FIRE BLIGHT: Above is a cropped graphic from the Maryblyt 7 program. Many apple trees are now near petal fall but with much bloom still open and susceptible. Late cultivars such as Rome are at full bloom. The temperature and wetting data are current through Wednesday morning, April 27. Predicted weather conditions are shown for April 27-May 2. 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). Based on predicted temperatures and wetting, the risk column shows that fire blight infection is possible with rainfall today and tomorrow, Apr 28 and would again be possible if wetting were to occur Apr 30-May 2 (note red color). For infection to be predicted, wetting must occur after the EIP (epiphytic infection potential) reaches 100 or higher. This bloom season has seen some sustained fire blight pressure. In high-risk situations, a protective streptomycin application is recommended ahead of predicted infection. This graphic will be updated April 29, or sooner if significant change warrants it. The BBS and CBS columns are tracking predicted blossom blight symptom (from infection Apr 11 and later ones as a, c and d) and canker blight symptom appearance, respectively. Numbers in these columns represent percent of required degree hours for early blossom symptom appearance and canker margin symptoms Apr 26. 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.
