Abstract
A high correlation was found between the incidence of damping-off and the isolation frequency of Pythium species for spinach in pot experiments with spinach-field soils. Pythium species isolated from diseased spinach were classified into two groups according to their hyphal growth rates at 10 and 35 C. Based on their morphological characteristics, they were identified as Pythium paroecandrum, heretofore not reported as a cause of spinach damping-off, and P. aphanidermatum, previously reported as a cause of damping-off of spinach in the USA and Japan. Both species caused severe pre- and post-emergence damping-off of spinach in pathogenicity tests, and both were pathogenic to cucumber, pumpkin, watermelon, kidney bean and soybean.
