At Winchester apple trees are mostly at mid-bloom, with later cultivars coming into bloom.
At the AREC we received an apple scab, quince rust and cedar-apple rust infection period Apr 12-13 with 15 hr wet at 57° with 0.74 in. rain. Earlier last week we also had a possible combined scab/rust infection period Apr 7-8 with 9 hr wetting at 57° with 0.94 in. rain. More than 95% of the scab ascospores are now mature in the Winchester area. At Winchester, we have had 10 days favorable for apple powdery mildew infection since spores were available.
Most of the commercial fruit production areas in Virginia had similar scab and rust infection conditions Apr 12-13, but with more rainfall east of the Blue Ridge and southward. Rainfall ranged from 1.5 inches at Sperryville and 2.3 inches at Manassas to 3.36 inches at Lynchburg. Such volumes of rainfall deplete fungicide protection, calling for fungicides with after-infection control for scab and rusts, as well as something for protection against powdery mildew in mildew-susceptible cultivars..
FIRE BLIGHT: With most apples in bloom, the current fire blight threat remains moderate to low in the Winchester area.
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| Graphic from Cougarblight, April 14, 2020. Click to enlarge. |
Above 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 3/30/20. Cougarblight shows color-coded risk assessment as “Cougarblight 4-Day DH” risk is moderate or low through Apr 19. The Roanoke area and areas east of the Blue Ridge south of Charlottesville had possible infection Apr 7-9 (graphics not shown), and after high risk Apr 13, are now also showing moderate to low infection potential through Apr 19.
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. Be aware that risk can change quickly with unpredicted warmer temperatures and wetting. In high-risk situations.
