Dispersal of Conidia of Zygophiala jamaicensis in Apple Orchards. T. B. Sutton, Department of Plant Pathology, North Carolina State University, Raleigh 27695-7616. . Plant Dis. 74:643-646. Accepted for publication 26 February 1990. Copyright 1990 The American Phytopathological Society. DOI: 10.1094/PD-74-0643.

Conidia of Zygophiala jamaicensis, the causal agent of flyspeck, were trapped in apple (Malus domestica) orchards or near reservoir inoculum sources from late May or early June through harvest (mid-September). Hourly spore concentrations were positively correlated with temperature and windspeed and negatively correlated with relative humidity and leaf wetness. Conidia concentration in the air was characterized by a distinct diurnal periodicity; most conidia were trapped between 0700 and 1300 hours. Fruit infections were usually observed about 1 mo after the first conidia were trapped. Management practices for flyspeck in apple orchards need to account for the presence and abundance of reservoir hosts, environmental conditions, orchard management strategies, and fungicide choice and timing.