<i>Phytophthora</i> Species and Their Associations with Chaparral and Oak Woodland Vegetation in Southern California

Evidence of unintended introductions of <i>Phytophthora</i> species into native habitats has become increasingly prevalent in California. If not managed adequately, <i>Phytophthora</i> species can become devastating agricultural and forest plant pathogens. Additionally, Calif...

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Main Authors: Sebastian N. Fajardo, Tyler B. Bourret, Susan J. Frankel, David M. Rizzo
Format: Article
Language:English
Published: MDPI AG 2025-01-01
Series:Journal of Fungi
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Online Access:https://www.mdpi.com/2309-608X/11/1/33
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author Sebastian N. Fajardo
Tyler B. Bourret
Susan J. Frankel
David M. Rizzo
author_facet Sebastian N. Fajardo
Tyler B. Bourret
Susan J. Frankel
David M. Rizzo
author_sort Sebastian N. Fajardo
collection DOAJ
description Evidence of unintended introductions of <i>Phytophthora</i> species into native habitats has become increasingly prevalent in California. If not managed adequately, <i>Phytophthora</i> species can become devastating agricultural and forest plant pathogens. Additionally, California’s natural areas, characterized by a Mediterranean climate and dominated by chaparral (evergreen, drought-tolerant shrubs) and oak woodlands, lack sufficient baseline knowledge on <i>Phytophthora</i> biology and ecology, hindering effective management efforts. From 2018 to 2021, soil samples were collected from Angeles National Forest lands (Los Angeles County) with the objective of better understanding the diversity and distribution of <i>Phytophthora</i> species in Southern California. Forty sites were surveyed, and soil samples were taken from plant rhizospheres, riverbeds, and off-road vehicle tracks in chaparral and oak woodland areas. From these surveys, fourteen species of <i>Phytophthora</i> were detected, including <i>P. cactorum</i> (subclade 1a), <i>P. multivora</i> (subclade 2c), <i>P</i>. sp. <i>cadmea</i> (subclade 7a), <i>P</i>. taxon ‘oakpath’ (subclade 8e, first reported in this study), and several clade-6 species, including <i>P. crassamura</i>. <i>Phytophthora</i> species detected in rhizosphere soil were found underneath both symptomatic and asymptomatic plants and were most frequently associated with <i>Salvia mellifera</i>, <i>Quercus agrifolia</i>, and <i>Salix</i> sp. <i>Phytophthora</i> species were present in both chaparral and oak woodland areas and primarily in riparian areas, including detections in off-road tracks, trails, and riverbeds. Although these Mediterranean ecosystems are among the driest and most fire-prone areas in the United States, they harbor a large diversity of <i>Phytophthora</i> species, indicating a potential risk for disease for native Californian vegetation.
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spelling doaj-art-a0b22dd9b4fd45f2b58847af35fbbbcb2025-01-24T13:37:18ZengMDPI AGJournal of Fungi2309-608X2025-01-011113310.3390/jof11010033<i>Phytophthora</i> Species and Their Associations with Chaparral and Oak Woodland Vegetation in Southern CaliforniaSebastian N. Fajardo0Tyler B. Bourret1Susan J. Frankel2David M. Rizzo3Department of Plant Pathology, University of California, Davis, CA 95616, USADepartment of Plant Pathology, University of California, Davis, CA 95616, USAUnited States Forest Service, Pacific Southwest Research Station, Albany, CA 94710, USADepartment of Plant Pathology, University of California, Davis, CA 95616, USAEvidence of unintended introductions of <i>Phytophthora</i> species into native habitats has become increasingly prevalent in California. If not managed adequately, <i>Phytophthora</i> species can become devastating agricultural and forest plant pathogens. Additionally, California’s natural areas, characterized by a Mediterranean climate and dominated by chaparral (evergreen, drought-tolerant shrubs) and oak woodlands, lack sufficient baseline knowledge on <i>Phytophthora</i> biology and ecology, hindering effective management efforts. From 2018 to 2021, soil samples were collected from Angeles National Forest lands (Los Angeles County) with the objective of better understanding the diversity and distribution of <i>Phytophthora</i> species in Southern California. Forty sites were surveyed, and soil samples were taken from plant rhizospheres, riverbeds, and off-road vehicle tracks in chaparral and oak woodland areas. From these surveys, fourteen species of <i>Phytophthora</i> were detected, including <i>P. cactorum</i> (subclade 1a), <i>P. multivora</i> (subclade 2c), <i>P</i>. sp. <i>cadmea</i> (subclade 7a), <i>P</i>. taxon ‘oakpath’ (subclade 8e, first reported in this study), and several clade-6 species, including <i>P. crassamura</i>. <i>Phytophthora</i> species detected in rhizosphere soil were found underneath both symptomatic and asymptomatic plants and were most frequently associated with <i>Salvia mellifera</i>, <i>Quercus agrifolia</i>, and <i>Salix</i> sp. <i>Phytophthora</i> species were present in both chaparral and oak woodland areas and primarily in riparian areas, including detections in off-road tracks, trails, and riverbeds. Although these Mediterranean ecosystems are among the driest and most fire-prone areas in the United States, they harbor a large diversity of <i>Phytophthora</i> species, indicating a potential risk for disease for native Californian vegetation.https://www.mdpi.com/2309-608X/11/1/33Mediterranean vegetationoomyceteplant pathogen
spellingShingle Sebastian N. Fajardo
Tyler B. Bourret
Susan J. Frankel
David M. Rizzo
<i>Phytophthora</i> Species and Their Associations with Chaparral and Oak Woodland Vegetation in Southern California
Journal of Fungi
Mediterranean vegetation
oomycete
plant pathogen
title <i>Phytophthora</i> Species and Their Associations with Chaparral and Oak Woodland Vegetation in Southern California
title_full <i>Phytophthora</i> Species and Their Associations with Chaparral and Oak Woodland Vegetation in Southern California
title_fullStr <i>Phytophthora</i> Species and Their Associations with Chaparral and Oak Woodland Vegetation in Southern California
title_full_unstemmed <i>Phytophthora</i> Species and Their Associations with Chaparral and Oak Woodland Vegetation in Southern California
title_short <i>Phytophthora</i> Species and Their Associations with Chaparral and Oak Woodland Vegetation in Southern California
title_sort i phytophthora i species and their associations with chaparral and oak woodland vegetation in southern california
topic Mediterranean vegetation
oomycete
plant pathogen
url https://www.mdpi.com/2309-608X/11/1/33
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