UBC Theses and Dissertations
Nematodes in British Columbia vineyards : indicators of soil food web responses to compost amendments and impacts of the plant-parasite, Mesocriconema xenoplax. Smit, Rosanne
Vineyard owners in the Okanagan valley of BC are increasingly reporting under-performing blocks of grapevines. Until recently, plant parasitic nematodes were overlooked as factors contributing to decreased vigor in Okanagan vineyards. Analysis of soil from several underperforming vineyards revealed the presence of several species of plant parasitic nematodes, including ring nematodes (Mesocriconema xenoplax), that could be causing economically important damage to grapevines. M. xenoplax has been associated with grapevines in most major grape-growing regions of the world. Research conducted in field microplots in Oregon and California indicate that M. xenoplax can cause significant reductions in grapevine growth. The impact of plant parasitic nematodes and M. xenoplax in particular on grapevines under British Columbia growing conditions has not yet been determined. The research objectives were to determine if M. xenoplax has detrimental effects on growth of self-rooted vines and three rootstocks growing in sandy soils typical of the most south Okanagan vineyards and also to determine if application of compost to the root zone of mature grapevines decreases M. xenoplax population densities and enhances nematode community indicators of soil food web enrichment and structure. After two growing seasons of microplot trials, M. xenoplax decreased trunk diameters and pruning weights of self-rooted vines (Merlot) but did not decrease growth parameters of any of the rootstocks evaluated (Riparia Gloire, 44-53M, 3309C). Composted layer manure was surface-applied to the root zone of established vines in two commercial vineyards for three consecutive years at modest rates. At the first sample date, six months after the last compost application, all nematode trophic groups were more abundant in the compost-amended plots than in the fertilizer-treated plots indicating fluxes of nutrients through the soil food web. The enhancement of the soil food web did not appear to persist through the second growing season. Results from this research show that compost applications are beneficial to free-living nematode communities in sandy soils of the Okanagan, at least in the short term, and may buffer root feeding damage by plant parasitic nematode populations, especially M. xenoplax, which is indeed detrimental to grapevines.
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