Late blight of Potatoes and Tomatoes are Spreading Quickly in Bordering areas of Ontario

Dr. Rishi Burlakoti, Weather INnovations Consulting LP, Chatham ON

July 23, 2014

Late blight diseases in potatoes and tomatoes have been quickly spreading in several states in USA including Ontario’s neighbouring states. To date, the disease has been reported in several counties of New York, Pennsylvania, North Carolina, New Jersey and other eastern states. Recently, the disease has been reported in Montcalm county of Michigan on July 16. The disease has been also reported in Erie County nearby Buffalo on July 18th ( Late blight has been also reported in Atlantic Canada, PEI and New Brunswick.

The weather pattern in the entire growing season in 2014 is favorable for late blight epidemics in potatoes and tomatoes. The continuous and frequent rainfall occurred during June and July in Ontario along with high humidity and cool to warm temperature are very favorable for the disease incidence if late blight pathogen inocula are present. Our late blight prediction map also showing high risk as indicated by high disease severity values (DSVs) in Ontario.


Since late blight has been already reported in several states in USA including neighboring states of Ontario as well as Atlantic Provinces in Canada, weather conditions are very favorable, the disease can pose risk for the crops. Therefore, it is suggested to take appropriate action to protect both tomato and potato plants from this devastating disease. To get the late blight risk map and management guideline, visit for Ontario Potato Growers and for Manitoba Potato Growers.

To get site-specific late blight advisory for tomatoes, login and register your field at

If you have any questions, please feel free to contact Dr. Rishi Burlakoti, Plant Pathologist at Weather Innovations (

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