Plant Pathology (2013) 62, 1063-1071

S. Prospero, A. Vercauteren, K. Heungens, L. Belbahri and D. Rigling (2013)
Phytophthora diversity and the population structure of Phytophthora ramorum in Swiss ornamental nurseries
Plant Pathology 62 (5), 1063-1071
Abstract: Invasive oomycete pathogens have been causing significant damage to native ecosystems worldwide for over a century. A recent well-known example is Phytophthora ramorum, the causal agent of sudden oak death, which emerged in the 1990s in Europe and North America. In Europe, this pathogen is mainly restricted to woody ornamentals in nurseries and public greens, while severe outbreaks in the wild have only been reported in the UK. This study presents the results of the P. ramorum survey conducted in Swiss nurseries between 2003 and 2011. In all 120 nurseries subjected to the plant passport system, the main P. ramorum hosts were visually checked for above ground infections. Phytophthora species were isolated from tissue showing symptoms and identified on the basis of the morphological features of the cultures and sequencing of the ribosomal ITS region. Phytophthora was detected on 125 plants (66 Viburnum, 58 Rhododendron and one Pieris). Phytophthora ramorum was the most frequent species (59·2% of the plants), followed by P. plurivora, P. cactorum, P. citrophthora, P. cinnamomi, P. cactorum/P. hedraiandra, P. multivora and P. taxon PgChlamydo. The highest incidence of P. ramorum was observed on Viburnum × bodnantense. Microsatellite genotyping showed that the Swiss P. ramorum population is highly clonal and consists of seven genotypes (five previously reported in Europe, two new), all belonging to the European EU1 clonal lineage. It can therefore be assumed that P. ramorum entered Switzerland through nursery trade. Despite sanitation measures, repeated P. ramorum infections have been recorded in seven nurseries, suggesting either reintroduction or unsuccessful eradication efforts.
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Link to article at publishers website
Database assignments for author(s): Daniel Rigling, Kurt Heungens

Research topic(s) for pests/diseases/weeds:
surveys/sampling/distribution

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Phytophthora plurivora		Switzerland
	Phytophthora cactorum		Switzerland
	Phytophthora citrophthora		Switzerland
	Phytophthora cinnamomi		Switzerland
	Phytophthora ramorum	Viburnum (crop)	Switzerland
	Phytophthora multivora		Switzerland
	Phytophthora taxon Pgchlamydo		Switzerland