Diagnosing Diagnosing Tree Disorders Tree Disorders
in the in the LandscapeLandscape
What is a plant disease?What is a plant disease?
Anything that damages plant healthAnything that damages plant health
Plant pathology deals with infectious Plant pathology deals with infectious organisms that reduce plant health, organisms that reduce plant health, multiply, and spread: biotic diseasesmultiply, and spread: biotic diseases
Plant DiseasesPlant Diseases
Biotic FactorsBiotic Factors– VirusesViruses– Bacteria Bacteria – FungiFungi– NematodesNematodes
Abiotic FactorsAbiotic Factors– Environmental Environmental
ProblemsProblems– HerbicidesHerbicides– Nutritional DeficienciesNutritional Deficiencies– PollutantsPollutants
Damage from herbivoresDamage from herbivores
Animals and RodentsAnimals and Rodents
Insects Insects
MitesMites
NematodesNematodes
Insect Damage IdentificationInsect Damage IdentificationKnow Common Pest Arthropod Groups!Know Common Pest Arthropod Groups!
Numerous lepidopteran caterpillars (ex. Numerous lepidopteran caterpillars (ex. armyworms, armyworms, cutworms)cutworms)Beetles (Order Coleoptera): numerous leaf-Beetles (Order Coleoptera): numerous leaf-feeding and wood-boring pestsfeeding and wood-boring pestsSawflies (Order Hymenoptera)Sawflies (Order Hymenoptera)Various flies (Order Diptera)Various flies (Order Diptera)Various insects with piercing-sucking Various insects with piercing-sucking mouthparts including scales, mealybugs, mouthparts including scales, mealybugs, whiteflies, aphids, psyllids, hoppers, various whiteflies, aphids, psyllids, hoppers, various other members of the Order Hemiptera.other members of the Order Hemiptera.Spider MitesSpider Mites
Symptoms vs. signsSymptoms vs. signs
SymptomsSymptoms are changes in growth or are changes in growth or appearance of a plant in response to a appearance of a plant in response to a damaging factordamaging factor
SignsSigns are evidence of the damaging factor are evidence of the damaging factor
Symptom or sign?Symptom or sign?
DiagnosisDiagnosis
Compare plants with disorder to healthy Compare plants with disorder to healthy plantsplants– Roots, stems, leaves, fruitsRoots, stems, leaves, fruits
Ask questions! Ask questions! – History, conditions, variety, soil, etc.History, conditions, variety, soil, etc.
Hypothesis of causeHypothesis of cause
Diagnosis - ContinuedDiagnosis - Continued
Look for signs of pathogen Look for signs of pathogen – Microscopic examinationMicroscopic examination– Culturing on artificial mediaCulturing on artificial media– Immunological methods (ELISA, etc)Immunological methods (ELISA, etc)– Nucleic acid methods (PCR, etc)Nucleic acid methods (PCR, etc)– Electron microscopeElectron microscope
Look for signs of insect or animalLook for signs of insect or animal– Organism itself, eggsOrganism itself, eggs– FrassFrass– HoneydewHoneydew– WebbingWebbing
What questions do you ask?What questions do you ask?
History: herbicide application, fungicide History: herbicide application, fungicide application, insect activityapplication, insect activity
Pattern: isolated plant, entire field, near Pattern: isolated plant, entire field, near edges, etc? Any spread?edges, etc? Any spread?
Any variety differences?Any variety differences?
Certified planting stock?Certified planting stock?
What are viruses and viroids?What are viruses and viroids?Very small particles of nucleic acid and Very small particles of nucleic acid and protein (viruses) or naked nucleic acid protein (viruses) or naked nucleic acid (viroids)(viroids)
icosahedral rods flexuous rods geminivirus
tospovirus viroid inclusion body
Symptoms of VirusesSymptoms of Viruses
Plum Pox VirusPlum Pox Virus
Bacterial diseasesBacterial diseases
Bacteria are single-celled, prokaryotic Bacteria are single-celled, prokaryotic organism (lack a membrane around the organism (lack a membrane around the nucleus of the cell)nucleus of the cell)Most plant pathogenic bacteria are Most plant pathogenic bacteria are gram negative, which means they do gram negative, which means they do not retain the stain crystal violet when not retain the stain crystal violet when you do a gram stainyou do a gram stain– LPS (lipopolysaccharide) layer around cell LPS (lipopolysaccharide) layer around cell
wall wall
What do bacteria look like?What do bacteria look like?Can’t see with the naked eye unless Can’t see with the naked eye unless there are a LOT of themthere are a LOT of them
Culture on artificial media (some are not Culture on artificial media (some are not culturable on media)culturable on media)
Bacterial disease symptomsBacterial disease symptoms
Fire blightFire blightErwinia amylovoraErwinia amylovora
Apple, pear, mountain Apple, pear, mountain ash, raspberry, ash, raspberry, hawthorne, contoneasterhawthorne, contoneaster
What are fungal diseases?What are fungal diseases?Cause the majority of economically Cause the majority of economically significant plant diseasessignificant plant diseases
Caused by fungi – organisms with Caused by fungi – organisms with threadlike hyphae and reproductive threadlike hyphae and reproductive structures (spores)structures (spores)
Fungal Plant DiseasesFungal Plant Diseases
Root Diseases - Soilborne Root Diseases - Soilborne and Residue borne and Residue borne – CankersCankers– RotsRots– WiltsWilts
Foliar Diseases – Foliar Diseases – Residue borne, wind-Residue borne, wind-blown and rain-splashed blown and rain-splashed sporesspores– Leaf spots and leaf moldsLeaf spots and leaf molds
Fungal symptoms & signsFungal symptoms & signs
Dutch Elm Disease in MontanaDutch Elm Disease in Montana
Beetle Galleries
Lesser European ElmBark Beetle
Staining in twig
Cytospora canker - SpruceCytospora canker - Spruce
Verticillium WiltVerticillium Wilt
Root Rots and DiseasesRoot Rots and Diseases
Wind-thrown Trees
ArmillariaPhytopthora
Sudden Oak Death Sudden Oak Death Phytopthora ramorumPhytopthora ramorum
RhizosphaeraRhizosphaera needle cast needle cast Rhizosphaera kalhkoffiiRhizosphaera kalhkoffii
Rainsplash dispersedRainsplash dispersed
Symptoms:Symptoms:– Reduced needle retentionReduced needle retention– Dead (brown) older needlesDead (brown) older needles– Healthy, new needles do not show signs of Healthy, new needles do not show signs of
infectioninfection
Powdery mildewPowdery mildewObligate Parasite Spores airborne over long distances –
Nematodes: a very small, worm-like Nematodes: a very small, worm-like animalanimal
Pine Wilt NematodePine Wilt Nematode
Piercing Sucking InsectsPiercing Sucking Insects
Insects with Insects with piercing-sucking piercing-sucking mouthparts cause mouthparts cause stippling and/or stippling and/or chlorosis on the host.chlorosis on the host.
Example groups: Example groups: aphids, true aphids, true bugs, bugs, hoppers, scale hoppers, scale
insects, insects, whiteflieswhiteflies
Plant Bugs
Aphids
Sooty MoldSooty Mold
Leaf minersLeaf miners
Insects that produce Insects that produce characteristic characteristic “mines” in leaves by “mines” in leaves by feeding.feeding.
Formed by various Formed by various insects including insects including flies, wasps, moths, flies, wasps, moths, and beetles.and beetles.
birch leafminer
Leaf DefoliatersLeaf Defoliaters
Damage caused to a Damage caused to a plant by insect plant by insect feeding. feeding.
““Skeletonizing” Skeletonizing” results when the results when the veins or the veins or the “skeleton” of the “skeleton” of the leaf is left behind.leaf is left behind.
Grasshoppers
Japanese Beetles
Spider Mite DamageSpider Mite Damage
•• Leaf damage Leaf damage includes flecking, includes flecking, bronzing, bronzing, and/or and/or scorching of scorching of leaves.leaves.
•• Several natural Several natural enemies. Most enemies. Most problematic problematic in heavy in heavy insecticide use insecticide use areas.areas.
twospotted spider mite
Damage by Boring InsectsDamage by Boring InsectsInsects that bore Insects that bore into a stem, or into a stem, or seedheadseedheadDamage often Damage often results in weakening results in weakening or killing the hostor killing the host
Emerald Ash BorerEmerald Ash BorerWhat does the damage look like?What does the damage look like?
1. Canopy starts to thin and water sprouts may start
2. Serpentine feeding just below bark3. Small, D-shaped exit hole4. Woodpecker damage another clue to
infestation
Emerald Ash BorerEmerald Ash BorerWhat does it look like?What does it look like?
1. Adult is metallic green, about ½ inch
2. Larvae are flat bodied, about 1 inch
3. Larvae pupate in the tree and adults emerge from D shaped exit holes
Cottony Ash PsyllidCottony Ash Psyllid
Woodpeckers and SapsuckersWoodpeckers and Sapsuckers
PorcupinesPorcupines
Deer and Elk RubsDeer and Elk Rubs
Drought DamageDrought Damage
Trees will shed leaves Trees will shed leaves and needles to and needles to prevent water lossprevent water loss
Herbicide?Herbicide?
HistoryHistory
Soil analysis or bioassaySoil analysis or bioassay
Tissue analysisTissue analysis
Symptoms of herbicide Symptoms of herbicide injuryinjury
Winter InjuryWinter Injury
Desiccation
Frost Damage
Seasonal Needle CastSeasonal Needle Cast
Planting too deepPlanting too deep
Iron Deficiency - ChlorosisIron Deficiency - ChlorosisCommon in high pH Soils
• Apply sulfur to lower soil pH• Apply chelated iron fertilizer foliar or soil applications
How to be a diagnosticianHow to be a diagnostician
Know the plant involved Know the plant involved – What a healthy plant looks like!What a healthy plant looks like!
Look for symptoms and signsLook for symptoms and signs
Look for patternsLook for patterns
Question the environmentQuestion the environment
Make a diagnosis, and check the facts!Make a diagnosis, and check the facts!
Montana State UniversityMontana State UniversitySchutter Diagnostic LabSchutter Diagnostic Lab
Physical addressPhysical address
121 Plant BioScience Bldg. (PBB)
Mailing AddressMailing Address
119 Plant BioScience Bldg.
P.O. Box 173150
Bozeman, MT 59717-3150
(406) 994-5150
http://diagnostics.montana.edu/