I’ve been keeping the notes that follow about frost damage to indicate our decision-making process amid changing conditions over the period of several weeks.

Thursday, April 10th:
We’ve had a cold spring with some serious frost at the very end of March when temperatures were below freezing for five hours and got as low as 26 degrees F.
Because frost damage can cause unevenness in growth and ripening, it complicates our decision-making. If we’ve lost some crop already, for example, should we thin more crop?

Luckily, Pinot Noir is a later variety and a lot of our vines hadn’t pushed out yet. Our Carneros topography of rolling hills was helpful, because those vines that were out up to two inches were in upper blocks, while the cold air, being heavier, flows into the low swales in the vineyards. Also, our vines are mostly cane pruned, so the secondary buds might be more fruitful and hopefully could make up most of the loss if the primary buds are damaged.

It got really cold and we don’t really understand yet what happened. Could the low temperatures have affected flow in the xylem, the tissue in the trunk that conducts water and dissolved nutrients up to the buds? We only have to deal with frost about one out of every four or five years, so we don’t have the extensive experience they do in Washington, for instance.

Normally we would sucker early, but now we are reluctant to rub off an extra bud when we may need it later. This situation forces you to be creative.

It’s really too early to tell, but I’d estimate loss in Carneros at five to ten percent, whereas in our Russian River Valley vineyard, it might be as high as 20%. We’ll see at flowering how even things are.

Thursday, April 17th:
We walked the vineyards again yesterday. There was one block in the flats that may have lost up to 10%, but everywhere else looked pretty good. We had a very warm weekend, up into the low 90′s, then cold again with another frost alert night on Monday. These extremes are not good.

We have been waiting, too gun shy to sucker, and we don’t like being timid. We want to move ahead with our work. What’s happening out there is a moving, shifting equation, and we have to try to understand the dynamic before acting. We have done all of our replanting and cultivation. The ground is really nice, and we have enough water, although it’s been dry since February.

We noticed that fruitfulness is good this year. We are seeing two and sometimes even three clusters per shoot, and wings on the clusters. So we have made our decision – we’ll begin suckering on Monday.

Monday, April 28th:
We had another severe frost for several nights over last weekend (April 19-21). We were hit hard for the second time on The Donum Estate in blocks 290 and 390, and the fruit is gone. We’ll be training canes for next year there. We estimate our loss at 30 tons of Pinot Noir, about 20% of the yield of the entire estate. In 290, we probably lost 10% of our Chardonnay.

In our Russian River Valley vineyard, the one-two punch did extensive damage where we’ve never had damage previously. A lot of secondary buds had pushed out after the first frost and they were fried. More buds that we thought were pushing are now dried out and not coming.

There have been so many nights with frost alarms this year. Normally we might have four or five cold nights, but this year we’ve probably had 25 over the past two months. People are running out of water. In areas where frost is not common, like our Russian River and Carneros vineyards, often vines have no protection. Where frost occurs more frequently, either wind machines or overhead sprinklers are used. Heavier cold air settles next to the ground, so the wind machines displace it and circulate warmer air from above to prevent freezing. Applying layer after layer of water also protects the tender shoots by constant freezing that, ironically, releases heat to prevent tissue damage.

We have gone from a normal, very promising year to a frost and now a terrible double frost. So far, this second frost is the defining moment of the 2008 vintage. A decade from now, this year may be referred to as the bad frost year. It’s an interesting vintage, and it drives home the fact that you cannot control nature. It’s a weather issue now, but it will affect wine quantity and pricing down the line. We’ll continue to track the impact in future posts.

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