Late Blight Decision Support Tool
Late blight is a devastating disease of tomatoes and potatoes in Ontario. The incidence of late blight in tomatoes has increased in Ontario and the eastern U.S. in recent years. Widespread occurrence of the disease in 2009 wiped out almost all organically-grown tomato fields in the northeast U.S. Epidemics of late blight of tomatoes are heavily dependent on weather, particularly free moisture in leaf surface due to rainfall, dew, irrigation, fog or clouds. The disease occurs in a wide temperature range (7-29°C). Disease progress is slowed under temperatures below 13°C and above 25°C.
** Site-specific weather-based advisory and decision support tools for fungicide timing is available to registered users. Registration is FREE.