Pythium perplexum isolated from soil in France: morphology, molecular characterisation and biological control

Pythium perplexum (F-926) was isolated from a soil sample taken in the Burg undy region in France. In 1907, it was mistakenly described by Bulter as P. vexans. Despite morphological resemblance, the comparison between the inte rnal transcribed spacer I regions of the ribosomal DNA of the two fungi lea ves no doubt of their different identities. P. perplexum was found to be highly pathogenic to cucumber seedlings. Dampi ng-off disease of cucumber caused by P. perplexum can effectively be contro lled by using the soil bacterium Serratia plymuthica (B-781). The details o f the morphology and the molecular characterisation of P. perplexum and its biological control with S. plymuthica are described here.