Effects of Temperature and Light on Virulence ofExserohilum turcicumon Corn

Abstract

Thakur, R. P., Leonard, K. J., and Leath, S. 1989. Effects of temperature and light on virulence of Exserohilum turcicum on corn. Phytopathology 79:631-635. Isolates of races 1, 2, and 4 of Exserohilum turcicum were tested for at 26/22 C and transferred to 22/18 C within 3 days after inoculation virulence at day/night temperatures of 22/18 or 26/22 C on seedlings with race 2, they developed normal susceptible-type lesions; if they were of corn inbreds H4460 and B37 and their backcross lines with the Htl transferred later, they developed intermediate- and susceptible-type gene for resistance. Race 2 was virulent on B37Htl at both 22/18 and lesions. If H4460 seedlings were grown at 22/18 C before inoculation, 26/22 C but avirulent on H4460Htl at 26/22 C. Race 2 induced normal the lengths of lesions induced by races 2 and 4 were significantly correlated susceptible-type lesions on inbreds B37 and H4460 at both 22/18 and with the number of days they remained at 22/18 C before transfer to 26/22 C, and the number of lesions per plant was greater at reduced 26/22 C, but if they were grown at 26/22 C and transferred to 22/18 C, light intensities. Seedlings of H4460Htl grown at 22/18 C before the lesion lengths were not significantly affected by the number of days inoculation became resistant to race 2 if they were transferred to 26/22 C at 26/22 C after inoculation. within the first 3 days after inoculation. Conversely, if they were grown Additional keywords: northern corn leaf blight, Setosphaeria turcica, Zea mays.