The Wine Knows

These are dangerous times for the Washington wine industry. The next couple of months are when grape growers and winemakers have the most fear of what are euphemistically known as "winter events."

Over the past 50 years, a "winter event" occurs every five to eight years. The last was four years ago, when a sudden freeze wiped out 90 percent of the crop in the Walla Walla Valley.

Prior to that, a Columbia Valley-wide freeze in 1996 took out about half of the state's wine grape crop. And a 1991 freeze also devastated Washington vineyards.

Here's what generally happens: In the dead of winter, temperatures will rise into the 50s, 60s or even 70s for several days. The grapevines start to think it's spring and begin to rehydrate. Suddenly, temperatures plunge 50 degrees. The water in the cells freezes, expanding the wood. This can damage buds or even kill everything above ground. Sometimes, the vines will need to be chainsawed at ground level, then retrained the next season, thus costing the vintner one vintage from those vines.

This is why all grapevines are grown on their own roots in the Columbia Valley. If they were planted on grafted rootstock - like California, Oregon and all of Europe - there would be no viable wine industry in Washington. The rootstock is not a classic European grapevine, but rather a hybrid meant to resist phylloxera, the root louse that wiped out 75 percent of the Europe's vineyards more than a century ago and has damaged Oregon and California vines in the past few decades.

In fact, there is phylloxera in Eastern Washington, but it doesn't move. Fortunately, phylloxera doesn't do well in Eastern Washington's sandy soil and cold winters. If, in fact, a strain of phylloxera was ever able to take hold in the Columbia Valley and wreak havoc, that likely would spell devastating problems for the Washington wine industry.

That's something to worry about for another day. For now, grape growers have their eyes on the skies.