Issue link: http://winesandvines.uberflip.com/i/107279
GRAPEGROWING Dr. Markus Keller developed a mathematical model that estimates cold-hardiness. The model runs at WSU's AgWeatherNet. Mendoza, Argentina. In 2011, Keller's book, "The Science of Grapevines: Anatomy and Physiology," was named best viticulture book of the year by the Organisation Internationale de la Vigne et du Vin (OIV). Wines & Vines: How often do the vineyards of eastern Washington experience frost or killing freezes? Markus Keller: Fall frosts occur every year and typically terminate the growing season by inducing leaf fall. The question is not whether fall frosts occur but how early. We probably have one before harvest somewhere in eastern Washington at least once every three years. The same applies to spring frosts, which are a threat until the middle of May. Killing freezes in winter occur in about one out of six years. None of these events usually affect the entire region. One AVA, or a particular vineyard site within an AVA, can be worse off in one year and better off in another. Our industry uses wind machines in fall, winter and spring to mitigate frost or freeze events. Site selection is key to damage avoidance (remember that Washington is still an expanding growing region, and expansion is on land that was not previously planted to grapes). Sites on free-draining slopes elevated above valley floors are usually better off than other sites. W&V: Most of the grapevines in eastern Washington are on their own roots, although some are grafted. Which do you recommend, given the weather condi- tions? If growers opt for grafted vines, what can they do to protect the graft when extremely cold weather hits? Keller: Because phylloxera has not spread in eastern Washington over the past 100 years, we continue to recommend own-rooted vines, because they are much easier and cheaper to retrain after a killing freeze. Retraining of ownrooted vines simply means cutting off the dead trunks a few inches above the ground, training suckers back up to the cordon wire and establishing new spur positions from lateral shoots in the same season. This usually permits a full crop the following year. With grafted vines, some growers resort to hilling up soil around the vines in the fall, followed by "unhilling" in spring. But since nobody knows if or when a killing freeze will occur, hilling needs to be done preemptively. If grafted vines are killed back, growers have to regraft on a rootstock sucker following trunk removal. This strategy has had limited success due to cool spring temperatures and short growing seasons that make field-grafting a bit of a gamble. If a grower opts for replanting, this often involves removal of the trellis structure and irrigation lines, which drives up the QUALITY STAINLESS TANKS QST offers its clients……. Professionally fabricated stainless tanks 35 years of tank fabrication experience Performance & reliability guarantees Custom designs & modern features Quick & competitive tank project pricing On site tank repairs & modifications Special application tanks of all sizes "In stock tanks" from 500 to 10,000 gallons 510 Caletti Ave. Windsor, Ca. 95492 Phone 707-837-2721 or Toll-Free 877-598-0672 www.qualitystainless.com Company Website winetanks@aol.com email contact/sales info Custom Fabricated Tanks for the perfect size & fit… or Ready to Ship "Stock Tanks" Either way QST is ready to assist our clients! Call QST today for information or pricing! Win es & Vin es F EB RUA RY 20 13 59