1. BECOME A PLANT
PROBLEM SLEUTH
Master Gardener Advanced Training Program
May 30, 2013
Heidi Kratsch, University of Nevada Cooperative
Extension

2. LEARNING OBJECTIVES
Recognize common plant
problems seen in northern
Nevada.
Learn to use our digital stereo
microscope

3. C.L.U.E.S.

4. COLLECT INFORMATION
 Identify species/cultivar
 How long have you noticed symptoms?
 Sun/wind exposure?
 Recent disturbances?
 Soil texture (if known)?
 Watering schedule?
 Chemicals used?

5. IDENTIFY THE AFFECTED
PLANT(S)

6. RECOGNIZE WHAT’S
NORMAL
Acer negundo ‘Flamingo’
Variegated juniper

7. LOOK FOR PATTERNS
 Sudden or gradual appearance of symptoms?
 Many plant species affected or only one?
 Symptoms on one side or area of the plant… or
all over the plant?

8. WILTING (COLLAPSE OF
TISSUES)
Causes:
 Under-watering
 Over-watering
 Root loss
 High soil salinity
 Insects feeding on the
conducting tissues
Caused by boring insect
Caused by water stress

9. LEAF NECROSIS (DEATH)
Causes:
 Lack of water
 Too much sun
 Frozen soil
 Drying winds
 Herbicide toxicity
 Look for patterns
Winter burn on Creeping Oregon Grape

10. LOOK FOR PATTERNS OF
LEAF NECROSIS
 Note the pattern of
necrosis on the entire
plant.
Interveinal necrosis
Leaf blotch Marginal necrosis

11. LEAF CHLOROSIS
(YELLOWING)
 Nutrient deficiency
 Disease or insects
 Mechanical damage
Interveinal chlorosis
caused by lack of iron.
Often a problem in
alkaline soils.
General chlorosis
caused by nitrogen
deficiency

12. LEAF CHLOROSIS
Rose mosaic virus
Stippling caused by
leafhopper Variegated cultivar of spotted laurel
Potassium deficiency

13. WHAT IS THIS?

14. BIOTIC VS. ABIOTIC
PROBLEMS
Biotic (caused by
living things)
 Physical evidence
 Spreads progressively
throughout a plant
 Limited to plants of a
particular species or
family
Abiotic (caused by
environmental
stress)
 No physical evidence
 May or may not
develop progressively
throughout a plant
 May affect many or all
plants in a landscape
 Affects only the part
of the landscape
affected by the stress

15. EVIDENCE OF INSECT
DAMAGE:
Chewed leaves Caterpillars, beetles,
sawflies, leaf miners
Bleached, yellowed, or
stippled leaves
Leafhoppers, aphids,
thrips, mites
Distortion of plant part Thrips, aphids
Dieback of twigs/branches Borers, scales
Presence of excrement or
dew
Aphids, whiteflies, thrips

16. WHAT DO YOU SEE?

17. BIOTIC OR ABIOTIC?

18. HOW IS THIS DIFFERENT?
Dothistroma Needle Blight
Austrian, ponderosa and mugo pines are
susceptible under the right conditions

19. BIOTIC OR ABIOTIC?
Phosphorus deficiency
Caused by planting when soils are too cold

20. BIOTIC OR ABIOTIC?
Marsonnina leaf spot

21. GUMMING (SAP FLOW)
 Common stress symptom on
Prunus and Pinus sp.
 Caused by water
deficit or mechanical injury.
 If accompanied by foaming or
foul odor, may be biotic
(bacterial or fungal).

22. BIOTIC OR ABIOTIC?

23. BIOTIC OR ABIOTIC?
 Bacterial – occurs on
plants in the Rose
family
 Twigs curl to form a
“shepherd’s crook”
 Conditions:
Temperatures
between 65 F and 86
F and relative
humidity above 65%

24. FIREBLIGHT?

25. BIOTIC OR ABIOTIC?
Cytospora canker

26. WHICH IS BIOTIC?

27. FUNGAL DISEASES
EXHIBIT PHYSICAL
EVIDENCE
Pycnidia of
cytospora

28. USE REFERENCES
 www.extension.org
 www.google.com (look for sites with .edu or .gov)
 Pests of Landscape Trees and Shrubs, UC-Davis
 Abiotic Disorders of Landscape Plants, UC-Davis
 Weeds of the West, U of Wyoming
 Weeds of California and Other Western States,
Volumes 1 &2, UC-Davis
 Garden Insects, Cranshaw
 Pest ID cards

29. MOST PROBLEMS START
OUT AS WEATHER OR
CULTURAL ISSUES.
Eliminate the most
obvious causes first:
 Improper watering
(cultural)
 Winter damage
 Alkaline and/or salty soil
 Southern or western
exposure
 Heavy, clay soils – poor
drainage
 Herbicide damage
 Insects and disease
are often a
secondary problem.

30. STATE YOUR TENTATIVE
DIAGNOSIS
 Rarely can say with absolute certainty.
 Often a choice among a few options.
 Offer the most reasonable and common
diagnosis.
 Provide a safe solution – and an alternate
strategy if that doesn’t resolve the problem.
 Let them know they can call again if their
problem is not resolved.

31. C.L.U.E.S.

32. INTRODUCTION TO THE
STEREO MICROSCOPE

33. WHAT IS LIGHT
MICROSCOPY?
 Light passes through or falls on a sample.
 Lenses focus that light (and the image of the
sample that the light carries).
 The sample seems to be brought nearer our eyes
for our careful examination.

34. WHAT IS A STEREO
MICROSCOPE?
 Uses two optical pathways (two eyepieces)
 Provides slightly different viewing angles to the
left and right eyes
 Produces a 3-dimensional image
 We have a 4-D microscope!
 You can focus and show your clients in real time.
 And you can take a picture and save to a file or print.

35. THE PARTS OF THE
MICROSCOPE
Stage
Focus knob
Zoom magnification adjustment (8x – 35x)
Eyepieces
(oculars
10x)
On/off switch on back
Carrying handle
Light source
(below)
Light sources
Indicator light/button for computer connection
Green = connected
Orange = not connected
Ilumination direction/brightness controls
Integrated 3.0 megapixel CMOS camera

36. ADJUST THE OCULARS TO FIT THE
SPACING OF YOUR EYES
 When the oculars are
too far apart, you will
see the sample as two
images.
Bring the oculars
together until you see
only one image.

37. MAGNIFICATION
 Magnification is making a sample appear
larger.

38. USE THE WHITE KNOB TO
MAGNIFY.

39. RESOLUTION
 Resolution is the minimum distance separating
two points which still allows them to be seen as
two distinct points.
 The better the resolution, the better we see
details of the image.
 Poor resolution results in a single blurry blob or
“pixelation” when viewing on a computer screen.

40. MAGNIFYING A
BLURRY IMAGE
PRODUCES A
LARGER
BLURRY
IMAGE!
Magnification is
much less
important to
microscopy
than resolution.

41. RESOLUTION
Adjust resolution by
focusing with this knob.
X Do not focus with this knob!

42. ILLUMINATION OF OBJECT
FROM ABOVE
+ –Use +/- controls
to increase or
decrease
brightness

43. ILLUMINATION OF OBJECT FROM
BELOW
Illumination
from below
allows for
viewing thinner
objects that
allow light to
penetrate.

44. USE TOP-LIGHTING FOR OPAQUE
OBJECTS
$5 bill magnified to show the striations of Lincoln’s beard

45. DIM LIGHT BRINGS OUT MORE
DETAIL
Pollen covering the stigma and style of a flower

46. TOP-LIGHT ON A LEAF SHOWS SURFACE
DETAIL
Hairs on a Rosemary leaf

47. LIGHT FROM BELOW SHOWS
INTERNAL STRUCTURE IN
TRANSPARENT OBJECTS
Stem of Sphagnum moss

48. FULL LIGHT FROM ABOVE AND
BELOW
Dracaena plant dead leaf (8x)

49. DIM LIGHT FROM ABOVE AND
BELOW
Dracaena plant dead leaf (8x)

50. DIM LIGHT FROM ABOVE
ONLY
Dracaena plant dead leaf (8x)

51. LIGHT FROM BELOW ONLY
Dracaena plant dead leaf (8x)

57. CARE OF THE MICROSCOPE
 Focus using the black focus knob.
 Do not use the zoom knob (smaller, upper knob)
to focus.
 Use a petri dish under most samples.
 Do not use dissecting tools directly on microscope
stage.
 Turn light off as soon as you are done.
 Cover when not in use to prevent dust and dirt
build up.