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BASIC PLANT PATHOLOGY Dr. Monica Elliott Ft. Lauderdale REC

BASIC PLANT PATHOLOGY Dr. Monica Elliott Ft. Lauderdale REC. WHAT IS A HEALTHY PLANT? . You can’t diagnose a plant problem without knowing how the plant looks when healthy!. PLANTS DON’T TALK! .

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BASIC PLANT PATHOLOGY Dr. Monica Elliott Ft. Lauderdale REC

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  1. BASIC PLANT PATHOLOGY Dr. Monica ElliottFt. Lauderdale REC

  2. WHAT IS A HEALTHY PLANT? You can’t diagnose a plant problem without knowing how the plant looks when healthy!

  3. PLANTS DON’T TALK! Information about a plant sample must come from person managing the plant ! Ask the right questions!

  4. Abiotic vs. Biotic

  5. But, first rule out those pesky insects

  6. Sooty mold is a fungus, but not a pathogen. It is feeding off insect excretions, such as honeydew.

  7. Abiotic • Injuries • Disorders • Pathogen is not causing problem • Biotic • Pathogen is the problem

  8. INJURY A destructive physical occurrence to the plant

  9. INJURY NOpathogen! • Lightning strikes, Tire tracks • Car or lawn equipment exhaust • Animals - moles, armadillos, urine

  10. DISORDER Interaction between the plant & its environment that is usually associated with imbalances of physical or chemical require- ments for plant growth.

  11. DISORDERS NO pathogen! • Cold or heat stress • Nutritional, usually deficiencies • Air pollution • Excessive rainfall or drought • Pesticide phytotoxicity

  12. Cold Damage

  13. Drought Oedema Both too much and too little water can cause disease-like symptoms.

  14. Sunburned palm leaf

  15. Manganese deficiency

  16. Manganese deficiency

  17. Potassium deficiency

  18. SPOTS & PATCHES • A plant with a spot does not • automatically mean it has a • disease. • A yellow or dead patch in • the lawn does not mean there • is a disease.

  19. Chinchbug damage

  20. Typical injury from growth regulator type herbicide

  21. DISEASE Interaction between the plant and a pathogen that disrupts the normal growth and appearance of the plant.

  22. DISEASE Three Components: • Susceptible host • Virulent pathogen • Conducive environment Disease Triangle

  23. Types of Pathogens • Fungi • Bacteria • Phytoplasmas(mlo) • Viruses • Viroids large small

  24. Most bacteria can be cultured on artificial media. Phytoplasmas, viruses and viroids cannot be cultured on media.

  25. Most fungi can be cultured on artificial media, but not all.

  26. PATHOLOGY TERMS • MYCELIA: thread-like material • that is body of fungus. • SPORES: reproductive structures • of a fungus or bacterium

  27. Bacteria – most enter through natural • openings or wounds • Viruses – transmitted through wounds • made mechanically or by vectors • Phytoplasmas – transmitted by vectors • Fungi – enter through natural • openings, wounds; or by mechanical • pressure or enzymes they produce

  28. FUNGUS - FUNGI • No chlorophyll, so no self energy • PATHOGEN: obtains energy • from living things • SAPROPHYTE: obtains energy • from dead things • SAME fungus can be BOTH a • pathogen and a saprophyte!

  29. PATHOLOGY TERMS • SYMPTOMS: how plant expresses • the fact it has a disease • leaf spots, patches, tip die back, etc. • SIGNS: actual pathogen parts • associated with a diseased plant • spores, mycelia, conks, mushrooms

  30. Signs of Disease

  31. Signs of Disease

  32. Signs of Disease

  33. Plant Organs And Functions Disease Symptoms

  34. Symptoms • spot – small, distinct lesion on leaf, fruit . . . • blight – spots that have coalesced or merged • together; more tissue being affected • rot – tissue is breaking down (fruit, roots); • usually mushy, but can be dry • wilt – plant droops due to water stress; can • be systemic (xylem) or due to root rot

  35. Symptoms • gall – masses of undifferentiated growth; usually on stems or woody tissue • (branches) but can be on roots • - wart, clubroot, witches’-broom • canker – sunken lesions; usually on stems or • woody tissue • patches, decline – terms often used in • association with grasses (turf, grain crops)

  36. Symptoms Caused by Bacteria • leaf spots and blights – water soaked, • greasy • soft rots of fruits • wilts (systemic – xylem) • gall (overgrowths/cell proliferation) • cankers

  37. Symptom:Water soaked or greasy leaf spots

  38. Symptom:Water soaked or greasy leaf blight

  39. Symptom:Wilt Symptom:Gall

  40. Symptoms Caused by Viruses • dwarfing or stunting to some degree • mosaics – light green, yellow or white • areas intermingled with green – leaves • or fruits • ring spots – chlorotic or necrotic rings – • leaves, fruits or stems • are always systemic infections

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