(CAPRadio) - When you hear 'vineyard' you may imagine a leafy canopy with green tendrils along a vine.

But if you're talking about the vast acres of wine grapes planted in the Central Valley, then machines are also a central aspect of the winescape.

On a visit to Lodi this week, winemaker Steve Millier is checking on Chardonnay grapes that will one day be bottled for Ironstone Vineyards, a winery in Murphys in the Sierra Foothills. 

As Millier walks between leafy rows hung with grapes nearly ready for harvest, he points out the width and height of the rows. They're taller and wider because this vineyard is laid out for mechanical harvest, as are most vineyards in the Central Valley.

"There's a very short window of time that they can be harvested and taken into the wineries," says Millier. "And so the one way to speed that process up is to machine harvest. There's just not enough crews to hand harvest every single grape we grow."

Millier is also a vintner in his own right in the Sierra Foothills and he sees the impact of farmworker shortages up close. 

The vineyards' geographic location adds another wrinkle to the ongoing problem of being able to find labor. Being farther away from the pool of agricultural workers clustered in the Central Valley makes it even harder to attract them.