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Garden CSI: Part II

Garden CSI: Part II. Jim Jacobi. Extension Plant Pathologist Alabama Cooperative Ext. System. Plant Problem Diagnosis A process of elimination. Identify the type of plant Start with a list of possibilities based on plant species and time of year

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Garden CSI: Part II

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  1. Garden CSI:Part II Jim Jacobi. Extension Plant Pathologist Alabama Cooperative Ext. System

  2. Plant Problem DiagnosisA process of elimination • Identify the type of plant • Start with a list of possibilities based on plant species and time of year • Red Maple – Phyllosticta leaf spot, gloomy scale • Flowering Dogwood – Powdery mildew, spot anthracnose, dogwood borer • Look for clues and patterns (symptoms and signs) • Rule out biotic and abioticproblems, narrow the list of possibilities • Repeat steps 3 and 4, if needed • Consult expert or send sample to a diagnostic lab

  3. Diagnostic Tools T. Stebbins. Univ. of TN

  4. Symptoms - visible evidence of a change in appearance of the plant

  5. Signs - Visible or physical presence of a pathogen or pest

  6. Symptoms • Identify and classify symptoms • Underdevelopment of plant tissues - stunting • Overdevelopment of plant tissues - galls • Necrosis or death – leaf spots, dieback • Identify plant parts affected

  7. Signs and Symptoms Types of arthropod feeding damage • Stippling • Chlorosis • Sooty Mold • Leafmining • Leaf Defoliaters • Spider Mites • Borers • Root Damage • Learn to recognize the different types of feeding damage 4 3 Lacy L. Hyche, Auburn University, Bugwood.org

  8. Signs and Symptoms • Look for signs of insect frass or insect fecal material • Can be an early warning sign of defoliators and other types on insects • Look for frass dropping on sidewalks, leaves, bark and around the base of trees. Lesser canna leafroller larvae and frass

  9. Signs and Symptoms Frass tubes from granulate ambrosia beetle

  10. Signs and Symptoms Over-development of tissues • Some insect and mite species can induce gall formation on a variety of host plant structures. • Gall-makers are generally host plant specific. Eyespot Gall A mite gall, Aculops laevigata on willow Photo: William M. Ciesla, Forest Health Management International, www.forestryimages.org Gall Mite Damage Photo: Petr Kapitola, Forestry and Game Management Research Institute - Czechia, www.forestryimages.org

  11. Signs and Symptoms Over-development of tissues • How do you know if an insect has caused this damage? • Closely examine plant deformation. • Cut open gall. • Exit holes, frass, empty larval chambers, etc. • Rear insects to adult stage. cynipid gall wasps Photo: Ronald F. Billings, Texas Forest Service, www.forestryimages.org  oriental chestnut gall wasp Photo: Jerry A. Payne, USDA Agricultural Research Service, www.forestryimages.org

  12. Signs and Symptoms Over-development of tissues • Bacterial and fungal galls may resemble insect galls. • Crown gall bacterium causes galls on roots, crowns and stems. • Fungi can also form large galls that superficially resemble crown gall Crown gall on eastern red cedar Photo: Edward L. Barnard, Florida Department of Agriculture and Consumer Services, www.ipmimages.org

  13. Signs and Symptoms Over-development of tissues • Phomopsis gall on oak • In this case, there are no exit holes, frass, empty larval chambers, etc.

  14. Signs and Symptoms Tissue Necrosis • Fungal leaf spots • Usually round, not vein-limited • Elongated on narrow leaves or stems • May have alternating zones of light and dark tissue • Sporulation, mycelia, or small dot-like fruiting bodies may be evident Leaf spot of Indian hawthorn. R. K. Jones

  15. Signs and Symptoms Fungal fruiting bodies Leaf spot on red maple cause by the fungus Phyllosticta

  16. Signs and Symptoms Tissue Necrosis Bacterial leaf spots • Often dark and water-soaked • Often vein-limited, giving angular shape • Bacterial “ooze” or ‘flow’ observed under microscope Bacterial leaf spot of hibiscus. A. R. Chase Bacterial ooze

  17. Example - English Ivy • Both bacterial and fungal leaf spots occur on English ivy. • Use signs and symptoms to determine the cause of the spots R. K. Jones/NCSU

  18. Example - English Ivy • Fungal Leaf Spot (Anthracnose) • Large, irregularly shaped, tan to brown spots • Have numerous, tiny, dark-brown dots (fruiting bodies) on lower surface of leaf Moorman PSU Moorman PSU

  19. Example - English Ivy • Bacterial Leaf Spot • Circular, dark-brown to black spots, often with yellow halo • Viewed on underside of leaf spots may appear greasy • No fruiting structures in spots Moorman Penn State Univ. A. S. Windham – Univ. Tenn.

  20. Signs and Symptoms Necrosis of tissue Dieback • Several possible cause for damage • Feeding damage from several types of insects can lead to limb dieback. • Bacterial and Fungal Cankers • Root problems • Death of the host may result. Botryosphaeria dieback on rhododendron  M. Daughtrey/APS Press 

  21. Signs and Symptoms Azalea lace bug damage Types of Insect Feeding Damage  Insects with piercing- sucking mouthparts cause stippling and/or chlorosis on the host.  Example groups: aphids, true bugs, hoppers, scale insects, whiteflies, etc. Lacebug Damage on Azalea

  22. Signs and Symptoms Types of Insect Feeding Damage • Presence of Sooty Mold may suggest an infestation of honeydew producing insects such as scales, mealybugs, whiteflies, or aphids. • Presence of ants may also be an indicator of these insects! • Look up. Insect problem maybe in nearby trees. Asian Woolly Hackberry Aphid Sooty mold on crape myrtle

  23. Signs and Symptoms oak skeletonizer Types of Insect Feeding Damage Leaf Defoliaters • Damage caused to a plant by insect feeding. • “Skeletonizing” results when the veins or the “skeleton” of the leaf is left behind. Top Photo: James Solomon, USDA Forest Service, www.forestryimages.org maple trumpet skeletonizer Bottom Photo: E. Bradford Walker, Vermont Department of Forests, Parks and Recreation, www.forestryimages.org

  24. Signs and Symptoms columbine leafminer Types of Insect Feeding Damage Leafmining • Insects that produce characteristic “mines” in leaves by feeding. • Formed by various insects including flies, wasps, moths, and beetles. • Some may be confused with leaf spot diseases Top Photo: Lisa Ames, UGA, www.forestryimages.org Solitary oak leafminer James Solomon, USDA Forest Service, Bugwood.org Aspen blotchminer

  25. Signs and Symptoms Types of Arthropod Feeding Damage Spider Mites • Leaf damage includes flecking, bronzing, and/or scorching of leaves. • Use hand-lens to see mites • Tap leaves on white paper • Several natural enemies. Most problematic in heavy insecticide use areas. Spider mite damage on hydrangea Photo: Mississippi State University Archives, Mississippi State University, www.forestryimages.org twospotted spider mite

  26. Signs and Symptoms Roots • Don’t forget to look for potential insect and disease damage on roots! Aspen root girdler Top Photo: Ostry, Mike. USDA Forest Service. http://www.forestryimages.org/ Scarab beetle larval feeding damage on root system of pine Bottom Photo: Robert L. Anderson, USDA Forest Service, www.forestryimages.org

  27. Case #1 – Leaf spots on Butterfly Bush (Buddleia x weyeriana) S. Jeffers/Clemson

  28. Case #1 – Leaf spots on Butterfly Bush (Buddleia x weyeriana) • Fungal sporulation on underside of leaf opposite chlorotic spots • Downy mildew Downy Mildew S. Jeffers/Clemson

  29. Case # 2 – Webbing on Rosemary

  30. Case # 2 – Webbing on Rosemary

  31. Southern Purple Mint Moth on Rosemary Southern purple mint moth larva Southern purple mint moth adult

  32. Case #3 – Leaf spots on Brunnera ‘Jack Frost’ T. Stebbins. Univ. of TN

  33. Case #3 – Leaf spots on Brunnera ‘Jack Frost’ • No fungal fruiting bodies or sporulation • No bacterial streaming or ‘ooze’ • Foliar nematode emerging from leaf tissue on microscope slide T. Stebbins. Univ. of TN

  34. Case #4 – Wilt of Oakleaf Hydrangea

  35. Case #4 – Wilt of Oakleaf Hydrangea • Adequate soil moisture • Presence of white fungal mycelium under bark • Armillaria root rot

  36. Case # 5 – Tip Dieback of Southern Magnolia

  37. Case # 5 – Tip Dieback of Southern Magnolia • Branch dieback of pencil sized branch tips • Small entrance holes (< 1mm) on bottom side of the limbs • Black twig borer (Xylosandrus compactus) within stems

  38. Black Twig Borer

  39. Some of the slides were adapted from NPDN slidesets developed by the following authors • Amanda C. Hodges, University of Florida • Amanda M. Ellis, University of Florida • Meg Williamson, Clemson University • Melissa Riley, Clemson University • Otis Maloy, Washington State University

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