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ARS Home » Pacific West Area » Corvallis, Oregon » Horticultural Crops Disease and Pest Management Research Unit » Research » Publications at this Location » Publication #422916
Research Project: Disease Management in Small Fruit and Nursery Crops Based on Knowledge of Pathogen Diversity, Biology, and Environmental Effects

Location: Horticultural Crops Disease and Pest Management Research Unit

Title: Occurrence of plant-parasitic nematodes in Pacific Northwest hopyards

Author
item Zasada, Inga
item NUNEZ-RODRIGUEZ, L - Oregon State University
item DURLING, E - Michigan State University
item USMAN, M - Michigan State University
item Wram, Catherine
item SANCHEZ-TOVER, E - Oregon State University
item Gent, David
item QUINTANILLA-TORNEL, M - Michigan State University

Submitted to: Plant Health Progress
Publication Type: Review Article
Publication Acceptance Date: 4/6/2025
Publication Date: N/A
Citation: N/A

Interpretive Summary: The Pacific Northwest of the U.S. (PNW; Idaho, Oregon, and Washington) is the most important hop producing region both nationally and internationally. However, little research on plant-parasitic nematodes has been conducted in the region. In this study, a total of 185 soil samples representing 93 hop yards were collected in the PNW to characterize the plant-parasitic nematodes associated with this crop. Ten different genera of plant-parasitic nematodes were found, with the hop cyst nematode, Heterodera humuli, second-stage juveniles (J2) being the most frequently encountered (54% of the total samples and 65% of surveyed hopyards). The identity of selected H. humuli populations was confirmed by Sanger sequencing of the 28S rRNA gene. Other nematode taxa encountered in order of frequency of occurrence were: Helicotylenchus, Telotylenchinae, Xiphinema, Paratylenchus, Pratylenchus, Trichodoridae, Dytilenchus, Gracilacus, and Mesocriconema. Heterodera humuli J2 densities were positively correlated with sand content based on the Spearman correlation coefficient. The host status of four hop varieties (‘Cascade’, ‘Centennial’, ‘Mosaic’, and ‘Citra’) to three Meloidogyne species was also assessed under greenhouse conditions. Meloidogyne incognita reproduced on all four hop varieties with reproduction factor values (RF = final population density/initial population density) ranging from 5 to 40. The hop varieties were non-hosts for M. chitwoodi (RF = 0.1) and varied from non-host to host (RF = 0.1 to 3) for M. hapla. This study demonstrates the wide distribution of the most important plant-parasitic nematode in hop production, H. humuli, in the PNW and host status of hop varieties to different Meloidogyne spp.

Technical Abstract: Plant-parasitic nematodes, microscopic worms that attack plants and can cause a reduction in yield of hop. This research was conducted to provide an up-to-date assessment of the occurrence and distribution of nematodes in hop production fields in the Pacific Northwest of the U.S. It was found that out of almost 100 surveyed fields, the hop cyst nematode was present in 77% of fields These results are significant because they report the widespread occurrence of this production-limiting nematode in the region. This information will be used by those involved in hop production to guide sampling and management recommendations.