Graduate Thesis Or Dissertation
 

Assessment of Grapevine Red Blotch Virus Impacts on Physiology, Productivity, and Fruit Composition of ‘Pinot noir’ Grown in Oregon’s Willamette Valley

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https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/3r0752413

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  • Grapevine red blotch disease (GRBD) is caused by Grapevine Red Blotch Virus, a virus in the Geminiviridae family. Observable symptoms can manifest in red cultivars, such as leaf blades that are partially to fully red, red veins, and different combinations of the two. Previous research has shown evidence of reduced total soluble solids, anthocyanins, and phenolic compounds in GRBD infected vines. In cool regions, such as Oregon’s Willamette Valley, GRBD could have a significant effect on fruit ripeness and wine quality. Most research on this disease to date has been conducted in New York and California. To understand the impacts of vine physiology, productivity, and fruit quality from GRBD in a cool climate, a field study was conducted in Oregon’s Willamette Valley from 2017 to 2019. A commercial Pinot noir vineyard containing both GRBD+ and GRBD- vines, including GRBD+ vines that were either symptomatic or asymptomatic was selected for this research. Vines were monitored through each growing season for visual disease symptoms and physiological measures. Visual symptoms began to appear on leaves at véraison in the basal portion of the shoots and continued acropetally as the season progressed. No consistent differences were observed in the physiological measures of photoassimilation, stomatal conductance, or leaf greenness. Véraison nutrient testing in all three years revealed a consistent magnesium deficiency in petioles of symptomatic GRBD+ vines compared to asymptomatic GRBD+ vines. Yield and berries per cluster did not differ between healthy and GRBD+ vines at harvest in any year, but cluster and berry weight were lower in symptomatic GRBD+ compared to asymptomatic GRBD- in 2017 and 2018. Fruit at harvest did not differ in total soluble solids in any year between healthy and GRBD+ vines. However, during 2018 and 2019 pH was higher and titratable acidity was lower in 2019 in symptomatic GRBD+ vines compared to asymptomatic GRBD+ vines. No consistent differences in total anthocyanin, total phenolic, or total tannins were measured based on virus or symptom status. This study suggests that there are few impacts of GRBD for Pinot noir grown under the cool climate conditions of Oregon’s Willamette Valley.
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  • Pending Publication
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  • 2020-06-11 to 2021-07-12
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