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ARS Home » Pacific West Area » Corvallis, Oregon » Horticultural Crops Disease and Pest Management Research Unit » Research » Publications at this Location » Publication #416607
Research Project: Knowledge Based Tools for Exotic and Emerging Diseases of Small Fruit and Nursery Crops

Location: Horticultural Crops Disease and Pest Management Research Unit

Title: Canker and dieback of Alnus rubra is caused by Lonsdalea quercina

Author
item IRUEGAS-BOCARDO, FERNANDA - Oregon State University
item SUTTON, WENDY - Oregon State University
item Grunwald, Niklaus
item CHANG, JEFF - Oregon State University
item PUTNAM, MELODIE - Oregon State University

Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/26/2024
Publication Date: 10/26/2024
Citation: Iruegas-Bocardo, F., Sutton, W., Grunwald, N.J., Chang, J.H., Putnam, M.L. 2024. Canker and dieback of Alnus rubra is caused by Lonsdalea quercina. Phytopathology. 1/1-5. https://doi.org/10.1094/phyto-06-24-0192-sc.
DOI: https://doi.org/10.1094/phyto-06-24-0192-sc

Interpretive Summary: Understanding the ecology of pathogens is important for disease management. Recently a devastating canker disease was found on red alder (Alnus rubra) planted as landscape trees. Bacteria were isolated from two groups of symptomatic trees and two strains were used to determine if the isolated bacteria indeed caused the disease. Results showed that these bacteria can not only cause disease on red alder but also on two other alder species. Unexpectedly, analyses of DNA of bacterial strains identified them as Lonsdalea quercina, a pathogenic species previously known to cause dieback of oak species, but not alder. Altogether, our findings indicate that L. quercina is a newly discovered, potential threat to Alnus species.

Technical Abstract: Understanding the ecology of pathogens is important for disease management. Recently a devastating canker disease was found on red alder (Alnus rubra) planted as landscape trees. Bacteria were isolated from two groups of symptomatic trees and two strains were used to complete Koch’s postulates. Results showed that these bacteria can not only cause disease on red alder but also on two other alder species. Unexpectedly, analyses of genome sequences of bacterial strains identified them as Lonsdalea quercina, a pathogenic species previously known to cause dieback of oak species, but not alder. Additionally, a core genome phylogeny clustered bacterial strains isolated from red alder within a subclade of L. quercina strains isolated from symptomatic oak trees. Consistent with the close phylogenetic relationship, there was no obvious evidence for divergence in genome composition of strains isolated from red alder and oak. Altogether, findings indicate that L. quercina is a potential threat to Alnus species.