Dear friend Will: Last week father went to Fresno, which is about three hundred miles northwest of here, in the San Joaquin valley. He took me with him, and we visited some of the great vineyards and raisin-packing establishments near and in that city.
Raisins are simply dried grapes. Although there are many countries where grapes grow, there are few where raisins are made. Dew, fog, and rain injure the fruit, so that the San Joaquin valley, with its dry, hot atmosphere, is well adapted to this industry.
There are a great many different kinds of grapes but only the green variety is used in making raisins. The raisin grapes are called muscats. If the grapes are left on the vines long enough, they become raisins. I have picked some pretty good raisins from the vines. Of course by being spread out, they dry quicker and more evenly.
The sugar that you find on and in the raisins is not put there by the people who dry the grapes. It comes from the juice of the grape.
Grapevines grow from both roots and cuttings. Of course cuttings are the cheaper. Often they may be had for the asking. Many think that it is better to set out rooted vines than cuttings.
They are planted in rows from six feet apart to twelve or fifteen feet. During the first year the young vines will grow several feet. In the fall, when the flow of the sap has been checked by frost, the vines are pruned. A vineyard in California looks quite different from one in the East. During the winter it is simply so many rows of stumps several inches in thickness and one or two feet high. During the summer the branches grow from these stumps and produce their beautiful clusters of grapes, only to be cut off in the fall or winter.
The trimmings are generally burned in the vineyard at the same time that they are cut off. A sort of furnace made of sheet iron is fastened between two wheels and drawn by horses up and down between the rows. A man pitches the cuttings into it, and they burn as it moves along.
In the early summer men go through the vineyards sprinkling a coating of sulphur on the vines. This is to prevent mildew, which damages the fruit very much.
During the last half of August and September the grapes are picked. Sometimes the harvest continues into October. Most of the grapes had been gathered when we visited the vineyards.
When the juice of the grapes is one fourth sugar, they are ready to pick. The grower generally tells the condition by the taste and color of the fruit, although there are instruments for determining the amount of sugar.