Parasitism of the Chytrid Dictyomorpha Dioica

SUMMARY

The chytrid, Dictyomorpha dioica, was found capable of infecting 8 identified species of Achlya, 2 unidentified isolates of Achlya, and Thraustotheca clavata. All isolates tested of Saprolegnia, Isoachlya, Dictyuchus, and Calyptralegnia were resistant to the parasite. The absence of a uniform pattern of infection among isolates of the same host species suggests the existence of biological races of the parasite or of its host. The optimal temperature for infection and sporulation of D. dioica in Achlya flagellata was 25 C. The age of the host culture at which maximal infection occurred was 24 hr.