NORTH BAY – Rainfall near long-term averages has some North Coast winegrape experts expecting a "normal" season in timing for maturation and crop size.

The first grapevine shoots started appearing, called "bud break," amid a stretch of warm days in March between rainfall. That warm break made the early vine growth proceed more quickly than in recent years, though bud break came a few days later than average in some cooler areas, according to Nick Frey, president of the Sonoma County Winegrape Commission.

"We're off to a good start," Mr. Frey said. "The streams are flowing and the rainfall has filled the ponds."

John Piña of Piña Vineyard Management, which farms about 800 acres mostly in central Napa Valley, said some grower reports of ahead-of-schedule vine development aren't visible in the mostly cabernet sauvignon grapes the company manages in more than 50 vineyards.

"We've had more rain than we've been used to in recent times, but it's a pretty normal year," he said.

Yet the vine development so far is exposed to frosty nights expected this time of year.

"We've had a half-dozen nights of frost,” Mr. Piña said. The company has been operating its frost-protection sprayers, and the near-average rainfall has helped some areas with strained groundwater reserves.

Barring major swings in temperature, vine bloom is expected in May and crop set in June. And after results from two quarters of wine sales are in for 2010, wineries will be able to better gauge how much of the average-sized crop they'll need this year, according to Mr. Frey.

The slowdown in higher-end wine sales early last year led to troubles for some growers who found themselves without buyers for their grapes or contracted buyers with cash-flow challenges after harvest.

Despite the near-average rainfall in many parts of the North Coast this year, the State Water Resources Control Board is set to consider at its April 27 meeting in Sacramento a draft North Coast Instream Flow Policy that would put into place a system of monitoring and enforcement of water use during frosty nights and parched years.

"It's a little complex when you're on the ground trying to manage a farming operation and you have to redo a reservoir," Mr. Frey said about the water-rights permitting process being adjusted under the draft policy.

In addition, on the heels of vine mealybug infestations and the light brown apple moth, the European grapevine moth has arrived. As of the end of March, the Napa County Agricultural Commissioner's Office logged 137 finds of moths or larvae. The European grapevine moth is particularly destructive because three successive generations burrow into the grape clusters and open the berries to rot.

"We're definitely in containment management mode on the European grapevine moth and the [vine] mealybug," Mr. Piña said.

The pest was discovered for the first time in North America in Napa Valley late last summer. In March state agriculture officials quarantined 167 square miles.

The first trapping of the European grapevine moth in Sonoma County was in Kenwood in late March.

"Until we find a second one we will be trapping," Mr. Frey said. "It may be a small enough area that it can be dealt with by treating with mating disruptor or insecticides."

Sonoma County Agricultural Commissioner's Office will be hosting an informational meeting on the European moth April 16 from 9:30 to 11:30 a.m. at the Santa Rosa Veterans Memorial Building. Reservations are required with a call to 707-565-2371.