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Cultural Techniques and Conditions Influencing Growth and Sporulation of Cercospora zeae-maydis and Lesion Development in Corn. Peter M. Beckman, Former graduate research assistant, Department of Plant Pathology, North Carolina State University, Raleigh 27650, Present address of senior author: Nickerson International Plant Breeders, S. A., P.O. Box 1787, Gilroy, CA 95020; Gary A. Payne, assistant professor, Department of Plant Pathology, North Carolina State University, Raleigh 27650. Phytopathology 73:286-289. Accepted for publication 23 August 1982. Copyright 1983 The American Phytopathological Society. DOI: 10.1094/Phyto-73-286.

Sporulating cultures of Cercospora zeae-maydis were obtained routinely by homogenizing freshly isolated or stored cultures in water, dispensing the homogenate on V-8 juice agar, and incubating the plates under a diurnal fluorescent light regime for 14 days. Sporulation was good on decoction media made from green or senescent corn leaves and on V-8 juice agar but was poor on potato-dextrose agar. Constant light inhibited conidial germination, mycelial growth, and sporulation. The optimum temperature range for germination and growth was 22- 30 C. Cultures of the fungus could be stored successfully for at least 23 mo at 4 C on several media. Lesion development on corn plants was obtained by misting inoculated plants for 3 sec every 4 min between the hours 2000 and 1000 each day for 2 wk. Lesion development in the greenhouse was greater from June through August, when the greenhouse was kept at 22- 28 C by wetpad cooling, than during the other months.

Additional keywords: gray leaf spot, maize.