Refining and Validating a Fungicide Timing Model for Controlling Flyspeck on Apples in the Hudson Valley

Abstract

Flyspeck is caused by the fungus Zygophiala jamaicensis and appears during the late summer as superficial blemished on apple fruit. Development of flyspeck is favored by the hot and humid summer climate in the Hudson Valley, but this disease causes commercial losses throughout the Northeast in wet years. In a recent three-year trial with Liberty apples in the Hudson Valley, flyspeck and sooty blotch in unsprayed trees caused losses averaging nearly $2,400 per acre per year (Rosenberger et al., 1996a). In the same study, losses to flyspeck still averaged $427/acre/year where IPM fungicide strategies were employed.