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Alberta conditions are excellent for late blight

July 19, 2013, Alberta – An Alberta Agriculture specialist says that conditions are excellent in most areas of Alberta for the development and spread of late blight.

“In recent years, late blight of potato and tomato has been found in varying degrees in various parts of the province,” says Robert Spencer, commercial horticulture specialist, Alberta Ag-Info Centre, Stettler. “So far this growing season, late blight has not been found in Alberta, but conditions are excellent for its development and spread.

“A great deal of effort has been expended to minimize the seasonal impact and limit the ongoing spread of this disease. As a result, the number of detections has been significantly reduced, but we need to stay vigilant.”

Spencer says the following conditions, all of which have been seen this growing season, favour the development of late blight:

• significant amounts of moisture, falling in regular intervals (days without any precipitation have been rare)
• high humidity (sometimes approaching 95 per cent)
• heavy dews and long leaf wetness periods
• moderate temperatures
• warmer nights (night time temperatures are not falling below 9°C)

“It is recommended that all growers of potatoes and tomatoes be extra vigilant to try and catch any diseased material early on before a significant outbreak occurs,” says Spencer. “Producers should monitor fields for potentially infected plants. Protective fungicide applications can be made in commercial operations.”

July 19, 2013  By Alberta Agriculture and Rural Development