Issue link: http://winesandvines.uberflip.com/i/400294
W i n e s & V i n e s n O V e M B e r 2 0 1 4 117 E ditor's Note: This column contains a collection of edited article abstracts published by viticultural authors east of the Rockies during the past year. Several of these were papers presented at the na- tional conference of the American Society for Enology & Viticulture in Austin, Texas, in June 2014, unless indicated otherwise. Measuring hardiness in vinifera Winter hardiness is a high priority for re- search in many jurisdictions in the East and Midwest. Dr. Jim Willwerth et al., of Brock University in St. Catharines, Ontario, examined the impact of cultural practices on the cold-hardiness dynamics of six Vitis vinifera cultivars. grapevine winter injury is a major limitation for premium wine pro- duction in marginal-climate locations such as Ontario. replicated factorial experiments of two cropping levels and multiple harvest dates were imposed for three white cultivars (Chardonnay, Sauvignon Blanc and ries- ling) and three reds (Pinot Noir, Cabernet Franc and Merlot) over a three-year period. Crop-level treatments consisted of two cluster-thinning levels of one or two clusters per shoot. Harvest occurred either at normal com- mercial maturity or with an extended additional three-week hang time. Vine- performance variables, yield components and fruit composition were compared to cold acclimation/deacclimation curves. In midwinter, there were few differences in cold hardiness among crop level treatments but some among cultivars. However, crop level and harvest date impacted rates of ac- climation and deacclimation for most culti- vars. There were also vintage effects due to cold-hardiness dynamics and interactions of crop level and harvest date. Full crops com- bined with late-harvest treatments resulted in slower vine acclimation, and crop levels had a greater impact on cold-hardiness dynamics of Chardonnay, Pinot Noir and Sauvignon Blanc. Maximum cold hardiness may be influ- enced more by cultivar based on rates of maturation than by cropload or harvest date. growing season conditions and tim- ing of maturity also play an important role in terms of the interactions between crop levels, hang time and cold hardiness. Smaller crop treatments and late harvests were characterized by lower yields, higher Brix, higher pH and lower TA. Therefore, by reducing crop levels and extending hang time, greater fruit quality can be achieved, but vine cold acclimation may be delayed for some cultivars. Development of cold tolerance Shouxin Li and Imed Dami of Ohio State University, Wooster, examined improving freezing tolerance of Pinot gris grapevines in Ohio using exogenous abscisic acid (ABA). Several cultivars popular in the East are sensitive to freezing temperatures below -20°C. Previous work from this group indicated that exogenous ABA application increased freezing tolerance of cold-sensi- tive cultivars. Their goal in this case was to improve freezing tolerance of another cold-sensitive cultivar, Pinot gris, by evalu- ating yield components, fruit composition and freezing tolerance in response to exog- enous ABA. Field-grown Pinot gris vines were sprayed with 400 mg/L ABA at different stages of development (véraison, post-véraison, and postharvest). ABA did not affect yield components or fruit composition, but it caused early leaf abscission, advanced bud dormancy and eventually increased freezing tolerance. Véraison and post- véraison treatments were most effective in increasing freezing tolerance. These findings are valuable to grape producers by providing another tool for frost protection and to the scientific community by providing better understanding of the mechanisms of freezing tolerance. Edelweiss and Amigo Oil Nebraska experiences cold winter tempera- tures as well as the potential for late spring freezes. Edelweiss, an important grape cultivar grown in the Midwest, is one of the earliest cultivars to break bud, making it very susceptible to late spring freezes. Its primary buds produce a significant amount of fruit, but unlike most other hybrids, its secondary and tertiary buds have little to no yield, which adds to the importance of pro- tecting the primary buds from late freezes. Ben Loseke et al., of the University of Nebraska, Lincoln, reported on delay of bud break in Edelweiss grapevines with multiple applications of Amigo Oil and naphthaleneacetic acid (NAA) in order to determine if the multiple applications might achieve a greater bud delay than single applications. Vines were treated in January, January and February, or January, February and March. Amigo Oil was applied at 10% (v/v) and NAA at 1,000 mg/L with a custom-built sprayer. All oil treatments led WineEast Wine East HIGHLIGHTS • scientists presented grapevine research at the national meeting for the American society for enology and Viticulture. • How to boost winter hardiness was a popular topic, with researchers testing cultivars and topical applications. • Leaf thinning was shown to affect cluster composition, yield, berry weight, pH and TA. Grapevine Mysteries Revealed Research probes grape breeding, cold hardiness and canopy management By Andrew Reynolds 24 48 1 2 hours hours week weeks -6 -8 -10 -12 -14 -16 -18 Time after ABA application Freezing tolerance (ºC) Control ABA Freezing Tolerance of Pinot Gris