Summer disease pressures remain high, with continued accumulation of wetting hours and a recent extended wetting period at warm temperatures. The extended wetting event was Aug 15-16: 17 hr at 78-70° with 0.24 in. rain. This favored bitter rot, initiated by rain-splashing of conidia, followed by extended wetting at these warm temperatures.
As of Monday, Aug 15, wetting hour accumulations (ACW) at Winchester: at 909 ft elevation, 770 hr (more than 3 times the 250-hr threshold which was reached June 5); at 952 ft elevation, 594 hr; and at the 983 ft elevation, 450 hr ACW.
Accumulated wetting hours in central Virginia are quite similar to Winchester this year: At Tyro, VA as of Aug 15, a sensor placed at the 941 ft elevation had accumulated 777 hr (with the 250-hr threshold reached June 6); the one at 1165 ft. elevation had accumulated 436 wetting hours, and the one 1465 ft. elevation had accumulated 484.
Disease management information directed mostly to the Frederick County Virginia tree fruit industry, updated as needed throughout the growing season. Keith Yoder, Virginia Tech Agricultural Research and Extension Center, Winchester, Virginia
About Me
- Keith Yoder
- Professor Emeritus of Plant Pathology, Virginia Tech Ag. Research and Extension Center, Winchester, VA
