1. Managing Late Blight in 2011 SSPGA/SVGA 2010

2. 2010 Late Blight widespread across N. America Arrives in SK in July Commercial growers (SVGA, SSPGA, SGGA) warned in advance Backyard tomatoes wiped out. Ghse = ?? Potatoes – mixed bag

3. Why so much Late Blight in 2010?

4. 2009 - blight arrives across SK late in the season - causes minor crop loss but did it get into the seed potatoes?

5. Why so much Late Blight in 2010? 2010 - ideal weather for development and spread of blight (cool, windy and wet) - very difficult to maintain a decent spray program

6. So, what about 2011?

7. So, what about Blight in 2011 ? Pathogen - Late blight overwinters in infected tubers - Disease spreads into next year if.... a) diseased tubers discarded as culls are not disposed of correctly b) diseased tubers used as seed

8. So, what about Blight in 2011 ? Pathogen Diseased seed - heavily infected tubers... - easy to detect - will likely rot after planting = no spread - may spread spores to otherwise healthy seed at cutting time

9. So, what about Blight in 2011 ? Pathogen Diseased seed - Lightly infected tubers... - infected late in fall or at cutting time - no visible signs of rot - will likely sprout and develop into diseased plant = starting point of field infection

10. Al-Mughrabi - 2010

11. So, what about Blight in 2011 ? Managing the Pathogen - Plant certified seed... but Late Blight is not specifically covered in Certification Standards - Ask your supplier about Blight pressure and their blight management program - Grow out test results ? - Check the seed carefully yourself

12. So, what about Blight in 2011 ? Managing the Pathogen - Blight bioassay - randomly select 50 (100 ?) tubers - cut + hold at 20 o C at high RH for 2 weeks - look for Late Blight sporulation (3 days

13. So, what about Blight in 2011 ? Managing the Pathogen Standard conditions for curing cut seed = ideal for sporulation of Blight CUT... then PLANT Disinfect cutting, handling equipment regularly Cut “problem” seed lots last

14. So, what about Blight in 2011 ? Managing the Pathogen - need to stop infected seed from sporulating and infecting adjacent healthy pieces - grade out any diseased pieces - apply seed piece treatments immediately after cutting

15. Immediate application of seed treatments both stops infection and prevents spore formation

16. So, what about Blight in 2011 ? Managing the Pathogen Seedpiece treatments Poor – Easout and Maxim Good – Tuberseal, PST, Maxim MZ Evolve = TBZ + MZ + cymoxanil

17. Seed Piece Treatments Work !!

18. So, what about Blight in 2011 ? Environment - Avoid high risk fields in 2011 - low spots - problem access fields - proximity to problems - Pay attention to weather at emergence - What’s going on next door ?

19. So, what about Blight in 2011 ? Managing the Pathogen Scout field at emergence Start preventative spray program early High risk fields.... - curzate MZ at 80% emergence, then again 2 weeks later

20. So, what about Blight in 2011 ? Host - Cultivar sensitivity Sensitive – all reds, Shepody Moderate – Norkotah, Burbank, Yukon Gold Tough – Alpine, Classic, Milva, Yukon Gem

21. Milva Burbank Y. Gold Shepody Research Supported by ADF