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

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Presentation on theme: "Disease Control Products for Stored Potatoes Jill Thomson and Doug Waterer Dept of Plant Sciences, University of Saskatchewan."— Presentation transcript:

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

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8 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

9 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

10 Control of Storage Diseases Purogene Efficacy against Soft rot –MB data –some control

11 Control of Storage Diseases Effect of Purogene on the amount of rot found on tubers (MANITOBA) CultivarConcentrationAvg Rot per Tuber (%) Russet B Shepody Shepody

12 Control of Storage Diseases Purogene vs Late Blight –MB data –Tubers treated immediately after inoculation –some control

13 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

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

15 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

16 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

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

18 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

19 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

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 - Efficacy

24 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

25 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 = $ /tonne –1% in humidification system = $1.78 per injection –How many injections into system over 5 month period?

26 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 ??

27 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

28 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

29 Control of Storage Diseases Generator unit, outside storage

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

31 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)

32 Control of Storage Diseases Ozone – Efficacy

33 Control of Storage Diseases Ozone – Efficacy

34 Control of Storage Diseases Ozone – Efficacy –O3 applied loading into storage

35 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

36 Control of Storage Diseases Ozone - Economics –generators + power –500 ppm during loading –2 ppm during storage ventilation –$ ?

37 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 ?

38 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

39 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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