cankers on branches and stems Twig killed by re blight Dead leaves cling to twig Young tree heavily infected with re blight FlGU RE 1 224 Disease cycle of re blight of pear and apple caused by Erwinia mnylouora 10 2 20 K D Hickey Vascular Wilts Move through xylem plugs wilts Bacterial wilt of cucurbits Erwinia tracheiphia Vector cucumber beetle Mgt control vector resistant varieties Bacterial canker amp wilt of tomato Cavibacter michiganense subsp michiganense Mgt clean seed clean seed bed Ring rot of potato Cavibacter michiganense subsp sepedonicum Mgt m seed tuber certification zero tolerance Southern bacterial wilt Flastoma soanacearum gt5 races Race 3 biovar 2 Mgt resistance crop rotation clean seed amp stem cuttings clean pruning knives Bacteria are deposited with the insect feces on leaf wounds erlum Bacteria enter xylem vessels of leaf veins and move down the petiole and vine Bacteria multiply in sap at the margins of wound Bacteria in vessels of vine vascular bundles The larvae attack young cucumber 39 1 plants Bacteria spread to 2 adjacent vessels through dissolved walls Beetles lay eggs nearyoung cucurbit plants Beetles feed on i and contaminate A cucurbit plants with bacteria E contaminated wit bacteria upon feeding vquot Emerging adults become 1 h l J L l i I I Bacteria overwinter 0 nfeCted Plants in the striped and 39 spotted cucumber BaCterIa ll and clog vessels of the plant beetles Entire plant wilts and dies Bacteria spreadto other vines FIG URE 1 221 Disease cycle of bacterial wilt of cucurbits caused by Erwinia tracheipbila S bac wilt F j V 39 Ring rot Galls Crown Gall Agrobacterium tumefaciens Integrates transfer DNA TDNA from tumor inducing Ti plasmid into host s DNA TDNA encodes Phytohormones auxin cytokinin Opines amino acid food for Agro Management Exclusion inspection Prevent reduce wounding Graft away from soil bud graft Biological control Agrobacterium radiobacter K84 treatment of seeds and seedlings GMO silences phytohormone gene Transformed cells divide rapidly T DNA is integrated into plant chromosomes plant cell is transformed Cell hyperplasia and hypertrophy leads to gall formation Older gaquot iT DNA leaves 39 I 39 ibacterium Bacteria multiply WIth several and enters and sprea new centers wounded intercellulary of activity j1pant cell Bacteria entering stem or root through wound Galls on stem and root of heavily infected plant Plant infected with crown K Crown gall bacteria l plant overwmtermg In SOIl m Bacterium becomes I attached to wounded TIplasmid plant cell r Bacteria from gall surface move into soil Disease cycle of crown gall caused by Agrobacterium tumefaciens FIGURE 1236 Crown gall on Euonymous V Nature s Genetic Engineer Agrobacterium Host Cell 7 nucleus Soft Rots Pectobacterium Erwinia caroto vora pv carotovora Epiphytic on healthy tubers Enters through wounds and lenticels Tissue Maceration numerous cell wall degrading enzymes Pectinases Degrade pectin in middle lamellae Cellulases Degrade cellulose in primary cell wall Host cells lyse amp release nutrients to bacteria Management difficult Sanitation clean debris from warehouses Avoid wounding tubers Control insects wounds Cold Storage wellventilated 95 RH no free water Bacteria spread from tuber into young 39 stem and roots Emerging bacteria infect new plants Bacteria in intercellular spaces and in collapsed cells Cork layer forms Maggots around infected pupate tissue in soil Contaminated Emerging larvae carry adults Icarry bacteria bacteria into tuber to other plants Stemend infection insect lays eggs of tu her from ver potato infected stolon seed piece t Inoculated plants develop soft rot Cross section of infected tuber Bacteria in soil may infect vegetables through wounds Infection spreads during storage Bacteria overwinter in insect pupae rotten vegetables on host parts and occasionally in soil Discarded rotten tubers FIGU RE 1 234 Disease cycle of bacterial soft rot of vegetables caused by softrotting Erwinia sp Scab of Potato Streptomyces scabies Actinomycete Filamentous Gram prokaryote Favored by soil pH 7080 alkaline Scabs act as important entry site for secondary infections by bacteria and fungi Management Clean seed potatoes treated with MnZn Keep wellwatered during tuber development Resistant varieties Crop rotations Green manures and reducing soil pH lt53 Germ tubes Spore infecting tuber through lenticel stoma d d39rect y 39 Spores Germinating 3 Sporogenous hypha Spo39e breaks into spores Sporogenous hypha Patho en rows developcrosswalls g g f m between and through cells Sporogenous hYPhae Cork layer forms around lesion Cork layer pushes Vegetative mycelium infected area outward w Spores a i V 39 a 5quot r 39 gt egi Ega iquot aNEb39Qg Eg Z39 2 an n g wasquot 39 Mycelium r y I Pathogen overwinters in the V soquot on infected plant tissue Potato tubers with different k nds As the first cork layer is penetrated a new of common scab symptoms on forms further in FIG U R E 1 2 4 3 Disease cycle of common scab of potato caused by Streptomyccs scabies Next Time Bacteria finished Assessment Wednesday Introduction to the fungi LAB finish bacteria start fungi 10122008 Lecture 14 Basidiomycetes Smuts and Bunts Basidiomycetes General Characteristics amp Taxonomy Smuts amp Bunts Ustilaginales Ustilago Tilletia Rusts Urediniales Puccinia Uromyces Gymnosporangium Rots of roots crowns and stems Armillaria Rhizoctonia Sclerotium Basidiomycetes Systematics based on DNA and morphology SEPTA Mushrooms Polypores Gastroids Jelly Fungi dolipore Basidiomycota SmutsBunts I Ustilaginales Rusts r Urediniales r I39Y PUlleywheel g Ascomycota simple Basidiomycetes Basidiospores Meiospores sexual spores products of meiosis Basidiospores gt G I 1N lt Sterlgmata Basidium O 0 Where meiosis occurs NN gt 2N gt 1N Clamp connection 10122008 Basidiomycetes 0 Most basidiospores are forcibly discharged termed ballistospores m Absent in the Smuts and Bunts Ustilaginales 532232Emit5223mitt g rstsiizigiiir z and Co London Basidiomycetes General Life Cycle Clamp connection Secondary Mycelium Basidiospores 39 NN 1N haploid Predominant somatic nuclear o o compatible mating types state of Basidiomycetes Eventually produces basidia Basidiomycetes Clamp connections maintain dikaryotic nuclear state Exception Absent in Rusts Urediniales 10122008 Smuts and Rusts Ustilaginales and Urediniales Teliospores thickwalled melanized resting spores orm basidia amp basidiospores Viable for 2 10 years Smut Diseases Most important on cereal crops Barley wheat oats sorghum and corn Also violets sugarcane forage grasses Smuts Ustilago spp Bunts Tilletia spp Economic Impacts Reduced yield grains replaced by teliospores Reduced quality offflavors and smells Quarantines Karnal bunt Smut Diseases Disease Cycles and Management Reproduce sexually m per season Only primary 1 0 inoculum No asexual secondary repeating spores Monocyclic epidemiology lnfects meristematic amp rapidly growing host ssues Management protect stage of host development that primary infection occurs varies with particular smut disease 10122008 Specific Smut Diseases o Corn Smut Ustilago maydis o Loose smut Ustilago tritici wheat U nuda barley U avenae oats o Common Bunt TiIIetia spp wheat o Karnal bunt TiIIetia indica wheat Corn Smut Ustilago maydis Primary inoculum soilborne telios ores produce basidia promycelium and BaSIdIospores sporidia that can live as saprobic yeast 1 N phase Dikaryotic NN hyphae are infectious Infection NN hyphae infect aH aboveground meristematic ssues Seedlings brace roots leaves tassels ears kernels through sulks Symptoms amp Signs galls filled with teliospores Systemically infected plants are taller than healthy Disease management Dent corn Resistant varieties Sweet corn avoid excess nitrogen Minor sanitation crop rotation foliar fungicides 3393 I quot Compatible Bosidiospores infect young Y g I bOSileSpOresp plants or growing tissues s of older plants 5 p39rariyml f quot chellum K i 399 In ec s erne w x N it through silk 1 II Eors of com gt 399 are infected quot I W through the Silk Infected kernel f o 39 enlarges and V i iv orms gall quotVaquot Bosldlospores g 1 39 Leaf or stem 4 infection 3 K t at 03 V y t 2 4 fir K gm Q Corn plant with golls Germi noting telio spore mote Teliospores K overwtntenng J on soil quot Dikaryotic cells Gulls full 0f 0 mycelium become teliospores teliospores in gull FIG U RE 1 1104 Disease cycle of com smut caused by Ustilago Hwydis 10122008 Corn Smut Disease Cycle astray YASSEL EAR LEAF AND sr39su aAsmicspoREs swam T0 HOSTS w av wmn AND young emquot FLAquot svusuma lulu BASIDIOSFORES BUD IN VEASY I LIKE mnuza BASIDIDSPORES FUSE A5 SAPROPHVYES To main DIKMYOYIG ggg g gg INFECTIOUS HVPHAE quotANURE aAsImo BASIDIHM w 5 i39 2 9WD 5 av WIND 5 IV TE AND RAIN a 39 MRHINATlNG YELIUEPORE WERWINTERINU DIKARYOYIO Dixmmnc HVFHAL CELLS ROUND UP TO BECOME TELlOSPORES Corn smut oi CuitIaco39clw Maize Muslimquot Loose Smut of Wheat and Barley Ustilago tritici amp U nuda Primary inoculum Teliospores gt basidium gt dikaryotic mycelium Primary infection Infects through flower invades ovary then embryo overwmters as mycelium Systemic infection of seedling then inflorescence Symptoms amp Signs Premature heading Kernels replaced with black powdery teliospores Naked rachis Disease Management Seed treatment with systemic fungicide Clean seed Resistant cultivars 39r Mycelium follows growlh ol growing poinl at man 39 inlarcellulorly K I I Mycelium Invades the spike and young kernels inlercellulurly Mycellol cells in kernels become lellospores Kernels m infecled pldnls are filled wilh lelmsporgs x Mytelium inwdes yOunq seedlings VI intracellulorly a 1 1 T311051an qermmmes an lower learyulic f Mycalium ouerwinters myceluum II39IfECIs 39 in the embryo 01 WW 1 ll infected cereal kernels l 1 4e Hrrua39nhrtme 4 39x 397 l 39 J I 7 tweaks lieliospores l 39 blown away by I 539 I 2 5 4 4 air currents 39 l 39 Teliospores land on Mycellum Invades quot parls 01 embryo Wm mi hemmy in seed Plums FIGURE 1 1 405 DjSEESC cycle of luosc smurs of barley and whcar Caused by Ustilago quotmay and LL rrr39n39cr 10122008 ii Loose Smut absent Basidiospores s Smut 0 rs Cop39girightAPS Press wr vv f Wheat l 39 LEAF BASES ggiwmmaa sp 39 Late m u m lt g rst W s MYOELIUM IN THE DEVELOPING SPIKE 4 PRIMORDIAL 0595 l W3 53 9311 TILLERS WITH e 3 WW MYCELIUM 39 if 3 n 4 mwmmm quot wgmmmmvw u E gt l y 39 W a Copyrig APS Press Mvunau Common Bunt of Wheat Tilletia spp Other names stinking smut or covered smut Primary Inoculum Teliospores soilborne and seedborne Basidiospores 1 N a Hspores NN a infectious dikaryotic mycelium NN Primary Infection Dikaryotic mycelium systemically infects emerging seedling Symptoms amp Signs Plants slightly shorter amp glumes spread apart by bunt balls Bunt balls break open filled with teliospores with fishy odor Disease Management Seed treatment with systemic fungicide Clean seed Resistant cultivars 101 22008 r wr w svmcmres i I M m t k r acv elmm mm penemes oycondm maniacle m glows alween cells 9 quot2 53 Mycelmm ranches and mod y L quot lollws qmwlng pm of SW 9 v p plant anury spondru 1 Z use to farm f m w wsnapea v 1 sonndium unuzks I see mg Secnndmy M d 553 sponamm qgvmmales Mycelmm qmws unm cleme umcugn 5m W p u and mm wheel kernels f mm mm f ansmmm Mycelmm heCume Mmmalmg lelrospme mlmcellulov m kernels Healthy when 39 head Smuxfed kernels break upon mwm MyCElIal cells and contaminate are transformed n quotno teliospores Smulled wheel kernel nu ol lelmspoves iii Seedborne or Soilborne wshumngvmd FIGUR E 1 M as Duane um mmd mmlHI1mmufuhnucmurdIn l vuwl 3 f Wh um 0 eat twentieth D39 C I amp 3959359 W e 522st 39 1 mum mums HIE mvzsm mm mum mm m ARE mam w LEAsmu M ssa a van mam mu mm Ya mum mm mrzam Yissuz or me mmst 2 aAsm los39onEI awquot mzkwmvma s v m w l N News 7 wan u 5 use EmL auRNE an le nr renown mmquot asz 3quotquw arena Loose Smut and Bunt are easily managed with seed treatments Usually contact fungicide combined with systemic fungicide Thiram or Captan AND Carboxin or Triazole EBI Karnal Bunt Tilletia indica First reported in the US in 1996 States bordering Mexico where it is endemic CA AZ NM TX Fishy odor in flour if 35 infected rare Quarantined by 80 importing countries Certification surveys must be performed annually to export Infects through flower Seed treatments not effective Fungicides can be applied at heading Teliospores last 35 years in soil 10122008 TiIIetia indica differs from loose smut and common bunt Soilborne teliospores Prolific production of primary sporidia basidiospores Prolonged epiphytic phase Production of secondary sporidia Penetrates glumes of inflorescence Flower infections lead to bunted kernels in same season Karnal Bunt Life Cycle TiIIetia indica Ljummnmr lamm w mu Mm 10122008 Comparison of Loose Smut Common Bunt and Karnal Hunt of Wheat y W Asas39irl a 0mm Farming 1 m 5m musty The burns and smuts are paused by Fungi that arm the seed or wheat and nthersmall grains and grasses Duly loose smut Fig 1 and mmman hunt mg 2 7 also nailed sunkmq mun occur u Oklahoma HowevEly Kamai bun 162 3 7 also nailed partial mm which does nntuocnr in Oklahoma is a uncem because gram that tens Daimve rm Kernel bunt can m mm esiy into mmmnal markets Fig 1 Laos Smut l Gram m ma lEDiazed with laws mass of mink was Smuttad g m mm mt Dicdute iccse h c All Gram omen mama m i am mass of saw mind marl mm Healthv camm Head mm Fig 2 Karllal Bunk am i mm m a m ma argpm m seed that a man and mamquot usually 3 it une my aim 5m Spares hm mmng um mu Kamal We Spores WE m mu m n tamed an Egg Mam mm m wheat rims mlmg m Dims n7 fullv hunted glam mmmmm A mummy mm me name and gammy a mmmnn am my mum m mam mm 1 hiveak um I piinlm the ma and 1003 my is WW commquot hunt and Inns 5 L5 3 ml gummy as w mm mm mm a ma mama Hut m d farmnmi of 5 and LS SEE aa m Bk nsmn may Handbook Inga mm n was mm was prllnuun or anuct yam mm 5mmquot Educator Baggyl a bong m Yable 1 mutualu mmmmbmiwthsaed humanism unawvashinglan emu sle 5 m s Unuukddm a can 421 7 finImus A 2 mm zoos Vrtavarmvam zar mizxmu murmur Ile 433 SJ 5 9r 5m 5 me new that gm 3 mm mm Elnvvde m ha cnhnl also mmemb rmar zed lrawenis aw in AV ya a 3m nutmeg um Imamquot magnumwm 3 I m I W 5 balmy I I a if u homagllly new a mi mum 1 5 x Kama aunt Kama mm quotmm has its renu ed in m mum States in m l 1 so i 2 mm m m s mum 2m Gallium Ntw mm m minus in ma slim ha at mm mm in mm hcma Kspa n crawl pr dby a ma lam wheat mu av m Animal a plan Heilm m w 5w whims a m n m can mm m u inter39Iibmwl man u K3 in mm mm mmmmsmdma mum Elegant 4 z wewdk unganum n fer mm 7 b Mia la H mm unquwmnms 50me hulmcs w I m wenszomn w lab rs ma Emily rm mml ms 1 m an n as my a limited vain 5mm A rm 75 years mums where a mm 1 a 14mm ammmn m gha my a4 m39mnl M xa mu m oumm is biluq mm a swim m an m m 5 no longv mum NIH Whamquot by ks a v 10122008 Plant Pathology 33435343 Principles of Plant Pathology Instructors Carla Garzon and Stephen Marek Teaching Assistant Mike Brown Lectures 108 NRC MW 830920am Lab 121 NRC Section 1 W 1030a1220p Section 2 W1230220p 1 Plant Pathology I Plant Biology Physiology Nutrition Anatomy Systematics Ecology Agronomy Soil Sciences Forestry Horticulture I Microbiology Mycology Bacteriology Virology Nematology Parasitology I ZoologyEntomology disease vectors I Tools microscopy molecular biology chemistry meteorology mathematical modeling w 1 What s wrong with this magazine article I Chestnut Nearl wi ed out at the turn of the 20th century by Dutch elm disease the American chestnut39s been crossbred with a Chinese chestnut variety The new resistant trees could be available for planting within two years Newsweek 821 2806 I l Drammteep a mmmha lmltmmm U firern the August EI T ZED e on h pdl39vmucsmm tucmrn39ZDUTlDEDWpDEs 15tenl1tml Chestnut tree poised for comeback A haltrid 2539 years in the making is designed to resist a devastating Night By Mark Clam n writer of The Christian Science Mmitcr WRENTHAM MASS Tromping thruugh a Massachusetts state forest Brad Smith sputs an old stump with lead shoots and one lone green sprout a sad but not uncommon remnant of a on ce nrnurl species 39lhe American chestnut tree Except tor a few mature trees the species has struggled for 50 years to survive It dues that in the same way Stumps send up sprnuts that are quicle attacked by the same invasive h ght that wiped out abeut 35 billion diestnut trees between thM and 1950 quotWhat you39re seeing is the former lring of the forest reduced tn surviving as a mere shnrlaf says Mr Smith president at the Massachusetts chapter ct the American Chestnut Foundation ACFJ Now however an American chestnut revival may he imminent Scientists using traditional plant breeding techniques are on the verge of a breakthrough ln tact Smith smiles and shares a little secret the quotholy grail of American chestnut trees a name supertree fully resistant to the blight is alive and growing down south Date Tue 5 Aug 2m Suume Banana Emu em ted lthllg banana ullblhg ut cumZEUSIBbananammalaysla hum Lawtalasxa Bananaxs39helndmustwldel culmzated 39un cuvmnuabuutm unnha nsnacms WALhatule rudumunufsl memctunes Abuut a v u a 5 WM mmm a quota Fusanum uxyspumm rsp uh u I mEEhamalmeans smlandmt2r and rausuwie m Lhe gm Braver Z yeazs Na effecuve thermal arrulmra mm mmsures arelmawn Musa mh a amiable v A mmwpm em a m nwmde mavericznu39y gm mm pzmwu yu as a c m a a and c 5 mm 2mm m as mm m gym WWW a ngmhasm 1 my mags Mammumym mm gr m hasemmmw mm mm M q 1 007124 45 21 mm mmenhego Manamseaswmm mm a 20mm 9 PLP 33435343 Principles of Plant Pathology Outline of Lecture 12 Some important diseases caused by Ascomycetes Fall 2008 1 Leaf and fruit spots blights 2 Fruit decays and rots 3 Vascular Wilts Overview of Ascomycota ascomycetes Classes of plant pathogenic Ascomycota and their ascomata mycota phylum mycotina subphylum mycetes class aes order Sordariomycetes Pyrenomycetes Helotiales Inoperculate Discomycetes Leotiomycetes cleistothecium chasmothecium Erysiphales powdery mildews Euriotiomycetes cleistothecium Dothideomycetes Loculoascomycetes pseudothecium bitunicate ascus SACCHAROMYCOTINA yeasts 39 ascus naked asci TAPHRINOMYCOTINA g BASIDIOMYCOTA ZYGOMYCOTA Powdery Mildews 1 Causal Fungi Class Leotiomycetes Order Erysiphales 2 Host range 3 Signs 4 Symptoms 5 Parasitism Yield effects 6 7 Conidia 8 Ascomata 9 Disease cycle 10 Important hosts 11 Conducive environment 12 Disease Management a b i Sulfur ii iii 13 formae speciales amp racespeci c resistance a Apple Scab Causal Fungus a Class Dothideomycetes Importance Symptoms Favorable environment Primary Inoculum Secondary Inoculum Disease cycle wsgvpuww Disease Management a b Leaf Spots 0f Cereals and Turf 1 weww Causal fungi formerly called a All Class Dothideomycetes b C d Spores Importance General Disease Management Southern Corn Leaf Blight a Causal fungus b Races 0 3 1 D quot1 i ii Disease Management i Disease Cycle i Primary inoculum ii Secondary inoculum Epidemic of 1970 Compared to Northern corn leaf spot i Causal fungus ii Affected corn cultivars 6 Turf Leaf Spots 7 multiple Helmz39nthosporium spp a Disease Management i Cultural 959 ii iii 7 Tan Spot of Wheat a Causal Fungus b Disease Management 1 ii Fruit Rots Brown Rot of Stone Fruits l Causal fungi Class Leotiomycetes Order Helotiales a b Hosts Tissues affects Postharvest rots 959 Disease cycle a Primary inocula i ii iii b Secondary inoculum 6 Disease Management a Sanitation i b Fungicides i Timing c Postharvest Vascular Wilts Fusarium and Verticillium Wilts 4 Causal fungi a Fusarium oxysporum Class Sordariomycetes Order Hypocreales i Resting structure b Verticillium dahliae Class Sordariomycetes Order Phyllachorales i Resting structure Host Range and Symptoms a Fusarium b Verticillium Vascular wilt pathogenesis a Symptoms due to Disease Management a b Vascular plugging due to Lecture 12 Some Important Diseases caused by Ascomycetes 1 Leaf and fruit spotsblights all plants 2 Fruit Decay and Rots fruit trees 3 Vascular wilts herbaceous plants and trees 4 Root and stem rots herbaceous plants J 5 Stern and trunk cankers woody perennals 5 Toxigenic diseases herbaceous plants 397 Ascospores in ascus from Classes of plant pathogenic Ascomycota and their ascomata mycota phylum mycotina subphylum mycetes class ales order I Helotiales lnoperculate Discomycetes Leotiomycetes igapolhecia cleislolhecium chasmolhecium Erysiphales powdery mildews L Euriotiomycetes I cleislolhecium 4 II K3 pseudolhecium bilunicale ascus SACCHAROMYCOTINA yeasts w asws TAPHHINOMYCOTINA BASIDIOMYCOTA L m n Leaf and fruit spotsblights Powdery Mildews numerous hosts Apple Scab Leaf spots of Cereals and Turf Powdery Mildews Causal fungi in order Erysiphales Occur on most plants Signs white to grayish patches conidia Oidium sp amp mycelia on plant tissues yellow to orange to black cleistothecia form in older areas of the infection Symptoms chlorosis tissue distortions necrosis late Obligate parasite infects epidermal cells with speCIa Ize austoria Decreased photosynthesis results in yield losses Conidia catenulate Oidium form genus Ascomata I Cleistothecia chasmothecia appendages m asci V overwinters Comdia o Coni Germination Myzelmm Canidmm 1 i5 Liberated 33 Comdium o o asmipmes on T Conidxa Aszospores Conidiophote 2 Mn Ascus Cleismrhedum Cleismrhszia inimed rose leaves budMWigs i I y 4 A Overwmterlng myzeiium lelslothxk Mycehmd appendages Aswgomu M Ovelwimeung ciaisxolheda Young and mycelmm leismhecrum FIGURE 1 1 50 Disease cycl of powdery mildew of roses caused by Splmerutlwm Mimosa r 5p rosau Powdery Mildew Fruit symptom Russeting Powdery Mildews cont Severely Affected crops Cereals grapes cucurbits ornamentals Favorable environment High humidity but no free water Disease Management Resistant varieties Fungicides during favorable weather Sulfur S Benomyl Ergosterol biosynthesis inhibitors it available Powdery Mildews of Cereals Host specific formae speciales Mildew Fungus Mildew Fungus Blumeria Erysiphe graminis Blumeria Erysiphe graminis f sp tritici f sp hordei Host Mm Wheat Triticum aestivum Barley Hordeum vulgare Apple Scab Causal Fungus Venturia inaequalis Most important disease of apple Symptoms scabby lesions on leaves amp fruit fruit stunting amp drop defoliation Favorable environment Cool moist springs and summers are conducive scab development Spring primary infections ascospores Summer secondary infections conidia FIGURE ugu limbnull nlIpplrquiummlh Mum mama Apple Scab cont Disease Management Contact m systemic fungicides Combined with disease forecasting models Genetic resistance g u Cultural practices Sanitation of dropped leaves Prune to increase air flow g Avoid overhead sprinklers R 3 Apple Scab cont Timing of fungicides is crucial Presymptom application Postsymptom application The importance of disease forecasting Leaf Spots of Cereals and Turf Fungi formerly all Helminthosporium spp V J Now split amongst l Anamorph Teleomorph Bipolaris or Curvularia Cochliobolus Drechslera Pyrenophora I Exserohilum Sefosphaeria Both mito and meiospores important A Necrotic leaf spots potentially lethal to midi susceptible cultivars Disease Management Genetic resistance widely deployed Cultural sanitation of debris tillage or removal Genera of leaf spot fungi infecting grasses Disease Anamorph Teleomorph Wheat Tan spot Drechsera Pyrenophora Septoria leaf blotch Septoria Phaeosphaeria Wilhelm Itself ight m m g Matthew 1 Mammy Turfgrass leaf spots amp melting out Bipolaris Cochliobolus Drechsera Pyrenophora Exserohium S etaspha eria Southern Corn Leaf Blight Causal fungus Cochliobolus heterostrophus Bipolaris maydis 2 Races Race 0 common minor tan spots Race T Appeared in 19691970 Highly virulent on corn with Texas cytoplasmic male sterility Tcms Hostspecific toxin Ttoxin Caused 1 billion losses in US Management Genetic Resistance normal cytoplasm cms C or cms S resist race T Monogenic and Polygenic Rgenes in most cv s Conieln germlnale on plan fissue by polar genn lube Mrcelmm imam 39 cutenelmnuleus leaf lissuos cells ueqln lo Ium blown and colluoss Gum lubes penelmle News diraelfy or lhrowb slomula V Conidiopberei and coniuia on infeclud emu Cerium cause l39 7 new infwlicns f lnfecleu emu I Con39d a luuflshagrh die and collapse 2 5 I39 rquot 39 Conidia curried 4 r to earn Flgnli by Manure onus g Auosporos wind nr splashing mloinlug T ru rl oucospores r A 1 I quot 3939 11 r quot r V In 743 hCDni ID Coc bw39rype a railing Purilhaclum canroininu fw quot sci Wm WSW Knuluru Snulhern corn leaf blith sympaoms on and heuran coniaiupharea 4 5 39 139 111 Mr I and comm N 3ng 7yfr cor em 5 corn husk s I l of Fungus wwrwiniars as mmium and spares g c iar in cam on bus FIG U R E 1 1 53 Disease cycle of southern corn leaf llllghl caused by Codu fobol us Micrograph race T Southern corn leaf blight Northern corn leaf spot rost ophus Cochliobolus carbonum I quotlr39fv i l V 39 FIGU RE 81 Development and northward spread of the southern corn leaf blight epidemic caused by ConM01701 bemrostropbus Helml39ntlyosporium maydis in the United States from June 15 to Sep tember 391 1970 From Zadoks and Schein 1979 Bipolaris leaf spot bluegrass Drechslera leaf spot 139 It I l bluegrass rec ss Drechslera leaf spot bluegrass hslera zonate leaf spot bermudagra Drechslera Bipolaris Curvularia and Exserohilum Diseases of Turf Disease Management Cultural Avoid excess fertilization Irrigate as seldom as possible deeply in am Reduce thatch inoculum reservoir Reduce soil compaction Improve air flow landscaping Genetic Resistance in Poa Festuca amp LoIium Fungicides Tan Spot of Wheat Pyrenophora triticirepentis Drechslera triticirepentis Fruit Rots Brown Rot of Stone Fruits The most important disease of stone fruits Prunus spp causal fungus Peach amp Nectarine Monilinia fructicola Apricot M Iaxa Almond M Iaxa Plum M Iaxa and M fructicola Cherry M Iaxa and M fructicola lnfects all aerial parts of trees fruit flowers twigs Postharvest activation of quiescent infections fruit fungicides required 539 31 V 7 so r J 39 N I Y R titanium z i x Q 39 sscou DARY mocmum If crosssection of ap othecium apothecia on tallermummy notcumrnon in nature Ulzlkl39l g cummsy Huh Brews Brown Rot of Stone Fruits Disease Management Sanitation remove mummies and cankered twigs Fungicides 2 3 before amp during flowering 2 3 during fruit ripening Postharvest Careful handling not overripe at harvest Fungicide application prior to storage Cold storage Vascular Wilts Fusarium amp Verticillium wilts utch Elm sease Fusarium amp Verticillium Wilts Soilinhabiting asexual fungi Resting structures Chlamydospores Fusarium oxysporum f spp Microsclerotia Verticillium dahliae Fusarium oxysporum hostspecific formae speciales and races Chlorotic flagging on one side of plant Verticillium broad host range amp wilt symptoms more phytotoxic Vshaped necrosis leaf margins phytotoxins Ring of discolored vessels in secondary xylem vessels In Infecte Xylem vessels stem or petiole u an Econidia in vessels in healthy stern a a or petiole 544 h We 1 Gum in vessels and adjacent cells Mycelium in vessels Root penetration through wounds Mycelium enters vesse O ation throng ls cru stormed by V gquot emerglrrgg lgteral 31343 Mycelium Or 7Vgerm tubes attack roots Germinating spore lee 4 7 WWW quot Microconidic n f I r x 1 k MUPIO Chlamyo Mycelium a conldla spares Spores formed by All stages present in infected tissues or soil mycellum In soul ls FIG U RE 1 1 73 Disease cycle of Fusarimn Wilt of tomato caused by Ftls rimn oxyspurmlz Fl chupcrsl39ri 1O COttO n Mt of Plant P halogy mlwrsit39y at Mir Vascular discoloration Fusarium amp Verticillium Wilts b I a 09611 a ors Wilt toxins auxins hormonal factors Endophytic fungal growth in xylem toxins hormones enzymes induce gumming and tyloses Disease Management Resistantvarieties tomato cucurbits cotton may Healthy seed amp transplants Tyloses I iea nazals4 m In 39 H x D 3 a H SEM
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