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ARS Home » Northeast Area » Frederick, Maryland » Foreign Disease-Weed Science Research » Research » Publications at this Location » Publication #408384
Research Project: Diagnostics and Biological Approaches for Management of Emerging Oomycete Plant Pathogens

Location: Foreign Disease-Weed Science Research

Title: Oomycetes associated with wild and cultivated areas in Vietnam

Author
item PFEUFER, EMILY - Former ARS Employee
item GROBEN, GLEN - Oak Ridge Institute For Science And Education (ORISE)
item HARRISON, LINDSAY - Former ARS Employee
item THU, PHAM QUANG - Vietnamese Academy Of Forest Sciences
item WIDMER, TIMOTHY - Former ARS Employee
item Puig, Alina

Submitted to: Frontiers in Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/6/2026
Publication Date: 2/3/2026
Citation: Pfeufer, E., Groben, G., Harrison, L., Thu, P., Widmer, T., Puig, A.S. 2026. Oomycetes associated with wild and cultivated areas in Vietnam. Frontiers in Microbiology. https://doi.org/10.3389/fmicb.2026.1606112.
DOI: https://doi.org/10.3389/fmicb.2026.1606112

Interpretive Summary: Oomycetes are a group of organisms that contain some of the world’s most damaging plant pathogens, such as those causing potato late blight and sudden oak death. To identify potential newly emerging pathogens, collections were done in forest and agricultural areas in Vietnam, which is considered one of the centers of origin for this group of organisms. The most frequently detected organisms were Phytopythium vexans and Phytophthora cinnamomi, making up 52% and 25% of the total. Fourteen different kinds of oomycetes were found in rivers in natural forest areas compared with six in forest soil and six in agricultural soil. Several of these organisms appear to be new species, and will be the focus of future research. The identification of oomycete species in a center of origin will help identify potential emerging pathogens that can become a threat to U.S. agriculture.

Technical Abstract: To determine the diversity of oomycetes in Vietnam, which is within the presumed center of origin of most Phytophthora taxa, isolations were done from rivers, agricultural soil, and forested areas. Identifications were made using sequences from the internal transcribed spacer (ITS) and the cytochrome 2 oxidase (cox2) regions of the genome. Of the 245 isolates included in this study, most (66.5%) were identified as Phytopythium spp., followed by Phytophthora spp. (31%) and Pythium spp. (2.4%). The most prevalent species were Phytopythium vexans and Phytophthora cinnamomi, making up 51.8 and 24.5% of all organisms obtained. Seventeen isolates appear to belong to multiple undescribed species. From agricultural soils, only a single isolate each of Phytophthora and Pythium were obtained with the remaining 93% belonging to the genus Phytopythium.