Part 10

While the spring frosts are injurious to the grapes, winter frosts are on the other hand most beneficial, if not necessary to a continued raisin cult. The raisin grape must have a season of recuperation, and winter frost is the only climatic phenomenon which, without injury to the vine, can procure it that rest which is so necessary for all deciduous trees, by nature destined to enjoy alternate periods of growth and sleep. The absence of frost causes the sap of the vine to circulate more or less in the wood, and the vine never ceases to grow. This is one of the reasons why our deciduous vines do not succeed well in the tropics, where there are no cold seasons to cause the leaves to fall and the sap to become dormant. In the tropics, therefore, our deciduous vines keep on growing, set little or no fruit, and prove unprofitable. This phenomenon is shared there with other trees, and peaches, pears and apples act in the same manner. They all appear to need the rest afforded them by the winter frosts. It is also a question of very great importance, whether the continued and unnatural activity of the vine, at a time when it should be dormant, does not invite diseases of various kinds, which find the exhausted vines unfit to withstand their ravages. It may be possible that _mal nero_, the vine plague and other similar and as yet insufficiently understood diseases, are especially destructive to vines growing in frost-free climates, while in colder climates they make but little headway, the vines as it were being protected by the heavy frosts, which either kill the enemies of the vine or enable the latter to gather the necessary strength to battle with them through the growing season. There can be little doubt that at present the healthiest vineyards are those growing in countries where winter frosts are severe, but on the other hand we know that grapevines have been growing for ages in temperate climates, where the frosts, even if not entirely unknown, are still of very rare occurrence.

_Summer Temperature_.--The temperature in summer time must be sufficient to properly ripen the grapes, but must not be so great as to injure them either while they hang on the vines, or while they are exposed to dry on the trays. The average heat required to do the work of maturing is not exactly known, but it is certain that a very high degree is not absolutely needed to produce sweet grapes. As far as our experience goes, it seems that cool weather, with the average temperature of ninety degrees Fahrenheit, would be most beneficial in the fore part of the season, while when the grapes begin to ripen a greater heat is desirable. It is not the warmest countries nor the warmest seasons which produce the earliest grapes. Thus while the season of 1888 was in California unusually cool, with the thermometer seldom reaching one hundred degrees in June and July, the raisin season was nevertheless a very early one, and much earlier than seasons remarkable for their early high temperature. In Malaga and Smyrna, the heat seldom reaches one hundred degrees, and the grapes ripen several weeks earlier than in Fresno, where the summer temperature averages ten degrees higher. In Fresno, on the contrary, the season is earlier than in Southern California, where probably the seabreezes retard the ripening of the grapes. A temperature of over one hundred and five degrees proves injurious to unprotected or exposed grapes in the central region of California, but in San Diego county several degrees less is sufficient to scald the grapes or give them a cooked flavor if they are already exposed on the trays to dry. It is certain that with an average highest temperature of ninety degrees, the grapes develop better and become larger and sweeter than where the heat is excessive and reaches one hundred and ten degrees or more.[6]

[6] Whenever the temperature is referred to it means the degree of heat (Fahrenheit) in the shade, and not in the sun except when so expressly stated.

The time when the greatest temperature occurs is of practical importance. Excessive heat can be tolerated by grapes protected by leaves and branches or otherwise sheltered, but if it happens at a time when the bunches are exposed to dry on the trays, the injury to the berries will be great or even ruinous. Early localities are especially apt to suffer in this way, and it is well to experiment before too much confidence is placed in very early regions. To such places, however, there remains the possibility of curing the raisins in partial shade, as is done in Chile, thus producing raisins of an entirely different type from the Malaga or California product.

_Winds, Injurious or Beneficial._--In the California raisin districts hot, electrical winds are much feared in the months of June and July, or before the grapes have begun to ripen. In the San Joaquin valley these winds come from the northwest and sweep down over the vines, often scorching the leaves and frequently drying the berries on the exposed side. In the course of a few days the berries dry up entirely, and the whole bunch is lost. These drying winds are not peculiar to any certain part of California, but occur from time to time in every raisin district on the coast, in the south as well as in the center, on the coast as well as inland. The remedy is to grow the vines low and to keep the berries well covered. The planting of windbreaks will also modify these winds, and in places where they formerly were common they have now entirely ceased or become so modified that they cause no injury to the grapes, but prove even beneficial on account of the quicker and better maturing of the fruit. In certain districts, especially in San Bernardino and in Orange, some very drying winds are experienced late in the season,--in September and October. For the raisin-growers these winds are a blessing. They quickly dry the exposed grapes, which have been retarded in drying, or perhaps even injured by a previous shower of rain or by continued heavy dews. These winds are undoubtedly desert winds, and similar to the Terral of Malaga, which, sweeping over the inland plains of La Mancha, reach the coast vineyards and quickly mature the grapes. In Malaga there is also a moist southern wind, the Levante, which retards the ripening and the curing of the grapes, and which must be considered as our southwesterly fall winds, which, saturated with moisture, swell the overdried raisins as well as prevent the yet green grapes from drying. They are precursors of the rainy season, and warn the grower to prepare his dryer if he possess one. In Greece and Smyrna such hot or moist winds are also known and feared, and cause at times much damage in one way or another. We might here also mention the cold “northers” which are common in the California raisin districts in springtime, and which sometimes both cause the young shoots to break off from the old wood and make it easy for the mildew to attack the flowers or the young berries of the vines. Against these northwest winds we have two remedies, summer pruning and sulphuring, which, if applied in time, are both quite effective.

_Fogs and Moisture in the Air._--It is certain that the air in the California raisin districts is much drier than that of the Spanish or Mediterranean districts generally. The night air is, in these districts, loaded with moisture, and dew is heavy and frequent, even in the middle of the summer. The air in Malaga and Smyrna feels quite moist, and without this moisture in the air the vines would grow less and require irrigation. In these places the raisin grapes grow on the steep hillsides without irrigation, but in California this could not be done anywhere except in El Cajon or in other parts of the San Diego district, where the air is considerably moister than elsewhere. This increased moisture is partly caused by the increased rainfall in these districts, and partly by their nearness to the sea and fogs. This moisture in the air will, when other conditions are equal, greatly benefit the grapes, causing them to grow larger, and the thickness of the skin is materially diminished. Combined with this moisture in the air, fogs are injurious or indifferent. There is always a great difference between warm fogs and cold fogs, and now I speak principally of fogs from the ocean. Warm fogs are not particularly injurious to the grapes, generally indifferent and sometimes even considerable of a benefit to the proper development of the grapes. In Malaga, San Diego and in Chile the Muscat grapes grow and thrive actually within the reach of the spray of the waves, and fogs are there not uncommon, but they are warm. It would seem that such a climate would cause mildew or oidium, but I cannot find that these fungi are particularly frequent in San Diego county, while in Malaga they are but little more common than in the inland districts of our State. But as we go north the cold fogs become more common, and the vines thrive less under their influence. North of Los Angeles county the Muscat vines do not enjoy the coast air, while even in Orange county the interior vineyards are preferred to those closer to the coast. But anywhere, even in the best situated districts, protection from the direct influence of the sea fogs is appreciated, and the best localities are those in which low hills afford this protection by modifying and increasing the temperature of the fog or sea air.

In Central, and in the larger part of Southern, California, the inland valleys are the most successful raisin-producing districts, while even in San Diego county, where the Muscats seem to thrive at the very seashore, the interior valleys alone afford the necessary heat and dry air for curing the grapes and transforming them into raisins. According to Consul G. H. Heap of Constantinople, the positions preferred for vineyards in Turkey are the slopes of elevated and sheltered undulating lands, or on the sunny hills that do not lie too near the coast, or are naturally protected from the cold winds and fogs of the sea. The Island of Cos or Zea is called the paradise of the Sultana grape, because Nature has given the cultivable land there the best possible protection from the direct influence of the fogs. In Malaga, according to Consul Marston, eighty per cent of the vineyards are situated on the hills and inland, ten per cent on the valley lands or plains, and ten per cent on the coast. With the exception of some of the San Diego vineyards, California cannot show any raisin vineyards as close to the coast as those found in Malaga. The main El Cajon vineyards are from ten to fifteen miles inland, while the former Santa Ana vineyards were situated from eight to twelve miles from the coast. The San Bernardino raisin vineyards are from twenty to thirty miles inland, while in the San Joaquin valley the raisin districts are more than a hundred miles from the coast, while the sea wind, before it reaches any of the vines, has been modified by passing over from two to three hundred miles of dry country.

_Ideal Conditions of Climate._--There remains only to draw some conclusions from the above facts. We are often asked what are the ideal conditions, as far as climate is concerned, for the proper development of the raisin grape, and for the proper curing of the raisins. Could we select such an ideal spot, where all the requirements for the raisin industry could be found in their highest perfection, with as few of the drawbacks as possible, our choice would be as follows: A moderately dry air, a frostless spring, a rainy winter and a rainless autumn. The temperature in the summer should vary between ninety and one hundred degrees, the fall months should now and then be visited by drying winds, while the winter frosts should be heavy and regular, but not below twelve degrees. Some have suggested that absolute freedom from any rain would be very desirable, as then no interference would be experienced with the cultivation of the grapes, but I doubt if the soil in such districts would not be rapidly exhausted through the want of weeds, the plowing under of which enriches the ground and enables it better to preserve the moisture provided for it by irrigation.

SOILS.

_General Remarks._--No one certain variety of soil can be said to be the best for raisin purposes, and both in different countries, as well as in the same district, various varieties of soils are valued equally. Every raisin district has, however, its favorite soil, which is supposed to have some peculiar advantages for the raisin grapes, but upon closer investigation we generally find other varieties of soils which are not inferior. Growers who have succeeded with raisin grapes on one variety of soil are only too apt to consider this kind preferable to any other. This is especially the case in California, where soils vary so much and where in some districts it is difficult to find forty acres with a uniform soil. Whether the soil is black, red or gray, it makes but very little difference, as long as it is rich and susceptible of the highest state of cultivation and has the faculty of retaining moisture. The deeper and richer the soil the better the Muscatel grape will thrive and produce, and as such soils are most generally found along the banks of creeks and rivers, or in their bottoms and sinks, we might conclude that in such localities the best soils for the Muscat grape may be found. Other varieties of raisin grapes, such as the Malaga (California) and the Sultana, do well in less rich soil; indeed, they bear profitably in places where the Muscat would be a failure. It is therefore important for every vineyardist to carefully select his soil and then plant on it the proper variety of vine.

_Malaga._--The soils of Malaga are of various kinds. The best is a reddish loam containing much gravel, both coarse and fine. This soil is very stiff and hard, and when dry is as solid as a brick. The red color is derived from oxide of iron or other iron compounds, which many of the best vineyardists consider a most desirable element in any raisin soil. The upland vineyards, or those on the slope of the hills, contain soils of decomposed clay and slate mixed with more or less gravel and sand. The Dehesa lands contain alluvial deposits of a black or gray color.

_Valencia and Denia._--In this district we find soils of many different grades and colors. The sandy and gravelly soils are considered as producing the finest flavored raisins, and those having the best keeping qualities, while the rich, loamy soils of the valleys produce raisins of inferior flavor and keeping qualities, but of larger size and more per acre. For economical reasons, the latter soils are preferred, as they alone can be irrigated and made to produce large crops. Some of the best vineyards in this district contain a gray, ashy soil, quite similar to the white ash of the Kings river lands, while others are growing on a red clayey loam similar to the California red soil.

_Smyrna._--The raisin-grapes of Smyrna in Asia Minor are almost exclusively grown on a white limestone soil, which consists of decomposed white rocks mixed with a stiff ocher-colored loam. This soil is so rocky that it must first be cleared, and the large rocks are carried away and used for boundary walls. This is the soil in the coast districts. In the interior the Sultana vines, as well as the Muscats, are replaced by fig orchards and other trees which delight in sandy soil,--too sandy to produce profitable raisin crops.

_Zante._--The soils of Zante, the home of the Currant grape, are of various kinds. The heavy marl of the plains, which contains a large percentage of gypsum or sulphate of lime, is considered the best; indeed the gypsum is by many considered indispensable, or at least highly beneficial, to the above variety of grape. Other soils are red clay, gray marl and gravelly loam, all containing an abundance of lime. The Currant grape grows well and produces well on all these different soils, but does the best on the gypsum soil, which is therefore the most valued. On other soils the bunches are less solid, and the quantity of grapes produced is somewhat less, while their quality is inferior.

_Chile._--The Huasco grape grows in the valley of Huasco, on the coast of Chile, in a soil that is very light and red, containing a great quantity of sand. While very light in weight, this soil is said to be very rich in plant food, and yields good crops.

_Fresno._--The Fresno soils are of several kinds, but the three principal varieties are red or chocolate-colored loam, white or gray ashy soil, and a light, very sandy, loam. To this may be added the deeper gray bottom soils or alluvial deposits of the Kings river. Each one of these varieties have different grades more or less suitable to the Muscatel grape. The best grades of each are equally valuable, while again the poorer grades are not to be recommended. The deep chocolate-colored loam is by many preferred, and the largest and most successful raisin vineyards are now located on this soil. But even in the best districts the soil varies to such an extent, that while one twenty-acre field will yield 250 boxes of raisins to the acre, the adjoining field, with only a slight change in the soil, will yield only seventy-five boxes to the acre. The best grades of the white ashy soil are also very good, and almost identical with the gray bottom-land deposits of Kings river. The light sandy soil should be avoided for Muscat grapes, but may do for Malaga and Sultanas, especially if judiciously fertilized.

_Other Soils in San Joaquin Valley._--In Merced the best soil is heavy chocolate-colored loam, in places redder, in others darker, almost blackish. It is generally mixed with some gravel. As a rule, all the red soil in the San Joaquin valley is of the same characteristics, and well suited to the Muscat grape, provided the ground is sufficiently level. In Tulare county the proper soil for the Muscat is found to be the bottom lands of Kings and Kaweah rivers, as well as the deposits of the smaller creeks. This variety of gray alluvial loam is exceedingly fertile, and there is none superior for the Muscat grape. But an admixture of alkali often spoils soils which otherwise would be considered the very best. A similar soil is found in Kern county, especially near Kern Lake, and which must be rated among the best in the State, its color being a deep bluish gray. The vineyards of Yolo and Solano counties are located on a very similar soil, rich in humus, lime and phosphates, but more yellowish or pale chocolate colored.

_Orange County._--A similar rich alluvial deposit is found in Orange county in the fertile district known as Santa Ana valley. The soil around Anaheim, Santa Ana, Orange and Tustin consists of a more or less dark alluvial loam of unsurpassed fertility, and especially adapted to the Muscat grape. It varies as to the percentage of sand and gravel. The sandiest soil in this district, while less rich, brings the earliest grapes, which come to perfect ripeness several weeks before those grown on the heavier soils, but the latter produce the best raisins.

_Redlands and Riverside._--The Redlands soil of the mesa lands is reddish, rather darker than the same quality of soil in Riverside and Fresno. It is mixed with sand and gravel, and partakes strongly of the nature of the red or chocolate-colored loams of the State. The Lugonia bottom soil consists of a very sandy loam, on which the Muscat grape has proved a failure. The best Riverside soil is red or chocolate-colored sandy loam, so often spoken of. Towards Rincon we find alluvial bottom soils producing grapes of superb quality and size. The soil of the San Bernardino district resemble the red Fresno soils, while the white ashy soil is not found there.

_El Cajon._--The El Cajon valley soils are of three or more kinds: Rich red clay mixed with gravel, with the color changing from lighter chocolate to deeper reddish. This is a very desirable soil,--a steel gray or slate gray adobe with much gravel of a coarse nature; a black adobe with some gravel; an alluvial sandy loam consisting of decomposed granite mixed with much vegetable matter and humus. The El Cajon soils, while sandy and gravelly, produce exceedingly sweet and highly flavored grapes but comparatively small crops.

_Subsoils._--The subsoil in a raisin vineyard is of great importance. Properly irrigated soils, if they are sufficiently rich, need not necessarily be very deep, as the raisin grapes, especially the Muscat, seldom extend deeper than eight feet below the surface. Even from four to five feet of rich soil may be considered as enough in irrigated vineyards, where the water is abundant. In poorer soils, or in districts with less irrigation, the roots of the vines penetrate much deeper, and the importance of the subsoil in such cases is apparent. Any rich subsoil will serve our purpose. It is always best to thoroughly investigate the subsoil before the vineyard is planted, and in doing this the following points must be considered: The subsoil should be as rich as possible, and there should, in no instance, be less than four feet of rich top soil. _Very_ sandy soil or pure sand is not a proper subsoil for raisin grapes. Such soil will cause the top soil to dry too quickly after each irrigation, and will cause the top soil to leach out, while it besides gives no nourishment to the vines. Hardpan is not desirable, not even admissible, except in places that are or will become subirrigated. Alkali or salty subsoils will soon spoil the quality of even the best top soil. This especially is the case in irrigated districts, where the salts of the subsoil are carried to the top by the rising waters or by the continued irrigation. Hardpan which readily dissolves when wet is not injurious.

_Hardpan Soils._--While I have alluded to them already, a few more remarks on these soils are here in place. The hardpan consists of a stratum of hard soil or hard rocky substance below the top soil. The depth at which the hardpan is found varies. In places where it is situated eight or ten feet below the top surface it does but very little harm, and may even prove beneficial in localities where water for irrigation is scarce, as it checks too rapid drainage. If the hardpan is situated closer to the top soil, it may seriously interfere with the vines, and if too close, or say within two or three feet from the top, it makes such soils entirely unfit for raisin grapes. If situated somewhat lower down, say from four to six feet, the hardpan does no great harm in subirrigated districts, while, in places where irrigation is not used, it leaves the top soil too shallow and too dry. But allowance must always be made as to the nature of the hardpan. Some varieties of hardpan are so hard that they can best be compared to regular stratified rocks, impenetrable to the roots of the vines, and impervious to water. Other hardpans again are softer, and allow the vine roots to penetrate more or less readily, while some again are so soft that they dissolve in water and make good soil for the vines. If the hardpan is very shallow, it may pay to blast holes through it, in order to allow the roots of the vines to penetrate to lower soils. But if the hardpan is thick and hard, and if there is no immediate prospect of subirrigation, it is better to use such land for some other purpose than for raisin-vines, which will only pay properly if grown under the most favorable circumstances, and on the best and deepest soils.