Grape (Wine & Juice Viticulture) Archives - Page 2 of 4

Botrytis Bunch Rot: Where, When, and What to use

Post author:Abby Clayton-Gearing
Post published:February 15, 2024
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From 2020-2022, eleven sites from nine different vineyards in Oregon, and four in Washington were surveyed for Botrytis by sampling grape inflorescence and developing fruits, vineyard floor debris (prior year grape rachis), and nuisance blackberries. Botrytis on grape inflorescence and fruits varied from site to site and year to year likely due to yearly disease pressure differences and unique site microclimates. Prior year dead grape rachis on the vineyard floor with sporulating Botrytis infestations varied from year to year as well, but generally declined as the season progressed. Incidence of Botrytis on vineyard floor debris in all but one site in 2021 was over 75% in late April and all sites sampled decreased over time to under 25% by September. Wild nuisance blackberry flowers and fruits adjacent to the vineyard were also found to be potential sources of Botrytis inoculum throughout the season. Inoculum estimation from historical spore trap DNA samples originally taken to monitor powdery mildew in the Willamette Valley were re- assayed for Botrytis inoculum.

Epidemiology and Management of Plant-parasitic Nematodes in Winegrapes

Post author:Abby Clayton-Gearing
Post published:February 2, 2024
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Nematodes are root feeding organisms that can cause direct damage and can also be a virus vector. Nematodes can severely limit the successful establishment of vines and vineyards and impact production yields by 5-20%. There are several products available to growers to assist in managing Nematode populations and increase successful vine establishment. This research evaluates combinations of synthetic (at half the recommended commercial rate) and biological nematicides to reduce populations of plant-parasitic nematodes, and increase populations of free-living beneficial nematodes and to increase vine productivity.

Heat stress in wine grapes: acclimation and potential mitigation

Post author:Abby Clayton-Gearing
Post published:October 20, 2023
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Heat stress poses challenges for the sustainable production of premium wine grapes in the Pacific Northwest. The intensity of heat waves has been increasing. For example, the series of heat wave events in 2021 broke temperature records in many locations in this region, and heat waves were again common during the 2022 and 2023 growing season. Growers need knowledge of how grapevines adjust to heat waves or sudden temperature changes to make informed management decisions. We grew potted grapevines in environmentally controlled growth chambers under different temperature regimes (simulating cool and warm growing seasons) before exposing the vines to sudden temperature changes with maximum temperatures varying from 77°F to 104°F. Photosynthesis measurements showed that grapevines might tolerate a sudden rise in temperature better in a warm than a cool season. During extended heat waves, however, the cool season-acclimated vines recovered faster than the warm season-acclimated vines.

Detection of wine faults using the electronic tongue

Post author:Abby Clayton-Gearing
Post published:June 29, 2022
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Faulted wines pose a serious economic problem to the wine industry, these off flavors can cause consumers, new to a region or variety, to reject that region entirely. Wine faults can include off-aromas or flavors associated with chemical compounds produced by spoilage organisms Brettanomyces, Acetobacter, Pediococcus or Lactobacillus. From the producers and winemakers’ perspective, early detection of wine faults would allow for remediation before the fault becomes more serious, intractable, and costly. Research in wine fault detection continues to develop as more sensitive and rapid analytical methods are identified that can reflect the complexity of the faulted wine.

Biology and Management of Cutworms in Washington Vineyards

Post author:Abby Clayton-Gearing
Post published:June 29, 2022
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Cutworms are capable of causing severe damage in vineyards during the early spring months when vines buds and tender shoots are at their most vulnerable. Damage to buds can cause severe crop loss in Washington vineyards, and this study supports the idea that the Cutworm species found on vineyard floors (on weeds, etc.) are a minor component of the fauna that actually damages grapevines. Vineyard sites with a large number of Cutworms on the vineyard floor did not necessarily sustain major bud damage. Conversely, sites with small numbers of Cutworms sometimes sustained major bud damage. This appeared to be related to ground cover presence/absence and/or type, but was also, in view of the rearing data, a consequence of most ground-dwelling species preferring to remain on the ground and not climb up grapevines.