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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 Plant Problems

Steve Sagaser NDSU Extension Service Grand Forks County

Diagnosing Toolkit

Narrow 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?

Environmental Conditions or What’s the Weather Been Like? • Warm spells followed by frost in the spring

• Dry weather may cause wilting and branch death

Spring frost damage to ash tree

Look for Symptoms

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?

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 Signs

• 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

• 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.

Know the Plant’s Normal Appearance Gold Flame Spirea

Frobel Spirea

• 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.

Know the Plant’s Normal Appearance

Know the Plant’s Normal Appearance

Norway Maple Leaf

• 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 Common Elderberry in summer Sambucus canadensis

Know the Plant’s Normal Appearance • Larix laricina • Larch in the summer

Golden Elder in summer Sambucus canadensis ‘Aurea’

Know the Plant’s Normal Appearance

Fall

Ponderosa Pine – Fall needle drop Larch tree in winter. Photo by Al Walters

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

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Define the Problem

Define the Problem

• Living Factors

• Examine the entire garden or landscape • Are other kinds of plants included in the damage? • Check for:

– Insects, mites, rodents, rabbits, deer, humans – Diseases – fungi, bacteria, viruses, nematodes)

• Non-living Factors

– Soil conditions – Flooding – Drought – Herbicide applications – Light – too much or too little – Mechanical damage

– Weather - wind, light, moisture, temperature, lightning, ice, hail, rain… – Mechanical breakage, cars, construction equipment – Chemicals– pesticides, fertilizers, winter de-icers.

Define the Problem

Define the Problem Symptoms random? Usually pest or disease

• 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

Zimmerman Pine Moth

Damage Caused by Living Factors

Damage Caused by Living Factors

Forest Tent Caterpillar

Japanese Beetle on Roses

• 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

Japanese Beetle feed on more than 300 hosts

Birch Leaf Miner Damage Photo by Whitney Cranshaw, Colorado State University, Bugwood.org

Damage caused by birds and skunks digging for grubs

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Damage Caused by Living Factors Insects Emerald Ash Borer & Damage

Damage Caused by Living Factors Mites and Insects

Damage Caused by Living Factors 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

Damage Caused by Living Factors Insects and Diseases – Hard to Distinguish

Spidermites

• Fungal fruiting structures are sometimes hard to see

Scale Insects

Scale Crawler Spruce Bud Scale Insects on Fat Albert spruce

Disease Triangle

Lirula Needle Cast on Meyer Spruce

Damage 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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Damage Caused by Living Factors Diseases Rhizosphaera Needlecast

Damage Caused by Living Factors Insects and Diseases – Hard to Distinguish • Fungal fruiting structures are sometimes hard to see

• Fruiting structures are sometimes visible Stigmina Needlecast

Spruce Bud Scale Insects on Fat Albert spruce

Damage Caused by Living Factors Diseases Bacterial Spot of tomato • Bacteria

Lirula Needle Cast on Meyer Spruce

Damage Caused by Living Factors Diseases • Viruses Tobacco Mosaic on tomato

Fireblight of Apple

Damage Caused by Living Factors Diseases

Tobacco Mosiac on orchid leaves

Damage Caused By Nonliving Factors De-icer used on street

Cucumber Mosaic Virus Mosaic pattern on cucumber leaf Photo: David B. Langston, University of Georgia, www.ipmimages.org

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Damage Caused By Nonliving Factors • Broken or girdled stems – String trimmers – Mowers – Car accident

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

Damage Caused By Nonliving Factors • 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

Damage Caused By Nonliving Factors • Freezing - death of exposed foliage

Damage Caused By Nonliving Factors • Drought and waterlogging = similar symptoms on aboveground parts of the plant

Elm, Ohio Buckeye, basswood, oak…

Damage Caused By Nonliving Factors

– Mainly chlorosis (yellowing leaves) – Abscission (shedding older leaves) – Wilt – from lack of moisture – Waterlogging of root zone = oxygen deficiency, death of roots, and wilt

Damage Caused By Nonliving Factors

Soluble salt injury on fern

• Iron Deficiency – interveinal yellowing Oedema on geranium leaf – too much water

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Damage Caused By Nonliving Factors

Damage Caused By Nonliving Factors Grape Leaf potassium deficiency

• Improperly applied chemicals = leaf distortion, burn, chlorosis, bleaching, plant death

• Lack of nutrients = stunting, yellowing, or death of older plant parts

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 Plants 12. 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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