PLANT PATHOLOGY. Plant disease Plant’s normal function is interrupted by a pathogen or the...
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Transcript of PLANT PATHOLOGY. Plant disease Plant’s normal function is interrupted by a pathogen or the...
PLANT PATHOLOGYPLANT PATHOLOGY
Plant diseasePlant disease
Plant’s normal function is interrupted Plant’s normal function is interrupted by a pathogen or the environmentby a pathogen or the environment
Plant diseasePlant disease
Is this a disease?Is this a disease?
Biotic damageBiotic damage
Caused by living pathogens or Caused by living pathogens or parasitesparasites
Biotic damageBiotic damage
SymptomsSymptoms: visible expressions of plant : visible expressions of plant reaction to the pathogenreaction to the pathogen
Biotic damageBiotic damage
SignsSigns: indications of disease from : indications of disease from direct visibility of a pathogendirect visibility of a pathogen– Actually Actually seeing the pathogenseeing the pathogen
DISEASE TRIANGLEDISEASE TRIANGLE
Disease needs all three to developDisease needs all three to develop– Only need to block one of themOnly need to block one of them
PathogenPathogen
Organisms capable of causing diseaseOrganisms capable of causing disease FungusFungus BacteriaBacteria VirusVirus Other micro-organismsOther micro-organisms
PathogenPathogen
ParasitesParasites: obtain food from living : obtain food from living organisms (host)organisms (host)
PathogenPathogen
Obligate parasiteObligate parasite: require (obligated : require (obligated to) living plant cells as food to to) living plant cells as food to complete life cyclecomplete life cycle
PathogenPathogen
Facultative parasiteFacultative parasite: obtain nutrition : obtain nutrition from either living or dead plantsfrom either living or dead plants
PathogenPathogen
SaprophyteSaprophyte: feeds on dead organic : feeds on dead organic material on plant or in soilmaterial on plant or in soil
HOSTHOST
SusceptibleSusceptible: no ability to retard or : no ability to retard or resist diseaseresist disease
Susceptible plant tissueSusceptible plant tissue– Fertilization Fertilization
HOSTHOST
ResistanceResistance: some ability to retard or : some ability to retard or tolerate diseasetolerate disease
HOSTHOST
ImmunityImmunity: complete resistance against : complete resistance against diseasedisease
ENVIRONMENTENVIRONMENT
MoistureMoisture and and temperaturetemperature are the are the predominant factorspredominant factors
ENVIRONMENTENVIRONMENT
MoistureMoisture, water is , water is criticalcritical
Dry springs can reduce Dry springs can reduce disease occurrencedisease occurrence
Often 24 to 48 hours Often 24 to 48 hours continually wetness continually wetness requiredrequired
Poor irrigation practicePoor irrigation practice
ENVIRONMENTENVIRONMENT
TemperatureTemperature, each pathogen has , each pathogen has optimal rangeoptimal range
Predisposed condition of hostPredisposed condition of host Host is stressed, can’t defendHost is stressed, can’t defend
FUNGUSFUNGUS
The vast majority of plant diseases The vast majority of plant diseases are fungalare fungal
FUNGUSFUNGUS
What is a fungus?What is a fungus? Microscopic organisms that lack Microscopic organisms that lack
chlorophyll, cannot produce own foodchlorophyll, cannot produce own food Multicellular organism that is Multicellular organism that is
threadlike in compositionthreadlike in composition
FUNGUSFUNGUS
Enormous genetic variabilityEnormous genetic variability due to due to rapid reproductionrapid reproduction
FUNGUSFUNGUS
Species of fungi are Species of fungi are subdivided into subdivided into strainsstrains that are very specific in that are very specific in
Plant species or Plant species or cultivarscultivars
VirulenceVirulence Temperature rangeTemperature range Moisture requirementsMoisture requirements
SPORESPORE
Fungal seedFungal seed Very distinct shape and size used to Very distinct shape and size used to
differentiate pathogensdifferentiate pathogens Single celled or multi-celledSingle celled or multi-celled
SPORESPORE
AsexualAsexual, not requiring the union of , not requiring the union of sexual parts to be produced sexual parts to be produced
ConidiaConidia
SPORESPORE
SexualSexual, requiring union of sexual , requiring union of sexual parts to be producedparts to be produced– Basidiospore, ascospore, oospore…Basidiospore, ascospore, oospore…
SPORESPORE
Where do you see spores when a plant Where do you see spores when a plant is infected?is infected?
Leaf surfaceLeaf surface– Appears as mold (powdery mildew)Appears as mold (powdery mildew)
SPORESPORE
Where do you see spores when a plant Where do you see spores when a plant is infected?is infected?
Fungal fruiting bodiesFungal fruiting bodies Spore producing pocketsSpore producing pockets Sporodochium, acervulus, Sporodochium, acervulus,
pycnidium…pycnidium…
HYPHAEHYPHAE
HyphaeHyphae is what germinates out of the is what germinates out of the sporespore
Branches out into tubular filamentsBranches out into tubular filaments
HYPHAEHYPHAE
MyceliumMycelium refers to all the hyphae as refers to all the hyphae as a whole, as the fungal bodya whole, as the fungal body
Inside the plant, or outside the plant Inside the plant, or outside the plant under high moistureunder high moisture
PLANT INVASIONPLANT INVASION
Fungus enters plant through any of the Fungus enters plant through any of the followingfollowing
WoundsWounds– MechanicalMechanical, pruning or handling, pruning or handling
PLANT INVASIONPLANT INVASION
WoundsWounds– InsectsInsects, vectors or egg laying, vectors or egg laying
PLANT INVASIONPLANT INVASION
WoundsWounds– Naturally occurringNaturally occurring
Secondary roots rupture the main root when Secondary roots rupture the main root when emergingemerging
Leaf scarsLeaf scars
PLANT INVASIONPLANT INVASION
Fungus enters plant through any of the Fungus enters plant through any of the followingfollowing
Natural openingsNatural openings– Lenticels Lenticels
PLANT INVASIONPLANT INVASION
Fungus enters plant through any of the Fungus enters plant through any of the followingfollowing
Direct penetrationDirect penetration– Pushing through tissuePushing through tissue– Resistance can come in the form of Resistance can come in the form of
thicker cuticle or hairy leafthicker cuticle or hairy leaf
FUNGAL LIFE CYCLEFUNGAL LIFE CYCLE
Peach brown rotPeach brown rot is used as an example is used as an example
FUNGAL LIFE CYCLEFUNGAL LIFE CYCLE
OverwinterOverwinter, ,
Disease is dormant in infected fruit Disease is dormant in infected fruit and stemsand stems
FUNGAL LIFE CYCLEFUNGAL LIFE CYCLE
DisseminationDissemination
Disease produces spores (conidia) that Disease produces spores (conidia) that are spread by wind and rainare spread by wind and rain
FUNGAL LIFE CYCLEFUNGAL LIFE CYCLE
InoculationInoculation
Spores contact susceptible bloomsSpores contact susceptible blooms
FUNGAL LIFE CYCLEFUNGAL LIFE CYCLE
PenetrationPenetration
Spore germinates and enters tissue Spore germinates and enters tissue directlydirectly
FUNGAL LIFE CYCLEFUNGAL LIFE CYCLE
InfectionInfection
Establishes hyphae in tissue and feeds Establishes hyphae in tissue and feeds on cellson cells
FUNGAL LIFE CYCLEFUNGAL LIFE CYCLE
Incubation periodIncubation period
Time between infection and Time between infection and appearance of symptomsappearance of symptoms
FUNGAL LIFE CYCLEFUNGAL LIFE CYCLE
InvasionInvasion
Spreads from bloom to other parts of Spreads from bloom to other parts of the plant within tissuethe plant within tissue
FUNGAL LIFE CYCLEFUNGAL LIFE CYCLE
DisseminationDissemination……
FUNGAL LIFE CYCLEFUNGAL LIFE CYCLE
OverwinterOverwinter
When temperature cools, fungus goes When temperature cools, fungus goes dormantdormant
Zombie FungusZombie Fungus
http://http://www.huffingtonpwww.huffingtonpost.com/ost.com/2011/09/14/2011/09/14/zombie-zombie-caterpillars-caterpillars-virus_n_962256.virus_n_962256.htmlhtml
Brazilian rain Brazilian rain forestforest
Controls antsControls ants
Infection pegs Infection pegs grow from grow from bodybody
Shoots at Shoots at passing antspassing ants