Shifting prevalence of plant- parasitic nematodes in orchards and vineyards of the Okanagan Valley, British Columbia

Authors: FORGE, T - Agriculture And Agri-Food Canada; MUNRO, P - Agriculture And Agri-Food Canada; MIDWOOD, A - Agriculture And Agri-Food Canada; PHILLIPS, L - Agriculture And Agri-Food Canada; HANNAM, K - Agriculture And Agri-Food Canada; NIELSEN, D - Agriculture And Agri-Food Canada; Zasada, Inga

Submitted to: Plant Health Progress
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/11/2021
Publication Date: 3/24/2021
Citation: Forge, T.A., Munro, P., Midwood, A., Phillips, L., Hannam, K., Nielsen, D., Zasada, I.A. 2021. Shifting prevalence of plant- parasitic nematodes in orchards and vineyards of the Okanagan Valley, British Columbia. Plant Health Progress. 22:113-121. https://doi.org/10.1094/PHP-10-20-0079-RS.
DOI: https://doi.org/10.1094/PHP-10-20-0079-RS

Interpretive Summary: Plant-parasitic nematodes, microscopic roundworms are a constraint to the production of apple, cherry, and grape. To determine the occurrence and distribution of nematodes in orchards and vineyards in the productive Okanagan Valley of British Columbia, Canada soil samples were collected and nematodes assessed. Plant-parsasitic nematodes were found to be widespread in the region. Counter to the current assumptions about nematodes in the region, it was found that there was a high prevalence of ring nematode in cherry orchards and grape vineyards and a different species of root lesion nematode in apple orchards. Results will be used by scientists and growers to develop management practices specific to the crop/nematode problem encountered in orchards and vineyards.

Technical Abstract: The Okanagan Valley of British Columbia hosts economically significant production of high-value perennial fruit crops. In the past thirty years, fruit production has shifted from being dominated by apple to a relatively even mix of apple, sweet cherry and wine grape production. This shift in the relative importance of cherry and grape warranted a new assessment of the plant-parasitic nematodes associated with perennial fruit crops in the region. Soil samples were collected from a total of 39 apple orchards, 61 cherry orchards, and 57 wine grape vineyards in the region in 2018 and 2012 (36 cherry orchards) and analyzed for plant-parasitic nematodes. Additionally, soil characteristics were assessed on collected soil samples. Genera found that are of potential significance to the crops were, in order of prevalence (common names in parentheses): Pratylenchus (root-lesion), Mesocriconema (ring), Xiphinema (dagger), Paratylenchus (pin), Paratrichodorus (stubby root), Hemicycliophora (sheath) and Meloidogyne (root-knot). Pratylenchus were found in 79, 98 and 81 percent of apple, cherry and grape plantings; Mesocriconema were found in 51, 79 and 82 percent; and Xiphinema were found in 59, 51 and 77 percent of the apple, cherry and grape plantings, respectively. Population densities of Pratylenchus, Mesocriconema and Xiphinema were influenced more by aspects of soil texture than any other soil properties, with Pratylenchus being negatively correlated with percentage clay, Mesocriconema being positively correlated with percentage sand, and Xiphinema being positively correlated with percentage silt. Based on surveys in the 1950s and 1980s which were focused on apple, Pratylenchus was already recognized as being relatively widespread in the region and a concern for apple and cherry production. The current study found that Pratylenchus is now more prevalent than in the earlier surveys. The high prevalence of Mesocriconema in sweet cherry orchards and vineyards in this region was not previously documented, and is highly significant because Mesocriconema is known to have significant impacts on other Prunus crop species and grapevines in other regions. This study, therefore, provides a different profile of nematode issues in the Okanagan Valley, and a rationale for increasing grower awareness and research efforts on the impacts and management of Mesocriconema in sweet cherry orchards and vineyards in the region.