Mycological Research (2001) 105 (10) (Werres et al.)

Sabine Werres, Rainer Marwitz, Willem A. Man In't veld, Arthur W.A.M. De Cock, Peter J.M. Bonants, Marjanne De Weerdt, Karin Themann, Elena Ilieva and Robert P. Baayen (2001)
Phytophthora ramorum sp. nov., a new pathogen on Rhododendron and Viburnum
Mycological Research 105 (10), 1155-1165
Abstract: Since 1993, a hitherto unidentified Phytophthora species has been found associated with twig blight disease in Rhododendron and, sporadically, Viburnum. The morphology and growth characteristics of fourteen isolates from Germany and the Netherlands were investigated, together with their breeding system, the internal transcribed spacer (ITS) regions of the ribosomal DNA, amplified fragment length polymorphism (AFLP) fingerprints, and isozyme profiles, which were compared to those of a number of outgroup species. Morphologically the isolates are characterized by abundant production of chlamydospores and elongate, ellipsoid, deciduous sporangia with a short pedicel, in which they resemble P. palmivora. However, sporangia were semi-papillate, chlamydospores were much larger and cardinal temperatures much lower than those of P. palmivora. Oogonia with amphigynous antheridia and plerotic oospores were produced in dual cultures with an A2 mating type strain of P. cryptogea. ITS1 and ITS2 sequences of the unidentified species were closest to those of P. lateralis, but differed in three and eight nucleotides respectively from the latter species. AFLP fingerprints and isozyme patterns of malate dehydrogenase (MDH-2) and malic enzyme (MDHP) showed that the isolates formed a homogeneous group, distinct from all examined outgroup species, including P. lateralis. It was concluded that they represent a new Phytophthora species, described here as P. ramorum sp. nov. In pathogenicity tests all isolates of P. ramorum were pathogenic to Rhododendron.
(The abstract has been supplied by the author or ISPI and is excluded from the Creative Commons licence.)
(original language: English)
Link to article at publishers website
Database assignments for author(s): Sabine Werres, Willem A. Man in 't Veld, Arthur W.A.M. De Cock, Peter J. M. Bonants, Robert P. Baayen

Research topic(s) for pests/diseases/weeds:
identification/taxonomy

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Phytophthora ramorum	Rhododendron (crop)	Netherlands
	Phytophthora ramorum	Viburnum (crop)
	Phytophthora ramorum		Germany