VIEW ARTICLE

Ecology and Epidemiology

Active Discharge Distance of Ascospores of Venturia inaequalis. Donald E. Aylor, Department of Plant Pathology and Ecology, The Connecticut Agricultural Experiment Station, P.O. Box 1106, New Haven 06504; Sandra L. Anagnostakis, Department of Plant Pathology and Ecology, The Connecticut Agricultural Experiment Station, P.O. Box 1106, New Haven 06504. Phytopathology 81:548-551. Accepted for publication 17 January 1991. Copyright 1991 The American Phytopathological Society. DOI: 10.1094/Phyto-81-548.

Ascospores of Venturia inaequalis were discharged into still air inside small chambers from pseudothecia on small wetted bits of leaf cut from diseased apple leaves that had overwintered on the orchard floor. Ascospores were actively projected away from the leaf surface over distances ranging from 0.1 to 8.1 mm (one reached 13.2 mm). Three-quarters of the ascospores were projected less than 4.1 mm from the surface (mean distance for all ascospores was 3.0 mm). Only 1% were projected as far as 6.6 mm. The observed discharge distances were shown to be consistent with those expected from the mechanical forces acting on the ascospores.