Persistence of the Swiss Needle Cast Outbreak in Oregon Coastal Douglas-fir, and New Insights from Research and Monitoring
Swiss needle cast (SNC), caused by Nothophaeocryptopus gaeumannii, is a foliage disease of Douglas-fir (Pseudotsuga menziesii), that reduces growth in native and exotic plantations worldwide. An outbreak began in coastal Oregon in the mid-1990’s and has persisted since that time. Here we review the current state of knowledge after 24 years of research and monitoring, with a focus on Oregon, although the disease is significant in coastal Washington and has emerged in SW British Columbia. We have new insights into the spread of SNC, landscape patterns, epidemiology, ecology, host-pathogen interactions, as well as trophic and hydrologic influences, while silviculture and management remain nuanced and closely associated with local site conditions. In Oregon, the SNC outbreak has remained geographically contained, but has intensified within the epidemic area. Finally, we consider the implications of climate change and recently emerged foliage diseases on the future of Douglas-fir plantation management.