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Diagnosis and plant disorders
1. Ann Koenig, Urban Forester
Missouri Department of Conservation
Ann.Koenig@mdc.mo.gov
573-882-8388 x 227
2. Distinguish between plant problems
caused by living and nonliving disorders.
Understand the principles of a
systematic approach to the plant
diagnostic process.
Learn to recognize the signs and
symptoms of tree disorders.
Become familiar with various types of
insect and disease problems and their
impact on trees.
3. The Key Terms as listed in
the Arborist’s
Certification Study
Guide will be defined
and highlighted
throughout the
presentation.
4. Trees don’t talk!
Asking all the
necessary questions
History is hard (or
impossible) to come
by and answers may
not be accurate.
Most of the time –
it’s too late
5. Symptom: how a tree
responds to a disorder
Often times not
specific to the disorder
Several at same time
Examples
Wilting
Chlorosis (yellowing)
Scorch
Dieback
Witch’s broom
Stunted growth
6. Sign: direct indication of the cause of the
problem, in other words something actually left
behind to whatever is causing the tree harm.
Insect holes
Fungal fruiting bodies
7. 1. Accurately identify the plant.
2. Look for a pattern of abnormality.
Multiple kinds of trees-abiotic
3. Carefully examine the site.
Drainage, construction, herbicide use,
4. Note the color, size and thickness of the
foliage.
5. Check the trunk and branches.
6. Examine the roots and root color.
8.
9.
10.
11.
12.
13. Time of year can help:
Fall webworm
Wilting oaks in summer
Certain species are vulnerable to specific problems
Oaks: oak wilt
Maples: girdling roots
Redbuds: herbicide sensitivity
80 % of tree problems come from adverse conditions
such as:
Soil compaction
Mechanical injury
Poor species selection
14. Can be cumulative and
lead to “spiral of
decline”
Necessary basic
factors: sufficient
water, air
movement, drainage, o
ptimal temperature
and light, and proper
balance of nutrients
15. Short term
Causes immediate
damage
More likely to recover?
Acute – disorder or
disease that occurs
suddenly or over a
short period of time
Examples
Lightning, herbicide, late
frost
16. Disorder or disease
occurring over a long
period of time
Examples:
Poor drainage
Soil compaction
Poor species selection
17. Reduced
growth
Abnormal
foliage color or
size
Vigorous
watersprouts
Premature leaf
drop
18. Not Right tree, right
place!
H 2O
extreme cold or heat
soil compaction
soil pH
mechanical damage
19. Biotic – pertaining to a living organism; pathogens
(microscopic disease organisms) e.g.
fungi, bacteria, viruses and nematodes [microscopic
roundworm] as well as insect pests, mites, and other
animals; a.k.a. infectious as they can spread from
one plant to the next.
Abiotic – non living; a.k.a. non-infectious and
include environmental problems such temperature
and moisture extremes, mechanical and chemical
injuries, mineral deficiencies and many others
20. Often the primary stress factor(s) that cause
the spiral of decline
Can be difficult to recognize – often mimic
biotic disorders and are part of a complex
Tree and site history often give the best clues
21. Soil and site problems
Right tree/right place helps
tons!
Physical injuries
Prevention more helpful than
treatment
Weather:
Frost , ice, hail wind damage
Lightning
Frost cracks
Sun scald on south side of
trunk. Thin barked, young trees
with no shade
Heat stress
De-icing salts
22. Competition
shade
turf
allelopathy
▪ Black walnut
▪ Sugar maple
▪ Black locust
Pollution damage
Difficult to
diagnose, often
seen in foliage
and mimics
nutrient
deficiency
23. Chemical injury
2, 4 D
From drift, movement through soil, root grafting
Leaves cup and curl, shoots twist
Chlorotic, browning
Most of the time, plants recover
24. Water availability
Girdling roots
Often not detected until symptoms in above ground portion.
Prevention is best. Plant at correct depth.
Can be possible to remove girding root
25. Insects and Other Pests
Disease
Fungus
bacteria
26.
27.
28. may or may not be host
specific
Japanese beetle vs. emerald
ash borer
May prey on harmful
insects
have complex life cycles
that may have both harmful
and innocuous stages
Either feeding or egg laying
damage
29. May feed on entire leaf
May feed on leaf margins
May skeletonize [leaves that have had the tissue
removed from between the veins by inects] Japanese
beetle
Leaf mining inside leaf
May bore through wood
EAB in inner bark
Asian Longhorn Beetle in wood itself
30.
31.
32.
33.
34. Some pierce plant
cells and feed on the
contents
Aphids
Scales, can go
undetected
Usually don’t kill
trees outright, but
cause stress
Honeydew=Liquid
poo! Substrate for
sooty mold
38. Can also be vectors, organism that transmits a
pathogen [causal agent of a disease]
39. Mite: very small, spider
like, can cause galls
Nematodes:
Microscopic
roundworms most of
which are not parasites
of plants
Scotch’s pine is an
example
May enter tree through
roots, wounds
41. Four requirements are
necessary for a pathogen to
infect
Most pathogens are host
specific
Some need alternate host
The afflicted plant part will
give an indication of the
severity of disease
Foliage, not so bad but noticeable
Vascular tissue, not so good
42.
43.
44. Most plant
diseases are
caused by fungi.
Not all are bad!
Mycorrhizae=
beneficial
relationship
between roots
and fungus.
Look for fruiting
bodies
45.
46. Anthracnose-
leaf fungus
white or grayish fungal
growth on the surface
of stems or foliage
47. Bacterial leaf scorch
Fire blight on pears,
kills young tissue
Infected plant tissues
may appear water
soaked and have a foul
odor
Bacterial wetwood
48. Extension
MDC
Missouri Community Forestry Council
Sample:
fresh,
cool,
interface between diseased and healthy tissue,
early in week,
good written description of problem and site