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Disease Detection and Losses

Halo Blight of Rye: Multiplicity of Symptoms Under Field Conditions. Barry M. Cunfer, Department of Plant Pathology, Georgia Station, University of Georgia, Experiment, GA 30212; Norman W. Schaad(2), and Darrell D. Morey(3). (2)Department of Plant Pathology, Georgia Station, University of Georgia, Experiment, GA 30212; (3)Department of Agronomy, Coastal Plain Experiment Station, Tifton, GA 31794 Phytopathology 68:1545-1548. Accepted for publication 1 June 1978. Copyright © 1978 The American Phytopathological Society, 3340 Pilot Knob Road, St. Paul, MN 55121. All rights reserved.. DOI: 10.1094/Phyto-68-1545.

Several types of symptoms were caused by Pseudomonas coronafaciens on rye in Georgia. Elliptical to linear brown lesions, surrounded by mild chlorosis, and often in association with frost injury, were observed on leaves during the winter when temperatures rarely exceeded 15 C. Halo symptoms were prominent in early spring when temperatures were mild (maximum 15-22 C). Chlorotic lesions were less common after heading. Halo lesions turned buff-colored within 1-2 days giving the lesions a “scalded” appearance. Scald symptoms were most common from flowering until maturity, but easily recognizable halo symptoms persisted on leaf sheaths nearly until host maturity. Minute halos sometimes were found on the glumes but more commonly the entire floret blighted, dried, and became white. Failure to recognize all symptoms may lead to an underestimation of losses from the disease or to an inaccurate diagnosis of the causal agent.