On 11 April, 2022, cold temperatures, snow and frost arrived in the Willamette Valley. The pre-dawn hours of 15 April were particularly devastating, with numerous vineyards registering overnight lows of minus three to zero degrees Celsius. Gregory Jones, a research climatologist and CEO of Abacela Winery in Roseburg, Oregon, refers to the event as ‘February in April’ in his weather and climate newsletter.
The frost’s timing was disastrous. Thanks to a warmer, drier Oregon winter, Chardonnay and Pinot Noir buds were already breaking. The frost and sub-freezing temperatures hit those water-filled buds and young grapevines with a vengeance.
The Willamette Valley is defenceless against such attacks because few wineries feel the need to own frost fans or overhead frost protection systems. Given that the region’s last major early frost event occurred in May 1985, this attitude is understandable.
A few days after the frost cleared, Stirling Fox, a vineyard manager and founder of Stirling Wine Grapes, Inc. in Newberg, Oregon, thought some vineyards he visited will end up producing zero fruit. In contrast, others appeared to have little-to-no damage. How many vineyards will end up toward the zero fruit end of the spectrum is up for debate.
‘Based on what I’ve seen and what my peers are reporting, between 50% and 100% of the primary buds in many Willamette Valley vineyards were burned by the frost. At many of these sites, 50% of the secondary buds are burned. Realistically, we’re looking at the Willamette Valley losing half its crop this year,’ Fox said.
After a recent survey of her client’s vineyards, Jessica Cortell of Vitis Terra Vineyard Services in Amity, Oregon, reported seeing the least damage in the Eola-Amity Hills American Viticultural Area (AVA). She described ‘significant damage’ in the Chehalem Mountains AVA, with Chardonnay buds particularly hard hit.
Cortell also agreed with her colleague’s assessment. ‘Overall, it doesn’t look good out there. I think Stirling’s 50% number will be pretty close to what actually happens,’ she said.
Not everyone in the industry is ready to commit to such a dire loss figure however. Leigh Bartholomew is the director of viticulture for Results Partners, a McMinnville, Oregon, company that manages 120 sites in the Willamette Valley. ‘It is hard to know what the crop is going to be like because we can’t see the clusters easily right now,’ she said.
Bartholomew added that she is analysing the damage to primary buds in the approximately two dozen client sites her company describes as ‘severely damaged’. She reports that 40% – 50% of the primary buds appear to be alive even in the worst blocks of the hardest hit locations. She said, ‘That doesn’t even count how many secondary buds will pop out, and we don’t know how fruitful they will be.’
Although there isn’t much research on the topic, a general “rule of thumb” is to expect secondary buds to yield approximately 30% of the crop that primary buds typically produce.
Bartholomew also reports that the damage she sees is mainly located in lower elevation sites. ‘That’s the biggest correlation that we’ve seen. Higher elevation sites that were further behind on bud break are less impacted [by the frost]. Sites that are typically later look better.’
When asked when she thought she might have more concrete answers, Bartholomew said, ‘I keep saying “wait two weeks,” but then it keeps raining, and it is cold and things aren’t as apparent as I want them to be. Once we get past this next rain period, and if it dries out next week, we should have a better idea of the extent of the damage by 13th May.’
It is worth noting that, following the frost that hit the Willamette Valley some 37-years ago, 1985 turned out to be one of the Willamette Valley’s great vintages. The only problem was there was less wine to share with the world.