The Ontario Fire Blight Prediction Maps for apples and pear are now available for the 2026 season!
With bloom beginning in the earliest regions of the province, risk of blossom infection in now possible. Use these maps and predicted forecast for your area to prepare for potential infection periods.
Growers can access the maps on the ONfruit homepage or bookmark the direct link below. Links within the prediction maps page will help users jump to the section they are looking for as both apple and pear maps are together.
Bookmark onfruit.ca/fire-blight-map/ in your browser for quick reference.
Risky Business
The risk of fire blight infection is possible if the following conditions are met:
- Flowers are opened and/or are opening – There is no risk of infection if bloom is not present in the orchard despite the fire blight maps stating caution to extreme; however, keep an eye on any early signs of bloom as it can happen quickly.
- Enough heat units have accumulate based on forecasting models – The fire blight maps use Cougarblight but this applies to MaryBlyt as well. Similar to degree days, daily temperature is accumulated and must reach a certain point before risk increases.
- A wetting event is predicted – Any type of wetting event will wash the bacteria into the open bloom including rain, dew or even the artificial rain shower you create with the sprayer during critical infection periods.
These maps provide the current 7-day predicted risk of fire blight infection for various regions throughout southwestern Ontario, based on the Cougar Blight model. Predicted risks are updated daily.
Using Risk Maps
Since 2023, OMAFRA has partnered with Weather Source to provide OnPoint Weather. The locations on the map are based on agricultural production and use all nearby weather data and geography to provide accurate forecasting data.
The maps are animated and will cycle through the daily fire blight risk predictions based on the 7-day weather forecast. Follow the animated risk of the region that best corresponds with your orchard location. If predicted risk differs between overlapping locations, err on the side of caution and use the higher risk prediction.
As with any model, the fire blight risk maps are a general guide. Environmental conditions may be more conducive for fire blight infection in a particular orchard than what is indicated by the maps.