Although the Unified Wine and Grape Symposium coming up in January in Sacramento is larger as a national event, the Wine + Grape Expo sponsored by the Napa Valley Grapegrowers on Nov. 14 at the Expo has become a vital event for local growers — and winemakers.

The theme this year is “Connecting Vineyard Practices to Wine Quality.”

One reason it’s so important is that the Grapegrowers focus on education for its members, and not just on growing grapes, so it designs a seminar program that attracts wide interest,

The Expo will feature discussions by industry leaders on aromas in wine, mastering balance through lower alcohol wines and more.

The Expo also includes sessions in Spanish to help educate vineyard workers, some of whom are more comfortable in their native language while others don’t really speak English.

The Spanish sessions are at 7 and 9:30 a.m. and include “Advances in New Technology” by Ruben Flores of Walsh Vineyards Management and “What Makes a Vintage?” — with tasting — by Michael Sipiora of Quintessa.

Other sessions include two (9-10 a.m., repeated 1:30-2:30 p.m.) on vineyard trials of grape varieties resistant to Pierce’s disease by respected vine specialist Dr. Andy Walker, of UC Davis, at 9:30-10:30 a.m. and 12:30-1:30 p.m.

Walker has crossed PD-resistant native grapevines like vitis arizonica (canyon grape) with vinifera vines, finding that a very small portion of the local vine provides resistance to the scourge spread by sharpshooters.

The session will include tasting, and it will be interesting to find what a vine that’s primarily cabernet, for example, tastes with a little arizonica component.

The vines could be a huge boon for growers not only here but in other parts of the country, like Texas, but wineries have boxed themselves in a bit by heavily promoting wines by variety rather than location, as is common in Europe.

Perhaps the rise of proprietary-named blends will help reduce that obstacle.

Two panels will complete the seminars. One is “Between the Evocative and the Precise: A Discussion of Aroma in Wine” from 10 to 11:30 a.m. with Alyssa Harad, author of “Coming to My Senses,” and winemaker Dawnine Dyer of Dyer Straits Wine Co., best known for her long reign at Domaine Chandon.

The other panel, from 1:30 to 2:30 p.m., will focus on a controversial subject, lower-alcohol wines, specifically those created through vineyard management rather than technology like reverse osmosis or spinning cones (or adding water).

The title is “Mastering Balance and Vineyard Expression Through Lower Alcohol Wines.”

The San Francisco Chronicle has added to this discussion by listing the alcohol content of the wines it recommends, and some retailers and restaurateurs flatly refuse to sell or serve wines with alcohol levels above 14 percent. This is the legal dividing line between table and what were once fortified wines, but a level that is now typical of most Napa Valley wines.

Jon Bonné, wine editor of the Chronicle, is on the panel, as are Duncan Arnot Meyers of Arnot-Roberts, Paul Draper of Ridge Vineyards, Nick Gislason of Screaming Eagle and Steve Matthiasson of Matthiasson and Premiere Viticultural Services.

Maybe Darrell Corti, an avowed opponent to high-alcohol wines, will attend, too.

Space is limited and these sessions always sell out.

While the seminars are interesting, the exhibitions in the trade show are fascinating, too. From testing services to giant harvesters, universities to organic chemicals, a wide range of exhibitors will round out the show.

Get information and register at NapaGrowers.org or 944-8311. Grapegrower members pay $150 and others $250 for the whole day including the seminars, while attendance at the trade show is $20. Lunch is included.

The Spanish seminars are free for two people per member company and $20 for additional attendees.

Email Paul Franson at paul@paulfranson.com.