Continued summer disease pressures

Summer disease pressures have advanced at a relatively steady pace over the past two weeks, with several extended wetting periods and continued accumulation of wetting hours.  As of Monday, July 18, we were more than 2 weeks past the 250-hr accumulated wetting hour threshold (ACW) for all of the wetness sensors at our AREC, Winchester and for Tyro, VA. Altough the volume of rainfall has not been excessive, shower activity has favored spread of fungal spores for fruit rots such as bitter rot on apples and brown rot on peaches and other stone fruits.

Wetting hour accumulation (ACW) at Winchester: at 909 ft elevation, 555 hr (with the 250-hr threshold reached June 5); at 952 ft elevation, 419 hr (near the threshold); and at the 983 ft elevation, 341 hr ACW. At Tyro, VA  as of July 18, a sensor placed at the 941 ft elevation had accumulated 529 hr (with the 250-hr threshold reached June 6); the one at 1165 ft. elevation had accumulated 309 wetting hours, and the one 1465 ft. elevation had accumulated 341 . 

At Winchester in the past two weeks we had three significant extended wetting events favorable for SBFS and fruit rot development: July 4-5: 20 hr at 71-67°, with 0.74 in. rain, July 12-13: 13 hr at 77-66° with 0.04 in. rain, and July 16-17: 15 hr at 77-65° with 0.34 in. rain. Bitter rot was observed on apple fruit at Winchester as early as June 22, and all of these recent wetting periods were at temperatures favorable for bitter rot. Specific treatment against the SBFS fungal complex and rot diseases is advised.

We have installed a new, publicly accessible weather station at our AREC in Winchester. The station, which updates hourly, is located near the labooratory building at an elevation of 933 feet. This station is part of the NEWA system, so to access it one can either click on the  NEWA weather station locator map, or go directly to: 
       http://newa.cornell.edu/index.php?page=weather-station-page&WeatherStation=va_win

A caution about the station is that because it was installed after the beginning of this year's wetting hour accumulation period (May 14), it will not be up to date for predictions in the sooty blotch/flyspeck model.