Fire Blight Alert and Risk Map Overview

Apple and pear trees are approaching bloom, especially in southwestern Kentucky. Infection by the fire blight bacterium occurs during bloom, thus, protectant antibiotics should be applied when risk is high.

Risk for infection can be assessed using the Fire Blight Disease Prediction Model. Growers can assess local risk by selecting their county and orchard history. This model incorporates the previous 4 days of weather data plus adds a 7-day forecast for estimating leaf wetness and temperature (thereby estimating risk for bacterial growth and infection). There are 66 Mesonet weather stations throughout Kentucky, thus, weather information for the model is based on data from the closest weather station. For a mobile (phone or tablet) friendly version of this site, visit

Remember that apple and pear trees must be in bloom for predictions to be accurate. The map overview presented here indicates fire blight risk as of March 25, 2019 (Figure 1). According to the current assessment, risk is low due to the cool dry weather. A rain event, however, can increase that risk. Growers are encouraged to check the model regularly for the most accurate analyses and county-specific forecasts.

Information regarding prevention and management of fire blight can be found in:

  • Plant Diseases of Fruit Prediction Models for Kentucky Counties (PPFS-FR-T-07)
  • Commercial Fruit Pest Management Guide (ID-232)
  • Backyard Apple Disease Management Using Cultural Practices (PPFS-FR-T-21)
  • Fire blight (PPFS-FR-T-12)
  • Fire blight of Apple (Video)

Figure 1: Fire blight risk for Kentucky counties as of March 25, 2019.


Nicole Ward Gauthier, Extension Specialist and Kimberly Leonberger, Extension Associate



Posted in Fruit