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Common Greenhouse Viruses

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This is from a workshop given in Denver in Dec 2009.

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Common Greenhouse Viruses

  1. 1. Front Range Greenhouse IPM Workshop:Viruses Affecting Production<br />Brooke Edmunds, Ph.D.; CSU Extension<br />Laura Pottorff, M.S.; CO Department of Agriculture<br />
  2. 2. Questions we will answer today:<br />What is a virus?<br />How do viruses enter the greenhouse?<br />How do virus spread in greenhouses?<br />What are common symptoms<br />How are viruses detected?<br />How can you manage virus diseases?<br />What is phytosanitary certification?<br />
  3. 3. What is a virus?<br />Submicroscopic particle<br />Genetic material (nucleic acid, usually RNA) surrounded by a protein coat<br />Requires host plant for reproduction<br />Photo: webs.wichita.edu<br />
  4. 4. What is a virus? (cont.)<br />No chemicals that kill viruses<br />Once infected, a plant remains infected<br />Millions of virus particles produced in each infected cell!<br />Aster with TSWV<br />
  5. 5. How viruses are named<br />Acronyms are commonly used<br />INSV (Impatiens Necrotic Spot Virus)<br />TSWV (Tomato Spotted Wilt Virus)<br />Refers to 1st plant found on & symptoms<br />Name is not limiting!<br />Some can infect 100’s of genera, others only a few<br />
  6. 6. How do viruses enter & spread within greenhouses?<br />Infected plant material<br />Workers<br />Insects<br />Other vectors<br />Seed<br />Mites<br />Fungi<br />Nematodes<br />Photo: http://www.visionaryplants.com/images/th_salvia_divinorum_rooted_cutting.jpg<br />
  7. 7. Example: TMV and workers<br />Tobacco Mosaic Virus<br />Able to survive in processed tobacco<br />Can enter greenhouse by workers who smoke<br />Can survive for years in dried tissue & clothing<br />How to prevent:<br />Consider lab coats for propagation areas<br />Worker sanitation is very important<br />Wash hands with soap and hot water and dry with paper towel<br />
  8. 8. Insect Vectors: Aphids<br />30 species, depending on the crop<br />Green peach aphid (Myzuspersicae)<br />Three lines on back<br />Cornicles/tailpipes are green with tips brown or black<br />
  9. 9. Melon or Cotton Aphid<br />Green or dark gray<br />Cornicles/tail pipes are solid black<br />Aphids pick up virus and transmit for short period of time<br />
  10. 10. Insect Vector: Thrips<br />Very small (1/16”)<br />Difficult to scout<br />Direct damage & virus vector<br />1st and 2ndinstar accumulates virus<br />Systemically infected<br />Onion thrips<br />Western flower thrips<br />
  11. 11. Symptoms of virus infection<br />Easily confused with:<br />Nutrient disorders<br />Chemical injury<br />Leaky heating system<br />Insect feeding<br />Other pathogens (bacteria, fungi…)<br />
  12. 12. Symptoms-common terms<br />Mosaic<br />Mottle<br />Ringspots<br />Line patterns<br />Bronzing<br />Necrotic lesions<br />Stunting<br />Streaking<br />Distortion<br />Cup shape<br />Crinkling<br />Epinasty<br />White patches or lines on flowers<br />Breaking<br />Photo: http://www.clemson.edu/public/regulatory/plant_industry/plant_prob_clinic/images/tswv_fruit.jpeg<br />
  13. 13. What affects “Symptom Expression”?<br />Temperature<br />Depends on the virus<br />CMV more symptoms at lower temps<br />TSWV more symptoms at higher temps<br />Stress<br />Stressed plants show more symptoms<br />Drought, heat, light, etc<br />Plant age<br />Plant variety<br />Some plants may be completely symptom-free but able to transmit virus<br />
  14. 14. Most common greenhouse viruses<br />INSV<br />TSWV<br />CMV<br />TMV<br />CbMV<br />Plants can get more than one virus!<br />
  15. 15. INSV<br />Impatiens Necrotic Spot Virus<br />Hosts: >600 species (Almost all greenhouse crops except roses & poinsettias)<br />Symptoms: stunting, necrotic & yellow spotting, stem cankers, line patterns, ringspots<br />Spread by: Western flower thrips, propagation<br />
  16. 16. INSV on ranunculus-Easily confused with fungal disease!<br />
  17. 17. INSV on Gerbera Daisy<br />
  18. 18. INSV on Chrysanthemum<br />
  19. 19. INSV on Begonia<br />Photo: http://www.apsnet.org/online/feature/tospovirus/images/figure3.htm<br />
  20. 20. INSV on Impatiens<br />
  21. 21. TSWV<br />Tomato Spotted Wilt Virus<br />Hosts: >600 species, almost all greenhouse crops except roses & poinsettias<br />Symptoms: stunting, necrotic & yellow spotting, stem cankers, line patterns, ringspots<br />Spread by: several species of thrips, propagation<br />
  22. 22. TSWV on Gloxinia<br />
  23. 23. TSWV on Impatiens<br />
  24. 24. Black line pattern caused by Tomato spotted wilt virus (TSWV) on hellebore<br />
  25. 25. CMV<br />Cucumber Mosaic Virus<br />Hosts: over 400 species<br />Ornamentals, vegetables, woody & semi-woody<br />Symptoms: mosaic, color breaking, flecking, leaf distortion<br />Spread by: aphids, sap, propagation, seed & pollen in petunias<br />
  26. 26. Mosaic on Ajuga caused by CMV<br />
  27. 27. CMV on Vinca<br />
  28. 28. Bronzing caused by CMV on lobelia<br />
  29. 29. TMV<br />Tobacco Mosaic Virus<br />Hosts: 100’s of species<br />Symptoms: yellow mottling, leaf curling, stunting<br />Spread by: sap and plant parts, workers handling tobacco products, VERY stable<br />Non-symptomatic infected plants can occur<br />
  30. 30. TMV on Calibrachoa<br />Photo: www.ipm.uconn.edu<br />
  31. 31. TMV on Petunia<br />Photo: http://www.greenhousegrower.com/articles/image/200902/Online%20Only%20Lewandowski/Figure_1.jpg<br />
  32. 32. CbMV<br />CalibrachoaMottle Virus<br />Hosts: Calibrachoa, petunia<br />Symptoms: leaf yellowing, dieback, spotting<br />Easily confused with iron deficiency<br />Spread by: sap & propagation<br />
  33. 33. CbMV on Calicrachoa<br />Photo: L. Pottorff<br />
  34. 34. Other viruses<br />
  35. 35. ToMV on Tomato<br />Photo: www.omafra.gov.on.ca<br />
  36. 36. Canna Yellow Mottle Virus<br />
  37. 37. White ring spots form on meadow-rue infected with Tobacco rattle virus<br />
  38. 38. Rings and chlorotic lines caused by Tobacco Rattle Virus on Epimedium<br />
  39. 39. Begonia leaves with virus-induced chlorotic mottling and necrosis<br />
  40. 40. White patches <br />Alstroemeria mosaic virus<br />
  41. 41. Tulip Breaking Virus<br />
  42. 42. Odontoglossumringspottobamovirus, ringspot on orchid<br />Photo: www.agdia.com<br />
  43. 43. Odontoglossumringspottobamovirus causing flower break on orchid<br />Photo: www.agdia.com<br />
  44. 44. Unknown orchid virus<br />Photo: www.aos.org/AM/Images/pest+diseases/Virus2003.jpg<br />
  45. 45. Virus Testing<br />ELISA (Enzyme Linked ImmunoSorbentAssay)<br />Uses antibodies and color changes to detect<br />
  46. 46. Lab based<br />Crop screens for multiple viruses<br />In-house ImmunoStrips<br />For common viruses<br />
  47. 47. Other resources:Virus Testing<br />Agro Check kits from Hydros Inc. 230 Jones Road, Falmouth , MA 02540 Phone: 508 540 2229, http://www.hydros.cc/ . <br />Alert Kits from Neogen Company 620 Lesher Place Lansing, MI 48912 Phone: 800/234-5333 (USA/Canada) http://www.adgen.co.uk/ (Information about the test kits are on Neogen Europe website) <br />
  48. 48. CSU Extension Adams CountyPlant Diagnostic Lab<br />Disease and insect diagnosis for greenhouse and nursery industry<br />Stock Agdia tests for common viruses<br />Discount services for CNGA members<br />9755 Henderson Rd, Brighton; 303/637-8016<br />brooke.edmunds@colostate.edu<br />
  49. 49. Insect Management<br />Sanitation-no holdovers!<br />Remove weeds in and around greenhouse<br />Air-lock or double-door entrances<br />Insect screening<br />Scouting & monitoring<br />Control strategies<br />
  50. 50. Scouting for thrips<br />Hot pink or blue sticky cards<br />5-10/acre plus near doors and vents<br />Just above tops of plants<br />Plant inspections:<br />Feeding scars & black feces<br />Depending on plant-on upper or lower foliage<br />Tap foliage over white paper and look for adults<br />Photo: http://www.omafra.gov.on.ca/english/crops/facts/03-075f1a.jpg<br />
  51. 51. Indicator Plants<br />Petunia ‘Super Blue Magic’, ‘Summer Madness’, ‘Calypso’, etc<br />Fava bean ‘Toto’<br />Feeding scars show up rapidly<br />Brown ring if INSV is present<br />
  52. 52. Insect Screening<br />Photo: http://edis.ifas.ufl.edu<br />
  53. 53. Insecticides to control Thrips<br />Organophosphates<br />Carbamates<br />Pyrethroids<br />Chloronicotinyls<br />Botanicals<br />Drench at transplant, followed by foliar applications<br />ROTATE to avoid resistance!<br />
  54. 54. Sanitation<br />Benches, pots, equipment:<br />3% TSP (trisodium phosphate)<br />Virkon S<br />Quaternary ammonia<br />Hydrogen dioxide<br />Bleach<br />For workers:<br />Skim milk deactivates TMV<br />Powdered or fresh<br />So does soap and water!<br />95-100% effective <br />
  55. 55. Worker sanitation<br />Wash hands with soap before starting work and after smoking<br />Don’t allow visitors to handle plants without washing hands<br />Keep propagation area off-limits to workers handling older plants<br />
  56. 56. Sanitizer Study<br />Greenhouse Grower, Feb ‘09<br />Compared 8 sanitizers for TMV control<br />Dipped razorblade in TMV infected petunia sap<br />Sanitized the razorblade with different treatments<br />Cut new petunias and rated for TMV development<br />
  57. 57. From: Greenhouse Grower, Feb 2009<br />

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