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Introduction to Greenhouse Diseases Seminar for ProGreen2009

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Introduction to Greenhouse Diseases Seminar for ProGreen2009

  1. 1. Plant Disease Certified Greenhouse Grower Brooke Edmunds Colorado State University Extension
  2. 2. Definition of Disease? <ul><li>Abnormal growth or dysfunction of a plant </li></ul><ul><li>Caused by: </li></ul><ul><ul><li>Abiotic </li></ul></ul><ul><ul><ul><li>non-living factors = environmentally induced disease </li></ul></ul></ul><ul><ul><li>Biotic </li></ul></ul><ul><ul><ul><li>living organisms=pathogens, etc. </li></ul></ul></ul>
  3. 3. Biotic disease <ul><li>Pathogen types </li></ul><ul><ul><li>Fungi* </li></ul></ul><ul><ul><li>Bacteria* </li></ul></ul><ul><ul><li>Viruses* </li></ul></ul><ul><ul><li>Phytoplasmas </li></ul></ul><ul><ul><li>Nematodes </li></ul></ul><ul><ul><li>Parasitic plants </li></ul></ul>
  4. 4. Plant Disease Triangle Susceptible plant Suitable Environment Pathogen DISEASE
  5. 5. Steps to Diagnose Plant Disease <ul><li>Identify the plant </li></ul><ul><li>Examine the plant </li></ul><ul><ul><li>What are the common diseases affecting this plant? </li></ul></ul><ul><ul><ul><li>90% of the time the common problems will be mine too </li></ul></ul></ul><ul><ul><ul><li>Become familiar with the symptoms and signs of the common diseases </li></ul></ul></ul><ul><li>Examine the environment </li></ul><ul><ul><li>What factors influence the common diseases? </li></ul></ul>
  6. 6. What else can be done to ID disease on-site? <ul><li>What’s been happening recently on this crop and in other areas/other growers? </li></ul><ul><ul><li>diagnosingplantdiseases.blogspot.com/ </li></ul></ul><ul><li>Narrow down by looking at pictures: </li></ul><ul><ul><li>Trade articles </li></ul></ul><ul><ul><li>University/Extension newsletters </li></ul></ul><ul><ul><li>If you get stuck: submit to Adams County Plant Clinic </li></ul></ul>
  7. 7. Symptom vs Sign ( effect vs cause) <ul><li>Symptom = The plants response to stress </li></ul><ul><li>Sign= The reproductive or vegetative structure of the pathogen </li></ul>
  8. 8. A. Greenhouse Tomato
  9. 9. B. Pumpkin Transplant
  10. 10. C. Powdery Mildew seen through a hand lens
  11. 11. D. Rotted base of hydroponic lettuce
  12. 12. Biotic diseases <ul><li>Pathogen types </li></ul><ul><ul><li>Fungi </li></ul></ul><ul><ul><li>Bacteria </li></ul></ul><ul><ul><li>Virus </li></ul></ul><ul><ul><li>Phytoplasma </li></ul></ul><ul><ul><li>Nematodes </li></ul></ul><ul><ul><li>Parasitic plants </li></ul></ul>
  13. 13. Fungi Filamentous or thread-like body called hyphae (plural). A mass of hyphae is called mycellium.
  14. 14. Fungi - reproduce by spores
  15. 15. Fungi <ul><li>Parasite or Saprophyte </li></ul><ul><li>Move in plant parts, water, soil, air currents, on tools, and help of insects. </li></ul><ul><li>Enter plant through wounds, natural openings, or on their own </li></ul><ul><ul><li>Use enzymes to break down plant cells and absorb nutrients </li></ul></ul>
  16. 16. Where do fungi commonly attack? Foliage Root/Crown Vascular system
  17. 17. Foliar Fungal Diseases <ul><li>Leaf spots with margins (smooth or feathery), or concentric rings </li></ul><ul><li>Blights </li></ul>
  18. 18. Powdery Mildew <ul><li>100’s of hosts </li></ul><ul><li>Spores spread in air </li></ul><ul><li>White talcum powder spores </li></ul><ul><li>Purple lesions </li></ul><ul><li>Favored by </li></ul><ul><ul><li>High relative humidity </li></ul></ul><ul><ul><li>DRY leaf surface </li></ul></ul><ul><ul><li>Plant stress </li></ul></ul>
  19. 19. Powdery Mildew Management <ul><li>Sanitation both inside and outside of Ghse </li></ul><ul><li>Lower relative humidity (increase air circulation) </li></ul><ul><li>Avoid plant stress </li></ul><ul><ul><li>Proper lighting </li></ul></ul><ul><ul><li>Proper fertility </li></ul></ul><ul><li>Fungicides </li></ul><ul><ul><li>Chlorothalonil (Daconil) </li></ul></ul><ul><ul><li>Copper sulfate </li></ul></ul><ul><ul><li>Sulfur </li></ul></ul><ul><ul><li>Myclobuntanil (Systhane) </li></ul></ul><ul><ul><li>Piperalin (Pipron) </li></ul></ul><ul><ul><li>Thiophanate methyl (3336) </li></ul></ul><ul><ul><li>Triadimefon (Strike) </li></ul></ul><ul><ul><li>Triflumizole (Terraguard) </li></ul></ul><ul><ul><li>ALWAYS CHECK LABEL! </li></ul></ul>
  20. 20. Downy Mildew <ul><li>Less common than powdery mildew </li></ul><ul><li>Red, purple or yellow angular areas on leaves. </li></ul><ul><li>Gray/brown spores on leaf underside </li></ul><ul><li>Requires WET leaf surface </li></ul><ul><li>Potential hosts: </li></ul><ul><ul><li>Snapdragon </li></ul></ul><ul><ul><li>Rose </li></ul></ul><ul><ul><li>Potentilla </li></ul></ul>
  21. 21. Downy Mildew Management <ul><li>Remove infected plants </li></ul><ul><li>Avoid: </li></ul><ul><ul><li>Prolonged leaf wetness </li></ul></ul><ul><ul><li>High relative humidity </li></ul></ul><ul><li>Use sanitation </li></ul><ul><ul><li>Weed control </li></ul></ul><ul><ul><li>No standing water </li></ul></ul><ul><ul><li>No plant debris </li></ul></ul><ul><li>Fungicides </li></ul><ul><ul><li>Mancozeb (Dithane/Manzate) </li></ul></ul><ul><ul><li>Fosetyl al (Chipco Aliette) </li></ul></ul><ul><ul><li>Mefanoxam (Subdue Maxx) </li></ul></ul><ul><ul><li>ALWAYS READ THE LABEL! </li></ul></ul>
  22. 22. Botrytis <ul><li>Diagnosis via presence of “signs” </li></ul><ul><ul><li>Many hosts </li></ul></ul><ul><ul><li>‘ Grey Mold’ </li></ul></ul><ul><ul><li>1 0 or 2 0 </li></ul></ul><ul><ul><ul><li>Likes wounds </li></ul></ul></ul><ul><ul><li>Favored by </li></ul></ul><ul><ul><ul><li>High relative humidity </li></ul></ul></ul><ul><ul><ul><li>Cool temps (< 60 F) </li></ul></ul></ul><ul><ul><ul><li>Water on leaf surface </li></ul></ul></ul><ul><ul><li>Spores travel in air currents </li></ul></ul>Signs
  23. 23. Botrytis Management <ul><li>Increase air circulation </li></ul><ul><li>Decrease relative humidity </li></ul><ul><ul><li>Vent + heat </li></ul></ul><ul><ul><li>Fans </li></ul></ul><ul><ul><li>Space plants farther apart </li></ul></ul><ul><li>Eliminate debris and standing water </li></ul><ul><li>Fungicides </li></ul><ul><ul><li>Iprodione (26GT) </li></ul></ul><ul><ul><li>Chlorothalonil (Daconil) </li></ul></ul><ul><ul><li>Mancozeb (Dithane) </li></ul></ul><ul><ul><li>Vinclozalin (Ornalin) </li></ul></ul><ul><ul><li>Fenahexamid (Decree) </li></ul></ul><ul><ul><li>Copper (Phyton 27) </li></ul></ul><ul><ul><li>ALWAYS READ THE LABEL! </li></ul></ul>
  24. 24. Thielaviopsis root rot of petunia Photos: Kansas State Univ. Pythium on Geraniums Fungal Root & Crown Rots
  25. 25. Rotted roots Healthy roots
  26. 26. Pythium on watermelon transplants
  27. 27. The Fungi involved <ul><li>Rhizoctonia </li></ul><ul><li>Pythium & Phytophthora </li></ul><ul><li>Thielaviopsis </li></ul><ul><li>The only way to identify which fungus is involved is under the microscope. </li></ul>Thielaviopsis spores in root tissue Rhizoctonia mycelium in root tissue
  28. 28. Root & Crown Rot Management <ul><li>Reduce plant stress </li></ul><ul><li>Proper water and temperature </li></ul><ul><li>Sanitation/Disinfection </li></ul><ul><ul><li>Pots </li></ul></ul><ul><ul><li>Benches </li></ul></ul><ul><ul><li>Hoses </li></ul></ul><ul><ul><li>Other equipment </li></ul></ul><ul><li>Rogue diseased plants </li></ul>
  29. 29. Management of Root & Crown Rots: Fungicides <ul><li>Rhizoctonia </li></ul><ul><ul><li>Heritage (Azoxystrobin) </li></ul></ul><ul><ul><li>26GT (Iprodione) </li></ul></ul><ul><ul><li>Medallion (Fludioxinil) </li></ul></ul><ul><ul><li>Contrast (Flutolanil) </li></ul></ul><ul><ul><li>3336 (Thiophanate methyl) </li></ul></ul><ul><ul><li>Banrot (Etridiazole + thiophanate methyl) </li></ul></ul><ul><li>Pythium </li></ul><ul><ul><li>Aliette (Fosetyl-Al) </li></ul></ul><ul><ul><li>Sudbdue Maxx (Mefanoxam) </li></ul></ul><ul><ul><li>Heritage </li></ul></ul><ul><ul><li>Truban (Thiadiazole) </li></ul></ul><ul><li>Thielaviopsis </li></ul><ul><ul><li>Banrot </li></ul></ul><ul><ul><li>3336 </li></ul></ul><ul><ul><li>Domain </li></ul></ul><ul><ul><li>Terraguard </li></ul></ul>Always read the label!
  30. 30. <ul><li>Fusarium Wilt on Cyclamen (very common) </li></ul>Vascular Wilt caused by Fungi Botrytis mycelium
  31. 31. Management of Vascular Wilt <ul><li>Sanitation and disinfection </li></ul><ul><ul><li>Rogue = throw away </li></ul></ul><ul><ul><li>Clean planting media </li></ul></ul><ul><ul><ul><li>Soil pasteurization (kill bad guys, leave many good guys) </li></ul></ul></ul><ul><ul><ul><ul><li>Heat soil to 140 – 160 F for 30 min. </li></ul></ul></ul></ul><ul><ul><ul><li>Chemical fumigation </li></ul></ul></ul><ul><ul><li>Clean up debris from floors and benches </li></ul></ul><ul><ul><li>Weed control </li></ul></ul><ul><li>Don’t overwater </li></ul><ul><li>Good air circulation </li></ul><ul><li>Use clean stock/seed </li></ul>
  32. 32. Bacteria <ul><li>Single celled </li></ul><ul><li>Parasite or Saprophyte </li></ul><ul><li>Don’t produce spores </li></ul><ul><li>Require wet & humid conditions to cause infection </li></ul><ul><li>Enter plants through wounds or natural openings </li></ul>
  33. 33. Symptoms of Bacterial Disease <ul><li>Galls, Vascular Wilts, Cankers, Fruit Rots, Leaf Spots </li></ul>Crown Gall
  34. 34. Symptoms of Bacterial Disease <ul><li>Leaf spots – angular or round, water-soaked (‘wet’), often do not cross major leaf veins. </li></ul>
  35. 35. Diagnosis of Bacterial Disease <ul><li>In the Greenhouse: </li></ul><ul><ul><li>Look for ooze or bacterial streaming </li></ul></ul>Photo: Penn State Univ.
  36. 36. Diagnosis of Bacterial Diseases <ul><li>In the lab: </li></ul><ul><ul><li>Bacterial streaming or ooze under microscope </li></ul></ul><ul><ul><li>Immunoassays </li></ul></ul><ul><ul><li>Culture </li></ul></ul>
  37. 37. Erwinia soft rot <ul><li>Common on cyclamen </li></ul><ul><li>Symptoms similar to Fusarium wilt </li></ul><ul><li>Mushy, rotten tissue-smells bad </li></ul><ul><li>Control through sanitation and disinfection </li></ul>Poinsettia
  38. 38. Xanthomonas <ul><li>Geranium </li></ul><ul><ul><li>X. campestris pv. pelargonii (XCP) </li></ul></ul><ul><li>Hedera Ivy </li></ul><ul><ul><li>X. campetris pv hedera </li></ul></ul>
  39. 39. Pseudomonas <ul><li>Causes leaf spots and stem cankers </li></ul><ul><li>Common on impatiens, pothos & tomato </li></ul><ul><li>Control with copper-based chemicals </li></ul>
  40. 40. Ralstonia <ul><li>Vascular wilt </li></ul><ul><li>Hosts: </li></ul><ul><ul><li>Geranium </li></ul></ul><ul><ul><li>Tomato </li></ul></ul><ul><ul><li>Potato </li></ul></ul>
  41. 41. Management of Bacterial Diseases <ul><li>Remove symptomatic plants and debris </li></ul><ul><li>Clean tools and hands </li></ul><ul><li>Improve air circulation/decrease relative humidity </li></ul><ul><li>Avoid overwatering and leaf wetness </li></ul><ul><li>Sprays of copper? </li></ul>
  42. 42. Viruses <ul><li>Obligate parasites </li></ul><ul><li>Systemic in plants </li></ul><ul><li>Vectored by insects, people, nematodes </li></ul><ul><li>INSV & TSWV are most important to greenhouses </li></ul>
  43. 43. Impatiens Necrotic Spot Virus (INSV) <ul><ul><li>Vectored by Western Flower Thrips </li></ul></ul><ul><ul><li>100’s of hosts </li></ul></ul><ul><ul><li>Diverse symptoms </li></ul></ul><ul><ul><ul><li>Ring spots </li></ul></ul></ul><ul><ul><ul><li>Stunting </li></ul></ul></ul><ul><ul><ul><li>Leaf spots </li></ul></ul></ul><ul><ul><ul><li>Necrosis </li></ul></ul></ul><ul><ul><ul><li>Line patterns </li></ul></ul></ul>
  44. 44. Tomato Spotted Wilt Virus (TSWV) <ul><ul><li>Transmitted by several species of thrips </li></ul></ul><ul><ul><li>More common on vegetables and dahlias </li></ul></ul>
  45. 45. Diagnosis of INSV/TSWV <ul><li>In the greenhouse: </li></ul><ul><ul><li>Is/was the vector present? </li></ul></ul><ul><ul><li>Leaf tissue is still supple? </li></ul></ul><ul><ul><ul><li>Fungus – leaf tissue often dries up/becomes crispy </li></ul></ul></ul><ul><ul><li>Immunoassay strip test </li></ul></ul><ul><li>In the lab: </li></ul><ul><ul><li>Confirmed via </li></ul></ul><ul><ul><ul><li>Immunoassay test </li></ul></ul></ul><ul><ul><ul><li>Serology (ELISA) </li></ul></ul></ul><ul><ul><ul><li>Sap transmission </li></ul></ul></ul>
  46. 46. Management of Virus Diseases <ul><li>Remove entire plant and destroy </li></ul><ul><li>Monitor and control vector </li></ul><ul><ul><li>i.e. Thrips control to prevent INSV/TSWV </li></ul></ul><ul><li>Preventive </li></ul><ul><ul><li>Purchase symptom-free plants </li></ul></ul><ul><ul><li>Quarantine or separate newly arriving stock </li></ul></ul>
  47. 47. Abiotic Diseases <ul><li>Environmentally induced, non-living </li></ul><ul><ul><li>Temperature extremes </li></ul></ul><ul><ul><li>Moisture extremes </li></ul></ul><ul><ul><li>Soil properties </li></ul></ul><ul><ul><li>Culture of plant </li></ul></ul><ul><ul><ul><li>Planting techniques </li></ul></ul></ul><ul><ul><ul><li>Fertility </li></ul></ul></ul><ul><ul><li>Pesticide misuse (phytotoxicity) </li></ul></ul>
  48. 48. Common Abiotic Diseases/Disorders Edema
  49. 49. Common Abiotic Diseases/Disorders Leaf Scorch
  50. 50. Blossom End of Tomato Common Abiotic Diseases/Disorders
  51. 51. <ul><li>diagnosingplantdiseases.blogspot.com/ </li></ul>

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