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Diseases Of Houseplants And Annuals


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This is a talk given by Keith Funk of Gard'n-Wise Distributors, Inc. and Brooke Edmunds of Colorado State University Extension at the 2010 ProGreen Expo held in Denver.

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Diseases Of Houseplants And Annuals

  1. 1. Houseplants and Annuals: Diseases & Controls Keith Funk Gard’N-Wise Distributors Brooke Edmunds CSU Extension
  2. 2. The life of houseplants and annuals <ul><li>STRESS, STRESS, STRESS! </li></ul><ul><ul><li>Fertility </li></ul></ul><ul><ul><li>Water </li></ul></ul><ul><ul><li>Light </li></ul></ul><ul><ul><li>Humidity </li></ul></ul><ul><li>Stress leads to disease susceptibility </li></ul>
  3. 3. 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 = environment stress </li></ul></ul></ul><ul><ul><li>Biotic </li></ul></ul><ul><ul><ul><li>Living factors= pathogens </li></ul></ul></ul>
  4. 4. Disease Factors <ul><li>Abiotic diseases </li></ul><ul><ul><li>Water stress </li></ul></ul><ul><ul><li>Nutrient Stress </li></ul></ul><ul><ul><li>Temperature </li></ul></ul><ul><li>Biotic Diseases </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>
  5. 5. Plant Disease Triangle Susceptible plant Suitable Environment Pathogen DISEASE
  6. 6. 3 Steps to Diagnosing Diseases <ul><li>Identify the plant/host </li></ul><ul><li>Examine the plant </li></ul><ul><ul><li>What are the common diseases affecting this plant? </li></ul></ul><ul><li>Examine the environment </li></ul><ul><ul><li>What factors influence the common diseases? </li></ul></ul>
  7. 7. General Disease Management <ul><li>Review existing cultural practices. </li></ul><ul><ul><li>Light, temp, moisture, weather, plant choice. </li></ul></ul><ul><ul><li>Correct cultural stresses if not too late. </li></ul></ul><ul><li>Remove disease vectors. </li></ul><ul><ul><li>Insect control, sanitation </li></ul></ul><ul><li>Determine treatment method. </li></ul><ul><ul><li>Cultural, Organic vs. Synthetic </li></ul></ul><ul><li>Apply control product per label directions. </li></ul><ul><ul><li>Dosage, method, frequency, environment </li></ul></ul>
  8. 8. Powdery Mildew Photos: K. Funk
  9. 9. Photo: L. Pottorff
  10. 10. Photo: L. Pottorff
  11. 11. Powdery Mildew Management <ul><li>Prevention </li></ul><ul><li>Right plant right place. </li></ul><ul><li>Plant PM resistant varieties. </li></ul><ul><li>Observe proper cultural practices. </li></ul><ul><li>Treatment of infected plants. </li></ul><ul><li>Improve air circulation by thinning and pruning </li></ul><ul><li>Don’t fertilized until the problem is corrected. Don’t water plants from above </li></ul><ul><li>Keep infected debris removed from the area. </li></ul><ul><li>Some very bad cases warrant the removal of the infected plants. </li></ul><ul><li>Apply a fungicide: There are many fungicides available. Check the label to be sure they are safe and effective on the type of plant that is infected. </li></ul><ul><ul><li>Systemic </li></ul></ul><ul><ul><ul><li>Ornamentals only. Typically long lasting. Do not wash off. </li></ul></ul></ul><ul><ul><ul><li>Spray and drench types available </li></ul></ul></ul><ul><ul><li>Non-systemic </li></ul></ul><ul><ul><ul><li>Ornamentals and edibles. Typically not long lasting. Easily wash off. </li></ul></ul></ul><ul><ul><ul><li>Frequent reapplication. Spray and drench types available </li></ul></ul></ul>
  12. 12. Systemic Fungicides Organic & Natural Fungicides Non-Systemic Fungicides
  13. 13. Photos: K. Funk Root & Crown Rot
  14. 15. Photos: K. Funk
  15. 16. Photo: B. Edmunds
  16. 17. Photo: L. Pottorff
  17. 18. Photo: L. Pottorff
  18. 19. Management of Root Rot <ul><li>Cultural </li></ul><ul><li>Prevention is your best bet. </li></ul><ul><ul><li>Buy disease free plants. </li></ul></ul><ul><ul><li>Sanitation </li></ul></ul><ul><li>Proper Cultural practices. </li></ul><ul><li>Always use sterile, quality potting soil or a soil less mix. </li></ul><ul><li>Use new pots or sterilized used pots. </li></ul><ul><ul><li>Used pots should be thoroughly scrubbed to remove soil residues and salt rings. To sterilize, pots should be soaked for 30 minutes in 82°C (180°F) or hotter water, or soaked in a 1:9 solution of household bleach to water for 10-15 minutes. </li></ul></ul><ul><li>Use pots with drainage holes in the bottom. </li></ul><ul><li>Do not let plants stand in water. </li></ul><ul><li>If a plant is suspected of having root rot, </li></ul><ul><ul><li>gently lift the plant and root ball from the pot and check the roots </li></ul></ul><ul><ul><li>Prune away severely rotted roots, and re-pot the plant in fresh soil and clean pot. </li></ul></ul>
  19. 20. Management of Root Rot <ul><li>Chemical </li></ul><ul><ul><li>Chemicals are only effective if root rot is not extensive and environmental conditions are improved. Control is not possible if root rot is extensive and infected plants should be discarded. </li></ul></ul><ul><ul><li>Products including Subdue and Aliette are available to use as a soil drench but may not work on all species of rot fungi. </li></ul></ul>Fertilome Liquid Systemic Fungicide
  20. 21. Damping Off Photos: K. Funk
  21. 22. Management of Damping Off <ul><li>Sanitation </li></ul><ul><ul><li>Plant seeds and root cuttings only in sterilized seedling mix using only sterilized containers. </li></ul></ul><ul><ul><li>Place seed trays on clean, sterilized benches. </li></ul></ul><ul><ul><li>Do not allow soiled hands and tools to come into contact with the sterile media. </li></ul></ul><ul><ul><li>Remove any trays with damping-off immediately.   </li></ul></ul><ul><li>Cultural. </li></ul><ul><ul><li>Adequate light </li></ul></ul><ul><ul><li>Bottom heat may speed germination. </li></ul></ul><ul><ul><li>Avoid planting seeds too deeply. </li></ul></ul><ul><ul><li>Sow seeds thinly to allow air to circulate between seedlings. </li></ul></ul><ul><ul><li>Avoid excessive humidity and watering.   </li></ul></ul><ul><ul><li>Milled sphagnum moss top dress. </li></ul></ul>
  22. 23. <ul><li>Fungicides </li></ul><ul><li>Fungicide treated seeds. </li></ul>Management of Damping Off
  23. 24. Gray Mold/Botrytis Blight
  24. 27. Photos: K. Funk
  25. 28. Botrytis Management <ul><li>Prevention. </li></ul><ul><li>Sanitation. </li></ul><ul><ul><li>Remove diseased plant parts and destroy . </li></ul></ul><ul><ul><li>When plant surfaces are dry. </li></ul></ul><ul><li>Promote rapid drying with good air circulation. </li></ul><ul><li>Fungicide sprays </li></ul><ul><ul><li>Preventative sprays outdoors during cool wet weather. </li></ul></ul>
  26. 29. Foliar Leaf Spots and Discoloration <ul><li>Many causes: </li></ul><ul><ul><li>Fungi </li></ul></ul><ul><ul><li>Bacteria </li></ul></ul><ul><ul><li>Environmental </li></ul></ul><ul><ul><li>Fertility </li></ul></ul>
  27. 30. Alternaria Leaf Spot on Basil Photo:
  28. 31. Alternaria Leaf Spot on Impatiens
  29. 32. Septoria Leaf Spot Photos: K. Funk
  30. 33. Snapdragon Rust Photos: K. Funk
  31. 34. Bacterial Leaf Spot Photo: J. Birn;
  32. 35. Managing Foliar Problems <ul><li>Prevention. </li></ul><ul><ul><li>Proper cultural practices for the plant grown. </li></ul></ul><ul><li>Sanitation. </li></ul><ul><ul><li>Remove diseased plant parts and destroy. </li></ul></ul><ul><li>Promote rapid drying of foliage with good air circulation. </li></ul><ul><ul><li>Avoid evening watering. </li></ul></ul>
  33. 36. <ul><li>Fungicide sprays. </li></ul><ul><ul><li>Best used as preventative. </li></ul></ul><ul><ul><li>Systemics </li></ul></ul><ul><ul><li>Non-systemics </li></ul></ul>Managing Foliar Problems Systemic Fungicide Non -Systemic Fungicide
  34. 37. Aster Yellows Photos: K. Funk
  35. 38. Photo: M. Grabowski
  36. 40. Management of Aster Yellows <ul><li>No Cure. Pull and destroy infected plants. </li></ul><ul><li>Plant AY resistant plants. </li></ul><ul><li>Control Leafhoppers on remaining plants. </li></ul><ul><ul><li>Easily controlled with most any contact insecticide. </li></ul></ul><ul><ul><li>Typically doesn’t reduce the occurrence of AY but makes customer feel better. </li></ul></ul>Photos: K. Funk
  37. 41. Blossom End Rot Photos: K. Funk
  38. 42. <ul><li>Adjust watering. </li></ul><ul><li>Use fertilizer containing calcium </li></ul><ul><ul><li>Especially on potted plants. </li></ul></ul>Managing Blossom End Rot.
  39. 43. Late Blight Photos: K. Funk
  40. 45. Managing Late Blight <ul><li>Cultural control : Cultural controls alone won't prevent disease (if present) during seasons with wet, cool weather. </li></ul><ul><li>Plant disease free plants. No cultivars are resistant. </li></ul><ul><li>Rotate crops </li></ul><ul><li>Space, stake, and prune tomato plants to provide good air circulation. </li></ul><ul><li>Remove infected plants immediately. </li></ul><ul><li>Fungicides. </li></ul><ul><ul><li>Copper spray or broad spectrum fungicide as preventative during cool, wet weather. </li></ul></ul>
  41. 46. 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 common </li></ul>Photo: B. Edmunds
  42. 47. Snapdragon with INSV Photo: B. Edmunds
  43. 48. TSWV on Impatiens
  44. 49. Management of Virus Diseases <ul><li>No cure. </li></ul><ul><li>Plant disease free plants. </li></ul><ul><li>Pull and destroy infected plants. </li></ul>
  45. 50. Edema Photos: K. Funk
  46. 51. Photos: K. Funk
  47. 52. Edema Management <ul><li>Adjust watering </li></ul><ul><li>Adjust temperatures </li></ul>
  48. 53. Contact Information <ul><li>Keith Funk </li></ul><ul><li>Gard’N-Wise Distributors, Inc. </li></ul><ul><li>12770 East 39th Ave. </li></ul><ul><li>Denver, CO  80239 </li></ul><ul><li>303-371-0800 </li></ul><ul><li>[email_address] </li></ul><ul><li>Brooke Edmunds, Ph.D. </li></ul><ul><li>CSU Extension </li></ul><ul><li>Regional Specialist, </li></ul><ul><li>Commercial Greenhouse & Nurseries </li></ul><ul><li>303/637-8016 </li></ul><ul><li>[email_address] </li></ul>