Abstract
Heterothallic isolates of Pyricularia from crabgrass from the U.S.A. and from goosegrass and weeping lovegrass from Japan were used to study the effect of temperature, light, and culture media on perithecial production. The optimum temperature for perithecial production was about 20C for the crabgrass isolates and 22 to 25C for the goosegrass isolates. Although a few perithecia were occasionally produced by the goosegrass isolates in darkness, light was necessary for consistent perithecial production. A very low light intensity was sufficient to initiate perithecial production and short wavelengths (below 500nm) were most effective. Abundant perithecia were produced on oat meal agar and potato sucrose agar. The addition of zinc, methionine, and parts of various plants to modified Sachs agar increased perithecial production by the crabgrass isolates.
