Application Rates and Spray Intervals of Ergosterol-Biosynthesis Inhibitor Fungicides for Control of Entomosporium Leaf Spot of Photinia. K. L. BOWEN, Associate Professor, Department of Plant Pathology,Ornamental Horticulture Substation, Alabama Agricultural Experiment Station, Auburn University, Auburn 36849. A. K. HAGAN, Extension Specialist and Professor, Department of Plant Pathology, and J. OLIVE, Superintendent, and W. FOSTER, Former Superintendent, Ornamental Horticulture Substation, Alabama Agricultural Experiment Station, Auburn University, Auburn 36849. Plant Dis. 78:578-581. Accepted for publication 21 February 1994. Copyright 1994 The American Phytopathological Society 578. DOI: 10.1094/PD-78-0578.

The ergosterol-biosynthesis inhibitor (EBT) fungicides myclobutanil, tebuconazole, diniconazole, and flusilazole were compared with chlorothalonil and triforine for the control of Entomosporium leaf spot on photinia. Applied weekly, myclobutanil (0.15 g a.i./L) was equal to or better than chlorothalonil (1.35 g a.i./L) for control of leaf spot, and these two fungicides were superior to triforine. Tebuconazole and diniconazole provided good disease control but reduced growth of plants. Application of myclobutanil at 2-wk intervals was efficacious in controlling disease. All of the fungicides tested controlled Entomosporium leaf spot, but only myclobutanil caused no Phytotoxicity to photinia.

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