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  • Author or Editor: David Scurlock x
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The aim of this 5-year study was to investigate the influence of cluster thinning (CT) and harvest date on yield components, fruit composition, and bud cold-hardiness in ‘Vidal blanc’ (Vitis spp.) grapevines grown in northern Ohio. It is unknown whether delaying harvest of ‘Vidal blanc’ for ice wine production would impact negatively winter-hardiness. ‘Vidal blanc’ grapevines were cluster-thinned at post-fruit set [Eichhorn-Lorenz (EL) Stage 31] to two crop levels by retaining 40 (CT40) and 60 (CT60) clusters per vine. Each crop level was harvested at three dates: normal harvest (HD1), fall harvest (HD2) after the first killing frost, and winter harvest (HD3) corresponding to the typical commercial harvest for ice wine. Generally, and as expected, the high crop level CT60 increased crop weight and cropload and decreased total soluble solids and pH. Delayed harvest decreased crop weight, cluster weight, berry weight, and titratable acidity but increased total soluble solids and pH. Bud cold-hardiness, determined by thermal analysis and after two freezing events, was not different among all treatments. It was concluded that CT40 produced optimum vine size and cropload thus balanced vines. Furthermore, delaying fruit harvest in ‘Vidal blanc’ for ice wine production in the northeastern United States and Canada improves fruit composition but has no adverse influence on bud cold-hardiness.

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In the Spring and Summer 1997, severe die back of `Pinot Gris' and `Chambourcin' grape (Vitis vinifera) vines was observed by aerial surveillance in a commercial vineyard adjacent to Lake Erie. Vines grown over the tile lines grew well during 1997-99 following the excessively wet year of 1996. This was not the case for vines that were located betweentile lines. It was postulated that by digging and refilling the trench to insert the tile that either soil compaction or soil pH had been altered and could be responsible for the vine performance. Measurements indicated that these factors were not altered enough to explain the growth differences between vines growing over tile lines and those vines growing between tile lines. It appears that soil oxygen was improved by tiling and likely made the difference in cane dieback during the excessively wet year of 1996. By 1999, vines over tile and between tile had similar yields, and the pattern was no longer visible from the air. This study showed that heavy clay soils with naturally poor internal drainage caused cane dieback and poor growth of vines, especially in very wet years. Thus, it appears prudent on soils of this type, tile drainage is beneficial and spacing of lateral tile lines needs to be closer than 40 ft (12 m) in plateau silt loam soils to adequately protect vines from wet years.

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