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 Wednesday evening, Apr 14. Predicted weather conditions are shown for Apr 15-19. 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 fire blight infection occurred with wind-driven rains as predicted Apr 8. For infection to be predicted, wetting has to occur when the EIP (epiphytic infection potential) reaches 100 or higher. Currently, the fire blight threat has been reduced by cooler temperatures, but the risk will again increase with warmer temperatures then next two days and possible showers Friday, Apr 16. Based on cooler predicted temperatures, the risk should again subside through the weekend. Be aware that risks can increase quickly with warmer than predicted temperatures and unpredicted wetting. The Maryblyt 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.
