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Etiology

Etiology and Control of Onion Flower Blight. L. A. Ellerbrock, Graduate Research Assistant, Department of Plant Pathology, New York State College of Agriculture and Life Sciences, Cornell University, Ithaca, NY 14853; J. W. Lorbeer, Professor, Department of Plant Pathology, New York State College of Agriculture and Life Sciences, Cornell University, Ithaca, NY 14853. Phytopathology 67:155-159. Accepted for publication 16 August 1976. Copyright © 1977 The American Phytopathological Society, 3340 Pilot Knob Road, St. Paul, MN 55121. All rights reserved.. DOI: 10.1094/Phyto-67-155.

In recent years, a severe blighting of onion flowers and immature seed capsules has occurred in a number of Orange County, New York seed fields. Botrytis cinerea, B. squamosa, and B. allii frequently were isolated from blighted flowers. Field inoculation of inflorescences with B. cinerea, B. squamosa, and B. allii conidia caused flower blighting and seed yield losses of 98, 93, and 47%, respectively, compared to noninoculated controls. Lesions on main seed stalks, apparently caused by B. allii or B. squamosa, often girdled the stalks and resulted in death of the entire inflorescence, but incidence of such damage generally was less than 5%. Sprays of chlorothalonil (2.5 kg/ha), benomyl (1.1 kg/ha), and mancozeb (2.7 kg/ha) controlled flower blight in that order in four replicated field experiments and increased seed yield by an average of 142, 93, and 60%, respectively. Fungicide sprays did not appear to interfere with pollination of onion flowers by honey bees.