Diagnosis and Plant DisordersDiagnosis and Plant Disorders

Mark Grueber, Urban ForesterMark Grueber, Urban Forester

Missouri Department of ConservationMissouri Department of Conservation

Mark.Grueber@mdc.mo.govMark.Grueber@mdc.mo.gov

ObjectivesObjectives Distinguish between plant problems caused by living Distinguish between plant problems caused by living

and nonliving disorders.and nonliving disorders. Understand the principles of a systematic approach to Understand the principles of a systematic approach to

the plant diagnostic process.the plant diagnostic process. Learn to recognize the signs and symptoms of tree Learn to recognize the signs and symptoms of tree

disorders.disorders. Learn the various physiological disorders and injuries Learn the various physiological disorders and injuries

that can affect trees, and learn what treatments are that can affect trees, and learn what treatments are appropriate.appropriate.

Become familiar with various types of insect and Become familiar with various types of insect and disease problems and their impact on trees.disease problems and their impact on trees.

This is NOT an entomology and This is NOT an entomology and pathology class!pathology class!

Various plant pest classes are available at St. Various plant pest classes are available at St. Louis Community College @ MeramecLouis Community College @ Meramec

References can be a big help but References can be a big help but overwhelmingoverwhelming

Key TermsKey Terms

The Key Terms as listed in The Key Terms as listed in the Arborist’s the Arborist’s Certification Study Certification Study Guide will be defined Guide will be defined and and highlightedhighlighted throughout the throughout the presentation.presentation.

Challenges to diagnosisChallenges to diagnosis

Trees don’t talk!Trees don’t talk! Asking all the necessary Asking all the necessary

questionsquestions History is hard (or History is hard (or

impossible) to come byimpossible) to come by Tree owners don’t have Tree owners don’t have

a clue!a clue! Paradigm shift?Paradigm shift? Most of the time – it’s Most of the time – it’s

too latetoo late

What is disease?What is disease?

1.1. An impairment of health or a condition of abnormal An impairment of health or a condition of abnormal functioningfunctioning

2.2. Includes Includes anythinganything that damages plant health that damages plant health

Two Major Groups of Plant Health Two Major Groups of Plant Health ProblemsProblems

BioticBiotic – pertaining to a living organism; e.g. fungi, – pertaining to a living organism; e.g. fungi, bacteria, viruses and bacteria, viruses and nematodesnematodes [microscopic [microscopic roundworm] roundworm] as well as insect pests, mites, and other as well as insect pests, mites, and other animals; a.k.a. animals; a.k.a. infectious infectious as they can spread from one as they can spread from one plant to the next.plant to the next.

Abiotic Abiotic – – non living; a.k.a. non-infectious and include non living; a.k.a. non-infectious and include environmental problems such temperature and environmental problems such temperature and moisture extremes, mechanical and chemical injuries, moisture extremes, mechanical and chemical injuries, mineral deficiencies and many othersmineral deficiencies and many others

Diagnosis is a systematic processDiagnosis is a systematic process

A good diagnostician is A good diagnostician is a keen observer that a keen observer that looks at things logicallylooks at things logically

Unfortunately, we tend Unfortunately, we tend to shortcut the processto shortcut the process

Good diagnosis requires Good diagnosis requires careful examination and careful examination and systematic elimination systematic elimination of possibilitiesof possibilities

Systematic Steps to DiagnosisSystematic Steps to Diagnosis

1.1. Accurately identify the plant.Accurately identify the plant.

2.2. Look for a pattern of abnormality.Look for a pattern of abnormality.

3.3. Carefully examine the site.Carefully examine the site.

4.4. Note the color, size and thickness of the Note the color, size and thickness of the foliage.foliage.

5.5. Check the trunk and branches.Check the trunk and branches.

6.6. Examine the roots and root color.Examine the roots and root color.

1. Accurately identify the plant.1. Accurately identify the plant.

So, is this “normal?”So, is this “normal?”

2. Look for a pattern of abnormality.2. Look for a pattern of abnormality.

Non uniform usually = living causal Non uniform usually = living causal agentagent

Uniform usually = non-living causal Uniform usually = non-living causal agentagent

3. Carefully examine the site.3. Carefully examine the site.

Never underestimate site factors!Never underestimate site factors!

4. Note the color, size, and thickness 4. Note the color, size, and thickness of foliage.of foliage.

Various leaf irregularities may give Various leaf irregularities may give you a clue…you a clue…

5. Check the trunk and branches.5. Check the trunk and branches.

What caused this damage?What caused this damage?

6. Check the roots and root collar.6. Check the roots and root collar.

This frequently overlooked area is This frequently overlooked area is often the “root of the problem.”often the “root of the problem.”

Healthy roots and dead rootsHealthy roots and dead roots

What root/soil investigation can What root/soil investigation can show you…show you…

pH????

pH!!!

As you go through the process, try to As you go through the process, try to eliminate certain possibilities…eliminate certain possibilities…

???

X X

……and an opportunistic leaf spot. and an opportunistic leaf spot. Poor tree health is rarely the result Poor tree health is rarely the result of one condition, but rather a of one condition, but rather a complex complex [a combination of factors [a combination of factors that lead to the stress of decline of a that lead to the stress of decline of a tree] of abiotic and biotic tree] of abiotic and biotic contributors. Stress this to the tree contributors. Stress this to the tree owner!owner!

In Diagnosis, practice makes In Diagnosis, practice makes perfect…well, better.perfect…well, better.

The more you do diagnosis (properly), the The more you do diagnosis (properly), the better you’ll get.better you’ll get.

Don’t commit! Keep an open mind.Don’t commit! Keep an open mind. Look for the initial stressor – not necessarily Look for the initial stressor – not necessarily

what the tree owner is complaining about.what the tree owner is complaining about. NEVER, NEVER guess!NEVER, NEVER guess! Seek assistance – MDC, MoBot, SLCC, UMCSeek assistance – MDC, MoBot, SLCC, UMC

Diagnostic Process – Questions?Diagnostic Process – Questions?

Symptom vs. SignSymptom vs. Sign

SymptomSymptom – a plant’s reaction to a disorder– a plant’s reaction to a disorder SignSign – the physical evidence of a causal agent – the physical evidence of a causal agent

Symptom or Sign?Symptom or Sign?

Symptom or Sign?Symptom or Sign?

Symptom or Sign?Symptom or Sign?

Leaf spot – Leaf spot – patches of disease or patches of disease or other damage on plant foliageother damage on plant foliage

Size, shape and color Size, shape and color may varymay vary

Usually limited to a Usually limited to a small portion of the leafsmall portion of the leaf

Leaf blotchLeaf blotch – – irregularly shaped irregularly shaped areas of disease on plant foliageareas of disease on plant foliage

Larger than leaf spotsLarger than leaf spots Usually involves mostly Usually involves mostly

dead tissuedead tissue

BlightBlight – – any disease, regardless of any disease, regardless of causal agent, that kills young, plant causal agent, that kills young, plant

growing tissuesgrowing tissues

Involves death of leaves Involves death of leaves and twigsand twigs

A misused and A misused and misunderstood termmisunderstood term

ScorchScorch – – browning and shriveling of browning and shriveling of foliage, especially at the leaf marginfoliage, especially at the leaf margin

Tend to think of this Tend to think of this symptom related to symptom related to abiotic disordersabiotic disorders

Oak wilt foliage, Oak wilt foliage, bacterial leaf scorch bacterial leaf scorch (buckeye and oak)(buckeye and oak)

WiltWilt – loss of turgidity and – loss of turgidity and subsequent drooping of leavessubsequent drooping of leaves

Can look similar to Can look similar to blightblight

Leaves may or may not Leaves may or may not be deadbe dead

CankerCanker – – localized diseased area, localized diseased area, often shrunken and discolored, on often shrunken and discolored, on

stems and branchesstems and branches

Perennial vs. diffusePerennial vs. diffuse Another confused termAnother confused term

StuntingStunting – – growth reduction of growth reduction of organisms, in this case, plantsorganisms, in this case, plants

Be careful that it’s not Be careful that it’s not just new growthjust new growth

Foliage size can be Foliage size can be extremely variableextremely variable

Not just foliageNot just foliage

GummosisGummosis – – exudation of sap or exudation of sap or gum, often in response to disease or gum, often in response to disease or

insect damageinsect damage

Called Called resinosisresinosis in in conifersconifers

Sometimes found in Sometimes found in combination with combination with cankerscankers

RustRust – – disease caused by a certain disease caused by a certain group of fungi and characterized by group of fungi and characterized by

reddish brown spotsreddish brown spots

Can also form galls and Can also form galls and cankerscankers

GallGall – – swelling of plant tissues; swelling of plant tissues; frequently caused by insects frequently caused by insects nematodes, fungi, or bacterianematodes, fungi, or bacteria

Galls are a plant Galls are a plant response – not a cocoonresponse – not a cocoon

ChlorosisChlorosis – – whitish or yellowish whitish or yellowish discoloration caused by lack of discoloration caused by lack of

chlorophyll; often used in referring chlorophyll; often used in referring to a plant’s foliageto a plant’s foliage

Why is a lack of chlorophyll a problem?Why is a lack of chlorophyll a problem?

NecrosisNecrosis – – localized death of tissue in localized death of tissue in a living organisma living organism

DiebackDieback – – condition in which the condition in which the ends of the branches are dyingends of the branches are dying

Powdery MildewPowdery Mildew – white or grayish – white or grayish fungal growth on the surface of fungal growth on the surface of

stems or foliagestems or foliage

Vascular discolorationVascular discoloration – darkening of – darkening of the vascular tissues of woody plants the vascular tissues of woody plants

in response to diseasein response to disease

Witch’s broomWitch’s broom – plant disorder in – plant disorder in which a large number of accessory which a large number of accessory shoots developshoots develop

Trivia – what type of plants Trivia – what type of plants are sometimes created from are sometimes created from witch’s brooms?witch’s brooms?

Symptoms can be non-specificSymptoms can be non-specific

Will investigating this Will investigating this spot lead to a proper spot lead to a proper diagnosis?diagnosis?

Use other conditions Use other conditions (site, history etc.) to (site, history etc.) to form diagnosisform diagnosis

Signs and Symptoms Questions?Signs and Symptoms Questions?

Tree stressTree stress

Necessary basic factors: Necessary basic factors: sufficient water, optimal sufficient water, optimal temperature and light, temperature and light, and proper balance of and proper balance of nutrients – (Liebig’s law nutrients – (Liebig’s law of the minimum)of the minimum)

StressStress – factor that – factor that negatively affects the negatively affects the health of a treehealth of a tree

Acute stressAcute stress

Short termShort term Causes immediate Causes immediate

damagedamage More likely to recover?More likely to recover? AcuteAcute – disorder or – disorder or

disease that occurs disease that occurs suddenly or over a short suddenly or over a short period of timeperiod of time

ChronicChronic stress stress

Disorder or disease Disorder or disease occurring over a long occurring over a long period of timeperiod of time

How stress exhibits itselfHow stress exhibits itself

Reduced growthReduced growth Abnormal foliage color Abnormal foliage color

or sizeor size Vigorous watersproutsVigorous watersprouts Premature leaf dropPremature leaf drop Others?Others?

Common causes of stressCommon causes of stress

Site and/or environment Site and/or environment relatedrelated

Right tree, right place!Right tree, right place! HH22O, extreme cold, O, extreme cold,

adverse soil conditions adverse soil conditions (compaction), or (compaction), or mechanical damagemechanical damage

Can you “save” my tree?Can you “save” my tree?

Stress Questions?Stress Questions?

Break???Break???

Abiotic DisordersAbiotic Disorders

Often the primary stress factor(s) that cause Often the primary stress factor(s) that cause the spiral of declinethe spiral of decline

Can be difficult to recognize – often mimic Can be difficult to recognize – often mimic biotic disorders and are part of a complexbiotic disorders and are part of a complex

Tree and site history often give the best cluesTree and site history often give the best clues

Types of abiotic disordersTypes of abiotic disorders

Soil and site problemsSoil and site problems Physical and mechanical Physical and mechanical

injuriesinjuries Temperature extremesTemperature extremes Competition and Competition and

allelopathyallelopathy Pollution damagePollution damage Chemical injuryChemical injury

Soil and Site ProblemsSoil and Site Problems

Similar to root disorders Similar to root disorders this is commonly this is commonly overlookedoverlooked

Crown symptoms often Crown symptoms often are a result of poor root are a result of poor root healthhealth

““Transplant shock”Transplant shock” Urban soilsUrban soils

Physical and Mechanical InjuriesPhysical and Mechanical Injuries

Not Not physiological physiological disorderdisorder [a disorder not [a disorder not caused by insect, caused by insect, pathogen or injury]pathogen or injury]

Sudden injurySudden injury Extent of damage may Extent of damage may

initially be difficult to initially be difficult to assessassess

Very frustrating for tree Very frustrating for tree ownersowners

Competition and AllelopathyCompetition and Allelopathy

Plants are “vicious Plants are “vicious killers”killers”

Sunlight is usually the Sunlight is usually the primary factor resulting primary factor resulting in defect, reduced in defect, reduced growth or diebackgrowth or dieback

Available growing Available growing space is common space is common limiting factor in heavy limiting factor in heavy urban areasurban areas

Pollution DamagePollution Damage Acute and chronic injuryAcute and chronic injury Other factors: wind, Other factors: wind,

humidity, soil grade and humidity, soil grade and type, precipitation levels, type, precipitation levels, and conditionand condition

Mimic insect injury and Mimic insect injury and mineral deficienciesmineral deficiencies

Four major airborne Four major airborne pollutants: SOpollutants: SO22, fluoride, , fluoride,

ozone and PANozone and PAN Usually evident on foliageUsually evident on foliage

Chemical InjuryChemical Injury

Herbicides applied improperly most frequent culpritsHerbicides applied improperly most frequent culprits Trees are “broadleaf weeds”Trees are “broadleaf weeds” 2,4-D and dicamba work 2,4-D and dicamba work systemicallysystemically [substance that moves [substance that moves

throughout and is absorbed by the entire organism]throughout and is absorbed by the entire organism]

Biotic DisordersBiotic Disorders

Insects and Other PestsInsects and Other Pests Disease (in this case: fungi, bacteria, Disease (in this case: fungi, bacteria,

phytoplasmas, etc.)phytoplasmas, etc.)

What is an insect?What is an insect?

NOT an insect!NOT an insect!

Insects…Insects…

may or may not be host specificmay or may not be host specific may be predatory or parasitic on species of may be predatory or parasitic on species of

harmful insectsharmful insects have complex life cycles that may have both have complex life cycles that may have both

harmful and innocuous stagesharmful and innocuous stages most species have little to no effect on plant most species have little to no effect on plant

life – a fact that the tree owner may find life – a fact that the tree owner may find difficult to understanddifficult to understand

Feeding damage is characterized by Feeding damage is characterized by the mouthpartsthe mouthparts

Chewing – leaves, flowers, buds, twigs, stems Chewing – leaves, flowers, buds, twigs, stems (borers)(borers)

Piercing-sucking – leaves, flowers, buds, twigs Piercing-sucking – leaves, flowers, buds, twigs and stemsand stems

Chewing InsectsChewing Insects

May feed on entire leafMay feed on entire leaf May feed on leaf May feed on leaf

marginsmargins May May skeletonizeskeletonize [leaves [leaves

that have had the tissue that have had the tissue removed from between removed from between the veins by inects]the veins by inects]

May tunnel between May tunnel between leaf tissuesleaf tissues

May bore through woodMay bore through wood

““Marginal” feedersMarginal” feeders

Piercing-sucking Insects(?)Piercing-sucking Insects(?)

Some pierce plant cells Some pierce plant cells and feed on the contentsand feed on the contents

May also cause May also cause phytotoxic effects from phytotoxic effects from secreted chemicalssecreted chemicals

Usually don’t kill trees Usually don’t kill trees outright, but cause outright, but cause stressstress

Ewwww! Bug poop!Ewwww! Bug poop! Don’t forget the mites!Don’t forget the mites!

ScalesScales

Others…Others…

Insects…Insects…

Can also be Can also be vectorsvectors [organism that transmits a] [organism that transmits a] pathogenpathogen [causal agent of a disease] [causal agent of a disease]

NematodesNematodes

Microscopic Microscopic roundworms most of roundworms most of which are not parasites which are not parasites of plantsof plants

Important for organic Important for organic decaydecay

May enter tree through May enter tree through roots, wounds, stomata, roots, wounds, stomata, or directly into plant or directly into plant cellscells

DiseasesDiseases

Four requirements are Four requirements are necessary for a pathogen to necessary for a pathogen to infectinfect

Most pathogens are host Most pathogens are host specificspecific

The afflicted plant part will The afflicted plant part will give an indication of the give an indication of the severity of diseaseseverity of disease

Most plant diseases are Most plant diseases are caused by fungicaused by fungi

FungiFungi

Most plant diseases are caused by fungi.Most plant diseases are caused by fungi. Not all are bad! Don’t forget mycorrhizae.Not all are bad! Don’t forget mycorrhizae. Almost every plant can be infected by fungi – Almost every plant can be infected by fungi –

most are to some extent during the growing most are to some extent during the growing season.season.

Infection severity and extent depends on the Infection severity and extent depends on the resistance and vitality of the plant.resistance and vitality of the plant.

Diseases that cause Diseases that cause defoliationdefoliation – loss – loss of leaves from a tree or other plant of leaves from a tree or other plant by biological or mechanical meansby biological or mechanical means

Vascular DiseasesVascular Diseases

BacteriaBacteria

Only two of major Only two of major importanceimportance

Infected plant tissues Infected plant tissues may appear water may appear water soaked and have a foul soaked and have a foul odorodor

Phytoplasmas and Phytoplasmas and VirusesViruses

Used to be called Used to be called Mycoplasma like Mycoplasma like organisms (MLOs) now organisms (MLOs) now PLOsPLOs

Not much is knownNot much is known No important viral No important viral

diseases on treesdiseases on trees

How can I be learn more?How can I be learn more?

MDC Plant Diagnostic Lab – Dr. Bruce Moltzan MDC Plant Diagnostic Lab – Dr. Bruce Moltzan (Pathologist) and Dr. Rob Lawrence (Entomologist)(Pathologist) and Dr. Rob Lawrence (Entomologist)

Updates: My e-mail list: Updates: My e-mail list: Mark.Grueber@mdc.mo.govMark.Grueber@mdc.mo.gov Community Tree CouncilCommunity Tree Council Missouri ForestKeepers Network: Missouri ForestKeepers Network:

www.forestkeepers.orgwww.forestkeepers.org How to take a sampleHow to take a sample ReferencesReferences

Now that I know…Now that I know…

It’s all about preventionIt’s all about prevention Too much improper pesticide useToo much improper pesticide use More next week!More next week!