Studies in the genus Phytophthora-II

Abstract

Isolates of Phytophthora from castor, Agave, and breadfruit and authentic cultures of P. parasitica, P. parasitica var.piperina and P. colocasiœ were studied in detail in single strain cultures and in paired cultures in different combinations. It was found that the isolates from the different hosts under study easily combined with P. parasitica, P. parasitica var. piperina and P. colocasiœ, forming oospores. These oospores are of the same type and fall within the range of size recorded for P. palmivora and P. parasitica. The criteria on which the species under investigation are classified are critically examined and it is found that no significant differences exist between them. The three species are able to grow at 35°C. The readiness with which these combine to form oospores shows their specific affinity. It is argued that all the three species should be combined into one and the name P. colocasiœ is adopted for the emended species as it is the oldest.