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1
Plant Disease and Diagnosis
Dr. Tamla Blunt
Plant Pathologist
Colorado State University
Why Do We Need to Know Plant Pathology?• A lot of the questions at the Help Desk are about
plant problems• Plant Pathology give you a background in types of
plant problems• Terminology/definitions/descriptions are important
in Plant Pathology (kind of like a foreign language)• We use terms like ‘generally’, ‘usually’, ‘consistent
with’, ‘sometimes’, ‘it depends’• A background in PP can help you with the
diagnostic process; determine what questions to ask your clients
Plant Problem Diagnosis
Diagnosis –process used for the identification of problems; consider it ‘CSI’
for plants
Tools:• Plant sciences, especially plant pathology and
entomology• Art of investigation and detective work
Some Other Tools• Items that are handy to
have in a sample collection/plant diagnostic toolbox:• Hand lens/ magnifying
glass/binoculars;• Pocket knife;• Soil probe;• Shovel;• Small notebook
w/pencil;• Plastic baggies;• Small saw/hand pruners
What is a Plant Disease?Abnormal growth/ dysfunction of a plant
Environment Causal Agent
Host
Plant Disease Pyramid/Triangle
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Plant Problem Diagnosis Steps• Know the normal appearance of the plant
• Symptoms and Signs
• Abiotic vs. Biotic• Review environmental conditions
• How do symptoms/signs progress?
• Review cultural practices
• Observe patterns
• Ask questions
• Consult literature/control measures/final diagnosis
Identify The Plant
•Why?• Typical “MO”• Known “enemies”• Is this normal?• Is it normal this time of
year?
Identify The PlantKnow Normal Appearance
of Plant• Plant identification.
• Scientific vs. common names
• Variety or cultivar
• Recognize healthy plant appearance.
• What’s normal?
Is This Normal For These Plants?
Plant Problem Diagnosis Steps• Know the normal appearance of the plant
• Symptoms and Signs
• Abiotic vs. biotic• Review environmental conditions
• How do symptoms/signs progress?
• Review cultural practices
• Observe patterns
• Ask questions
• Consult literature/control measures/final diagnosis
SymptomsSymptom: A plant’s reaction
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Chlorosis: Loss of Green ColorMosaic: Varying Patterns of Light and Dark Plant Tissue
Necrosis: Dead Plant TissueBlight: Sudden Death
Wilting: Limp, Droopy Canker: Sunken, Discolored Areas
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Stunting: Lack of Plant Growth Galls: Localized Swellings
Distortion: Mal/De-formed Plant Tissue
Where are the Symptoms?
• Leaves
Phyton 27 damage to poinsettia
Where are the Symptoms?
• Stems (BUT leaves or other parts above stem may also show symptoms)
Where are the Symptoms?
• Roots (BUT plant parts above may show symptoms)
Root Rot
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Where are the Symptoms?
Flowers
Fruit
Plant Problem Diagnosis Steps• Know the normal appearance of the plant
• Symptoms and Signs
• Abiotic vs. biotic• Review environmental conditions
• How do symptoms/signs progress?
• Review cultural practices
• Observe patterns
• Ask questions
• Consult literature/control measures/final diagnosis
SignsSigns: Presence of the actual organism causing the problem
Ooze: Slime-like droplets(Bacteria)
Usu.edu
Fruiting Structures (Fungi)
Cleistothecia Acervuli with setae (bristles)
Perithecia
Fruiting Structures Embedded in Plant Tissue
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Hyphae: Thread-like Vegetative Growth of Fungi; Mycelium is a Mass of Hyphae
Spore Structures: Hold Masses of Fungal Spores
Mildew: Whitish Growth Produced by Specific Fungi
Mushrooms/Conks: Fleshy or Firm Reproductive Structures
Symptom vs. SignSymptom = effect Sign = cause
Symptoms vs. Signs
Example: Lilac
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Symptoms vs. Signs
Recently killed tissue (halo)
Fruiting Structures(underside)
Group Activity
But first, using a hand lens!Symptoms vs. Signs Activity 1
Symptoms vs. Signs Activity 2
This sample
These samples
+
Plant Problem Diagnosis Steps• Know the normal appearance of the plant
• Symptoms and Signs
• Abiotic vs. Biotic• Review environmental conditions
• How do symptoms/signs progress?
• Review cultural practices
• Observe patterns
• Ask questions
• Consult literature/control measures/final diagnosis
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Causal Agents of Plant Disease
• Biotic = living causes such as microorganisms
• Abiotic = non-living causes such as the environment
Abiotic Causes of Disorders:
• Too low/too high temperatures
• Lack of/excess soil moisture
• Lack of or excess light
• Nutrient deficiencies
• Soil type/pH
• Pesticide toxicity
Weather- Related Problems:
• Yearly dry fall/winter period
• Drought
• Late spring freezes
• Prolonged cool wet weather
• Early fall snow
• Sudden fall freeze
• Hail
• Flooding
Temperature
• High Temperature Effects• Plants are generally
injured faster and to a greater extent when temps become higher than the maximum for growth
• Sunscald• Cankers • Leaf scorch
Sunscald aka SW Disease of Trees• Intense radiation by
sunlight on south or southwest side of thin-barked trees
• De-acclimates bark• Predisposes to temperature
damage• Freezing/thawing
• Sunscald predisposes trees to canker pathogens
• Protect bark• White paint (water-based)
• Boards
• Paper wraps (be sure to remove in spring)
Photos by Bill Jacobi
Honeylocust & Ash tree
with sunscald damage
Temperature• Low Temperature Effects
• Does more damage to plants than high temps
• Kills buds, flowers, leaves and twigs
• Can cause root damage and bark splitting and canker development
• Early fall frost/freeze and late spring frost/freeze are the most susceptible times for most plants
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Weather: Spring Freeze Injury-Deciduous
• Blackened, wilted tissue
• Dead twigs, buds
• Sprouting
Freeze Injury
• Tip of leaf exposed
Spring Freeze Injury – Spruce, Fir
Iowa State University
Freeze – Rose Flowers• Spring/early summer 2008
• “Bullheading”
• Cold at time of floral organ development
Freeze- Summary
• Shows up 1-2 days after event
• Rapid necrosis
• Uniform damage to same-aged leaves
• Malformation to less severely damaged plant parts
• Late spring & early fall are most common times for low temp plant (flower/foliage) injury• Water freezes and disrupts cell membranes• Symptoms may resemble foliage/shoot diseases caused by
pathogens
Moisture
• Low soil moisture effects• Plants grow poorly• Plants are unproductive• Stunted appearance• Usually pale green to light
yellow• Can wilt and die• Scorched leaves• Dieback
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Moisture
• Scorch: Leaves turn brown from outer edges inward; generally evenly distributed around the leaf margin
Moisture
• Winter desiccation common on conifers• Needle scorching• Twig dieback
• Frozen soils don’t allow for water uptake which is needed because of transpiration during winter
Moisture
• Winter desiccation: needles brown from tips inward
Drought Injury Examples
How Does Drought Happen?
• Water lost faster than replacement
• May not have sufficient water for roots
• Water available, BUT roots not functioning/soil frozen
• Stem/trunk damage
Additional Facts:
• New growth usually masks damage
• Large percentagemust be damaged before plant health endangered
• Feel buds to check health
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Additional Facts:
• Disease organism erupts through needles
Hyg.ipm.illinois.edu
Cold damage starts at tips of needles and moves down; no organisms erupt through needles
Drought Management
• Identify possible causes/correct
• Fall and winter water: apply water monthly to absorbing roots from Nov 1 - March 1
• Fall water most critical
• Roots still functioning until soil temp drops below 40 degrees
Why Do Roots Not Function Well?
• Soil compaction
• Construction damage
• Dehydration
• Suffocation
• Planted too deep
•Leaves smaller than normal•Poor plant growth/yellowing•Slow death
Oxygen Starvation
Soil Oxygen Starvation
• Soil compaction
• Excess water
• Poor soil drainage
• Poor siting
• Excess mulch
• Stem girdling roots
Cultural/Soil Problems:Oxygen Starvation
• Leaves yellow/die from inside of plant outward and bottom up
• Premature leaf drop
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Stem Girdling Roots
• Holes too small, narrow
• Plant too large for container
• Soil texture differences
Symptoms of Stem Girdling Roots
• Off color foliage
• Smaller leaves
• Leaf scorch
• Dieback
• Early fall color
• Lower trunk bulged/flattened
Oxygen Starvation Caused by:
Compacted soil
Oxygen Starvation Caused by:
• Impermeable/slowly impermeable soil coverings
Mulch Volcanoes
• Traps/retains moisture….or sheds it
• Suffocates phloem under bark
• Root growth into mulch instead of soil
• Rodents/other mammal feeding
Oxygen Starvation Caused by:
Excess water
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Flooding• Standing water
• Sediment
• Even short term flooding can cause damage to trees• Moving soil from root
zone
• Oxygen deprivation
Oxygen Starvation Caused by:
• Planting too deep• No root flare
Tree Planting Depth Cultural example:
Overwatering, poor soil drainage
Possible Tree Damage Symptoms From Oxygen Starvation
• Iron chlorosis
• Crown dieback
• “Early fall”
• Poor growth
Oxygen Starvation Management
Determine the cause/make corrections (sometimes corrections are not possible)
• Improve soil drainage/ aeration
• Remove black plastic
• Pull mulch away from base
• Reduce mulch thickness
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Wind Damage
Rubbing
Tattering
Nutrients
• Macronutrients• Needed in relative large
quantities by plants• N, P, K
• Micronutrients• Most soils contain
sufficient micronutrients for growth but there are exceptions
• Ca, S, Fe, Mg, Mn, B, Zn
Nutritional Deficiencies
• Nitrogen• Highly mobile in plants• Plants grow poorly• Light green in color• Lower leaves turn
yellow or light brown• Stems are short and
slender
Nutritional Deficiencies
• Calcium• Young leaves become
distorted with tips hooked back and margins curled
• Leaves may be irregular in shape and ragged with brown scorching or spotting
• Terminal buds finally die• Plants have poor, bare root
systems• Causes blossom end rot of
many fruits• Increases fruit decay in
storage
Blossom End Rot• Physiological disorder caused by Ca
deficiency• Ca important component of cell walls,
membranes
• Very fast growing tissues (like fruit) may not have enough Ca, causing problems with cell wall formation
• Certain plants and varieties more prone to damage
• Damage more severe early in growing season
• Avoid rapid plant growth• Excessive N fertilizer and soil moisture
fluctuations promote disorder
Blossom End Rot
• Apply water to garden plants more evenly
• Apply mulch to soil to keep moisture levels more even
• Avoid excessive nitrogen fertilization
• Calcium sprays don’t work; calcium must be transported through vascular tissue
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Nutritional Deficiencies
• Iron• Young leaves become
severely chlorotic• Main veins remain
characteristically green• Sometimes brown spots
develop• Part of or entire leaves
may dry• Leaves may be shed
Factors that Aggravate Iron Chlorosis• Susceptible plant species
• Cool soils and conditions that restrict air movement
• Poorly drained soils
• Compaction or use of plastic mulching
• Removal of topsoil exposing lime-enriched soil
• Planting close to house foundations
Soil Amendments for Iron Chlorosis
• Acidifying nitrogen fertilizers• Ammonium sulfate
• Elemental sulfur• 1 to 1 ½ lbs sulfur per 100
square feet to lower pH by one unit (maybe)
• Iron sulfate
• Combination of sulfur + iron sulfate
Chemical Injury
• Cautions regarding diagnosing chemical injury:• Unless the client is willing to have the plant tested for
chemical injury, there can never be a positive diagnosis• When talking with clients, the terminology is ‘damage
appears consistent with’…………• Testing for chemicals is $$$$$$• Testing labs?
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Chemical Injury • Symptoms vary, depending on
product/chemical/application
• Loss of green leaf color, loss of interveinal leaf color, wilting
Often there is twisting, curling, distortion, spotting, browning, discoloration
Chemical Injury
Phenoxy (growth regulator) herbicide damage
Chemical Injury
Phenoxy type herbicide
Herbicide Symptoms• Phenoxy herbicides
Chemical Damage Example:
Dicamba applied under tree’s dripline.
Herbicide Symptoms
• Upward cupping of leaves
• Epinasty=bending, twistingof petioles and stems
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Epinasty on Tomato
Glyphosate
Herbicide Symptoms• “Feathering” or strap- like leaves
Chemical Injury
aka phytotoxicity—toxic effect on a plant by a compound/chemical
Plant Problems Which Mimic Herbicide Injury
Arthropod Injury to Plants
Plant Problems Which Mimic Herbicide Injury
• Poor drainage or other root zone problems
• Salt spray injury
• Virus diseases
• Environmental stresses
• Nutritional deficienciesMg deficiency in apple
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Abiotic Disorders Recap
Plant EnvironmentInteraction
Plant Problem Diagnosis Steps• Know the normal appearance of the plant
• Symptoms and Signs
• Abiotic vs. Biotic• Review environmental conditions
• How do symptoms/signs progress?
• Review cultural practices
• Observe patterns
• Ask questions
• Consult literature/control measures/final diagnosis
Causal Agents of Plant Disease
• Biotic = living causes such as microorganisms
• Abiotic = non-living causes such as the environment
Biotic Causes of Disease
• Living organisms that cause plant problems• Fungi• Bacteria • Virus• Phytoplasma• Nematodes• Parasitic Plants• Animals (not covered here)• Insects (a different
presentation)
Fungi and Bacteria Are Spread by:
• Wind
• Water (rain, irrigation)
• Soil
• Animals (including us)
• Equipment
• Plant Material
• Insects
Fungi and Bacteria Infect by:
• Entering the plant through natural openings• Stomates• Lenticils
• Entering through wounds
• Producing enzymes that break down cuticle
Lenticels
Sooty bark canker
Wound
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Fungi and Bacteria Cause:
• Leaf spots and curling
• Galls
• Soft rots
• Wilts
• Cankers
• Stem and root rots
Fungi Characteristics:
• Variety of sizes
• No chlorophyll
• Most harmless to plant health (saprophytes)
• Most reproduce by spores
Margins?•Marginal areas often exist between dead and healthy tissue in fungal infections
Distinct margins usually point to fungal problem and will often have a halo around the margin
But Beware of Exceptions…
Some fungal diseases have feathery margins!
Black spot rose
Apple scab
Fungal ID Tips
• Dry, fluffy (fuzzy)
• Distinct borders
• Damage is random
Powdery Mildew • Gray or white web-like covering
• Looks like flour or talcum powder spill
• Host specific
• Requires humidity but not free moisture
• Very common on plants in Colorado
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Plant Damage from P.M.
• Aesthetic damage – discoloration• Reddening?
• Distortion
• Premature leaf drop
• Chronic stress
Powdery Mildew Management
Plant
Organism Environment
Fungicides, sulfur
Water
Potassium or sodium bicarbonate
Neem or horticultural oil
Time
Use Caution! Cultural Management
• Site correctly (avoid dead air pockets)
• Space for good air circulation• Prune/thin appropriately for
plant• Avoid over fertilization• Avoid overwatering• Keep water out of plant • Water early in day• Remove infected material• Rake up fallen leaves …why?
Marssonina Leaf Spot
• Characteristics:• Spots are necrotic,
various sizes • May cause premature
leaf drop• May lead to chronic
stress
Marssonina Leaf Spot
• Infection occurs at budbreak
• Problem appears mid summer
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Marssonina Leaf Spot Management
Plant
Organism Environment
No resistant cultivars
Fungicide: Daconil(protectant - at bud break)
Rake up leaves
Proper spacing, thinning, pruning
Keep water out of canopy
Time
To Compost or Not to Compost, That is the Question…
• Must be “hot” compost ( at least140 degrees, consistent throughout the pile)
• Disease organisms are everywhere
Group Activity Activity 5
This picture and samples from the books
Activity 5
Black spot of rose
Cytospora Canker• Colorado’s #1 canker-causer
• Cottonwood, aspen, willow, spruce
• Weak pathogen, successfully attacks stressed plants
• What is a canker?• Sunken, usually discolored area • Fungal cankers contain fruiting
structures • Conductive tissue under canker is
killed
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Fruiting Structures embedded in the bark
Orange spore tendrils protruding from opened fruiting structures of aspen, cottonwood, willow
Colorado Spruce with CytosporaCanker
Cytospora Canker Management
Plant
Organism Environment
No resistant cultivars
No effective fungicides
Prune out affected tissue
Grow healthy tree
Time
Group Activity—How to Key Out a Problem But first, two things…
• Reference book
• Using a hand lens
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Activity 3
This picture and sample
Bacteria Characteristics:
• Single-celled, microscopic
• Move by flagella
• Reproduce by dividing in two
Bacteria ID Tips
• Often slimy
• Greasy or water-soaked appearance
• Stinky
• Leaf spots often angular
Example: Fireblight
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Fireblight
• Characteristics:• “Shepherd’s crooking”• Blossom blight• Fruit shrivels
• Damage• Bacteria kills tissue• Reduces food production• Affects fruit production• Aesthetics
Cankers form
Bacterial ooze formsBacterial Streaming
Fireblight Hosts:
• Must be in Rosaceousfamily
• Can occur on ornamentals, not just on pome-fruit bearing plants• Ornamental pears
• Apples• Fruiting pears
• Does not form on Prunus(cherry, plum)
Fireblight:
• Conditions:• Moisture present • Temperatures 60 to 65
degrees • Blossoms present in some
cases
• Fireblight spreads:• Insects (including pollinators)• From an old infection• Through pruning tools
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Fireblight Management
Plant
Organism Environment
Plant resistant varieties
Proper spacing, thinning
Keep water out of canopy
Pruning Fireblight Damaged Trees
• Prune 6-12 inches below visible infection (when dormant; if not dormant prune at least 18 inches below visible infection)
• Disinfect pruning tool between cuts
• Use 1:9 bleach solution OR
• Disinfectant sprays, rubbing alcohol
Group Activity—Bacteria
Activity 4This sample and book
Virus Characteristics
• Submicroscopic particles
•Nucleic acid and protein
•Disrupt cell metabolism
•Obligate parasite (can’t survive outside of host)
•Systemic
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Viruses
• One virus may infect one or dozens of different species of plants
• Each species of plant is usually attacked by many different kinds of viruses
• A plant may be infected by more than one kind of virus at the same time
• Viruses do not form reproductive structures, such as spores
Virus Dispersal and Infection
• Spread by someinsects, nematodes; in plant material and mechanically (tools)
• Insect spreads virus during feeding
How Do Viruses Move from Plant to Plant?
• Terminology: Vector/vectoring
• Viruses cannot move on their own• Non-motile
• Transmission• Mechanical
• Vegetative
• Insects and other arthropods (mites)
• Nematodes
• Dodder
• Seed
• Pollen
• Plasmodiophoromcyetes• Protists (fungal-like) that infect roots and
transmit viruses
Insect Transmission of Plant Viruses: The Jargon
• Vector = insect (or other means) of transmitting the virus from plant to plant
• Non-persistent (stylet-borne; e.g. aphids)
• Semi-persistent (foregut-borne)
• Persistent (Leafhoppers, Thrips)
Viruses Cause Symptoms:• Mottling
• Mosaic
• Crinkling
• Stunting
• Leaf spots
Tomato Spotted Wilt Virus
• Wide host range (500+)
• Directly affects plant health
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Tomato Spotted Wilt Virus• Transmitted by thrips
• Symptoms include stunting, fruit distortion, leaf flecking, dieback
TSWV Symptoms
• Wilting, spotting, crinkling
Ces.ca.uky.edu
TSWV Symptoms
Ringspots may form
Cankers may form
TSWV symptoms
Ringspots, malformation of fruit
Vector: Western Flower Thrips
•Larvae are tiny (1/16”), tubular•Pupate in soil under plant OR•In crevices on plant or in flowers
Recognizing Thrips Injury
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Tomato Spotted Wilt Virus Management
Plant
Organism Environment
Some resistant varieties (of tomatoes)
Remove infested plants
SpinosadSticky traps?
Other Virus Examples
Rose Mosaic Virus
Peony Ringspot Virus
Plant-disease.ippc.orstate.edu
Mechanical Transmission
• Classic example is tobacco mosaic virus• Virus affects
tobacco, tomato and many other solanaceous hosts
Photo courtesy D. Shew, N.C State
Tomato (Tobacco) Mosaic
• Mechanically transmitted
• Leaf yellowing and mottling; rugosity
• Fruit distortion
• Resistant varieties
Phytoplasma Characteristics
•Cellular
•Lack cell walls
•Obligate parasites (can’t live outside of host )
Phytoplasma Dispersal and Infection
• Infected plant material
• Insect vectors• Mostly leafhoppers• Migrate north
www.insectimages.org
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Phytoplasmas
• Characteristics:
• Distortion
• Sterile flowers
• Yellowing or purpling of foliage
• “Witches broom” or “rat tail” appearance
• Hairy roots (carrots)
• Several phytoplasmas:• Ash Yellows
• Aster Yellows
Phytoplasma Management
Plant
Organism Environment
No resistant cultivars
No chemical controls
Remove infected plants
Repeated sprays/short intervals (for insect control)
Parasitic Plants
• May have roots, stems, leaves and flowers
• Reproduce by true seeds• Have little to no
chlorophyll• Spread via:
• Sticky seeds• Wind• Animals
• Damage plants by removing food from the host plant
Nematode Characteristics:
• Microscopic roundworms (but not true worms)
• Plant pathogenic nemas have spear-like stylets (mouthparts)
• Require free water
• Reproduce by eggs
Mouth
Stylet Nematodes• Spread by:
• Moving in water
• Infected plant material
• Soil
• Insect vectors
• Symptoms of nematode problems:• Stunting• Yellowing• Root knots• Poor growth
• Wilting• Death
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How Do You Sort It All Out?
Abiotic• Uniform
• No signs
• Numerous species (usually)
Biotic• Random• Signs present (maybe)• One species or related species
Abiotic? Biotic?
• Random vs. Uniform
Group ActivityActivity 6Abiotic vs. Biotic
Activity 7: answer questions
These samples
Plant Problem Diagnosis Steps• Know the normal appearance of the plant
• Symptoms and Signs
• Abiotic vs. biotic• Review environmental conditions
• How do symptoms/signs progress?
• Review cultural practices
• Observe patterns
• Ask questions
• Consult literature/control measures/final diagnosis
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Plant Problem Diagnosis Steps
• How do symptoms progress?• Biotic disease –
symptoms progress and nearby plants become infected.
• Abiotic disease –generally a lack of symptom progression.
• Exception – nutritional symptoms progress slowly.
Plant Problem Diagnosis Steps• Know the normal appearance of the plant
• Symptoms and Signs
• Abiotic vs. biotic• Review environmental conditions
• How do symptoms/signs progress?
• Review cultural practices
• Observe patterns
• Ask questions
• Consult literature/control measures/final diagnosis
Plant Problem Diagnostic Steps
• Review cultural practices:• Proper planting
technique(s)?• Fertilizer use? • Pesticide application?
Phytotoxicity?• Insecticides• Herbicides• Fungicides
• Irrigation frequency and amount?
• Handwatering vs irrigation system?
• Soil type/compaction?
Plant Problem Diagnosis Steps• Know the normal appearance of the plant
• Symptoms and Signs
• Abiotic vs. biotic• Review environmental conditions
• How do symptoms/signs progress?
• Review cultural practices
• Observe patterns
• Ask questions
• Consult literature/control measures/final diagnosis
Plant Problem Diagnosis Steps
• Observe patterns:• Determine prevalence
of problem• Large area/All plants –
generally abiotic• Scattered, localized –
generally biotic• Check for distribution of
symptoms
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Examine Smaller Branches (Twigs)
Growth Increments
• Overall health clue• Sometimes easier to determine on conifers
Plant Problem Diagnosis Steps
• Know the normal appearance of the plant
• Symptoms and Signs
• Abiotic vs. biotic• Review environmental conditions
• How do symptoms/signs progress?
• Review cultural practices
• Observe patterns
• Ask questions
• Consult literature/control measures/final diagnosis• Use site:edu after search term when looking on the internet
Ask Questions
• Consider:• Many folks don’t offer
(know!) all the information• About 6 major symptoms for
hundreds of causes• Cause may be what
homeowner is doing/not
Ask More Questions! (More clues)
• Age of plant? • Exposure of plant?• When first noticed?• Has it happened before?• How has the plant been cared for?• Any other plants damaged?• What time of year is it?• Weather concerns?
Examine Smaller Branches
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Look at Leaves Look at Flowers
Ask for Photographs
Lower trunk
Upper trunk
Analyze information
• Research/read/references
• Is a lab test needed?
• Do you need more info?
• Analyze information
Analyze information
• Start with biotic
• Move to abiotic
• Consider primary vs. secondary (contributing) factors
Primary vs. Secondary Factor
• What is really causing the problem? (1)
• What is contributing to the problem? (2)
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Significance of Findings
• Is IT a problem or normal?
• Is IT affecting plant health (or will it)?
• Is IT affecting aesthetics?
• What does the client want?
• What can reasonably be done?
• Provide the client with all research based information-let them decide the course of action
“The first surefire rule of plant diagnostics is nothing is surefire” - Boggs, Draper, Chatfield, Ellis, Boehm, the OSU Extension
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