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60 WINES&VINES March 2016 GRAPEGROWING WINE EAST stages including endodormancy and ecodormancy. Endodormancy is triggered by cooler temperatures and shorter days at the end of the growing season and is due to in- trinsic features of the grapevine itself, which suppress metabolic activity in the face of unseasonably warm weather such as we experi- enced in November." They added that endodor- mancy transitions to ecodormancy after the chilling requirement of the grapevine tissue has been met. Grapevines require exposure to "chilling" temperatures (32° to 45° F) for a period of time before they can deacclimate and begin the bud growth of the next growing season. The period of time re- quired varies somewhat by grape species and possibly among variet- ies. During ecodormancy, bud de- velopment is no longer inhibited by the vine itself but by environ- mental (or "eco"logical) factors. Bud development is blocked by cool temperatures (less than 50° F) but is encouraged by warm temperatures. The requirement for chilling hours of endodor- mancy greatly retards grapevines from starting bud growth during seasonal temperature variations in late fall and early winter, such as the warm November tempera- tures we often experience in the mid-Atlantic region. Wolf and Hatch said, "For ex- ample, let's say you were to bring a cane into room-temperature conditions in the fall following a frost that defoliated the vines. The cane would not break bud rapidly (it would probably take a month or more), and bud break would be erratic along the cane even though it was exposed to warm temperatures. The grape- vine tissue inhibits bud develop- ment because it has not yet satisfied its chilling requirement; the cane is in endodormancy. "However, if you brought a grapevine cane inside in January, it would break bud more rapidly, and bud burst would be consis- tent along the cane (unless there had been some cold injury to the buds). The cane collected in January is in ecodormancy, hav- ing already satisfied the chilling requirements of endodormancy. While in ecodormancy the buds deacclimate and grow more readily when exposed to warm temperatures. The specific re- q u i r e m e n t s b e y o n d c h i l l i n g hours that grapevines need to transition from endodormancy to eco dormancy are not clear. Wolf and Hatch said grape- vines have modest chilling-hour requirements compared to other perennial crops like apples, and warm temperatures in late winter and early spring could accelerate bud deacclimation and result in an advanced bud burst. Christmas Massacre redux? As noted above, while the tem- perature drop in 2015 was even greater than the one in 1980, there were several different fac- tors involved. The decline this year took place not in 24 hours, but over more than a week, when the daytime highs gradually came down, and the nighttime lows dropped first into the 20°s, then the teens, and finally to single digits. And the ultimate low point of temperatures in both Virginia and New York—while cold—was still above 0° F. Hatch went into the vineyard Jan. 8 to cut buds and check canes on both Merlot and Cabernet Sauvi- gnon. He reported that "all the buds and canes were fine, with no appar- ent winter injury." Wolf added that the Merlot vineyard had had a low temperature of 7.5° F on Jan. 5. So far, "No problem," Wolf commented, but there is "lots of 'winter' left." Trellis Supplies • Notched Metal Post, Wood • Anchors • Wire • Tools • Gripples • Dura-Line Training & Tying Supplies •Tree-fix • Wire ties • AgLoc • Klip-on • Grow Tubes • Training Stakes • Tying Products Wildlife Control • Bird netting • Side Applied Netting • BirdGard • Scare Devices • Deer Fence & Deterrents Spring Pruning and Tying Supplies FINGER LAKES TRELLIS SUPPLY BUY ONLINE! www.fingerlakestrellissupply.com 315-904-4007 4041A Railroad Ave. info@fingerlakestrellissupply.com Williamson, NY 14589 - B E C O PA D - Y E A S T & E N Z Y M E S - C R U S H PA D E Q U I P M E N T - S T E R I L E F I LT R AT I O N - W I N E R Y H O S E - O A K A LT E R N AT I V E S "Dormancy can be thought of as a protective feature that keeps grapevines from taking a miscue from warm periods in the fall." —Tony Wolf, Virginia Tech Grape Juice for Winemaking • California • Italy • Chile • South Africa Bulk Wine— CA North Coast • Drums • Totes • Tankers CFP Winemakers Fruit Juice for Winemaking • Year-around availability • 15 varieties Wine Grapes • California • Chile • South Africa Logistic Solutions • Coast to Coast CFP Winemakers, Pittsbugh PA www.cfpwinemakers.com • 412-232-4507