by L.M. Archer Apr 28, 2022
“This is only the second frost event I remember in my history of grape growing, which began 40-plus years ago,” says Harry Peterson-Nedry, founder of RR Winery & Ridgecrest Vineyards. “The other event was 1985’s Mother’s Day frost.”
“In Burgundy, spring frosts are always something to watch out for before we get to the heat of the summer,” says Guillaume Large, winemaker at Burgundian-owned Résonance. “However, I have very rarely had to address dealing with frost during my time working harvest there.”
Currently, the scope of damage remain unclear. “I think the main point that everyone wants to know is how much will crops be decreased, but it’s too soon to tell,” says Jessica Mozeico, owner/winemaker at Et Fille Wines. “What I think is important is that we have no reason to believe that it’s going to be a quality impact at this point, but rather, a quantity crop load issue.”
Unfortunately, mid-twenties temperatures mid-April damaged buds coaxed open by earlier warm, dry conditions. Grape buds include a primary, secondary and tertiary bud. During bud break, the primary bud bursts open, releasing shoots and flower clusters. These flower clusters develop into fruit during growing season. If the first bud damages, the second bud develops, yielding less fruit. If the second bud damages, the third bud emerges, typically yielding no fruit.
“Frost impact is highly site specific and variable,” says Mozeico. “I will tell you that for our estate vineyard, which is at a very high elevation, we were not even close to bud break, so I don’t think that there will be an impact at that site, nor do I at two of my other higher elevation sites. It’s my lower elevation sites, that were just starting to go through bud break, that I’m concerned about. “
Adam Campbell of Elk Cove Vineyards concurs. “A lot of people don’t realize that the problems with elevation usually have to do with lower elevations, or sites that don’t have good air drainage,” he says. “What I see out there is that almost every site got cold enough to see some damage. And so, whether you’re in high elevation or low elevation, it got cold enough. Obviously that made a difference in terms of how budded out you were. Early sites, or those sites at lower sites, or even mid- elevation that budded out early did sustain some damage.”
The age of the vines also impacted the amount of damage. “The most serious, deleterious effects visibly apparent is on immature plants, i.e., newly planted and not yet bearing (planted in the last 3-4 years), where primaries are crisped,” says Peterson-Nedry.
Many point to climate change as a possible contributor. “Climate change can’t be dismissed as an actor in this frost event,” says Peterson-Nedry. “Climate change attributes not only include warmer growing seasons in general, changes to rainfall and other climate variables, but also an increased incidence of “extremes,” in which I would think this qualifies to be included.”
Consequently, some winemakers have increased crop insurance coverage. “Insurance coverage for this frost event is likely better because of the heightened awareness that 2020’s wildfires brought,” says Peterson-Nedry.” More winemakers HAVE insurance now than a couple years ago.” Oregon Wine Board reports 38% of Oregon winemakers currently carry wine grape insurance coverage.
Conversely, only a few employ frost mitigation programs. Valley View Winery in Applegate Valley, for example, uses sprinkler systems to encase buds in protective ice layers. Others use wind machines. “My guess is that less than 2% of Willamette Valley vineyards have frost mitigation control,” admits Campbell. “I know of vineyards that have it, but it’s extremely rare. It’s a good reminder that you have to have plans in place to be able to roll with Mother Nature.”
However, further studies may change future frost mitigation and protection methods. “As with wildfire smoke effects of 2020, frost event preparation will be improved because of the work we’re putting in to understand and troubleshoot this year’s event,” says Peterson-Nedry. “How different areas, varieties, viticultural approaches, etc. impact the variability of frost in the state is a topic for study, and will inform our approach to protection.”
Ultimately, patience proves essential in coping with Oregon’s frost fallout. “We just need to be patient (which is sometimes difficult), and wait a few weeks to see how things evolve and understand the extent of the impact,” concludes owner/winemaker Ximena Orrego of Atticus Wine. “As you may have heard from others, this only affects the quantity of grapes we will have available. I trust we will still have beautiful fruit at the end of the growing season that will allow us to make great wines.”