Quick jump
The following maps provide the current 7-day predicted risk of fire blight infection for various regions throughout southwestern Ontario, based on the Cougar Blight model.
New for the 2023 season, 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.
To use the maps below, orchards must be assigned to one of two categories based on the fire blight situation in the orchard last year and this year:
Apples
- Fire blight occurred in the orchard last year and is now active in your neighbourhood.
- Fire blight occurred in the neighbourhood last year.
Pears
- Fire blight occurred in the orchard last year and is now active in your neighbourhood.
- Fire blight occurred in the neighbourhood last year.
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.
APPLES
Current Growth Stages for Key Apple Growing Regions
County / Region | Growth Stage | Blossom Blight Risk? |
|---|---|---|
Essex – Chatham-Kent | Mature fruit | No |
Middlesex – Elgin | Mature fruit | No |
Norfolk | Mature fruit | No |
Niagara | Mature fruit | No |
Grey | Mature fruit | No |
Durham | Mature fruit | No |
Quinte | Mature fruit | No |
Ottawa Valley | Mature fruit | No |
Apples – Fire blight occurred in the orchard last year and is now active in your neighbourhood
Apples – Fire blight occurred in the neighbourhood last year
PEARS
Current Growth Stages for Key Pear Growing Regions
County / Region | Growth Stage | Blossom Blight Risk? |
|---|---|---|
Essex – Chatham-Kent | Mature fruit | No |
Norfolk | Mature fruit | No |
Niagara – West | Mature fruit | No |
Niagara – East | Mature fruit | No |
Grey | Mature fruit | No |
Durham | Mature fruit | No |
Pears – Fire blight occurred in the orchard last year and is now active in your neighbourhood
Pears – Fire blight occurred in the neighbourhood last year
Map Legend
The following risks are colour coded and designated as follows:
LOW
Indicates a low risk of fire blight occurring. Wetting of blossoms during these temperature conditions has not resulted in new infections in past years. The blossoms within a few meters of an active canker may be an exception.
CAUTION
Wetting of flowers under these temperature conditions is not likely to lead to infection, but the possibility increases if the weather becomes warmer and wetter. Weather forecasts should be carefully monitored. If antibiotic materials are not being used, blossom protection with other materials should be initiated one or two days prior to entering a high infection risk period. Continue appropriate protective sprays until the infection risk drops below the “high” threshold.
HIGH
Under these temperature conditions, serious outbreaks of fire blight have occurred. Orchards that recently had blight are especially vulnerable. The risk of severe damage from infection increases during the later days of the primary bloom period, and during petal fall, while blossoms are plentiful. Infection is common, but more scattered when late blossoms are wetted during high risk periods. The potential severity of infection increases if a series of high risk days occur.
EXTREME
Some of the most damaging fire blight epidemics have occurred under these optimum temperature conditions, followed by blossom wetting. These infections often lead to severe orchard damage, especially during primary bloom or when numerous secondary blossoms are present. As the season progresses, secondary blossoms tend to form less frequently, and hot summer temperatures of 35°C and above greatly reduce the frequency of new blossom infections.
Model Information and Cautions
As with any model, the risk is a general guide and environmental conditions may be more conducive for fire blight infection in your orchard than what is indicated by the maps. All growers are encouraged to run either the Cougar Blight or Maryblyt model with data generated in their orchard for a more accurate prediction.
Blossom blight risk predictions begin at first blossom open. If bloom in your orchard has not yet occurred, continue to check fire blight risk predictions and monitor bloom daily. Infection cannot occur without open blossoms.
A risk has been calculated for each date for each station/region based on the weather prediction. The Cougar Blight model predicts risk based on the following assumptions:
- Enough heat units have accumulated to reach a threshold level of inoculum;
- A wetting event (rain, dew, etc) occurs to wash the bacteria into the blossom; and
- The average temperature is above 15.5C.
If two or more of these assumptions are met while bloom is present, risk is increased and management should be considered.