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62 WINES&VINES March 2016 GRAPEGROWING WINE EAST Wine Packaging by Packaging Designed & Manufactured by a Wine Maker, for a Wine Maker 4138 Vineyard Road Stewartstown, PA 17363 Tel: 800-292-3370 Fax: 717-993-9460 Phone: 717-993-2431 Naylor Wine Cellars is a lifetime member of Wine America, Pennsylvania Wine Assoc, Ohio Wine Producers and NY Wine & Grape Foundation WPN is a premier supplier to over 2,000 wineries and wine & spirits shops. Our auto bottom carriers & shippers are the perfect sturdy solution for your retail & online sales! www.NaylorPackaging.com Features & Benefits - Extra sturdy construction for the most protection - Quick & easy to pack & set up - Folds to conform to many different bottles - Trademarked design - Bio-degradable - Quick delivery from our stock - Lies flat for easy storage - Takes up half the space of comparative packages - Tested & approved by UPS and Federal Express as a preferred method of shipping bottles - Custom imprinting and packaging is available to display your logo, enhancing your brand image "In autumn, green shoots turn brown from the base outward toward shoot tips as the cork cambium forms (a ring of cells outside the phloem), producing a layer of water-resistant cork cells called the periderm. As these cells are produced and die, they become impervious to water. Buds are only weakly connected to the vine's vascular system, which isolates bud tissue and lim- its the potential for them to take up water. At leaf fall, buds are moderately cold-hardy and can survive temperatures ranging from 5° to 20° F. "After the onset of below-freezing tem- peratures, buds continue to gain cold-har- diness through further desiccation and redistribution of water to the intercellular spaces. As ice forms outside of cells, dif- ferential vapor pressure draws water out of the cells and onto the surface of the ice crystals. This response is highly correlated with the vine's exposure to low winter tem- peratures. For example, buds exposed to lower winter temperatures in New York have median lethal temperatures (LT50) 2° to 3° F lower than buds exposed to more moder- ate winter temperatures in Virginia." Losing cold hardiness Martinson then describes what happens to the cold-hardy grapevines when the weather be- gins to warm up. "After attaining their maxi- mum cold hardiness in midwinter, buds deacclimate in response to milder tempera- tures, and deacclimation is often more rapid than the acclimation process. Warmer tempera- tures increase ambient humidity, and vine tis- sues gradually gain water. As soils warm up, capillary action draws water up the trunk, and 'sap flow' occurs. By the time of bud swell, rehydrated bud tissue is vulnerable to freeze injury at only a few degrees below freezing. "Each grapevine bud contains a primary, sec- ondary and tertiary bud. The primary bud is most well developed and is typically less cold-hardy than secondary or tertiary buds. Freeze injury in response to low temperatures typically affects the primary bud first. "We measure bud freezing temperatures by collecting canes from vineyards, cutting off buds and placing them on thermo- couples in a controlled tempera- ture freezer. As the temperature in the freezer gradually de- creases, each bud will release a small amount of heat (called a low temperature exotherm) as it freezes, allowing a precise estimate of the lethal tem- perature for that bud. A collection of buds from a single vineyard will exhibit a range of bud freezing temperatures that vary from 2° to 6° F. The median freezing temperature from a collection of 30 buds, called the LT50, is a common measure of cold hardiness. Mea- surements of LT50 bud-freezing tempera- tures from leaf fall to bud burst reveal that bud hardiness undergoes constant change in response to weather conditions. "The winter low temperatures that injure buds limit where a cultivar can be grown. Cold-sensitive V. vinifera cultivars may have significant bud injury below -3° F, but buds of cold-hardy varieties with V. riparia parent- ADJUSTMENTS BY BUD MORTALITY In the 2007 article "Winter Injury to Grapevines and Methods of Protection" in the Michigan State University Extension Bulletin, Tom Zabadal et al. recommended the following: Less than 15% injury No adjustment 15%-35% bud mortality Retain 35% more buds 35%-50% mortality Retain 100% more buds More than 50% mortality Minimal or no pruning