Application Rates and Spray Schedules of Ergosterol-Biosynthesis Inhibitor Fungicides for Control of Black Spot of Rose. A. K. Hagan, Extension Plant Pathologist and Associate Professor, Department of Plant Pathology, Alabama Agriculture Experiment Station, Auburn University, Auburn 36849. C. H. Gilliam, D. C. Fare, and K. Bowen. Professor, Department of Horticulture, Research Associate, Department of Horticulture, and Assistant Professor, Department of Plant Pathology, Alabama Agriculture Experiment Station, Auburn University, Auburn 36849. Plant Dis. 75:1143-1146. Accepted for publication 6 June 1991. Copyright 1991 The American Phytopathological Society. DOI: 10.1094/PD-75-1143.

The ergosterol-biosynthesis inhibitor (EBI) fungicides myclobutanil, flusilazole, and tebuconazole were compared with chlorothalonil and triforine for the control of black spot on rose. Myclobutanil at 0.024 or 0.048 g a.i./L and flusilazole at 0.07 or 0.14 g a.i./L, applied weekly, were as effective as chlorothalonil and superior to triforine in controlling black spot. Disease control with myclobutanil and flusilazole at 14-day spray intervals gave poorer control than weekly applications. Tebuconazole did not control black spot. None of the sterol-biosynthesis fungicides screened was phytotoxic to rose plants.