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Controlled-Environment Studies of the Epidemiology of Yellow Leaf Blight of Corn. L. L. Castor, Research Assistant and Graduate Student, Department of Plant Pathology, The Pennsylvania State University, University Park 16802, Present address of senior author: Department of Plant Sciences, Texas A & M University, College Station 77843; J. E. Ayers(2), and R. R. Nelson(3). (2)(3)Associate Professor, and Evan Pugh Professor, respectively, Department of Plant Pathology, The Pennsylvania State University, University Park 16802. Phytopathology 67:85-90. Accepted for publication 9 June 1976. Copyright 1977 The American Phytopathological Society, 3340 Pilot Knob Road, St. Paul, MN 55121. All rights reserved.. DOI: 10.1094/Phyto-67-85.

The effects of environmental factors on the development of Phyllosticta maydis on corn (Zea mays) leaves were determined in controlled-environment tests. Optimum temperature for conidial germination ranged from 12 to 18 C for times of 4 to 5 hours. The average number of infections was greater at temperatures from 16 to 20 C with 9- to 12-hour dew periods. Colonization, as determined by lesion size, was greatest at 21 to 27 C after 14 to 16 days. Largest numbers of pycnidia were produced at 18 to 27 C after 4 to 5 days; however, the optimum temperature for pycnidia formation was 18 C from 7 through 11 days. Greatest spore release (via oozing from pycnidia) occurred at 24 to 27 C from 4 through 9 days. More pycnidia were produced at all temperatures and times from lesions which developed at 18 C than from those which developed at 24 C.

Additional keywords: Phyllosticta maydis, Mycosphaerella zeae-maydis, maize.