Tuesday, June 1, 2010

Summer disease outlook

Accumulated wetting hours (starting April 29, 10 days after petal fall, Apr 19): 165 hr. The threshold for presence of sooty blotch and flyspeck fungi on unprotected fruit is 250 hr. As of May 25 a hygrothermograph in Rappahannock county (Washington, VA) had logged 163 wetting hours, also using the Apr 19 petal fall and Apr 29 start accumulation date.

For practical purposes, cedar-apple rust galls near our AREC have completed their sporulation for this year. Rust lesions are still showing up on apple leaves that were not protected two weeks ago.