An early freeze struck Washington state’s prime grapegrowing regions on the night of Nov. 23, with temperatures reaching -10° F in some areas. The cold inflicted damage on vines in the Columbia Valley, particularly in the Walla Walla appellation. Growers and winemakers are still assessing their vineyards but early estimates suggest a slight reduction in the 2011 crop.
“[It was] one of the most spotty freezes I’ve experienced,” said Kevin Corliss, vice president of winemaking at Ste. Michelle Wine Estates, the largest producer in the state. Corliss reported that Ste. Michelle has called its vineyard staff back from vacation to check the buds on cane samples taken from different vineyards to determine the extent of the damage.
The main threat to the vines was damage to the buds that will sprout into flowers and grape bunches come spring and summer. Vineyard location and the grape type also determined the extent of the damage. “Normally these temperatures would not be a problem,” said Jonathan Sauer of Red Willow vineyard in the Yakima Valley. "However, coming so early in the winter, the vines were not yet fully hardened off."
Hugh Shiels, founder of Côte Bonneville, predicts "a tough year ahead," after assessing the damage in his DuBrul Vineyard in Yakima Valley. "Cutting buds is not encouraging," he said. "Chardonnay and Syrah got hammered hard, Merlot and Cabernet not as bad."
Walla Walla Valley experienced some of the coldest temperatures. Dusted Valley’s Chad Johnson reported that some low-lying vineyards were hit the hardest. “[We had] 75 percent bud kill on the valley floor,” he said. Less cold-resistant varieties like Grenache, Sangiovese and Sémillon were particularly vulnerable. Johnson said Merlot was also hit.
But bud kill isn’t the same thing as crop loss. Each bud has three layers, a primary, a secondary and a tertiary bud. If the primary is damaged, the secondary will sprout but with about half the yield. Vintners can compensate for freeze damage by pruning their vines. It’s a normal procedure during the winter, when growers determine the overall yield by pruning the vines to a specific amount of buds per each plant. When the buds are damaged, growers can compensate by allowing for more buds to grow.
How the size of the 2011 harvest will be affected remains to be seen. Winemakers are optimistic that the freeze won’t have a strong effect. “I would be surprised as a state if [the damage] has a 10 percent impact [on the crop],” said Marty Clubb, winemaker at L’Ecole No. 41 in the Walla Walla Valley. But that will require plenty of work before spring.