Winegrowers Respond to Quirky Spring

 Nick Leras of Leras Vineyards says the Russian River Valley already has seen frost, rain, heat and humidity this spring.Healdsburg, Calif. -- At a time when global climate change is starting to make atypical weather seem typical, winegrape growers in the Russian River Valley of Sonoma County have faced some of the most extreme conditions of all: "So far this year, we've had every obstacle: frost, a heat spell, a rainy spell and now humid conditions," says grower Nick Leras.

Such troubles come on the heels of the 2008 growing season, when frost hit areas that normally are immune to such weather, leading to decreased growth for some vines. "I see frost as a two-year hit," says Leras. "It gets you this year when it hits, then next year, there's stunted growth."

Still, some growers are optimistic. "It looks like average or slightly higher yields, which should be good for growers in this economy," notes Lee Martinelli Jr., president of Martinelli Farms and this year's president of the Russian River Valley Winegrowers. He warns, however, that bloom is just starting. "I saw the first bloom in Pinot Noir Sunday," so it's a little early to predict with much certainty.

Frost has worried growers the past two years, but the biggest concern has probably been unseasonably heavy rains. The ground had been drying, inspiring many growers to consider irrigation, but 3.5 inches of rain fell during the first weekend in May, dispelling that idea. Before the rain fell, however, many growers disked their vineyards, anticipating a water deficit. (Cultivation preserves moisture for later in the season, and helps assimilate organic matter into the soil.)

It's better to see the rain now than in three weeks to a month, when all varieties will be blooming in the Russian River Valley. However, the rain has combined with warm weather and led to high humidity and concerns about fungus and mildew. These conditions create a possible incubator for phomopsis mildew spores, which attack green tissues present in the vines. The leaf, the shoot, the flower cluster and tip of shoot are all at risk.

Growers like Leras note that the heavy rain has washed all preventive sprays off the vines, so he dusted with sulfur. "I normally don't dust at all, but we had to get out there this time," Leras says. He dusted his vines with sulfur first because it's lighter than liquid fungicides, a consideration since the rain has also made the ground very soggy. The lighter materials made the tractors less likely to bog down. He then sprayed with Rally as soon as possible.

The growers are hoping for warm, dry conditions and light winds that would dry the leaves quickly. "Now it looks like nice weather until bloom," says Martinelli. "It should provide a good set and uniform berries."

The heavy rainfall and warm weather also initiated fast growth during bloom and excessive growth can cause shatter, the loss of berries. "The vines are taking up all this water and growing rapidly," says Mark Sanchietti of Sanchietti Farming. The rapid growth because of this heat spell can result in fast-growing shoots that tend to be weak.

One remedy to prevent rapid shoot growth and shatter is to leave more shoots than normal while suckering to compensate for what may be lost from this year's conditions, as well as last year's frost. After last year's extreme frost, Sanchietti says he is going to wait for thinning until after bloom, when he knows he's out of danger. "We're not shoot thinning as early as usual. We want to leave a few more shoots for insurance and can remove them later," he says.

In the same pass while suckering, they are also moving wires to control the shoots that they are leaving. The wires hold the shoots in place to protect them from breaking and to maintain their vertical position.

Another possible solution to excessive growth due to the rain and warmth is to pinch the slightest bit off of the very end tip of a shoot. This method slows down the growth of the entire shoot and redirects the fast growth. One has to be careful to only take a minuscule tip so as not to produce laterals.

There is still potential for frost, however. Nick Leras uses both wind and water for frost protection, and he didn't have damage last year in his vineyards. "It's a calculated risk to protect," he says, noting the shortage of water and cost of pumping or running wind machines. He says you need to start with wind machines at 35 degrees to move the inversion layer before it's too late. "Water is more effective, and you can start it at 33 degrees."