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Dan Berger

Harvest time is when grapegrowers occasionally learn more about their vineyards than they wish to know.

When harvest begins, everyone connected to the growing and making of wine is alert to the hard work, long hours, and many demands and pressures everyone faces.

A typical scenario includes growers getting little rest, being in the vineyard at times when most people still have hours to sleep, then perhaps going to a coffee shop to meet other growers at 5 a.m. to talk of problems they face.

In 1988, the late grapegrower Tim Murphy told me that as soon as harvest began, after a tour of his vineyards, he would be at his morning stomping ground, the defunct Tip Top Café in Healdsburg, to swap stories with other growers.

He said any vineyard maladies seen by anyone would be a topic of conversation.

This year, the topic among some growers is a curious problem some people are calling SAD.

Sugar Accumulation Deficit is a strange vineyard phenomenon that’s happening haphazardly in some grape varieties in the north coast and which is worrisome because it isn’t always visibly evident.

The malady is hard to describe other than to say that unexpectedly some clusters lose most of their sugar and the grapes become mush.

Ted Bennett of Navarro Vineyards in Mendocino County said he experienced SAD last year in some muscat vines, and this year it was seen in his sauvignon blanc vineyards.

Affected clusters “smell awful,” said Glenn McGourty, UC Farm adviser for Mendocino and Lake counties. He said if such a cluster should end up in the fermentation tank it could ruin the entire batch.

Something mystical is going on, he said, because occasionally other clusters actually gain sugar a lot more rapidly than anticipated.

Rhonda Smith, UC Extension Farm Adviser for Sonoma County as well as researchers at UC Davis have done work in this area without much of a solution, said McGourty.

Growers I have spoken with who are aware of the problem usually have no answer as to why it is occurring. One of them theorized that it could have something to do with large crop loads.

But in several cases, I mentioned SAD to Sonoma County growers who had not even heard of the problem.

“Rhonda said grapes taste like poison,” said McGourty.

He added that the problem may be related to vineyards that are high in magnesium and where potassium uptake to the vine is affected.

He said additions to the soil such as gypsum and lime have been used and are continuing to be looked at as possible solutions, but for now it is nothing more than a mystery that has growers edgy.

As hardy as grapevines are (most can grow and produce fruit without irrigation for decades), they are notoriously susceptible to all sorts of problems, some with no solutions other than tearing out the vine and starting over.

Among the issues growers face are “dead arm,” red blotch, black goo, various forms of mildew and rot — not to mention insect, vermin, and wildlife damage.

So just add SAD to the headaches growers face at this time of the year.

Wine of the Week: 2015 Jana Riesling, Mendocino County ($22): This fascinating wine has an aroma of fresh anise and a trace of mint to go with its spot-on riesling character. It has a faintly sweet entry, and dry finish and goes well with spicy foods. Wine maker Scott Harvey, born in Germany and educated in wine making there, got fruit from an old vineyard just north of Hopland and made a wine he says is in the dry Kabinett style. Terrific now, and it will get better with a few years of cellar aging. Best to buy it direct from

Dan Berger lives in Sonoma County, where he publishes “Vintage Experiences,” a weekly wine newsletter. Write to him at

Dan Berger lives in Sonoma County, where he publishes "Vintage Experiences," a weekly wine newsletter. Write to him at