Influence of Temperature and Light on Severity of Bacterial Blight of Corn, Oats, and Wheat. N. W. Schaad, Associate Professor, Department of Plant Pathology, University of Georgia College of Agriculture Georgia Experiment Station, Experiment 30212. D. R. Sumner, Associate Professor, Department of Plant Pathology, University of Georgia College of Agriculture Coastal Plain Experiment Station, Tifton 31794; and G. O. Ware, Experiment Stations Statistician, College Station, Athens, GA 30602. Plant Dis. 64:481-483. Copyright 1980 American Phytopathological Society. DOI: 10.1094/PD-64-481.

Two experiments using five strains of Pseudomonas avenae and five day/night temperature regimens were conducted to determine the influence of temperature and light on the severity of bacterial leaf blight of corn, wheat, and oats. The first experiment showed that light had no effect on lesion development. In the second experiment, plant growth data for corn and wheat were recorded also. The effects of temperature on blight severity differed with the host. On corn, lesion development was not affected by temperature but plant growth was significantly reduced at the three intermediate temperature regimens. Average lesion size was significantly greater with strain C-71 than with strain 19860 at temperatures of 22/14 and 18/14 C but not at 30/26, 30/22, or 22/18 C. On oats, P. avenae strain significantly affected lesion development and disease was generally more severe at higher temperatures. On wheat, blight symptoms were generally more severe at higher temperatures but P. avenae strain had no significant effect. Under Georgia conditions, bacterial blight should be less severe in oats and wheat sown late in the fall season when the temperature is cooler. With corn, plant growth should be less reduced when the mean evening temperature is ≥22 C. Strains of P. avenae should affect the severity of bacterial leaf blight of corn and oats but not of wheat.