VIEW ARTICLE

Ecology and Epidemiology

The Effect of Postinoculation Periods of Leaf Wetness on the Response of Wheat Cultivars to Infection by Septoria nodorum. Z. Eyal, Former Postdoctoral Research Fellow, U.S. Department of Agriculture (USDA), Agriculture Research Service (ARS), Western Region, Department of Plant Pathology, Montana State University, Bozeman, MT 59715; J. F. Brown(2), J. M. Krupinsky(3), and A. L. Scharen(4). (2)(3)(4)Former Postdoctoral Research Fellow, Biological Research Technician, and Research Plant Pathologist, respectively, U.S. Department of Agriculture (USDA), Agriculture Research Service (ARS), Western Region, Department of Plant Pathology, Montana State University, Bozeman, MT 59715, (2)(3)(4)Present address of authors: Department of Botany, Tel-Aviv University, Ramat-Aviv, Israel; Department of Botany, University of New England, Armidale, N.S.W. 2351, Australia; and Department of Plant Pathology, Montana State University, Bozeman, MT 59715, respectively. Phytopathology 67:874-878. Accepted for publication 3 January 1977. Copyright © 1977 The American Phytopathological Society, 3340 Pilot Knob Road, St. Paul, MN 55121. All rights reserved.. DOI: 10.1094/Phyto-67-874.

The length of postinoculation wet periods had varying effects on symptom expression in spring and winter wheat cultivars inoculated at the seedling stage of growth with pycnidiospores of Septoria nodorum. A progressive increase in the wetting period had a marked effect on the number of lesions and area of necrosis produced per leaf of the spring wheat cultivars, with each cultivar responding in a characteristic manner. Winter wheats showed more resistance to infection and less response to length of wet period than spring wheats, but differences in response to infection by S. nodorum also were observed among the winter wheat cultivars. The differences in disease damage among spring and winter wheat cultivars in response to prolonged postinoculation wet periods can be used to detect resistant germplasm and for screening segregating populations in breeding material.