Starting in late August and continuing through September, the grapes are harvested. At this point in the year they are at their optimum sweetness. Bunches of grapes are handpicked by field workers and placed on paper trays, which are laid out on the ground between the vine rows. To provide a good surface for the trays, the soil between the rows is leveled.
Depending on the weather, the grapes are allowed to dry on the trays for two to four weeks. During this time, the moisture content of the grape is reduced from 75% to under 15% and the color of the fruit changes to a brownish purple. At night, the trays are rolled to minimize the accumulation of sand and protect against raisin moth infestation. The paper trays are embedded with a compound, which kills insects that can damage the grapes as they dry. After the fruit is dried, the paper trays are rolled up around the raisins to form a package. The rolls are gathered and stored in boxes or bins before being transported by truck to a processing plant.