Electronic Grape Black Rot Predictor for Scheduling Fungicides with Curative Activity. M. A. Ellis, Associate Professor, Department of Plant Pathology, Ohio State University, Ohio Agricultural Research and Development Center, Wooster 44691. L. V. Madden, Associate Professor, and L. L. Wilson, Research Assistant, Department of Plant Pathology, Ohio State University, Ohio Agricultural Research and Development Center, Wooster 44691. Plant Dis. 70:938-940. Accepted for publication 18 May 1986. Copyright 1986 The American Phytopathological Society. DOI: 10.1094/PD-70-938.

A microprocessor programmed to predict grape black rot infection periods was evaluated in the field during two growing seasons. It was effective in determining infection periods and was used to time curative fungicide applications for control of black rot. Triadimefon and CGA-71818 applied 72 or 96 hr after the initiation of an infection period provided excellent control of berry and leaf infection by Guignardia bidwellii, causal agent of grape black rot. Fenarimol did not provide satisfactory control. Well-timed curative spray programs of triadimefon and CGA-71818 were as effective as protectant spray programs of ferbam and required four fewer sprays to achieve equal control.