Diagnosing Plant Problems - North Dakota State University · plant death Damage Caused By Nonliving Factors •Lack of nutrients = stunting, yellowing, or death of older plant parts

3/22/2015

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Diagnosing Plant Problems

Steve Sagaser

NDSU Extension Service

Grand Forks County

Diagnosing

“Bee’s ”

a good detective

very observant

a good listener

open minded until all

facts are collected

aware - multiple causes

must be considered

Diagnosing ToolkitNarrow Down The Possibilities

Know What Questions To Ask

• Accurately identify the

plant

• Use Latin name including

cultivar

• Common names can cause

confusion

– Evergreen = pine, spruce,

juniper, yew, arborvitae

– Shade tree?

– Fruit tree?

What has changed recently?• Trenching

• Pesticides and fertilizers

• Mulch – organic / inorganic

• Standing water

• Construction or grade change

• Soil cultivation

• Pruning

• String trimmers

• Mowers

How Long Has the Plant Been in It’s

Current Location?

• Recently planted /

transplanted

• Balled and burlapped?

• Container grown?

• Potted?

• Bare Root?

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Recent Culture

• When was the problem first noticed?

• How quickly did the damage progress?

• What is the age of the plants?

• Is it one or all of the plants?

• How severe is the damage?

Recent Culture

• How was it planted?

• What pesticides and

fertilizers have been

used?

• Has it received regular

water?

• What’s the soil like –

acidic or alkaline / sodic?

Environmental Conditions or

What’s the Weather Been Like?

• Warm spells followed

by frost in the spring

• Dry weather may

cause wilting and

branch deathSpring frost damage to ash tree

What’s the Weather Been Like?

• Mild fall weather - may

encourage growth that won’t

harden off – plants are

damaged by sudden freezing

temperatures

• Dry fall and winter – may cause

sunscald on evergreen trees in

winter

Look for Symptoms

• Slow growth

– Short internodes on branches

• Quick growth

• Dried leaves

• Abnormal growth

– Twisted, galls, cankers, blisters,

• Dead plant parts

• Mosaic patterns on leaves…..alternating dark and light green patterns

Look for Signs

• Insects present – insect frass, mites &

webbing, insect eggs

• Fungal fruiting bodies

– Rhizosphaera

– Stigmina

– Powdery Mildew

– Bacterial Ooze (cucumber wilt)Brown Marmorated Stink

Bug Eggs

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Know the Plant’s Normal Appearance

• Plant species & cultivars have unique characteristics.

• Does the plant’s appearance differ from “normal?”

• Know a healthy plant to recognize an unhealthy plant.


• Many plants have leaf colors other than green.

• Some cultivars have naturally yellow to pale

green leaves.

Gold Flame Spirea Frobel Spirea


• Compare the "normal"

appearance of the

plant’s

– Overall size & shape

– Leaf shape & coloration

– Bark, stem or trunk

texture

• Season of the year Sugar Maple

leaf in fall

color

Norway Maple Leaf


Common Elderberry in summer

Sambucus canadensisGolden Elder in summer

Sambucus canadensis ‘Aurea’


• Larix laricina

• Larch in the

summer

Fall

Larch tree in winter.

Photo by Al Walters


Image Citation:WilliamM. Ciesla, Forest Health Management International, Bugwood.org

Ponderosa

Pine – Fall

needle

drop

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Define the Problem• Living Factors

– Insects, mites, rodents, rabbits, deer, humans

– Diseases – fungi, bacteria, viruses, nematodes)

• Non-living Factors

– Weather - wind, light, moisture, temperature, lightning, ice, hail, rain…

– Mechanical breakage, cars, construction equipment

– Chemicals– pesticides, fertilizers, winter de-icers.

Define the Problem• Examine the entire garden or landscape

• Are other kinds of plants included in the

damage?

• Check for:

– Soil conditions

– Flooding

– Drought

– Herbicide applications

– Light – too much or too little

– Mechanical damage

Define the Problem

• Examine the entire plant first

– leaves, stems, roots, fruit, and flowers

• Then - Look for patterns

• Symptoms easily distinguished

– Clear patterns? –probably caused by physical, mechanical, chemical

Glyphosate Damage

Define the ProblemSymptoms

random?

Usually pest

or disease

Zimmerman Pine Moth

Damage Caused by Living Factors

• If insects are present - look for patterns of damage

– Chewed ragged leaves = grasshopper, beetles, caterpillars, slugs

– Tunnels between upper and lower leaf surfaces = leaf miners

– Rolled leaves = leaf rollers

Photo by Whitney Cranshaw, Colorado State

University, Bugwood.org

Forest Tent Caterpillar

Birch Leaf Miner Damage

Damage Caused by Living Factors Japanese Beetle on Roses

Japanese

Beetle feed

on more

than 300

hosts

Damage caused by birds and

skunks digging for grubs

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Insects

Emerald Ash Borer

& Damage


Insects

– Sucking insects – cause

stippling, puckering,

spotting, yellowing –

could be mites, thrips,

scale, aphids

– Holes in branches,

trunk, stems, = borers

or sapsuckers

– Overall decline could be

soil born insects

Photo by Janet Knodel, ND SU Extension Service

Yellow-bellied Sapsucker &

damage


Mites and Insects

Spidermites

Scale Insects

Scale Crawler


Insects and Diseases – Hard to

Distinguish

• Fungal fruiting structures are sometimes hard to see

Lirula Needle Cast on

Meyer SpruceSpruce Bud Scale Insects on Fat

Albert spruce

Disease TriangleDamage Caused by Living Factors

Diseases

• Fungi = stem rots,

round leaf spots,

concentric rings,

discoloration, or

wilt

Tomato Early Blight

Note the

concentric rings

Tomato Late Blight

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Diseases

• Fruiting

structures are

sometimes

visible

Rhizosphaera

Needlecast

Stigmina

Needlecast


Insects and Diseases – Hard to

Distinguish

• Fungal fruiting structures are sometimes hard to see

Lirula Needle Cast on

Meyer SpruceSpruce Bud Scale Insects on Fat

Albert spruce


Diseases

• Bacteria

Bacterial Spot of tomato

Fireblight of Apple


Diseases

• Viruses

Tobacco Mosaic on tomato

Tobacco Mosiac on orchid leaves


Diseases

Photo: David B. Langston, University of Georgia, www.ipmimages.org

Cucumber Mosaic

Virus

Mosaic pattern on

cucumber leaf

Damage Caused By Nonliving Factors

De-icer used on street

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• Broken or girdled

stems

– String trimmers

– Mowers

– Car accident


• Freezing - death of exposed foliage

• Rapid low light to high light or vice versa = yellowing of leaves, reduced growth, leaf drop or death


• Too little light

reduces, delays, or prevents flowering, also results in very lanky, sparse growth

• Excessive heat = scorch symptoms on leaf tips and inter-veinal areas Elm, Ohio Buckeye, basswood, oak…


• Drought and waterlogging = similar symptoms on aboveground parts of the plant– Mainly chlorosis

(yellowing leaves)

– Abscission (shedding older leaves)

– Wilt – from lack of moisture

– Waterlogging of root zone = oxygen deficiency, death of roots, and wilt


Soluble salt injury on fern

Oedema on geranium leaf –

too much water


• Iron Deficiency

– interveinal

yellowing

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• Improperly

applied

chemicals =

leaf distortion, burn, chlorosis, bleaching, plant death


• Lack of

nutrients =

stunting,

yellowing,

or death of

older plant

parts

Grape Leaf potassium deficiency

Questions for Diagnosing Sick Plants

1. What kind of plant are you diagnosing?

2. What does a healthy plant look like?

3. What are common problems for the plant? (Example: What diseases

is the plant known to get? Does it always need a lot of sun or shade?)

4. What do you see that looks abnormal? (Example: Is the plant wilting?

Is the soil dry?)

5. Is part of the plant sick or the entire plant?

6. What are the signs and symptoms?

7. Are other plants in the same location sick too?

8. What does the site or environment around the plant look like?

9. Who knows about the plants or takes care of the plants?

10. When did the symptoms first appear?

11. What is the horticultural history, what’s been the care?

Questions for Diagnosing Sick Plants12. What is the environmental history, is the site known to be really wet

or really dry?

13. What does the client think the problem is? (too much fertilizer, too

much water, accidentally apply herbicide)

14. What diagnostic tools do you need to use? – pruning shears, camera,

microscope?

15. How will you take samples?

16. What resources are available - local extension agents, diagnostic lab,

soils lab?

17. What other information do you need to help you find the problem?

18. What is your diagnosis?

19. What is the significance of the problem?

20. What are your recommendations - management strategies or

control measures?

References

Alex X. Niemiera. Diagnosing Plant Problems. 426-714, Virginia

Cooperative Extension Retrieved, 11/2/2013 from

http://pubs.ext.vt.edu/426/426-714/426-714.html

Riley, M.B., M.R. Williamson, and O. Maloy. 2002. Plant disease

diagnosis. The Plant Health Instructor. DOI: 10.1094/PHI-I-2002-1021

Retrieved 11/5/13 from

https://www.apsnet.org/edcenter/intropp/topics/Pages/PlantDisease

Diagnosis.aspx

Ellis, Sarah D., Boehm, Michael J., and Chatfield, Jim. Diagnosing Sick

Plants. OSU Extension. Retrieved 11/5/13 from

http://ohioline.osu.edu/hyg-fact/3000/pdf/PP401_02.pdf

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Diagnosing Plant Problems - North Dakota State University · plant death Damage Caused By Nonliving Factors •Lack of nutrients = stunting, yellowing, or death of older plant parts