Seated at a small table, listening to her grandson’s high school classmates on stage, Nan Tucker McEvoy looks more like a proud matriarch than a groundbreaking agricultural entrepreneur.

It’s McEvoy’s olives, not the jazz, that drew nearly 600 friends and visitors to her annual harvest party last weekend at McEvoy Ranch of 550 acres of rolling hills covered with neat rows of mint-colored olive trees.

The annual bash featuring music, wine and a sit-down dinner of organic, locally produced delicacies is McEvoy’s way of showing the neighbors what’s going on at the ranch. She enjoys sharing “the beauty of the place and the pleasure we can bring with the olive oil,” said McEvoy, a plainspoken and down-to-earth 87-year-old.

McEvoy’s roots are far from humble. Her grandfather, Michel H. deYoung, founded the San Francisco Chronicle. McEvoy herself served as chairman of the newspaper’s board until she was ousted in 1995 over a disagreement about whether to sell the Chronicle to Hearst Corp.

She also was an early member of the Peace Corps, serving as special assistant to Sargent Shriver, brother-in-law of former President John F. Kennedy. She married Dennis McEvoy, a senior editor at Reader’s Digest, in 1948 and the couple had a son before divorcing.

In 1991, she bought the former cattle ranch sight unseen to give her three grandchildren “a place where they can run free,” she explained.

The property just west of Petaluma is an Eden of duck ponds and flower gardens.

The land was zoned for agricultural use, but McEvoy didn’t want livestock or fruit orchards. She settled on olives.

On trips to Italy, she’d fallen in love with the olives and thought the trees were pretty. When county agriculture officials told McEvoy they didn’t grow well here, it only strengthened her resolve to make it work. They’ve since apologized.

“I didn’t know anything about olives or making olive oil,” a laughing McEvoy said in an interview in her kitchen a few days before the harvest party.

Her son, Nion, who runs Chronicle Books, encouraged her to read “Feast of the Olive,” by Maggie Klein, which featured an Italian olive oil expert named Maurizio Castelli.

McEvoy flew to Radda, a small village in Chianti, to meet Castelli personally. She brought along soil samples, weather data and asked him whether she could grow olives in northern Marin County.

“I said, ‘In my opinion, yes, you can plant olives,’” said Castelli, who attended the harvest party.

Castelli selected the first 1,000 trees — five Tuscan varieties — and traveled to California to plant them for McEvoy.

“Mercifully, he turned out to be correct,” McEvoy said. “That was the beginning of it.”

The 18,000 trees now growing at the ranch were propagated from those first 1,000.

McEvoy’s frantoio, or olive mill, is the only one of its kind in the U.S. Partygoers get to see the massive stones in action, crushing the green and black olives, pits and all. In the mill, the sharp, fresh scent is pleasantly overwhelming.

Outside, giant, plastic bins hold thousands of olives with stems and leaves still attached. The fruit is picked by hand and with motorized rakes that gently shake the olives from the trees onto black tarps.

Last year, 150 tons of olives were pressed, yielding 4,500 gallons of oil. In 2006, halfway through harvest, ranch officials estimated the crop at 120 tons, likely producing about 4,200 gallons of oil.

McEvoy ranch is now the largest private-estate bottler of olive oil in the U.S.

Castelli still visits several times a year to monitor production and attend the harvest party.

“Harvest is nice because it’s the finishing of the job,” he said.

On the Net: http://www.mcevoyranch.com