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Time will tell the extent to which Willamette Valley vineyards were damaged by frost in mid-April, growers say.

NEWBERG, Ore. — Willamette Valley winegrape growers are assessing what they fear could be significant losses in their vineyards after an unseasonable spring frost nipped vulnerable buds that were just beginning to emerge from dormancy.

Temperatures dipped below freezing April 14-15 across the region, which produces nearly three-quarters of the state’s winegrapes. Cold weather can kill buds or stunt vine growth, reducing crop load come harvest in September and October.

However, producers say the frost’s impact varies by location, making it hard to determine the full extent of the damage.

“As much as we all want to know right now what is the estimated (yield) decrease for the whole region, we just don’t know yet,” said Jessica Mozeico, owner of Et Fille Wines in Newberg and president of the Willamette Valley Wineries Association.

Mozeico said whether a particular vineyard was affected depends on two factors — if the vines had reached “bud break,” and if it was cold enough locally to damage them.

Bud break typically happens during mid-April in the Willamette Valley, and refers to the period when vines “wake up” from winter. The buds eventually grow new shoots and flowers, which develop into winegrapes as the season progresses.

Mozeico said vines had not reached bud break at her estate vineyard in the Chehalem Mountains, which is at a higher elevation. She does not expect to see a major impact there, though Et Fille Wines does manage blocks at eight other vineyards that could see reduced yields.

“The question becomes, How much less?” Mozeico said. “That’s the stage we’re all in. We’re trying to get some estimates and calculate that.”

Harry Peterson-Nedry, who founded Ridgecrest Vineyards near Newberg in 1980, said spring frost is unusual in the Willamette Valley. The last time he remembers it happening was around Mother’s Day in 1985.

Ridgecrest Vineyards sits atop Ribbon Ridge and was on the cusp of bud break in some blocks, though Peterson-Nedry said it is still too early to draw any firm conclusions.

“You really need to wait until the buds push out before you find out what you got, and what you don’t have,” he said. “That is the key to this … patience and not making a judgment until they have made it themselves.”

Kim Bellingar, of Bellingar Estates in Newberg, said that unfortunately she is seeing “pretty significant” damage in her 5-acre vineyard, particularly among Chardonnay grapes, which is typically the first variety to reach bud break.

As for Pinot noir, the Willamette Valley’s signature wine, Bellingar said more secondary buds are starting to emerge.

“We’re optimistic those will continue to develop, but we are expecting lower fruitfulness from the entire vineyard just because of the damage we saw,” Bellingar said.

Bellingar and Mozeico emphasized that frost damage is an issue of winegrape quantity, not quality. Mozeico said there is no reason to believe any wines from the 2022 vintage will experience a dip in quality due to the cold snap.

“What we know is it is very likely we will have lower crop loads than we had hoped for,” she said. “What we don’t know is how much lower.”

Sam Tannahill, co-founder of A to Z Wineworks in Newberg, said that while some vineyards were undoubtedly impacted, the frost did not appear to cause widespread or catastrophic damage statewide. A to Z buys grapes from 70 vineyards across Oregon, south to the California border and as far east as Umatilla.

Tannahill said cooler weather this spring may have delayed bud break in some areas, protecting more grapes from frost damage.

“If all the buds had broken, we could have seen significant damage,” he said. “The fact is, we dodged a bullet.”

Unlike the Willamette Valley, vineyards in Southern Oregon and the Columbia River Gorge also typically have frost protection, such as windmills that pull warmer air from higher altitudes and push it down to the vineyard floor.

At first blush, Tannahill said it appears the crop load for A to Z Wineworks may be down 10%, though that will likely change.

“We’ve got a long way to go before harvest,” he said. “There’s a lot that can happen.”