CAUTION: The observations, conditions, and recommendations reported for Winchester, VA are provided as a guide to fire blight risk assessment only for the immediate area of the Virginia Tech AREC located six miles southwest of Winchester. Use of the information reported here for making orchard management decisions outside of that area is not our intent. Fruit producers outside of that area are encouraged to consult their state extension specialists for information similar to that provided here.
FIRE BLIGHT: Above is a cropped graphic from the Maryblyt 7 program. With most apple orchards still near full bloom, here is a prediction for trees with first bloom open Monday, Apr 5, 2010. The temperature and rainfall data are current through Friday evening, Apr 16. Predicted weather conditions are shown for Apr 16-19. The components of fire blight risk are indicated in the columns labeled B (blossoms open), H (degree hours for epiphytic bacterial populations), W (wetting by rain or dew), and T (average daily temperature 60 F or above). The risk column shows that wetting today would result in predicted fire blight infection. For infection to be predicted, wetting (from rain, heavy dew, or a spray application) has to occur when the EIP (epiphytic infection potential) reaches 100 or higher. With cooler predicted temperatures tomorrow, the risk should again decline well into next week. However, be aware that risks can increase quickly with warmer than predicted temperatures and unpredicted wetting. Growers are advised to be alert to changes in forecasts on a day to day basis and protect high-risk blocks through late bloom as needed. The Maryblyt graphic will be updated Apr 19. The weather conditions used in the predictive part of this graphic come from the Weather Channel for Winchester, supplemented by site-specific data from Skybit, Inc.
