managing late blight in 2011 sspga/svga 2010. 2010 late blight widespread across n. america arrives...
TRANSCRIPT
Managing Late Blight in 2011
SSPGA/SVGA 2010
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
Why so much Late Blight in 2010?
Why so much Late Blight in 2010?
2009
- blight arrives across SK late in the season
- causes minor crop loss but did it get into the seed potatoes?
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
So, what about 2011?
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
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
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
Al-Mughrabi - 2010
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
So, what about Blight in 2011 ?
Managing the Pathogen
- Blight bioassay
- randomly select 50 (100 ?) tubers
- cut + hold at 20oC at high RH for 2 weeks
- look for Late Blight sporulation (3
days
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
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
Immediate application of seed treatments both stops infection and prevents spore formation
So, what about Blight in 2011 ?
Managing the Pathogen
Seedpiece treatments
Poor – Easout and Maxim
Good – Tuberseal, PST, Maxim MZ
Evolve = TBZ + MZ + cymoxanil
Seed Piece Treatments Work !!
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 ?
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
So, what about Blight in 2011 ?
Host
- Cultivar sensitivity
Sensitive – all reds, Shepody
Moderate – Norkotah, Burbank, Yukon Gold
Tough – Alpine, Classic, Milva, Yukon Gem
MilvaBurbankY. Gold
Shepody
Research Supported by ADF