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 organ ism. Phytophthora macrochlamydospora is a Group VI Phytophthora species, pr oducing non-papillate sporangia, and sex organs in paired culture with Phyt ophthora 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. Ant heridia of P. macrochlamydospora are always amphigynous. Phytophthora macro chlamydospora produces large (up to 90 mum), thick-walled chlamydospores th at distinguish it from all other Group VI species.