Phytophthora ramorum shows limited aerial spread
Phytophthora ramorum was never detected on any of the sentinel plants (Rhododendron, Viburnum, and Loropetalum spp), indicating very limited aerial spread under suboptimal meteorological and environmental conditions. An infection experiment with host plants placed in the immediate vicinity of symptomatic plants proved the potential for short-distance (1 to 2 m) aerial transmission of P. ramorum.
Other Phytophthora spp. causing symptoms similar to P. ramorum were detected during the rainy season (January to May) on the sentinel plants, among them potentially two novel species. These data reveal how sentinel monitoring at NORS-DUC allows for seasonal assessments of disease incidence and provide longitudinal data to assess the threat of P. ramorum movement in nurseries.
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