Sexual reproduction by Phytophthora macrochlamydospora: a Group VI Species

lThe description of Phytophthora macrochlamydospora J.A.G. Irwin is emended, following further taxonomic studies with additional isolates of the organism. Phytophthora macrochlamydospora is a Group VI Phytophthora species, producing non-papillate sporangia, and sex organs in paired culture with Phytophthora cambivora (Petri) Buisman, A(1) mating type. Sex organs have never previously been described for P. macrochlamydospora, and this research has shown that P. cambivora A(1) induces selfing in P. macrochlamydospora. Antheridia of P. macrochlamydospora are always amphigynous. Phytophthora macrochlamydospora produces large (up to 90 mum), thick-walled chlamydospores that distinguish it from all other Group VI species