Raisin harvest is evolving

The proportion of California raisin grapes harvested mechanically has reached 30 percent for the first time, according to a government survey.

The 2017 California Raisin Grape Mechanical Harvest Report, issued last week, said 45,548 acres of raisin grapes were mechanically harvested last year, just more than 30 percent of the state's total acreage of raisin-type grapes.

"Most California raisins are produced by sun drying after placing bunches on paper trays on terraces between vine rows," the report said. "The Overhead Trellis System has led to increased production of dried-on-the-vine raisins."

The report said the overhead trellis system accounted for about 9 percent of total raisin acreage last year.

The continuous-tray harvesting system was used on 20 percent of the raisin acreage. Other mechanical systems mentioned included open gable, 0.9 percent, and south-side trellis, 0.4 percent.

One-quarter of Thompson seedless grapes, 70 percent of Fiesta grapes and 63 percent of Selma Pete were harvested mechanically.