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Ontario late blight update

July 25, 2013  By Janice LeBoeuf OMAF

Late blight symptoms on leaves.

July 25, 2013 – To date, there are no confirmed cases of late blight in Ontario, but the disease has shown up in neighbouring states.

Here’s a summary:

  • July 17 – Wayne County, northern Ohio – tomato
  • July 17 – Genesee County, (near Buffalo) New York – potato
  • July 14 – Lancaster County, SE Pennsylvania – tomato
  • July 13 – Allegan County, SW Michigan – potato
  • July 11 – Madison County, (near Syracuse) New York – potato (US-23)
  • July 10 – Erie County, (near Buffalo) New York – tomato (US-23)
  • July 9 – Erie County, (near Buffalo) New York – potato (US-23)
  • Late blight has also been confirmed in Wisconsin (July 3, potato and tomato), Massachusetts (July 11, tomato), New Jersey (July 4, potato, US-23; July 4, tomato; June 28, tomato), and several states further south.

Remember that conventional tomato growers using a recommended fungicide program for early blight, septoria leaf spot, and anthracnose, are also protecting the crop from late blight infection. Cloudy and high humidity or wet conditions are favourable for late blight. The pathogen prefers cool temperatures. The disease is suppressed by hot, dry weather, but it can continue developing and spreading when suitable conditions return. READ MORE


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