NOTE: Most apple varieties in the Winchester area are at early to mid-bloom. Below are the fire blight risk assessments, comparing graphics from Maryblyt 7, and also from the Cougarblight model as shown on our NEWA site. We will be using the same weather data from our NEWA station to make these comparisons. We thank Dr. Mizuho Nita for hosting the Maryblyt 7.1 download site.
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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| Graphic from Maryblyt 7, April 27, 2018. Click to enlarge. |
FIRE BLIGHT: Above is a cropped graphic from the Maryblyt 7 program. With first bloom open Apr 14. The temperature and rainfall data are current through Friday evening, April 27. Predicted weather conditions are shown for April 28-May 3. 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). For infection to be predicted, wetting must occur after the EIP (epiphytic infection potential) reaches 100 or higher, and this must coincide with an average daily temperature of 60°F or more. Based on recorded temperatures and wetting, the risk column shows high risk Apr 28, then declining to low to moderate risk for Apr 29-May 1, then high risk for May 2-3, when only the wetting requirement is lacking. Consider including streptomycin with any spray application May 1-3.
Below is the graphic from the Cougarblight model as shown on our NEWA site. We selected orchard blight history option as “Fire blight occurred in your neighborhood last year” and first blossom open date as 4/14/2017. Cougarblight shows color-coded risk assessment as “Cougarblight 4-Day DH” risk is high or extreme for May 2-3.
