Phytophthora infestans, the cause of the devastating late blight disease of potato and tomato, exhibits a clonal reproductive lifestyle in North America. Phenotypes such as fungicide sensitivity and host preference are conserved among individuals within clonal lineages, while substantial phenotypic differences can exist between lineages. Whole P. infestans genomes were...
Gene regulation by small RNA pathways is ubiquitous among eukaryotes, but little is known about small RNA pathways in the Stramenopile kingdom. Phytophthora a genus of filamentous oomycetes, contains many devastating plant pathogens, causing multibillion-dollar damage to crops, ornamental plants, and natural environments. The genomes of several oomycetes including Phytophthora...
Oomycetes form a deep lineage of eukaryotic organisms that includes a large number of plant pathogens which threaten natural and managed ecosystems. We undertook a survey to query the community for their ranking of plant-pathogenic oomycete species based on scientific and economic importance. In total, we received 263 votes from...
Pythium species are important soilborne pathogens occurring in the forest nursery industry of the Pacific Northwest. However, little is known about their genetic diversity or population structure and it is suspected that isolates are moved among forest nurseries on seedling stock and shared field equipment. In order to address these...
Phytophthora infestans causes potato late blight, an important and costly disease of potato and tomato crops. Seven clonal lineages of P. infestans identified recently in the United States were tested for baseline sensitivity to six oomycete-targeted fungicides. A subset of the dominant lineages (n = 45) collected between 2004 and...
Root rot of raspberry (Rubus idaeus), thought to be primarily caused
by Phytophthora rubi, is an economically important disease in the
western United States. The objectives of this study were to determine
which Phytophthora species are involved in root rot, examine the efficacy
of different isolation methods (cane, root, and...
Many microbial, fungal, or oomcyete populations violate assumptions for population
genetic analysis because these populations are clonal, admixed, partially
clonal, and/or sexual. Furthermore, few tools exist that are specifically designed for
analyzing data from clonal populations, making analysis difficult and haphazard.
We developed the R package poppr providing unique tools...
Phytophthora infestans, the causal agent of late blight disease, has been reported in North America since the mid-nineteenth century. In the United States the lack of or very limited sexual reproduction has resulted in largely clonal populations of P. infestans. In 2010 and 2011, but not in 2012 or 2013,...
Nursery plants are important vectors for plant pathogens. Understanding what pathogens occur in nurseries in different production stages can be useful to the development of integrated systems approaches. Four horticultural nurseries in Oregon were sampled every 2 months for 4 years to determine the identity and community structure of Phytophthora...
Mefenoxam and fosetyl-Al are common fungicides used to supplement
disease control of Pythium damping-off and root rot in forest nurseries
of the western United States. However, it is unknown whether fungicide-resistant Pythium isolates are present or whether new fungicide
and biological treatments might also provide supplemental disease
control. Isolates of...