The Raisin Industry / A practical treatise on the raisin grapes, their history, culture and curing

by Gustavus A. Eisen

—To this date but few grape-growers manure their soil. California has not yet been engaged in the raisin business twenty years, and her vineyards are comparatively virgin. The first raisin vineyards were planted on the deepest and richest soil, the soil which would naturally hold out the longest, but the croppings of a raisin vineyard are enormous, and when from eight to ten tons of green grapes have been taken from the soil year after year, it is but natural that the land should become gradually exhausted. In Spain it is considered that even the richest soils require manuring after ten years of constant cropping with Muscats, and the same experience is likely to become ours in California. So far, I know of not one vineyard which has yielded Muscat grapes for ten continuous years and still keeps yielding as much as formerly. Yearly the crop must become less, and finally will not be large enough to pay. The manuring of the Muscatel vines is fully understood in Spain, where all kinds of manures are used. When home manures fail in supply, the Spaniards use imported fertilizers, such as Mexican phosphates, etc. This fertilizer brings in Spain sixty-five dollars per ton, and is brought there from our very doors,—the Gulf of Lower California. It could be laid down here for, and is actually sold here now at, forty dollars per ton, or twenty-five dollars less than in Spain; still to my knowledge only very few raisin-growers in Fresno use it for their vines. In one year one of these succeeded, with the aid of this phosphate, in raising the crop of an acre of Sultana grapes from a very poor yield to over eight tons. The grapes were grown on a piece of sandy soil of the kind well known to Fresno vine-growers, and which is generally considered as less suited to raisins, lacking in fact in more than one of the necessary qualities of a good raisin soil.

It is certainly a wrong policy to crop the soil until the grape crops begin to fail. The soil will then be so exhausted of several of its ingredients, that it will take the most scientific treatment to bring it back again to what it was formerly, and it is even questionable if this could be done in a way that would prove profitable. Experience in Spain teaches that vineyards which formerly used to yield from eight to ten tons of green grapes to the acre now, after years of neglect, only yield two tons to the acre, and even with expensive manuring can in no way be brought back to their former fertility. On the other hand, we know that vineyards which have been fertilized from the beginning have for fifty years been kept up in apparently as good condition as at first; it is accordingly this method that must be recommended. The manure or fertilizer must be varied occasionally. In rotation, phosphates, bone dust, guano, stable manure, sheep manure, lime and plaster of Paris or gypsum may be used, but it is best to have every variety of soil in the vineyard analyzed, and to apply from year to year that kind of fertilizer which is particularly needed. The phosphates are those which will first give out in our California soils. Phosphates must therefore be considered as the best fertilizers we can use, but the quantity to be used must always be determined by a practical chemist. Of these chemical fertilizers, it is dangerous to use too much, as they might injure the vines, and from fifty to a few hundred pounds to the acre may in some instances suffice and produce better crops than would four or five times as much. But, regardless of chemical fertilizers, the cautious raisin-grower should endeavor to return to the soil as much as he possibly can out of the wastes of his crop. The refuse of stems and berries, which are wasted at the stemmer and in the packing-house, should not be burned, as is generally the case, but returned to the vineyard, and applied one year on one piece of ground, and another year on some other piece. If, however, these wastes must be used as fuel in the dryer, etc., the ashes should be carefully collected and spread over the soil, and kept dry and shaded until thus used.

Another most valuable fertilizer generally wasted is the trimmings. In our careless California farming, these trimmings of the vines are put in piles on the roads, outside of the vineyards, and there burned. Thus the ground loses the most powerful soluble salt, which would greatly increase the yield of grapes and the profits to the farmer. Where the vines are planted far enough apart, the trimmings may be burned between the rows of the vines without injury to them, but, when the vines are set close, there is no other way than to carefully collect the ashes and spread them evenly over the soil. Some vineyardists use large troughs made of galvanized iron and perforated with holes. These vats are drawn through the vineyard by a team, and scatter the ashes evenly over the soil. The vats may be so constructed that the cuttings are burned in them directly as they are being pulled along, thus saving much labor as well as ashes. Such contrivances will probably only prove profitable in large vineyards, where there are long rows and few turnings for the teams. Even the stable manure in our State is not used as it should be. It is hardly possible to understand how vineyardists can be thoughtless enough to haul loads upon loads of stable manure on their roads or in holes and waste places, while their vines adjoining are suffering from the want of sufficient nourishment. In the irrigated districts, this is a very common sight, and the wet places on the road are often deep with manure and strongly smelling of ammonia. If the manure had been placed around the vines, the increase in crops would probably have been sufficient to enable the owner to macadamize or otherwise permanently fix the roads.

IRRIGATION.

Introductory Notes.

—The irrigation of the raisin grapes was, for several years, considered as a practice entirely peculiar to California, but as our knowledge extended it was found that, far from being anything at all new, it had been practiced successfully for centuries in some of the Mediterranean countries. We have already mentioned how irrigation is customary both in the Valencia and Denia districts, as well as in Greece. It is evident that irrigation there is only limited by the supply of water, and that there is no question about its usefulness. As regards the methods of irrigation in these foreign countries, we beg to refer to the [chapters] treating of these countries. Here our efforts shall be to consider irrigation in its relation to the following points, which are of more general interest to the Californian growers: Necessity of irrigating the raisin-vines; the health of irrigated vines; the bearing quality of irrigated vines; the quality of the irrigated grape; supposed unhealthiness of irrigated vineyards; irrigation by flooding; irrigation by furrowing; subirrigation; seepage; drainage; irrigation and its influence on the soil.

The Necessity of Irrigating the Raisin-vines.

—When the irrigation of raisin grapes was first attempted in Fresno and Riverside, hardly any one was acquainted with or knew that irrigation had ever been used for such a purpose before, and irrigation was considered as a venture which did not promise well for the future. Later on it was found that the raisin grape really would grow and do well in some localities without irrigation, and the latter practice was accordingly condemned. To-day, however, the practical knowledge of irrigation is greater and more generally distributed, and it is now fully understood that irrigation is not only not injurious, but beneficial and necessary in localities where the raisin-vine will not grow or bear sufficiently without it. The questions then arose, When is irrigation necessary, and how much irrigation is required? The first object in raisin-growing is the profit; a secondary object is how to so treat the vines that they will last as long as possible. To attain the first object, we must raise plenty of grapes, and when a larger quantity of good raisin grapes can be grown with irrigation than without it, irrigation is justifiable and necessary. In Spain, especially in the Denia district, irrigation of the raisin grapes is practiced wherever water can be had, and the same is the case in Greece and Italy.

In California the tendency is now to irrigate wherever water can be had, and wherever it is profitable to procure it. In Fresno, Tulare and Kern counties, raisin grapes could not be grown without irrigation. These same conditions are also found in San Bernardino county, while in Los Angeles and Orange counties all the best vineyards are irrigated, and only occasionally do we find the conditions such that irrigation is not absolutely necessary. In Northern California, raisin-vines may be grown without irrigation, but the latter is considered of such advantage that expensive pumping works have been erected in places where no other means were had for irrigating the vines. In San Diego county, especially in El Cajon and Sweetwater valleys, irrigation is not absolutely necessary, in fact it is not practiced there at all, although water could be had, but as a consequence the crops there are not as large. In Smyrna, in Asia Minor, the largest raisin center in the world, the raisin-vines receive no irrigation, but the unusually heavy rainfall of this section makes the want of irrigation less felt. Of course, outside of the raisin districts proper, Muscatels or other raisin-vines may be grown, and are grown to good advantage without irrigation, but the climate in those places is generally unsuited to the drying of the grapes.

Should we inquire into the reasons why raisin grapes may in some localities be grown and actually prove profitable without irrigation; we find the same to depend not alone upon the rainfall of the locality, but principally upon such other circumstances as dew, fog, the nature of the subsoil, and the moisture of the air. In Smyrna the rainfall of the wet season is from twenty-four to thirty-six inches annually, and greater than in any other raisin district. In El Cajon the rainfall is only half that much, and the moisture in this case must be sought partly in the subsoil, which is especially retentive of moisture, as well as in the dew, and the warm fogs from the ocean. The subsoil has the greatest possible influence, as in other valleys near by, where the fog and the dew are the same, but, where the subsoil is different, no raisin grapes can be grown without irrigation. Malaga is in this respect very similar to El Cajon and Sweetwater valleys, but it enjoys more rainfall than the latter places, while probably the dew and fog is about the same. Still in Malaga irrigation is used in a few isolated localities where it can be obtained, the nature of that country being such, that no general irrigation system is possible, and this is probably, more than anything else, the reason why the vines are not more generally irrigated there. In Chile, in the valley of the Huasco, the Muscat vines are grown both with and without irrigation, the conditions there appearing to be very similar to those of El Cajon valley in San Diego county. From the above we might draw a general conclusion, that wherever the raisin-vines cannot grow without irrigation, and wherever water can be had in sufficient quantities, irrigation is practiced in order to increase the crops and to make the business more profitable.