Fusarioid community diversity associated with conifer seedlings in forest nurseries across the contiguous USA

J T Dobbs; M-S Kim; G J Reynolds; N Wilhelmi; R K Dumroese; N B Klopfenstein; S W Fraedrich; M M Cram; J Bronson; J E Stewart

doi:10.3389/fpls.2023.1104675

Fusarioid community diversity associated with conifer seedlings in forest nurseries across the contiguous USA

Front Plant Sci. 2023 Jan 25:14:1104675. doi: 10.3389/fpls.2023.1104675. eCollection 2023.

Authors

J T Dobbs¹, M-S Kim², G J Reynolds³, N Wilhelmi⁴, R K Dumroese⁵, N B Klopfenstein⁵, S W Fraedrich⁶, M M Cram⁷, J Bronson⁸, J E Stewart¹

Affiliations

¹ Colorado State University, Department of Agricultural Biology, Fort Collins, CO, United States.
² USDA Forest Service, Pacific Northwest Research Station, Corvallis, OR, United States.
³ USDA Forest Service, Forest Health Protection - Region 3, Albuquerque, NM, United States.
⁴ USDA Forest Service, Forest Health Protection - Region 3, Flagstaff, AZ, United States.
⁵ USDA Forest Service, Rocky Mountain Research Station, Moscow, ID, United States.
⁶ USDA Forest Service, Southern Research Station, Athens, GA, United States.
⁷ USDA Forest Service, Forest Health Protection - Region 8, Athens, GA, United States.
⁸ USDA Forest Service, Forest Health Protection - Region 6, Medford, OR, United States.

Abstract

Introduction: Fusarioid fungi that cause damping-off and root diseases can result in significant losses to conifer crops produced in forest nurseries across the USA. These nurseries are vital to reforestation and forest restoration efforts. Understanding the diversity of Fusarioid fungi associated with damping-off and root diseases of conifer seedlings can provide an approach for targeted management techniques to limit seedling losses and pathogen spread to novel landscapes.

Methods: This study identifies 26 Fusarium spp. (F. acuminatum, F. annulatum, F. avenaceum, F. brachygibbosum, F. clavus, F. commune, F. cugenangense, F. diversisporum, F. elaeagni, F. elaeidis, F. flocciferum, F. fredkrugeri, F. fujikuroi, F. grosmichelii, F. ipomoeae, F. lactis, F. languescens, F. luffae, F. odoratissimum, F. oxysporum, F. queenslandicum, F. redolens, F. torulosum, F. triseptatum, F. vanleeuwenii, & F. verticillioides), 15 potential species within Fusarium and Neocosmospora species complexes (two from F. fujikuroi species complex, nine from F. oxysporum species complex, three from F. tricinctum species complex, and one from Neocosmospora species complex), and four Neocosmospora spp. (N. falciforme, N. metavorans, N. pisi, & N. solani) and associated host information collected from conifer-producing nurseries across the contiguous USA.

Results: Phylogenetic analyses identified Fusarioid fungi haplotypes that were associated with 1) host specificity, 2) localization to geographic regions, or 3) generalists found on multiple hosts across diverse geographic regions.

Discussion: The haplotypes and novel species identified on conifer seedlings should be considered for further analysis to determine pathogenicity, pathogen spread, and assess management practices.

Keywords: Fusarium; conifer nurseries; damping off pathogens; geographic regions; haplotype diversity.