Phytophthora podocarpi sp. nov. from Diseased Needles and Shoots of Podocarpus in New Zealand

Abstract

Foliage samples from Podocarpus totara with severe needle browning and needle loss in the lower part of the crown were observed in 2011 in the Gisborne region of New Zealand. A Phytophthora genus-specific test applied directly to the needles gave a strong positive result, and subsequent isolations yielded colonies of a slow-growing oomycete. Morphological examination in vitro revealed a Phytophthora species. Preliminary comparisons of the rDNA (ITS), and ras-related protein (Ypt) gene regions with international DNA sequence revealed low sequence similarity to species from the downy mildew genus Peronospora, as well as clade 3 Phytophthora species. Other studies have also demonstrated the close relationship with Peronospora. The species was given the interim designation Phytophthora taxon tōtara pending further examination. Here, we formally describe Phytophthora podocarpi sp. Nov. and its associated disease, tōtara needle blight.