Master Gardener Volunteer Management System Instructions
2013 Green Industry Training: Tree Insects and Diseases
1. Landscape Pests & Diseases:
Diagnosis and Treatment
Leslie Lyles, M.S.
Horticultural Consultant
I.S.A. Certified Arborist (#WE-1220A)
2. Have you ever noticed…
There are more insect and disease
problems in the urban forest than
in natural forests.
3. Urban Forest VS Natural Forests
Increase stress pre-disposes trees to vigor related
diseases. Since the forest is the normal ecological
niche for trees, it would be expected, in most
cases, that more stress would be found in shade
trees than in forest trees.
4. Don’t Stress Me Out!
When a plant is stressed, it is much more susceptible
to attack by insect and disease organisms. Typically,
95% or greater of the problems seen in the landscape
can be traced back to a cultural (abiotic) cause.
5. Stresses affecting plant health:
Compacted soil
Reflective heat
Sparse or excessive water supply
Insufficient nutrients
Chemicals (pesticides, fertilizers)
Soil Problems (salinity, pH, Boron)
Air Pollution
Accidents, vandalism, neglect
Infestation by pests and disease organisms
6. Urban Forest VS Natural Forests
Increase stress pre-disposes trees to vigor related
diseases. Since the forest is the normal ecological
niche for trees, it would be expected, in most
cases, that more stress would be found in shade
trees than in forest trees.
A major responsibility of the diagnostician is to
provide necessary information regarding care to
maintain vigor and to prevent or alleviate as many
adverse stress factors as possible.
8. What can cause Problems?
Abiotic Causes:
Environmental stress
9. What can cause Problems?
Abiotic Causes:
Environmental stress
– Flooding or Drought
10. What can cause Problems?
Abiotic Causes:
Environmental stress
– Flooding or Drought
– Soil problems (Salinity, Boron)
11. What can cause Problems?
Abiotic Causes:
Environmental stress
– Flooding or Drought
– Soil problems (Salinity, Boron)
– Freeze
12. What can cause Problems?
Abiotic Causes:
Environmental stress
– Flooding or Drought
– Soil problems (Salinity, Boron)
– Freeze
– Scorch
13. What can cause Problems?
Abiotic Causes:
Environmental stress
– Flooding or Drought
– Soil problems (Salinity, Boron)
– Freeze
– Scorch
– Air Pollution
14. What can cause Problems?
Abiotic Causes:
Environmental stress
– Flooding or Drought
– Soil problems (Salinity, Boron)
– Freeze
– Scorch
– Air Pollution
– Reflective Heat
15. What can cause Problems?
Abiotic Causes:
Environmental stress
People pressure
16. What can cause Problems?
Abiotic Causes:
Environmental stress
People pressure
– Soil compaction and construction damage
17. What can cause Problems?
Abiotic Causes:
Environmental stress
People pressure
– Soil compaction and construction damage
– Lawn mower and string trimmer damage
18. What can cause Problems?
Abiotic Causes:
Environmental stress
People pressure
– Soil compaction and construction damage
– Lawn mower and string trimmer damage
– Children
19. What can cause Problems?
Abiotic Causes:
Environmental stress
People pressure
– Soil compaction and construction damage
– Lawn mower and string trimmer damage
– Children
– Improper handling and planting
20. What can cause Problems?
Abiotic Causes:
Environmental stress
People pressure
– Soil compaction and construction damage
– Lawn mower and string trimmer damage
– Children
– Improper handling and planting
– Poor plant selection and placement
21. What can cause Problems?
Abiotic Causes:
Environmental stress
People pressure
– Soil compaction and construction damage
– Lawn mower and string trimmer damage
– Children
– Improper handling and planting
– Poor plant selection and placement
– Poor cultural practices
22. What can cause Problems?
Abiotic Causes:
Environmental stress
People pressure
Biotic Causes:
Micro-organisms
Macro-organisms
23. What can cause Problems?
Biotic Causes:
Micro-organisms
– Fungi
– Bacteria
– virus
24. What can cause Problems?
Biotic Causes:
Micro-organisms
– Fungi
– Bacteria
– virus
Macro-organisms
– Insects
– Animals
– parasitic plants
25. In general:
Non-infectious disorders (abiotic causes)
typically affect the entire plant and more
than just one plant.
26. In general:
Non-infectious disorders (abiotic causes)
typically affect the entire plant and more
than just one plant.
Infectious disorders (biotic causes) typically
affect only a portion of a plant, and not
necessarily every plant of the same species.
28. What is disease?
Abnormal physiology resulting from the
continuous interaction between a host and
a primary causal agent resulting in
characteristic symptoms.
29. Disease Triangle
Environment Pathogen
Ab
s
bu
Diseas e severity
es
un
nd
en
da
a
bl
nc
ra
e
vo
Fa
Duration V irulence
Resistance Disease escape
Host Plant
There must be three factors present for disease development:
susceptible host, pathogen, and a suitable environment. If
any of these factors are absent, there is no disease.
32. Most common pathogens:
Fungi - powdery mildew, vascular wilts,
Cytospora, Dutch elm disease
Bacteria- Fireblight, some bacterial wilts,
wetwood
33. Most common pathogens:
Fungi - powdery mildew, vascular wilts,
Cytospora, Dutch elm disease
Bacteria- Fireblight, some bacterial wilts,
wetwood
Virus - Rose mosaic virus
34. Treatment of disease:
Cultural control – Work to prevent the
disease and it’s spread
– Appropriate watering
– Removal of diseased plant tissue
– Select resistant varieties
– Crop rotation
35. Treatment of disease:
Foliar disease
– Practice good cultural control
– typically, fungicidal sprays are effective
42. Treatment of disease:
Foliar disease
Stem
– typically no good chemical control
– preventative sprays for some i.e., Fireblight
– Practice good cultural control; proper pruning
(proper cut, timing, disinfect tools)
51. Treatment of disease:
Foliar
Stem
Root
– keep trees vigorous
– avoid wounding roots and heavy pruning
– Practice good cultural control (manage
irrigation, prevent soil compaction or root
damage, avoid infected plants)
55. Treatment of disease:
Foliar
Stem
Root
Vascular
– increase vigor with fertilization and water
– systemic chemicals in very early stages
– cultural control (control insect vectors,
eradicate infected host plants)
59. Treatment of insect problems:
Not all insects cause problems! Know what the
insect is and the plant’s/client’s level of tolerance
before treating.
64. Earwig
Garden spider
Parasitic wasp
Assassin bug
Beneficial? Yes
65.
66.
67. Treatment of insect problems:
Not all insects cause problems! Know what the
insect is and the plant’s/client’s level of tolerance
before treating.
Consider cultural control and least toxic methods
first (hosing plant, soap solutions, oil sprays,
pruning).
77. Treatment of insect problems:
Not all insects cause problems! Know what the
insect is and the plant’s/client’s level of tolerance
before treating.
Consider cultural control and least toxic methods
first (hosing plant, soap solutions, oil sprays).
Is the cost of cure worth the expense (example:
Protecting birch from the Bronze Birch Borer)?
79. Treatment of insect problems:
Not all insects cause problems! Know what the
insect is and the plant’s/client’s level of tolerance
before treating.
Consider cultural control and least toxic methods
first (hosing plant, soap solutions, oil sprays).
Is the cost of cure worth the expense (example:
Protecting birch from the Bronze Birch Borer)?
If a few plants have an infestation that needs
treating, don’t broadcast spray the entire yard.
82. Treatment of insect problems:
Not all insects cause problems! Know what the insect is
and the plant’s/client’s level of tolerance before you treat.
Consider cultural control and least toxic methods first
(hosing plant, soap solutions, oil sprays).
Is the cost of cure worth the expense (ex. Protecting birch
from the Bronze Birch Borer)?
If a few plants have an infestation that needs treating,
don’t broadcast spray the entire yard.
Know the pest (where is it feeding) and the mode of action
of the chemical (contact or systemic).
87. Treatment of insect problems:
Not all insects cause problems! Know what the insect is
and the plant’s/client’s level of tolerance before you treat.
Consider cultural control and least toxic methods first
(hosing plant, soap solutions, oil sprays).
Is the cost of cure worth the expense (ex. Protecting birch
from the Bronze Birch Borer)?
If a few plants have an infestation that needs treating,
don’t broadcast spray the entire yard.
Know the pest and the mode of action of the chemical
(contact or systemic).
If repeat spraying is necessary, don’t always use the same
chemical.
89. Accurate diagnosis of plant
problems depends on:
Observation of subtle differences from the normal
90. Accurate diagnosis of plant
problems depends on:
Observation of subtle differences from the normal
Knowledge of plants, soil, climate, cultural practices,
pests…
91. Accurate diagnosis of plant
problems depends on:
Observation of subtle differences from the normal
Knowledge of plants, soil, climate, cultural practices,
pests…
Recent history of plants, site, cultural practices, climate
92. Accurate diagnosis of plant
problems depends on:
Observation of subtle differences from the normal
Knowledge of plants, soil, climate, cultural practices,
pests…
Recent history of plants, site, cultural practices, climate
Analytical approach to problem solving
93. Plant identification is critical as it can help
lead one to proper diagnosis; some diseases
are host specific.
(Example: Fireblight is only found in plants of
the family Rosaceae)
94. Knowledge of how a tree is put together and
functions is essential before one can determine
if some part of a tree's system is abnormal or
diseased.
103. Disease Diagnosis: look for signs and
symptoms that can help with the diagnosis
Sign - evidence of the pathogen itself
– mycelium
– fruiting body
– Pycnidia
– Oozing
105. Disease Diagnosis: look for signs and
symptoms that can help with the diagnosis
Sign
Symptom - Plant's response to the pathogen
(general appearance of the plant)
107. Diagnosis: Where to start?
What part of plant is affected? (leaves, stem, roots, fruit)
108. Diagnosis: Where to start?
What part of plant is affected? (leaves, stem, roots, fruit)
What are the symptoms? (wilts, spots, chlorosis, curling...)
109. Diagnosis: Where to start?
What part of plant is affected? (leaves, stem, roots, fruit)
What are the symptoms? (wilts, spots, chlorosis, curling...)
How many plants are affected?
110. Diagnosis: Where to start?
What part of plant is affected? (leaves, stem, roots, fruit)
What are the symptoms? (wilts, spots, chlorosis, curling...)
How many plants are affected?
Are they all the same type of plant, or many species?
111. Diagnosis: Where to start?
What part of plant is affected? (leaves, stem, roots, fruit)
What are the symptoms? (wilts, spots, chlorosis, curling...)
How many plants are affected?
Are they all the same type of plant, or many species?
When did the symptoms first appear?
118. Diagnosis: Where to start?
What part of plant is affected? (leaves, stem, roots, fruit)
What are the symptoms? (wilts, spots, chlorosis, curling...)
How many plants are affected?
Are they all the same type of plant, or many species?
When did the symptoms first appear?
Is there a pattern to the symptoms?
121. Diagnosis: Where to start?
What part of plant is affected? (leaves, stem, roots, fruit)
What are the symptoms? (wilts, spots, chlorosis, curling...)
How many plants are affected?
Are they all the same type of plant, or many species?
When did the symptoms first appear?
Is there a pattern to the symptoms?
Are there any signs of insects or disease?
124. Diagnosis: Where to start?
What part of plant is affected? (leaves, stem, roots, fruit)
What are the symptoms? (wilts, spots, chlorosis, curling...)
How many plants are affected?
Are they all the same type of plant, or many species?
When did the symptoms first appear?
Is there a pattern to the symptoms?
Are there any signs of insects or disease?
Any major changes in the vicinity of the plant in the last few
years? (excavation, grading ...)
125.
126. Diagnosis: Where to start?
What part of plant is affected? (leaves, stem, roots, fruit)
What are the symptoms? (wilts, spots, chlorosis, curling...)
How many plants are affected?
Are they all the same type of plant, or many species?
When did the symptoms first appear?
Is there a pattern to the symptoms?
Are there any signs of insects or disease?
Any major changes in the vicinity of the plant in the last few
years? (excavation, grading ...)
What were the cultural practices in the previous seasons?
127.
128.
129.
130.
131.
132. Conclusions:
Be observant
Ask questions
Don’t jump to conclusions (many pests and
diseases are secondary to a more serious
cultural problem)
If you are unable to diagnose the problem,
do some research, talk to others, or refer it
to someone who can