Plant-parasitic nematodes on hemp in the Pacific Northwest of the United States

Abstract Background Plant-parasitic nematodes are one of the most important biotic factors that impact crop production globally. Since hemp cultivation in the U.S. was banned from 1970 to 2018, little information is available about current plant-parasitic nematode pressure on U.S. hemp production. T...

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Main Authors: Lester A. Núñez-Rodríguez, Hannah M. Rivedal, Cynthia M. Ocamb, David H. Gent, Inga A. Zasada
Format: Article
Language:English
Published: BMC 2025-07-01
Series:Journal of Cannabis Research
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Online Access:https://doi.org/10.1186/s42238-025-00301-y
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author Lester A. Núñez-Rodríguez
Hannah M. Rivedal
Cynthia M. Ocamb
David H. Gent
Inga A. Zasada
author_facet Lester A. Núñez-Rodríguez
Hannah M. Rivedal
Cynthia M. Ocamb
David H. Gent
Inga A. Zasada
author_sort Lester A. Núñez-Rodríguez
collection DOAJ
description Abstract Background Plant-parasitic nematodes are one of the most important biotic factors that impact crop production globally. Since hemp cultivation in the U.S. was banned from 1970 to 2018, little information is available about current plant-parasitic nematode pressure on U.S. hemp production. The production of hemp has gained interest in Washington and Oregon, states where several genera of plant-parasitic nematodes have been associated with various crops. This report is the first to define plant-parasitic nematodes associated with hemp in these states in the Pacific Northwest. Methods Soil and root samples from hemp fields were collected in early autumn in 2021, 2022, and 2023. The occurrence, population density, and identity of plant-parasitic nematodes in these samples were determined using morphological and molecular identification methods. A Bayesian analysis of available sequence data was used to analyze phylogenetic relationships of nematode species found in hemp fields. Additionally, the host status of hemp ‘Alpha Explorer’ to three plant-parasitic nematodes, Meloidogyne chitwoodi, M. hapla, and Pratylenchus neglectus, was tested under greenhouse conditions. The occurrence of plant-parasitic nematodes and reproduction factor (final population density/initial population density) values of the three nematode species were analyzed with non-parametric methods. Results Pratylenchus spp. were the most frequent plant-parasitic nematodes recovered from soil samples, being present in ~ 63% of samples (n = 107). Only two endoparasitic nematodes, Meloidogyne spp. and Pratylenchus spp., were found in root samples, with Pratylenchus spp. as the most frequent (20 out of 24 fields). A large diversity of Pratylenchus spp. was detected in hemp root samples. Hemp ‘Alpha Explorer’ was a poor host for P. neglectus, resulting in low reproduction values (< 1). Additionally, results of our study indicated that hemp is not a host for M. chitwoodi. Conclusions Pratylenchus spp. were the most frequent plant-parasitic nematodes found in hemp fields in Oregon and Washington. This study reports for the first time five Pratylenchus species (Pratylenchus crenatus, P. fallax, P. hexincisus, P. neglectus, and P. scribneri) associated with hemp in Oregon and Washington; P. penetrans was also found in the region on hemp. The host status results indicate that hemp can be considered a non-host for M. chitwoodi and a poor host for M. hapla and P. neglectus.
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spelling doaj-art-5f7fd6926a8d4b869ed5da855f24405c2025-08-20T03:05:57ZengBMCJournal of Cannabis Research2522-57822025-07-01711810.1186/s42238-025-00301-yPlant-parasitic nematodes on hemp in the Pacific Northwest of the United StatesLester A. Núñez-Rodríguez0Hannah M. Rivedal1Cynthia M. Ocamb2David H. Gent3Inga A. Zasada4Department of Botany and Plant Pathology, Oregon State UniversityForage Seed and Cereal Research Unit, USDA-ARSDepartment of Botany and Plant Pathology, Oregon State UniversityForage Seed and Cereal Research Unit, USDA-ARSHorticultural Crops Disease and Pest Management Unit, USDA-ARSAbstract Background Plant-parasitic nematodes are one of the most important biotic factors that impact crop production globally. Since hemp cultivation in the U.S. was banned from 1970 to 2018, little information is available about current plant-parasitic nematode pressure on U.S. hemp production. The production of hemp has gained interest in Washington and Oregon, states where several genera of plant-parasitic nematodes have been associated with various crops. This report is the first to define plant-parasitic nematodes associated with hemp in these states in the Pacific Northwest. Methods Soil and root samples from hemp fields were collected in early autumn in 2021, 2022, and 2023. The occurrence, population density, and identity of plant-parasitic nematodes in these samples were determined using morphological and molecular identification methods. A Bayesian analysis of available sequence data was used to analyze phylogenetic relationships of nematode species found in hemp fields. Additionally, the host status of hemp ‘Alpha Explorer’ to three plant-parasitic nematodes, Meloidogyne chitwoodi, M. hapla, and Pratylenchus neglectus, was tested under greenhouse conditions. The occurrence of plant-parasitic nematodes and reproduction factor (final population density/initial population density) values of the three nematode species were analyzed with non-parametric methods. Results Pratylenchus spp. were the most frequent plant-parasitic nematodes recovered from soil samples, being present in ~ 63% of samples (n = 107). Only two endoparasitic nematodes, Meloidogyne spp. and Pratylenchus spp., were found in root samples, with Pratylenchus spp. as the most frequent (20 out of 24 fields). A large diversity of Pratylenchus spp. was detected in hemp root samples. Hemp ‘Alpha Explorer’ was a poor host for P. neglectus, resulting in low reproduction values (< 1). Additionally, results of our study indicated that hemp is not a host for M. chitwoodi. Conclusions Pratylenchus spp. were the most frequent plant-parasitic nematodes found in hemp fields in Oregon and Washington. This study reports for the first time five Pratylenchus species (Pratylenchus crenatus, P. fallax, P. hexincisus, P. neglectus, and P. scribneri) associated with hemp in Oregon and Washington; P. penetrans was also found in the region on hemp. The host status results indicate that hemp can be considered a non-host for M. chitwoodi and a poor host for M. hapla and P. neglectus.https://doi.org/10.1186/s42238-025-00301-yHempIdentificationPlant-parasitic nematodesPratylenchus spp
spellingShingle Lester A. Núñez-Rodríguez
Hannah M. Rivedal
Cynthia M. Ocamb
David H. Gent
Inga A. Zasada
Plant-parasitic nematodes on hemp in the Pacific Northwest of the United States
Journal of Cannabis Research
Hemp
Identification
Plant-parasitic nematodes
Pratylenchus spp
title Plant-parasitic nematodes on hemp in the Pacific Northwest of the United States
title_full Plant-parasitic nematodes on hemp in the Pacific Northwest of the United States
title_fullStr Plant-parasitic nematodes on hemp in the Pacific Northwest of the United States
title_full_unstemmed Plant-parasitic nematodes on hemp in the Pacific Northwest of the United States
title_short Plant-parasitic nematodes on hemp in the Pacific Northwest of the United States
title_sort plant parasitic nematodes on hemp in the pacific northwest of the united states
topic Hemp
Identification
Plant-parasitic nematodes
Pratylenchus spp
url https://doi.org/10.1186/s42238-025-00301-y
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AT cynthiamocamb plantparasiticnematodesonhempinthepacificnorthwestoftheunitedstates
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