@article{leblanc_cubeta_crouch_2021, title={Population Genomics Trace Clonal Diversification and Intercontinental Migration of an Emerging Fungal Pathogen of Boxwood}, volume={111}, ISSN={["1943-7684"]}, DOI={10.1094/PHYTO-06-20-0219-FI}, abstractNote={ Boxwood blight was first documented in Europe, prior to its recent colonization of North America, where it continues to have significant negative impacts on the ornamental industry. Due to near genetic uniformity in the two sister species of fungal plant pathogens that cause boxwood blight, understanding historical disease emergence and predicting future outbreaks is limited. The goal of this research was to apply population genomics to understand the role of pathogen diversification and migration in disease emergence. Specifically, we tested whether the primary pathogen species Calonectria pseudonaviculata has remained genetically isolated from its European-limited sister species C. henricotiae, while diversifying into clonal lineages that have migrated among continents. Whole-genome sequencing identified 1,608 single-nucleotide polymorphisms (SNPs) in 67 C. pseudonaviculata isolates from four continents and 1,017 SNPs in 13 C. henricotiae isolates from Europe. Interspecific genetic differentiation and an absence of shared polymorphisms indicated lack of gene flow between the sister species. Tests for intraspecific genetic structure in C. pseudonaviculata identified four genetic clusters, three of which corresponded to monophyletic phylogenetic clades. Comparison of evolutionary divergence scenarios among the four genetic clusters using approximate Bayesian computation indicated that the two C. pseudonaviculata genetic clusters currently found in the United States were derived from different sources, one from the first genetic cluster found in Europe and the second from an unidentified population. Evidence for multiple introductions of this pathogen into the United States and intercontinental migration indicates that future introductions are likely to occur and should be considered in plant disease quarantine regulation. }, number={1}, journal={PHYTOPATHOLOGY}, author={LeBlanc, Nicholas and Cubeta, Marc A. and Crouch, Jo Anne}, year={2021}, month={Jan}, pages={184–193} }
 @article{salgado-salazar_leblanc_wallace_daughtrey_crouch_2020, title={Peronospora monardae, Hyaloperonospora daughtreyae and H. iberidis: new species associated with downy mildew diseases affecting ornamental plants in the United States}, volume={157}, ISSN={["1573-8469"]}, DOI={10.1007/s10658-020-01989-9}, number={2}, journal={EUROPEAN JOURNAL OF PLANT PATHOLOGY}, author={Salgado-Salazar, Catalina and LeBlanc, Nicholas and Wallace, Emma C. and Daughtrey, Margery L. and Crouch, Jo Anne}, year={2020}, month={Jun}, pages={311–326} }
 @article{salgado-salazar_shiskoff_leblanc_ismaiel_collins_cubeta_crouch_2019, title={Coccinonectria pachysandricola, Causal Agent of a New Foliar Blight Disease of Sarcococca hookeriana}, volume={103}, ISSN={0191-2917 1943-7692}, url={http://dx.doi.org/10.1094/PDIS-09-18-1676-RE}, DOI={10.1094/PDIS-09-18-1676-RE}, abstractNote={ Woody plants of the Buxaceae, including species of Buxus, Pachysandra, and Sarcococca, are widely grown evergreen shrubs and groundcovers. Severe leaf spot symptoms were observed on S. hookeriana at the U.S. National Arboretum in Washington, DC, in 2016. Affected plants were growing adjacent to P. terminalis exhibiting Volutella blight symptoms. Fungi isolated from both hosts were identical based on morphology and multilocus phylogenetic analysis and were identified as Coccinonectria pachysandricola (Nectriaceae, Hypocreales), causal agent of Volutella blight of Pachysandra species. Pathogenicity tests established that Co. pachysandricola isolated from both hosts caused disease symptoms on P. terminalis and S. hookeriana, but not on B. sempervirens. Artificial inoculations with Pseudonectria foliicola, causal agent of Volutella blight of B. sempervirens, did not result in disease on P. terminalis or S. hookeriana. Wounding enhanced infection by Co. pachysandricola and Ps. foliicola on all hosts tested but was not required for disease development. Genome assemblies were generated for the Buxaceae pathogens that cause Volutella diseases: Co. pachysandricola, Ps. buxi, and Ps. foliicola; these ranged in size from 25.7 to 28.5 Mb. To our knowledge, this foliar blight of S. hookeriana represents a new disease for this host and is capable of causing considerable damage to infected plants. }, number={6}, journal={Plant Disease}, publisher={Scientific Societies}, author={Salgado-Salazar, Catalina and Shiskoff, Nina and LeBlanc, Nicholas and Ismaiel, Adnan A. and Collins, Maxton and Cubeta, Marc A. and Crouch, Jo Anne}, year={2019}, month={Jun}, pages={1337–1346} }