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2013 Advanced Master Gardener Training Program: Become a Plant Problem Sleuth

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2013 Advanced Master Gardener Training Program: Become a Plant Problem Sleuth

  1. 1. BECOME A PLANT PROBLEM SLEUTH Master Gardener Advanced Training Program May 30, 2013 Heidi Kratsch, University of Nevada Cooperative Extension
  2. 2. LEARNING OBJECTIVES Recognize common plant problems seen in northern Nevada. Learn to use our digital stereo microscope
  3. 3. C.L.U.E.S.
  4. 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. 5. IDENTIFY THE AFFECTED PLANT(S)
  6. 6. RECOGNIZE WHAT’S NORMAL Acer negundo ‘Flamingo’ Variegated juniper
  7. 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. 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. 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. 10. LOOK FOR PATTERNS OF LEAF NECROSIS  Note the pattern of necrosis on the entire plant. Interveinal necrosis Leaf blotch Marginal necrosis
  11. 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. 12. LEAF CHLOROSIS Rose mosaic virus Stippling caused by leafhopper Variegated cultivar of spotted laurel Potassium deficiency
  13. 13. WHAT IS THIS?
  14. 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. 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. 16. WHAT DO YOU SEE?
  17. 17. BIOTIC OR ABIOTIC?
  18. 18. HOW IS THIS DIFFERENT? Dothistroma Needle Blight Austrian, ponderosa and mugo pines are susceptible under the right conditions
  19. 19. BIOTIC OR ABIOTIC? Phosphorus deficiency Caused by planting when soils are too cold
  20. 20. BIOTIC OR ABIOTIC? Marsonnina leaf spot
  21. 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. 22. BIOTIC OR ABIOTIC?
  23. 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. 24. FIREBLIGHT?
  25. 25. BIOTIC OR ABIOTIC? Cytospora canker
  26. 26. WHICH IS BIOTIC?
  27. 27. FUNGAL DISEASES EXHIBIT PHYSICAL EVIDENCE Pycnidia of cytospora
  28. 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. 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. 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. 31. C.L.U.E.S.
  32. 32. INTRODUCTION TO THE STEREO MICROSCOPE
  33. 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. 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. 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. 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. 37. MAGNIFICATION  Magnification is making a sample appear larger.
  38. 38. USE THE WHITE KNOB TO MAGNIFY.
  39. 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. 40. MAGNIFYING A BLURRY IMAGE PRODUCES A LARGER BLURRY IMAGE! Magnification is much less important to microscopy than resolution.
  41. 41. RESOLUTION Adjust resolution by focusing with this knob. X Do not focus with this knob!
  42. 42. ILLUMINATION OF OBJECT FROM ABOVE + –Use +/- controls to increase or decrease brightness
  43. 43. ILLUMINATION OF OBJECT FROM BELOW Illumination from below allows for viewing thinner objects that allow light to penetrate.
  44. 44. USE TOP-LIGHTING FOR OPAQUE OBJECTS $5 bill magnified to show the striations of Lincoln’s beard
  45. 45. DIM LIGHT BRINGS OUT MORE DETAIL Pollen covering the stigma and style of a flower
  46. 46. TOP-LIGHT ON A LEAF SHOWS SURFACE DETAIL Hairs on a Rosemary leaf
  47. 47. LIGHT FROM BELOW SHOWS INTERNAL STRUCTURE IN TRANSPARENT OBJECTS Stem of Sphagnum moss
  48. 48. FULL LIGHT FROM ABOVE AND BELOW Dracaena plant dead leaf (8x)
  49. 49. DIM LIGHT FROM ABOVE AND BELOW Dracaena plant dead leaf (8x)
  50. 50. DIM LIGHT FROM ABOVE ONLY Dracaena plant dead leaf (8x)
  51. 51. LIGHT FROM BELOW ONLY Dracaena plant dead leaf (8x)
  52. 52. 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.

Editor's Notes

  • Maple, elm, ash, chestnut, and poplar
  • Interveinal necrosis due to herbicide toxicity or to severe manganese deficiency.
  • Pin oak and silver maple are particularly susceptible.
  • Viruses cannot be controlled with pesticides – cannot survive outside of their host, so control is by prevention of their spread.
  • Salt burn on strawberry – client used fresh horse manure on his plants
  • Leaves do not abscise – look for ooze on affected tissues (usually only leaves). Susceptible trees include rose family –especially crabapple, pear, and serviceberry. Avoid over-fertilization. Usually treated with copper sprays to prevent spread (not an eradicant). Also use Streptomycin.
  • Leaves do not abscise – look for ooze on affected tissues (usually only leaves). Susceptible trees include rose family –especially crabapple, pear, and serviceberry. Avoid over-fertilization. Usually treated with copper sprays to prevent spread (not an eradicant). Also use Streptomycin.
  • Left-cytospora canker; right-sunscald

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