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Ecology and Epidemiology

Effects of Dew-Period Temperature on Germination of Conidia and Systemic Infection of Maize by Sclerospora sorghi. M. R. Bonde, Research Plant Pathologist, Plant Disease Research Laboratory (PDRL), Agricultural Research Service, U.S. Department of Agriculture P.O. Box 1209, Frederick, MD 21701; C. G. Schmitt(2), and R. W. Dapper(3). (2)Research Plant Pathologist, Plant Disease Research Laboratory (PDRL), Agricultural Research Service, U.S. Department of Agriculture P.O. Box 1209, Frederick, MD 21701; (3)Biological Aid, PDRL. Phytopathology 68:219-222. Accepted for publication 20 July 1977. Copyright 1978 The American Phytopathological Society, 3340 Pilot Knob Road, St. Paul, MN 55121. All rights reserved.. DOI: 10.1094/Phyto-68-219.

The optimum temperatures for conidia germination and germ-tube growth of an American isolate of Sclerospora sorghi were 15 and 22 C, respectively. Germination, however, was high from 10 to 19 C and germ-tube growth was good from 14 to 22 C. An air temperature range of 14 to 22 C during a 2-hr dew period was near optimum for systemic infection of maize. Systemic infection consistently occurred from 10 to 33 C when plants were exposed to a dew-chamber period of at least 4 hr. The American isolate had a lower optimum temperature range for conidia germination than that reported for an Indian isolate of S. sorghi which indicates the existence of biotypes.

Additional keywords: epidemiology, sorghum downy mildew.