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

1. Front Range Greenhouse IPM Workshop:Viruses Affecting Production Brooke Edmunds, Ph.D.; CSU Extension Laura Pottorff, M.S.; CO Department of Agriculture

2. Questions we will answer today: What is a virus? How do viruses enter the greenhouse? How do virus spread in greenhouses? What are common symptoms How are viruses detected? How can you manage virus diseases? What is phytosanitary certification?

3. What is a virus? Submicroscopic particle Genetic material (nucleic acid, usually RNA) surrounded by a protein coat Requires host plant for reproduction Photo: webs.wichita.edu

4. What is a virus? (cont.) No chemicals that kill viruses Once infected, a plant remains infected Millions of virus particles produced in each infected cell! Aster with TSWV

5. How viruses are named Acronyms are commonly used INSV (Impatiens Necrotic Spot Virus) TSWV (Tomato Spotted Wilt Virus) Refers to 1st plant found on & symptoms Name is not limiting! Some can infect 100’s of genera, others only a few

6. How do viruses enter & spread within greenhouses? Infected plant material Workers Insects Other vectors Seed Mites Fungi Nematodes Photo: http://www.visionaryplants.com/images/th_salvia_divinorum_rooted_cutting.jpg

7. Example: TMV and workers Tobacco Mosaic Virus Able to survive in processed tobacco Can enter greenhouse by workers who smoke Can survive for years in dried tissue & clothing How to prevent: Consider lab coats for propagation areas Worker sanitation is very important Wash hands with soap and hot water and dry with paper towel

8. Insect Vectors: Aphids 30 species, depending on the crop Green peach aphid (Myzuspersicae) Three lines on back Cornicles/tailpipes are green with tips brown or black

9. Melon or Cotton Aphid Green or dark gray Cornicles/tail pipes are solid black Aphids pick up virus and transmit for short period of time

10. Insect Vector: Thrips Very small (1/16”) Difficult to scout Direct damage & virus vector 1st and 2ndinstar accumulates virus Systemically infected Onion thrips Western flower thrips

11. Symptoms of virus infection Easily confused with: Nutrient disorders Chemical injury Leaky heating system Insect feeding Other pathogens (bacteria, fungi…)

12. Symptoms-common terms Mosaic Mottle Ringspots Line patterns Bronzing Necrotic lesions Stunting Streaking Distortion Cup shape Crinkling Epinasty White patches or lines on flowers Breaking Photo: http://www.clemson.edu/public/regulatory/plant_industry/plant_prob_clinic/images/tswv_fruit.jpeg

13. What affects “Symptom Expression”? Temperature Depends on the virus CMV more symptoms at lower temps TSWV more symptoms at higher temps Stress Stressed plants show more symptoms Drought, heat, light, etc Plant age Plant variety Some plants may be completely symptom-free but able to transmit virus

14. Most common greenhouse viruses INSV TSWV CMV TMV CbMV Plants can get more than one virus!

15. INSV Impatiens Necrotic Spot Virus Hosts: >600 species (Almost all greenhouse crops except roses & poinsettias) Symptoms: stunting, necrotic & yellow spotting, stem cankers, line patterns, ringspots Spread by: Western flower thrips, propagation

16. INSV on ranunculus-Easily confused with fungal disease!

17. INSV on Gerbera Daisy

18. INSV on Chrysanthemum

19. INSV on Begonia Photo: http://www.apsnet.org/online/feature/tospovirus/images/figure3.htm

20. INSV on Impatiens

21. TSWV Tomato Spotted Wilt Virus Hosts: >600 species, almost all greenhouse crops except roses & poinsettias Symptoms: stunting, necrotic & yellow spotting, stem cankers, line patterns, ringspots Spread by: several species of thrips, propagation

22. TSWV on Gloxinia

23. TSWV on Impatiens

24. Black line pattern caused by Tomato spotted wilt virus (TSWV) on hellebore

25. CMV Cucumber Mosaic Virus Hosts: over 400 species Ornamentals, vegetables, woody & semi-woody Symptoms: mosaic, color breaking, flecking, leaf distortion Spread by: aphids, sap, propagation, seed & pollen in petunias

26. Mosaic on Ajuga caused by CMV

27. CMV on Vinca

28. Bronzing caused by CMV on lobelia

29. TMV Tobacco Mosaic Virus Hosts: 100’s of species Symptoms: yellow mottling, leaf curling, stunting Spread by: sap and plant parts, workers handling tobacco products, VERY stable Non-symptomatic infected plants can occur

30. TMV on Calibrachoa Photo: www.ipm.uconn.edu

31. TMV on Petunia Photo: http://www.greenhousegrower.com/articles/image/200902/Online%20Only%20Lewandowski/Figure_1.jpg

32. CbMV CalibrachoaMottle Virus Hosts: Calibrachoa, petunia Symptoms: leaf yellowing, dieback, spotting Easily confused with iron deficiency Spread by: sap & propagation

33. CbMV on Calicrachoa Photo: L. Pottorff

34. Other viruses

35. ToMV on Tomato Photo: www.omafra.gov.on.ca

36. Canna Yellow Mottle Virus

37. White ring spots form on meadow-rue infected with Tobacco rattle virus

38. Rings and chlorotic lines caused by Tobacco Rattle Virus on Epimedium

39. Begonia leaves with virus-induced chlorotic mottling and necrosis

40. White patches Alstroemeria mosaic virus

41. Tulip Breaking Virus

42. Odontoglossumringspottobamovirus, ringspot on orchid Photo: www.agdia.com

43. Odontoglossumringspottobamovirus causing flower break on orchid Photo: www.agdia.com

44. Unknown orchid virus Photo: www.aos.org/AM/Images/pest+diseases/Virus2003.jpg

45. Virus Testing ELISA (Enzyme Linked ImmunoSorbentAssay) Uses antibodies and color changes to detect

46. Lab based Crop screens for multiple viruses In-house ImmunoStrips For common viruses

47. Other resources:Virus Testing Agro Check kits from Hydros Inc. 230 Jones Road, Falmouth , MA 02540 Phone: 508 540 2229, http://www.hydros.cc/ . 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)

48. CSU Extension Adams CountyPlant Diagnostic Lab Disease and insect diagnosis for greenhouse and nursery industry Stock Agdia tests for common viruses Discount services for CNGA members 9755 Henderson Rd, Brighton; 303/637-8016 brooke.edmunds@colostate.edu

49. Insect Management Sanitation-no holdovers! Remove weeds in and around greenhouse Air-lock or double-door entrances Insect screening Scouting & monitoring Control strategies

50. Scouting for thrips Hot pink or blue sticky cards 5-10/acre plus near doors and vents Just above tops of plants Plant inspections: Feeding scars & black feces Depending on plant-on upper or lower foliage Tap foliage over white paper and look for adults Photo: http://www.omafra.gov.on.ca/english/crops/facts/03-075f1a.jpg

51. Indicator Plants Petunia ‘Super Blue Magic’, ‘Summer Madness’, ‘Calypso’, etc Fava bean ‘Toto’ Feeding scars show up rapidly Brown ring if INSV is present

52. Insect Screening Photo: http://edis.ifas.ufl.edu

53. Insecticides to control Thrips Organophosphates Carbamates Pyrethroids Chloronicotinyls Botanicals Drench at transplant, followed by foliar applications ROTATE to avoid resistance!

54. Sanitation Benches, pots, equipment: 3% TSP (trisodium phosphate) Virkon S Quaternary ammonia Hydrogen dioxide Bleach For workers: Skim milk deactivates TMV Powdered or fresh So does soap and water! 95-100% effective

55. Worker sanitation Wash hands with soap before starting work and after smoking Don’t allow visitors to handle plants without washing hands Keep propagation area off-limits to workers handling older plants

56. Sanitizer Study Greenhouse Grower, Feb ‘09 Compared 8 sanitizers for TMV control Dipped razorblade in TMV infected petunia sap Sanitized the razorblade with different treatments Cut new petunias and rated for TMV development

57. From: Greenhouse Grower, Feb 2009