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Ecology and Epidemiology

Epidemiology and Control of Bacterial Leaf Blight of Corn. Donald R. Sumner, Assistant Professor, Department of Plant Pathology, University of Georgia, Coastal Plain Station, Tifton, GA 31794; N. W. Schaad, Assistant Professor, Department of Plant Pathology, University of Georgia, Georgia Station, Experiment, GA 30212. Phytopathology 67:1113-1118. Accepted for publication 7 March 1977. Copyright 1977 The American Phytopathological Society, 3340 Pilot Knob Road, St. Paul, MN 55121. All rights reserved.. DOI: 10.1094/Phyto-67-1113.

Bacterial leaf blight, which is caused by Pseudomonas avenae, was widespread in corn in southern Georgia from 1973 through 1976. The survival of the bacterium was determined by means of a basal salts agar medium containing D-sorbitol and neutral red (SNR agar). The bacterium did not survive in infected leaves on dead plants 2 mo after maturity, but did survive for 2 wk in infected green leaves buried in soil. Pseudomonas avenae was pathogenic to many other cultivars of gramineous species in greenhouse tests, but it was not isolated from plants other than corn in nature. Most cultivars of corn were resistant to the bacterium, but several were highly susceptible. The apparent infection rate (r) in a susceptible cultivar was 0.18 to 0.21 plants/day, compared with 0.13 to 0.16 plants/day in several resistant cultivars, during the 3- to 4-wk period before tasseling. Lesions were relatively small on leaves of resistant plants, and streaking and leaf shredding rarely occurred. The disease did not become epidemic in any of the cultivars after tasseling. The bacterium caused leaf blight but not stalk rot, shank rot, or ear rot. The in vitro dry matter digestibility of blighted plants at tasseling was not different from that of green plants.

Additional keywords: maize, ecology.