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.
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FIRE BLIGHT: Above is a cropped graphic from the Maryblyt 7 program. Although some cultivars have reach petal fall of early bloom, many still have much susceptible bloom and a prolonged bloom period is expected. Here is a prediction for trees with first bloom open Monday, March 23, 2012. The temperature and rainfall data are current through this morning, Apr 13. Predicted weather conditions are shown for Apr 13-19. 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). After going through 11 days of light to moderate blossom blight risk, the risk column shows that risk of fire blight infection will increase with warmer temperatures through this weekend and into next week. For infection to be predicted, wetting must occur after the EIP (epiphytic infection potential) reaches 100 or higher and there must be wetting. Wetting from rain, a spray application, or heavy dew would trigger infection Apr 15-16, and infection conditions are predicted with wetting for Apr 17 and 19. In high-risk situations, a protective streptomycin application is recommended ahead of predicted infection and with any spray applications of other materials. This graphic will be updated Apr 16. 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.
