Phytophthora stem rot of purple passionfruit in Vietnam

Abstract

In August 2012 a severe stem rot (stem canker) disease was observed in a purple-fruit variety of passionfruit, Passiflora edulis, in Nghe An province, Vietnam. The stem rot progressed rapidly along the stem affecting branches and fruit, leading to chlorosis, wilting and death of the distal part of the stem. It did not progress below the graft junction into the stem or roots of the rootstock, Passiflora edulis var. flavicarpa. The disease spread within and between plantings causing 100 % loss of some plantings. Phytophthora nicotianae was consistently isolated from diseased tissue and the morphological identification was confirmed by sequencing, and two cultures were deposited in the Murdoch University Culture Collection as MUCC707 and MUCC708. The former culture proved pathogenic in stem inoculations and P. nicotianae was reisolated fulfilling Koch’s postulates. This report represents a new record of Phytophthora stem rot of purple passionfruit in Vietnam.