Perspectives in Diagnosing Landscape Plant Problems HCS Course

1
Perspectives in Diagnosing Landscape Plant
ProblemsHCS Course 210 - Landscape
HorticultureNovember 4, 1999
Jim Chatfield Ohio State University Extension
2
The study, diagnosis, and treatment of plant
diseases, penetrating to the very heart of
darkness of nature gone wrong, is mans most
pressing calling.
- Jacques le Mauvais
3
Plant Disease Defined

• A malfunctioning of host cells and tissues that
  results from their continuous irritation by a
  pathogenic agent or environmental factor and
  leads to the development of symptoms. Disease is
  a condition involving abnormal changes in the
  form, physiology, integrity or behavior of a
  plant. Such changes may result in partial
  impairment or death of the plant or its parts.
• From Plant Pathology - Agrios

4
For disease to occur which of the following are
necessary?

• A. A virulent pathogen.
• B. An environment conducive to disease
  development.
• C. A susceptible host plant.
• D. All three are necessary
• for disease to occur.

5
True or False.
To control diseases with fungicides, applications
must be made before the fungus enters plant
tissue.
6
Which of the following is not a plant pathogen?

• A. Fungus (pl. fungi)
• B. Bacterium (pl. bacteria)
• C. Virus (pl. viruses)
• D. Aphid (pl. aphids)
• E. Nematode (pl. nematodes)

7
Are there plant pathogens in each of the five
kingdoms of life on earth?

• A. Animals
• B. Plants
• C. Monera (Bacteria)
• D. Protista
• E. Fungi

8
Which of the following are ways that fungi and
bacteria spread?

• A. Contaminated seed
• B. Wind-blown rain
• C. Pruning shears
• D. Animals
• E. All of the above

9
Which of the following diseases is caused by the
same fungus that causes powdery mildew of rose?

• A. Powdery mildew of bluegrass.
• B. Powdery mildew of lilac.
• C. Powdery mildew of zinnia.
• D. All of the above.
• E. None of the above.

10
True or False.
Prior to World War II, rose black spot was worse
than powdery mildew on greenhouse-grown roses
after World War II, powdery mildew was worse than
black spot.
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Which of the following are helpful in controlling
black spot of roses?

• A. Avoiding overhead irrigation, to the extent
  possible.
• B. Plant in a sunny location.
• C. Enhance air movement by weeding and pruning
  surrounding vegetation.
• D. Use resistant varieties.
• E. Use preventive fungicides.
• F. All of the above.

12
Taxus (yew) does not thrive in overly wet,
poorly-drained soil. Is this because its roots
become unhealthy in such soils or because the wet
soils are ideal for certain plant pathogens, such
as water mold fungi?
13
With each of the following diseases, how do the
fungal pathogens survive from one year to the
next?

• Crown gall
• Verticillium wilt
• Dutch elm disease
• Apple scab disease
• Diplodia tip blight

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Phytopathological Paradigms

• 1. Timing is everything for chemical disease
  control.
• 2. Most plant problems are not infectious
  diseases.
• 3. Most infectious diseases cause little plant
  harm.
• 4. Symptoms develop well after infection.
• 5. Many pathogens have narrow host ranges.

15
Anthracnose Leaf Blights
The time is late June. You have positive
confirmation of anthracnose on samples of ash and
sycamore that you sent in to the OSU Plant and
Pest Diagnostic Clinic. You have tall tree
spraying equipment and labeled fungicides for
control of these diseases? Should you spray?
16
Phytophthora Root and Crown Rots
True or False. If you have a plant with
Phytophthora root rot it will ultimately be
killed by this fungus.
17
Rose Black Spot

• This disease is caused by a fungus that infects
  rose leaves only if there is moisture on these
  leaves for a certain number of hours. Yet, there
  were tremendous outbreaks of this disease in some
  large rose gardens this past summer several weeks
  following a long, intense hot and dry spell.
• WHY?

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Verticillium Wilt Diseases
What about this list is relevant to a discussion
of Verticillium wilt disease?

• All Conifers
• Birch
• Crabapple
• Dogwood
• Holly

• Oak
• Pear
• Planetrees
• Sweet Gum
• Willow

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Verticillium Wilt Diseases
What about this list?

• Ash
• Barberry
• Catalpa
• Elm
• Magnolia

• Maple
• Redbud
• Russian Olive
• Tuliptree
• Viburnum

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Verticillium Wilt Prevention Management

• Purchase of Verticillium-free plant material.
• Water management
• Maintain root health
• Overall health management
• Use of resistant varieties

21
Apple Scab Prevention Management

• Use crabapple selections with good scab
  resistance and good horticultural qualities.
• Early-season sprays, as soon as petals fall.
• Proper pruning and sanitation.

22
Diplodia (Sphaeropsis) Tip Blight Prevention
Management

• Site susceptible pines in moist, well-drained
  sites.
• Promote root health.
• Provide for good air movement.
• Time sprays just before new growth develops.

23
Nematodes do which of the following?

• Parasitize plant roots
• Parasitize plant stems
• Feed on bacteria and fungi
• Cause human disease
• Live in soil
• Live in water
• Help control insects

24
Assisted Herb-icide
Are you guilty of the seven deadly sins of
iatrogenicide?

• Poor Plant Selection
• Planting Too Deep
• Overmulching
• Overwatering
• Overfertilizing
• Overmowing
• Second Degree Girdling

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Ten Contributing Factors In Disease Complexes

• Defoliation by diseases or insects.
• Drought or excess water.
• Cold injury to bark tissue.
• Root injury from compaction.
• Direct root damage during construction.
• Root injury from soil added over root system.
• Girdling roots
• De-icing salts
• Trunk wounds
• Nutrient deficiency

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Tree Decline Prevention Management

• Match tree to site.
• Proper irrigation, fertilization, pruning and
  other maintenance.
• Limit major environmental changes.
• Proper diagnosis.
• Realistic prognosis and removal decisions.

From Plant Health Care for Woody
Ornamentals - Lloyd (Rane Pataky)
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Ten Keys to Plant and Site Selection
1. Timing is everything. 2. Read the
site. 3. Test the site. 4. Read the
client. 5. Horticulturists, know they plants.
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Ten Keys to Plant and Site Selection - CONTINUED
6. Size does matter. 7. Disease and pest
resistance. 8. Consider all selection
factors. 9. Special situations. 10. Expand
our palettes.
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Dr. Treevorkians Ten Rules for Plant Selection.

• 1. Death Taxus - Plant in wet sites.
• 2. Shade your rose garden unter der lindens.
• 3. Promote Japanese maples as the next grate
  street tree.
• 4. Try silver maples as foundation plants.
• 5. Companion plant tip of the day Walnuts and
  tomatoes.

• 6. Plant No Hopa crabapples.
• 7. White pines for the white
• lines.
• 8. Basic Rhody Cocktail Lots
• of Water with a Lime
• Chaser
• 9. Forever Impatiens.
• 10. Zoysiagrass Grave blankets of the
  future.

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All crabapples are pretty much the same, except
for disease resistance. - George
Blakeslee
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Malusize Your Mind!
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Apple Scab Rating System

• 0 No scab noted.
• 1 Slight scab, less than 5 of leaves affected.
• 2 Moderate scab, 5-20 of leaves affected,
  some
• yellowing, little or no defoliation.
• 3 Extensive scab, 20-50 of leaves affected,
• significant defoliation.
• 4 Heavy scab, 50-80 of leaves affected,
  severe
• defoliation.
• 5 Extreme scab, 80-100 of leaves affected,
  complete or near-complete defoliation.

33
Secrest Crabapple Trials No Scab - 1993-1996

• Malus baccata Jackii
• Beverly
• Bob White
• Dolgo
• Prairifire

• Red Jewel
• Malus sargentii
• Silver Moon
• Malus tschonoskii
• White Angel

Based on 14 ratings over 4 years.
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Key Features of Ornamental Crabapples

• Fruit
• Flower
• Form
• Foliage

35
The term fruitless crabapple is an oxymoron!
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Aesthetics Rating System
Based on flower, foliage, fruit or form at time
of ratings.

• 1 Exceptionally ornamental crabapple
• 2 Highly ornamental crabapple
• 3 Adequate as ornamental crabapple
• 4 Substandard as ornamental crabapples
• 5 Unacceptable as ornamental crabapple.
• Not recommended.

37
Secrest Crabapple Trials Aesthetic Ratings -
1993-1996

• Molten Lava 1.7
• Donald Wyman 2.2
• Red Jewel 2.2
• Prairifire 2.4
• Sentinel 2.4
• Mary Potter 2.5

• Strawberry 2.5
• Parfait
• White Cascade 2.5
• Bob White 2.6
• Sugar Tyme 2.6

Based on 50 ratings over 4 years.
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Secrest Crabapple Trials Aesthetic and Scab
Ratings - 1993-1996

• Molten Lava 1.7 1.1
• Donald Wyman 2.2 1.1
• Red Jade 2.2 1.2
• Prairifire 2.4 0.0
• Sentinel 2.4 0.7
• Mary Potter 2.5 0.5
• Strawberry Parfait 2.5 0.1
• White Cascade 2.5 2.2
• Bob White 2.6 0.0
• Sugar Tyme 2.6 0.7

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Secrest Crabapple Trials Scab and Overall
Ratings - 1993-1996

• Malus baccata Jackii 0.0 2.8
• Beverly 0.0 3.7 Ugly fruit mummmies
• Bob White 0.0 2.6
• Dolgo 0.0 4.1 Large, messy fruits
• Prairifire 0.0 2.4
• Red Jewel 0.0 2.2
• Malus sargentii 0.0 3.1
• Silver Moon 0.0 3.4
• Malus tschonoskii 0.0 DEAD Fireblight
• White Angel 0.0 3.6 Awkward shape

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OSU Crabapple Team Projects

• Aesthetic Evaluations
• Fruit and Flower Longevity Studies
• Disease and Insect Evaluations
• Rootstock Studies
• Fertilization Studies
• Crablandia
• Crabaganza 2000!
• CrabNet
• Brooklyn Botanic Gardens

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All hollies do poorly in wet sites.
A. True B. False
42
Plants typically considered acid-loving include
A. River birch B. Red maple C. Pin oak D. All
of the above
43
Once planted, it is easy to alleviate iron
chlorosis problems on trees.
A. True B. False
44
Which plants in each of the following pairs will
do better in wet sites
A. Taxus or Taxodium B. Norway maple or red
maple C. American holly or winterberry holly
45
Which of the following three components of the
disease triangle should be considered when making
plant selection decisions.
A. Susceptible host plant B. Virulent pathogen C.
Environment conducive to disease D. All of the
above
46
For which of the following plants should
susceptibility to Verticillium wilt disease be a
selection consideration in replant decisions?
A. Smokebush B. Japanese maple C. Redbud D.
All of the above
47
Dolgo crabapple has excellent genetic
resistance to apple scab disease
A. True B. False
48
Dolgo crabapple is an excellent choice for a
site near a sidewalk entrance to a hospital
A. True B. False
49
Which of the following is not true?
A. Tomatoes are sensitive to juglone from black
walnut trees. B. Adirondack crabapples
are spreading weepers. C. In most cases, tar
spot of maple causes little damage to plant
health. D. Cytospora canker is a common disease
of spruce.
50
Flowering dogwoods should be planted in either
full sun or dense shade situations.
A. True B. False
51
True or False

• Bald cypress should be planted only in wet,
  swampy sites.

52
True or False

• Katsuratree should only be planted in shady,
  protected locations.

53
True or False
All rhododendrons need shady locations.
54
Guignardia Leaf Blotch of Aesculus
Which of the following is least susceptible to
this disease?

• Aesculus glabra
• Aesculus hippocastanum
• Aesculus pavia
• Aesculus octandra
• Aesculus x arnoldiana Autumn Splendor
• Aesculus parviflora

55
Examples of Roses Resistant to Black Spot

• Hybrid Teas Chrysler Imperial, Tropicana
• Floribundas/Grandifloras Betty Prior, Sonia
• Shrub Roses All That Jazz, Carefree Wonder
• Miniatures Gourmet Popcorn, Rose Gilardi
• Rugosa Hybrids Polyantha, The Fairy
• Note Resistance may vary from one area to
  another.

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PLANT FAMILIES
What is the plant family for these ornamentals?

• A. Amelanchier --- serviceberry
• B. Aronia --- chokeberry
• C. Cotoneaster --- cotoneaster
• D. Crataegus --- hawthorn
• E. Malus --- crabapple
• F. Potentilla --- potentilla or cinquefoil

G. Prunus --- cherry, almond, plum H. Pyracantha
--- firethorn I. Pyrus --- pear J. Sorbus ---
mountainash K. Rosa --- rose L. Spiraea ---
spiraea
57
These plants are all in the rose family
(Rosaceae).

• True or False
• Bacterial fireblight occurs only on plants in the
  rose family.

58
What family are the following plants in and what
are a few cultural requirements that they share?

• A. Enkianthus
• B. Kalmia
• C. Rhododendron
• D. Vaccinium

59
Diagnose this problem.

• You own a garden center and one of your best
  customers brings in several twigs of a
  rhododendron. Some of the leaves are gone but
  others still remain on the twig, brown and rolled
  up in little cylinders. What might the problem
  be?

60
Diagnose this problem.

• You are a landscape installer and while on a
  job, a neighbor of your customer stops over,
  admires your work , and asks you to take a look
  at a few plants in their yard. They expect that
  the problem is due to lawncare herbicide injury.
  They show you a silver maple that has new foliage
  with parallel venation and leaf strapping, Taxus
  that has yellowed new foliage, and a Trident
  maple with curled leaves. What do you tell them?

61
Dieback of branches on maple might be due to
which of the following

• A. Verticillium wilt disease
• B. Root decline
• C. Salt injury
• D. Winter injury
• E. Trunk damage
• F. All of the above

62
Common Ornamental Fungicides

• Common Name
• metalaxyl
• PCNB
• thiophanate-methyl
• triadimefon
• triforine
• vinclozolin

• Brand Name(s)
• Subdue
• Terrachlor
• Clearys 3336, Domain, Fungo
• Bayleton
• Funginex
• Ornalin

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Plant Disease Publications You Should Have

• Buckeye Yard and Garden Line (fischnich.1_at_osu.ed
  u) and Buckeye Yard and Garden online on
  Horticulture in Virtual Perspective
  (http//hortwww-2.ag.ohio-state).
• Diseases of Landscape Plants. OSU Extension
  Offices. Revised edition due out in Winter of
  1997.

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Plant Disease Publications You Should Have

• Common Insect Pests and Diseases of Ornamental
  Trees and Shrubs. Slide sets, color pictures,
  fact sheets developed by OSU Extension.
  Published by Ohio Nursery and Landscape
  Association.
• 800-825-5062.
• Diseases of Trees and Shrubs. Wayne A.
  Sinclair, Howard H. Lyon Warren T. Johnson.
  1987. Cornell University Press, 124 Roberts
  Place, Ithaca, NY 14850.

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Buckeye Yard Garden LineE-mail
SubscriptionJim ChatfieldOSU Extension -
Northeast District1680 Madison AvenueWooster,
OH 44691Phone [phone]FAX
330/263-3667E-Mail chatfield.1_at_osu.edu
66
Buckeye Yard Garden onLinehttp//www.hcs.ohio
-state.edu/bygl.html
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In What Other Job Would You Get to

• Teach in a one-room schoolhouse by kerosene
  lantern?
• Disagree with Ronald Reagan on Network TV?
• Have pesticide recommendations be received with
  hallelujahs?
• Intertwine stories of family plant growth for
  hundreds of thousands?
• Have freedom to create informational resources
  used nationwide?

68
The average salaries for OSU Extension Agents are

• Agr. Natural Resources - 42,707
• Family Consumer Sciences - 38,840
• 4-H - 37,368
• Community Res. Development - 38,578

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What Field Faculty Do

• Writing for trade publications, media, journals.
• Teaching a wide variety of topics locally and
  state-wide.
• Representing OSU and agricultural science to the
  media and public.
• Troubleshooting diagnostic challenges.
• Team-Working at many levels.
• Creating new ways to help clientele.
• Developing specialized expertise.

70
BONUS Which of the following song
lyrics are correct?

• . Clown control to Mao Zedong.
• . Ants are my friends.
• . The girl with colitis goes by.
• . Scuse me while I kiss this guy.
• . And Lady Mondegreen.
• . None are correct.