The perils of naïve use of open source data: A comment on “Spatiotemporal distribution of sudden oak death in the US and Europe”

Authors: FRANKEL, SUSAN - Us Forest Service (FS); GARBELOTTO, MATTEO - University Of California Berkeley; JONES, CHRIS - North Carolina State University; Grunwald, Niklaus; VENETTE, ROBERT - Us Forest Service (FS)

Submitted to: Agricultural and Forest Meteorology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/7/2025
Publication Date: 4/14/2025
Citation: Frankel, S.J., Garbelotto, M., Jones, C., Grunwald, N.J., Venette, R. 2025. The perils of naïve use of open source data: A comment on “Spatiotemporal distribution of sudden oak death in the US and Europe” . Agricultural and Forest Meteorology. https://doi.org/10.1016/j.agrformet.2025.110553.
DOI: https://doi.org/10.1016/j.agrformet.2025.110553

Interpretive Summary: Phytophtora ramorum is an invasive pathogen causing sudden oak death in the US, ramorum dieback on ornamental plants such as rhododendron in the US and Europe, and sudden larch death in UK larcha plantations. A recent study by Kang et al. (2024) anlayzed avaialbe data and inferred the spatiotemporal dynamics of this pathogen in the US and Europe. However, the analysis and conclusions are flawed because of a lack of understanding of the pathosystems analyzed which led the authors to select improper methods for their analysis. This study illustrates that the use of publicly available data presents specific challenges that need to be considered in spatiotemporal analyses to obtain meaningful results.

Technical Abstract: Kang et al. (2024) published a paper on the spatiotemporal analysis of Phytophthora ramorum outbreaks from 2005 to 2021 in the United States and Europe. However, the analysis and conclusions are flawed because of a lack of understanding of the pathosystems analyzed which led the authors to select improper methods for their analysis. The open-source data they analyzed does not include sampling over all seasons of the year; Sampling is primarily conducted in the spring which makes the data unbalanced and inappropriate for examination of seasonality without transformation. Differences in characteristics, and significant driving factors (e.g., relative humidity) between the locations where infection clusters occur, irrigated nurseries or gardens with complex sources of inoculum and modified environments versus natural forests subject to only ambient environmental conditions, were not considered when analyzing relationships between moisture conditions and pathogen establishment and spread. Additional open-source occurrence records exist for P. ramorum in the United States and the United Kingdom, but they were not included in the analysis. The use of clear descriptive language, and proper study design are required to understand how environmental conditions influence P. ramorum establishment and spread so they can inform forest management and regulations to protect the resources at risk. An understanding of the temporal and spatial dynamics of Sudden Oak Death, Sudden Larch Death, Ramorum Blight and other diseases caused by P. ramorum is critical to serve as the basis for management strategies to limit losses and pathogen spread. The use of publicly available data presents specific challenges that need to be considered in spatiotemporal analyses to obtain meaningful results.