Perennation of Powdery Mildew in Buds of Grapevines. Mary Ann Sall, Assistant Professor, Department of Plant Pathology, University of California, Davis 95616. Jeanette Wrysinski, Staff Research Associate, Department of Plant Pathology, University of California, Davis 95616. Plant Dis. 66:678-679. Accepted for publication 19 October 1981. Copyright 1982 American Phytopathological Society. DOI: 10.1094/PD-66-678.

The presence of perennating bud infections caused by Uncinula necator was confirmed on grapevines (Vitis vinifera) in California. These perennating infections tend to occur on the same vines in successive years. They are formed more frequently on buds arising from spurs than from the vine arm. Infected buds open slightly later than uninfected ones. Judging from the masses of conidia found on their surface, the mildew flag shoots begin to liberate inoculum shortly after the onset of growth.

Keyword(s): epidemiology.