Mechanization Of The Raisin Industry

Vine Lines: Mechanization Of The Raisin Industry

Advertisement

Economic conditions during the last 10 years, combined with decreased availability of farm labor, have moved the raisin industry in California rapidly forward with a transition to mechanization that began about 25 years ago. As recently as ten years ago, about 4% of raisin production was mechanized. In 2010 an estimated 45% of the crop was harvested using mechanized approaches (see “Raisin Production Methods”).

Production Methods

Traditional Method — The production of raisins has traditionally been a labor-intensive operation that begins with hand picking of grapes that are placed on 24- by 36-inch paper “trays” which have been laid on the smoothed soil surface within the vineyard rows. The hand picking of grapes typically occurs during the first two weeks of September and the grapes require 12 to 14 days to dry into raisins. After the grapes are dry and have become raisins, the paper trays are individually rolled, then removed from the field with a tractor and trailer using fruit bins.

Mechanized Methods — Starting in about 1990, growers began experimenting with what is called the “continuous tray” process. The vine fruiting canes are first severed to start a drying process in early September, then seven days later the slightly withered grapes are harvested using a mechanical grape harvester (the same equipment used for picking winegrapes). The grapes are removed from the vines and placed on a “continuous” paper tray. Instead of individual paper trays, the continuous tray is 36 inches wide and more than 1,000 feet long. After eight to 10 days, the grapes have dried into raisins and are mechanically moved from the continuous tray to fruit bins. Yields are equal to the traditional process at a slightly lower cost with much less reliance on labor.

Top Articles
Have a Plan For Climate Change? Why Fruit Growers Need To Act Now

Also starting in about 1990, growers began producing raisins by a “drying-on-the-vine” (DOV) method. With this technique, in early/mid August the vine fruiting canes are severed, and the grapes hang on the vines until they are dried into raisins and harvested with a standard grape harvester directly into a fruit bin. It requires six to eight weeks for these grapes to dry into raisins. Utilizing new raisin grape varieties with more extensive trellis systems, yields are significantly higher at 4 to 5 tons per acre with a lower cost per ton to produce and much less reliance on labor.

Raisin Industry History

In 2000 the global supply of raisins reached a peak resulting in a major decline in U.S. grower returns. Faced with lower prices and competition in the export market from low-cost foreign producers, California growers started moving to mechanization to reduce production costs. During more recent years, the decreased availability of farm labor has directly contributed to the movement to mechanization. In addition, the market demand for raisins has remained fairly flat over the last 10 years and with more producing acreage than needed, growers began a process of removing vineyards.

Reductions In Acreage

During the last 10 years 75,000 to 80,000 acres of raisin-producing vineyards have been removed. Utilizing data from the California Agricultural Statistics Service for raisin type grape vineyards, we can observe a 25% to 30% decline in producing acres with a significant increased proportion of raisins produced using mechanized approaches and a corresponding decline in the traditional method (see “Raisin Type Grapes”).

Labor Supplies

California, like all U.S. agricultural producers, has experienced a decrease in availability of farm labor. The current issues of “Amber Waves” (produced by the USDA Economic Research Service) includes an excellent discussion of how six different labor-intensive agricultural crops in the U.S. have responded to decreased farm labor supplies (available online here).

During the 2010 raisin crop harvest, farm labor was in such short supply that growers using the traditional approach experienced labor shortages, which forced them to delay harvest by a few days to more than a week. This is particularly interesting in that in 2000 we had a sufficient labor supply to traditionally harvest about 270,000 acres, but in 2010 there was insufficient labor to harvest about 115,000 acres in a timely fashion. This would lead one to the conclusion that we have experienced a 55% to 60% decline in available farm labor for raisin grape harvesting in the last 10 years.

0