Diagnosis and plant disorders

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Diagnosis and plant disorders

  1. 1. Ann Koenig, Urban ForesterMissouri Department of Conservation Ann.Koenig@mdc.mo.gov 573-882-8388 x 227
  2. 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. 3. The Key Terms as listed in the Arborist’s Certification Study Guide will be defined and highlighted throughout the presentation.
  4. 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. 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. 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. 7. 1. Accurately identify the plant.2. Look for a pattern of abnormality.  Multiple kinds of trees-abiotic3. 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. 8.  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
  9. 9.  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
  10. 10.  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
  11. 11.  Disorder or disease occurring over a long period of time Examples:  Poor drainage  Soil compaction  Poor species selection
  12. 12.  Reduced growth Abnormal foliage color or size Vigorous watersprouts Premature leaf drop
  13. 13.  Not Right tree, right place! H 2O extreme cold or heat soil compaction soil pH mechanical damage
  14. 14.  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
  15. 15.  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
  16. 16.  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
  17. 17.  Competition  shade  turf  allelopathy ▪ Black walnut ▪ Sugar maple ▪ Black locust Pollution damage  Difficult to diagnose, often seen in foliage and mimics nutrient deficiency
  18. 18.  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
  19. 19.  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
  20. 20.  Insects and Other Pests Disease  Fungus  bacteria
  21. 21.  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
  22. 22.  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
  23. 23.  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
  24. 24.  Galls are a plant response – not a cocoon
  25. 25. Can also be vectors, organism that transmits a pathogen [causal agent of a disease]
  26. 26.  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
  27. 27.  Sapsuckers Deer, bud feeding Squirrel, bark stripping Rabbits in winter
  28. 28.  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
  29. 29.  Most plant diseases are caused by fungi. Not all are bad! Mycorrhizae= beneficial relationship between roots and fungus. Look for fruiting bodies
  30. 30. Anthracnose- leaf funguswhite or grayish fungalgrowth on the surface of stems or foliage
  31. 31.  Bacterial leaf scorch Fire blight on pears, kills young tissue Infected plant tissues may appear water soaked and have a foul odor Bacterial wetwood
  32. 32.  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

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