Fire Blight Biology
Open blossoms must be present for a blossom blight risk. Fire blight bacteria are transported from overwintering canker sites to open flowers by the action of insects and rain. These bacteria then reproduce on the stigma of flowers and are washed down into the base of the flower by a wetting event – a minimum of just 0.25 mm of rain or heavy dew – which then initiates an infection if adequate bacterial populations are present. An average daily temperature of at least 15.6°C is needed to establish infections and the infection potential rises with consecutive hours above 18.3°C. Blossom blight risk increases with warm temperatures between 23°C and 27°C, especially when occurring over consecutive days because this temperature range is ideal for bacterial reproduction. The Maryblyt model criteria is used to predict blossom blight infections.
Monitoring for Blossom Blight
Open blossoms must be present for a blossom blight risk. Fire blight bacteria are transported from overwintering canker sites to open flowers by the action of insects and rain. These bacteria then reproduce on the stigma of flowers and are washed down into the base of the flower by a wetting event – a minimum of just 0.25 mm of rain or heavy dew – which then initiates an infection if adequate bacterial populations are present. An average daily temperature of at least 15.6°C is needed to establish infections and the infection potential rises with consecutive hours above 18.3°C. Blossom blight risk increases with warm temperatures between 23°C and 27°C, especially when occurring over consecutive days because this temperature range is ideal for bacterial reproduction. The Maryblyt model criteria is used to predict blossom blight infections.
Monitoring for Blossom Blight
This year, all NSFGA-owned weather stations are being used for industry monitoring and alerts. Those weather stations are located in the following ten communities: Atlanta, Aylesford, Grafton, Grand Pre, Melvern Square, Morristown, Moschelle, North Medford, Windsor, and Woodville.
- If you would like to join the alert contact list, please let me know or sign up online.
- Alerts will be delivered on weekends and holidays.
- Short notice blossom blight alerts will be delivered directly to your email inbox. Periods with high fire blight bacterial populations are defined by Maryblyt as having an Epiphytic Infection Potential (EIP) greater than 100. Notifications will be sent as soon as it is evident that the EIP will approach 100 for apples and pears.
- Please watch for and take note of your first blossom date which is the first flower that opens on your orchard.
- Ideally you will monitor your own farm-specific conditions and improve your management decisions using PomeBlight that was developed for Nova Scotia apple and pear growers.
- Create a free account here: www.farmdatatools.perennia.ca.
- A Quickstart video is available here.
- Follow along at your own pace, print, and save the information for reference using the PDF document.
- Contact me if you need a quick refresher or need help setting up.
- Run the model using your own temperature, rainfall, bloom and spray dates (industry alerts will offer limited scenarios).
