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Disease Control Products for Stored Potatoes

Disease Control Products for Stored Potatoes. Jill Thomson and Doug Waterer Dept of Plant Sciences, University of Saskatchewan. Control of Storage Diseases. Challenge - need dependable control of various diseases during storage/handling Challenge - need safe, affordable products

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Disease Control Products for Stored Potatoes

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  1. Disease Control Products for Stored Potatoes Jill Thomson and Doug Waterer Dept of Plant Sciences, University of Saskatchewan

  2. Control of Storage Diseases • Challenge - need dependable control of various diseases during storage/handling • Challenge - need safe, affordable products • Challenge - products must be readily applied with available equipment

  3. Control of Storage Diseases • Traditional options • Mertec (TBZ) • spray applied during load-in • good coverage critical • not effective against bacteria • not effective against Late Blight • extensive resistance in Dry Rot and Silver scurf • $ 6.40/tonne at CDN label rate

  4. Control of Storage Diseases • Available options • Dithane (Mancozeb) • spray applied during load-in • good coverage critical • not effective against bacteria • effective against Dry Rot and Silver scurf • $ 11.06/tonne • only registered for use on seed

  5. Control of Storage Diseases • Alternate options • Purogene • Oxidate • Ozone

  6. Control of Storage Diseases • Purogene (Anthium) • UAP • Sodium chlorite + acid = Chlorine dioxide (gas) + other Cl species • applied as spray to potatoes going into storage and/or • added to ventilation air

  7. Control of Storage Diseases • Purogene • works by oxidation reactions • label indicates effective against L. blight, Silver Scurf, Dry Rot and Bacterial Soft rot • inactivated by soil • no residual activity • repeated or continuous treatment recommended

  8. Control of Storage Diseases • Purogene - Status • Researched by MSU, NDSU, Idaho, MB and AB. • 5th year of Class 18 Exemption in U.S. • Emergency use in Canada in 1999, 2000 and 2001 but not in 2002

  9. Control of Storage Diseases • Purogene Efficacy against Soft rot • MB data • some control

  10. Control of Storage Diseases Effect of Purogene on the amount of rot found on tubers (MANITOBA) Cultivar Concentration Avg Rot per Tuber (%) Russet B. 0 23.5 50 3.8 200 1.1 400 2.2 Shepody 0 9.1 50 5.8 400 3.2 Shepody 0 1.1 50 2.4 200 0.2 400 0.3

  11. Control of Storage Diseases • Purogene vs Late Blight • MB data • Tubers treated immediately after inoculation • some control

  12. Control of Storage Diseases • Purogene vs Rhizoctonia, Silver Scurf, Soft Rot and Dry Rot • AB data • Tubers sprayed at load in • Tubers treated in storage (weekly) • minimal control

  13. Control of Storage Diseases • Purogene - Safety • mixing step requires safety equipment (ClO2 vapors) • ventilate storage for 2 h prior to re-entry • potatoes must be washed prior to consumption • slowly corrodes copper, brass, aluminum

  14. Control of Storage Diseases • Purogene - Economics • 16-32 ml/ton applied at load-in • max rate of 16 ml/ton/month applied during storage humidifaction • $25/L • $ 2.50/ton for pre-treatment + continuous application over 5 months

  15. Control of Storage Diseases • Purogene Conclusions • variable results • problems getting full activation • problems with inactivation by soil • problems with uniformity of distribution of effective dosages • problems with adding humidity to problem storages • relatively safe and affordable

  16. Control of Storage Diseases • Oxidate • BioSafe • Hydrogen Peroxide + acetic acid • applied as spray to potatoes going into storage and/or • added to ventilation air

  17. Control of Storage Diseases • Oxidate • works by oxidation reactions • label indicates effective against L. blight, Silver Scurf, Dry Rot and Bacterial Soft rot • inactivated by soil • no residual activity • continuous treatment recommended

  18. Control of Storage Diseases • Oxidate - Status • approved in U.S. for use in wide range crops in field and storage • approved as an “organic” pesticide • “Emergency Use” in BC and AB in 2002 • full registration anticipated for April 2003 • NB has done some testing in potatoes

  19. Control of Storage Diseases • Oxidate - Efficacy

  20. Control of Storage Diseases • Oxidate - Efficacy

  21. Control of Storage Diseases • Oxidate - Efficacy

  22. Control of Storage Diseases • Oxidate - Efficacy

  23. Control of Storage Diseases • Oxidate - Safety • no mixing step • concentrated product is corrosive • no re-entry restriction • no limit to amount applied • no requirement to wash prior to consumption • slowly corrodes copper, brass, aluminum

  24. Control of Storage Diseases • Oxidate - Economics • 1-2% solution applied to wetness at load-in • 1:100 to 1:300 applied during storage humidifaction • $17.78/L • pre-treatment = $ 0.71-1.42/tonne • 1% in humidification system = $1.78 per injection • How many injections into system over 5 month period?

  25. Control of Storage Diseases • Oxidate – Conclusions • potential to reduce disease levels • high dosages and continuous application most effective • safe and affordable • need uniform delivery of effective dosages • adding humidity to problem potatoes ? • Impact on sprouting ??

  26. Control of Storage Diseases • Ozone • various manufacturers • O2 + high energy = O3 (gas) • applied at high levels to potatoes going into storage and/or • added to ventilation air

  27. Control of Storage Diseases • Ozone • works by oxidation reactions • lab studies indicates effective against range of bacteria and fungi • inactivated by soil • no residual activity • continuous treatment recommended

  28. Control of Storage Diseases • Generator unit, outside storage

  29. Control of Storage Diseases • Monitoring equipment mounted above conveyor. Injection of O3 into conveyor system, removal of excess O3.

  30. Control of Storage Diseases • Ozone - Status • well established in other food areas • data for storage use is limited • advantage = does not depend on water for delivery (spray or humidity)

  31. Control of Storage Diseases • Ozone – Efficacy

  32. Control of Storage Diseases • Ozone – Efficacy

  33. Control of Storage Diseases • Ozone – Efficacy • O3 applied loading into storage

  34. Control of Storage Diseases • Ozone - Safety • widely used to sanitize food and buildings • corrosive at high concentrations • exposure levels well established • no limit to amount applied • no requirement to wash prior to consumption

  35. Control of Storage Diseases • Ozone - Economics • generators + power • 500 ppm during loading • 2 ppm during storage ventilation • $ ?

  36. Control of Storage Diseases • Ozone - Conclusions • primarily provides contact control • most effective against surface problems (scurf and bacteria) • ineffective against aggressive or well established infections • economics ? • Impact on product/facilities ?

  37. Control of Storage Diseases • Conclusions • Purogene and Oxidate demonstrated to provide some control under certain conditions • Ozone also shows potential • Most effective against new, surface problems • Supplement to good harvest and storage management practices

  38. Control of Storage Diseases • In the future ? • No new chemical products in the pipeline • BioCide is developing granular products for time-release uses • Help overcome short reaction times of chlorine dioxide and improve in-storage distribution • Further out … Bacterial antagonists to common diseases

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