"Fifteen pounds of 'Greenbank's 98-per cent lye' are boiled in 100 gallons of water. This mixture is for grapes containing 25 per cent of sugar. Should their sugar content be less, enough lye is added to remove the bloom and open the pores of the skin of the grapes. After dipping, the grapes are spread on trays and sulphured for 1 to 11/2 hours. Observation will show whether it may be necessary to vary this formula a trifle to suit conditions of ripeness and influence of temperature. The length of time required for dipping is ascertained by experience, and differs with the strength of the lye, the heat of the solution, and the thickness of the skins of the grapes."
"The raisins as received at the packing house are weighed and the loose raisins and those that are to be shipped as dried grapes are immediately run through a stemmer and grader which stems, cleans, and assorts the raisins into three or four different grades, after which they are packed and shipped to various parts of the country, some also being exported. Those producing cluster or layer raisins (if they have not already been equalized) are first stored in the equalizing rooms. In these rooms the sweat boxes, filled with layers of new raisins, are stacked and left usually from 10 to 30 days, or long enough for the overdried berries to absorb moisture from the under-dried ones. This sweating also properly softens and toughens the stems, which prevents their breaking and enables them to hold the berries better. In California, where the climate is so dry, no first class pack could be made without thus first equalizing the raisins. After having been equalized the raisins are taken out, assorted into the different grades, and placed in trays holding 5 pounds each. The trays of the same grades are then pressed and stacked away in piles ready for packing.
"Pressing the raisins so that they look well and so none are burst open is work requiring experience and good judgment. It takes four pressed trays to fill a 20-pound box. The loose raisins that have dropped from the cluster through handling before they were equalized are also graded, the largest, of course, making the choicest pack."
"Previous to the consolidated organization of the packers the three best grades of raisins on the stems were known as 'Imperial,' 'Dehesia,' and 'Fancy Clusters,' respectively. The California Raisin Growers Association established classification and grades similar to those of the Spanish raisin packers, on which the French trade names are also based. The original Spanish, as well as English terms with which they correspond, and the different grades in descending order of quality are shown in the following table:
| Spanish Terms | French Terms | English Terms | California Terms |
|---|---|---|---|
| Imperial | Imperiaux Extra | Extra Imperial Cluster | Six-Crown Cluster |
| Imperial Bajo | Imperiaux | Imperial Cluster | Five-Crown Cluster |
| Royan Bajo | Royaux | Royal Cluster | Four-Crown Cluster |
| Cuarta (4a) | Surchoix Extra | Choicest | Three-Crown Cluster |
| Quinta (5a) | Choix Extra | Choice Cluster | Two-Crown Cluster |
"The grading is optical, as a result of experience, there being no linear or cubic measurement standard. Thus, a nice cluster with all berries of large size, would be a 'Six-Crown Cluster,' such being the very finest raisins on the stem. 'Five-Crown Clusters' were formerly the 'Dehesia' cluster, and 'Four-Crown Clusters' were formerly 'Fancy Clusters.' Grades less than 'Four-Crown' on the stems (the 'Three-Crown' and 'Two-Crown') are known as 'Layers,' or 'London Layers.' These are placed in boxes containing 20 pounds net; in half boxes of 10 pounds; and quarter boxes of 5 pounds; and in fancy boxes containing 21/2 pounds. Loose raisins, or raisins off the stem, are graded into Two-Crown, Three-Crown, and Four-Crown raisins by being run through screens the meshes of which are thirteen thirty-seconds, seventeen thirty-seconds, and twenty-two thirty-seconds of an inch in size, respectively. The Sultanina (erroneously called Thompson Seedless), and the Sultana are packed in 12-ounce cartons, 45 to the case."
"The invention of a raisin-seeding machine by George E. Pettit in the early seventies, and its use, has had a wonderful effect on the industry.
"Seeded raisins were first put on the market by the late Col. William Forsythe, of Fresno, Cal., who at first found it very difficult to dispose of 20 tons. The output in the last 15 years has increased from 700 tons to 50,000 tons per annum, and their popularity is constantly increasing. In 1900 about 14,000 tons were placed on the market, in 1905 about 21,000 tons, in 1910 about 31,000 tons, and in 1913 about 49,000 tons. The seeding machines in present use can turn out 300 tons per day. Seeded raisins are now the most important branch of the raisin industry.
"A brief outline of how seeded raisins are prepared will prove interesting. The raisins are first exposed to a dry temperature of 140° F. for three to five hours, after which they are put through a chilling process so that the pedicels can be easily removed, and are then thoroughly cleansed by being passed through cleaning machines. They are then taken by automatic carriers to another room, spread out on trays, and exposed to a moist temperature of 130° F. to bring them back to their normal condition. The raisins pass to the seeding machine, where they are carried between rubber-faced rollers and the impaling device of the seeding machine which catches the seeds and removes them from the fruits as they are flattened between the surfaces of the rollers. The impaled seeds are removed from the roller by a whisking device in such a way as to be caught in a separate receptacle. The seeded raisins pass through chutes to the packing tables on the floor below.
"The seeded or loose raisins are packed in 50-pound boxes; in 1-pound cartons, 36 to the case; in 12-ounce cartons, 45 to the case; and some in bulk in 25-pound boxes.
"Information has recently been sent out to the effect that the California Associated Raisin Co. is arranging to do away with the grades in seeded raisins, so there will only be one grade. This contemplates using all of the Three-Crown, the smallest of the Four-Crown, and the best of the Two-Crown in one blended grade.
"From the seeds, formerly used as a fuel, a number of by-products are now made.
"The seeds and pedicels removed from the raisins in seeding vary from 10 to 12 per cent of the original weight of the raisins according to their conditions and quality.
"The grading, seeding, facing, and packing have become separate branches of the industry, and the work is nearly all done by especially trained women, who have become experts at it. The establishments in which this work is done furnish employment for over 5000 persons. The aggregate pay roll each month during the season is between $200,000 and $350,000."
A very good vinegar can be made from grapes, although as yet this outlet for over-production is not largely utilized in America. Grapes which are unsuitable for raisins, dessert, wine-making or grape-juice can be used for vinegar-making. Under the most favorable conditions, grape-vinegar cannot compete in cheapness with vinegar made from numerous other products and must, therefore, always sell at a high price. Indeed, it is doubtful whether a high-grade grape-vinegar can be manufactured at a less price than good wine. The production of grape-vinegar requires as much care, but possibly not as much expert knowledge, as the making of wine. Unlike the latter, however, the vinegar can be produced on a small scale for domestic purposes by any one possessing a knowledge of wine-making or vinegar-making.
Grape-vinegar may be manufactured from either white or red grapes, although that from white grapes is generally preferred. It may be made either directly from grapes or from wine, the acetifying process being the same for both. There are, therefore, two distinct stages in the manufacture of this product. First, there must be alcoholic fermentation by which the sugar in the grape is changed into alcohol with the escape of carbonic acid gas. Second, acetic fermentation must follow the alcoholic fermentation by which the alcohol is changed into acetic acid.
There are several valuable by-products in the wine-making and grape-juice industries, and even raisin-making yields a by-product in the seeds taken from the raisins. The utilization of these wastes has been rendered profitable in Europe, and there is no reason why by-products should not yield considerable profit in America, as a few already do. Good authorities state that if all the wastes of the grape crop could be utilized the value of the crop would be increased over 10 per cent.
The pomace or marc, the residue left after grape pressing, is the most valuable of the by-products of the wine and grape-juice manufacturers. If the pomace is permitted to ferment, and afterwards is distilled, a product called pomace-brandy is made. Unscrupulous wine-makers often add water and sugar to pomace, after which it is refermented and the resulting product is sold as wine. Notwithstanding the fact that the word "wine" as applied to this product is a misnomer, the total amount of such wine made and consumed in America is large. Piquette is another product in which the pomace is put into fermenting vats, sprinkled with water and the liquid after a time is drawn off, carrying with it the wine contained in the pomace. This liquid is re-used in other pomace, until it is high enough in alcoholic strength, when it is distilled into "piquette" or "wash."
In Europe, the pomace from stemmed grapes is said to make a sheep and cattle food of more or less value when salted slightly and stored in silos. The pomace is also oftentimes used as a manure, for which it has considerable to recommend it, being rich in potash and nitrogen. Acetic acid is made from pomace by drying it in vapor-tight rooms, during which process 50 to 60 per cent of the weight of the pomace becomes vapor, and this, condensed, yields considerable quantities of acetic acid.
The lees of wine, the sediment which settles in the casks in which new wine or grape-juice is stored, form a grayish or reddish crust on the inside of the receptacle. This is the argol or wine-stone of the wine-maker, and from it is made cream-of-tartar, an article considerably used in medicine, the arts and for culinary purposes. From 20 to 70 per cent of the lees consist of either cream-of-tartar, or of calcium tartrate, the latter also having commercial value. Red wines are much richer in argol than white wines. A ton of grapes yields from one to two pounds of argol. This product becomes a source of considerable profit in large wineries and in grape-juice manufacturing plants.
In Europe, the seeds are separated from the pomace and used in various ways. They are also utilized to a smaller extent in America, especially when separated from raisins. The seeds are used as food for horses, cattle and poultry, for which they are said to have considerable value. If crushed and ground, the seeds yield a clear yellow oil which burns without smoke or smell and which may also be employed as a substitute for olive oil. A ton of grapes yields from forty to one hundred pounds of seeds from which may be made from three to sixteen pounds of oil. This oil is also used as a substitute for linseed oil and in soap-making. Besides oil, the seeds yield tannin. After the oil and tannin have been taken from the seeds, there remains a meal which may still be utilized as a stock food or as a fertilizer.
At present, when food conservation is being emphasized everywhere, mention of the domestic use for grapes is particularly appropriate. The country over, no fruit is more generally grown than the grape; yet grape products are not as common for home use as those of several other fruits, although many attractive and appetizing preserves can be made from grapes without the use of large quantities of sugar, spices or other ingredients. Few housekeepers realize the high quality and the cheapness of the products that can be made from the grape. Thus, grape-juice, jelly, jam, marmalade, grape-butter, catsup, spiced grapes, canned grapes, conserves in which grapes are used, preserves and mince-meat are among the desirable culinary products easily and cheaply prepared from home-grown grapes or those bought in the market. Only simple domestic utensils are needed in the preparation of any of these products.
Grape-sirup is less easily produced, yet can be made in any home without the addition of sugar. It is not only a good table sirup, but is a most useful sugar substitute for the preparation of other culinary products. The Muscadine grapes in the South, to be purchased by almost every householder in southeastern United States, in particular, are useful for these domestic products. Recipes for all of these products can be found in cook books, and one or two bulletins and circulars from the United States Department of Agriculture give recipes for preparing grapes for domestic purposes. Farmers' Bulletin 859 entitled Home Uses for Muscadine Grapes is a particularly valuable publication on this subject.
It is interesting to note that several large manufacturers of grape-juice are putting on the market grape jams, jellies and marmalades. It would seem that these delicious and wholesome products would find a ready sale in the markets of the country, and that their manufacture would prove profitable to the maker and to the grape-grower. The greater the use of grapes for their products, the better the grower can breast the blows of unfavorable markets and over-production.
GRAPE-BREEDING
Chance, pure and simple, has been the greatest factor in the production of varieties of American grapes. From the millions of wild plants, an occasional grape of pre-eminent merit has caught the eye of the cultivator and has been brought into the vineyard to be the progenitor of a new variety. Or in the vineyards, more often in near-by waste lands, from the prodigious number of seedlings that spring up, pure or cross-bred, a plant of merit becomes the foundation of a new variety. An interesting fact in the domestication of the four chief species of American grapes is that none came under cultivation until forms of them, striking in value, had been found. Catawba, representing the Labrusca grapes; the Scuppernong, the Rotundifolias; Norton, from Vitis æstivalis; Delaware and Herbemont from the Bourquiniana grapes; and Clinton from Vitis vulpina, are, after a century, scarcely excelled, although in each species there are now many new varieties.
That our best grapes have come from chance is not because of a lack of human effort to produce superior varieties. Of all fruits, the grape has received most attention in America from the generation of plant-breeders just passing. Grape-breeders have produced 2000 or more varieties, a medley of the heterogeneous characters of a dozen species. That so many of this vast number are worthless is due more to a lack of knowledge of plant-breeding than to a lack of effort, for the order and system in plant-breeding that now prevail, disclosed by recent brilliant discoveries, were unknown to grape-breeders of the last century.
As early as 1822, Nuttall, a noted botanist, then at Harvard, recommended "hybrids betwixt the European vine and those of the United States which would better answer the variable climates of North America." In 1830, William Robert Prince, Fig. 48, fourth proprietor of the then famous Linnean Botanic Nursery at Flushing, Long Island, grew 10,000 seedling grapes "from admixture under every variety of circumstance." This was probably the first attempt on a large scale to improve the native grapes by hybridizing, although little seems to have come of it. Later, a Dr. Valk, also of Flushing, grew hybrids from which he obtained Ada, the first named hybrid, the introduction of which started hybridizers to work in all parts of the country where grapes were grown.
Soon after Valk's hybrid was sent out, E. S. Rogers, Fig. 49, Salem, Massachusetts, and J. H. Ricketts, Newburgh, New York, began to give viticulturists hybrids of the European Vinifera and the American species which were so promising that enthusiasm and speculation in grape-growing ran riot. Never before nor since has grape-growing received the attention in America as given during the introduction of Rogers' hybrids. It was the expectation of all that we were to grow in America, in these hybrids, grapes but little inferior, if at all, to those of Europe.
A statement of the difference between European and American grapes shows why American viticulturists have been so eager to grow either pure-breds from the foreign grape or hybrids with it.
European grapes have a higher sugar-and-solid content than the American species; they, therefore, make better wines and keep much longer after harvesting and can be made into raisins. Also, they have a greater variety of flavors, which are more delicate, yet richer, with a pleasanter aroma, seldom so acid, and are always lacking the disagreeable, rancid odor and taste, the "foxiness," of many American varieties. There is, however, an unpleasant astringency in some of the foreign grapes, and many varieties are without character of flavor. American table-grapes, on the other hand, are more refreshing, the unfermented juice makes a pleasanter drink, and lacking sweetness and richness, they do not cloy the appetite so quickly. The bunches and berries of the European grapes are larger, more attractive and are borne in greater quantities. The pulp, seeds and skins are somewhat objectionable in all of the native species and scarcely so at all in the Old World sorts. The berries of the native grapes shell from the stem so quickly that the bunches do not ship well. The vines of the Old World grapes are more compact in habit and require less pruning and training than do those of the native grapes; and, as a species, probably through long cultivation, they are adapted to more kinds of soil, to greater differences in environment and are more easily propagated than the American species.
Because of these points of superiority in the Old World grape, since Valk, Allen and Rogers showed the way, American grape-breeders have sought to unite by hybridization the good characters of the Old World grape with those of the American. Nearly half of the 2000 grapes cultivated in eastern America have more or less European blood in them. Yet, despite the efforts of the breeders, few of these hybrids have commercial value. Whether because they are naturally better fixed, or long cultivation has more firmly established them, the vine characters of Vitis vinifera more often appear in varieties arising as primary hybrids between that and the native species, and the weaknesses of the foreign grape, which prevent their cultivation in America, crop out. Hybrids in which the vinifera blood is more attenuated, as secondary or tertiary crosses, give better results.
Several secondary hybrids now rank among the best of the cultivated grapes. Examples are Brighton and Diamond. The first is a cross between Diana-Hamburg, a hybrid of a Vinifera and a Labrusca, crossed in its turn with Concord, a Labrusca; the second is a cross between Iona, also a hybrid between a Vinifera and a Labrusca, crossed with Concord. Both were grown from seed planted by Jacob Moore, Brighton, New York, in 1870. Brighton was the first secondary hybrid to attract the attention of grape-breeders, and its advent marked an important step in breeding grapes.
The signal success achieved by hybridizers of the European grape with native species quickly led to similar amalgamations among American species. Jacob Rommel, of Morrison, Missouri, beginning work about 1860, hybridized Labrusca and Vulpina grapes so successfully that a dozen or more of his varieties are still cultivated. All are characterized by great vigor and productiveness; and, although they lack the qualities which make good table-grapes, they are among the best for wine-making. Rommel has had many followers in hybridizing native species, chief of whom was the late T. V. Munson, Fig. 50, Denison, Texas, who literally made every combination of grapes possible, grew thousands of seedlings and produced many valuable varieties.
Selection, continued through successive generations, so important in the improvement of field and garden plants, has played but small part in the domestication of the grape. The period between planting and fruiting is so long that progress would be slow indeed were this method relied on. Moreover, selection, as a method in breeding, is possible only when plants are bred pure, and it is the experience of grape-breeders that in pure breeding this fruit loses in vigor and productiveness and that the variations are exceedingly slight and unstable. Many pure-bred grapes have been raised on the grounds of the New York Agricultural Experiment Station under the eyes of the writer, of which very few have surpassed the parent or have shown promise for the practice of selection.
Bud-sports or mutations now and then arise in grapes. But not more than two or three of the 2000 varieties now under cultivation are suspected of having arisen in this way. It is true that mutations seem to occur rather often in grapes, but they are easily confused with variations due to environment and are usually too vague to lay hands on. Until the causes of these mutations are known and until they can be produced and controlled, but little can be hoped for in the amelioration of grapes through mutations.
Hybridization has been the chief means of improving the grape. At present, from what is being accomplished by many workers, it looks as if it will long continue to be the best means of improving this fruit. Since the grape-grower must depend on new varieties for progress, as old varieties cannot be changed, it should be the ambition of growers to produce varieties better than those we now have. Many amateur and professional grape-growers in the past have found breeding grapes a pleasing and profitable hobby, so that much knowledge has accumulated in regard to manipulating the plants in hybridization, and the results that follow in the offspring of hybridization.
It is assumed that the reader is familiar with the botany of flowers and the essential principles in crossing plants. If he is not, he must carefully study the structure of flowers, especially those of the grape, so as to be able to distinguish the different organs and to discover when the pollen and stigma are ready for the work of pollination. He should, also, read any one of several current books on plant-breeding.
The first task in crossing grapes is to remove the anthers before the flower opens, a process known as emasculation. This is necessary to prevent self-pollination. This first operation having been performed, the cluster of grape-flowers must be tied securely in a bag to protect it from foreign pollen which otherwise would surely be carried to the stigma by insects. As soon as the stigma is ready to receive the pollen, the bag is removed and pollen from the male parent is applied, after which the bag is again put on the flower to remain until the grapes are well set. By examining the stigmas in the flowers of uncovered grapes, the operator can tell approximately whether the covered stigma is ready to receive pollen. The time required after covering depends, of course, on the age of the bud when emasculation takes place. It is, by the way, best to delay emasculation until just before the flowers open, but one must be certain that the anthers have not discharged their pollen before the flower has been emasculated.
Emasculation is a simple operation. The essential organs of the grape-flower are covered by a small cap; this in some grapes must be removed before the anthers can be reached. In many native grapes, however, the cap and the anthers may be removed at one stroke by the operator. The best tool for this is a small pair of forceps. Each of the blades of the forceps in working with native grapes should have a sharp cutting surface, but with Vinifera sorts, where the cap must be removed before the anthers can be reached, forcep blades with a flat surface are best. There is, of course, some danger when the buds are well developed that the pollen may be squeezed out and so reach the stigma or adhere to the instrument and thus contaminate future crosses. The first danger must be avoided carefully by the skill of the operator, while the second is easily overcome by sterilizing the forceps in alcohol. An effort should be made to fertilize as many of the flowers in the cluster as possible, but success is not always certain; when there is doubt, the uncertain flower should be removed from the cluster.
The flower from which the pollen is to be taken must be protected from wind and insects; otherwise pollen from another flower may be left on it. Protection should be given by tying the flowers in a bag while still in bud. There are various ways of obtaining pollen from ripe anthers and applying it to the stigma of the flowers to be crossed. The simplest is to crush the anthers, thus squeezing out the pollen, after which, with a brush, scalpel or other instrument, it may be placed upon the stigma. A brush is very wasteful of pollen and often becomes a source of contamination to future crosses, so that the scalpel is the better implement of the two. When pollen is plentiful, as will usually be the case when a man is working with vines in his own vineyard, by far the best method is to take the cluster from the male vine and apply the pollen directly to the stigma of the flower to be crossed, thereby making certain of fresh pollen and an abundance of it. The stigma, if pollen suffice, should be covered with pollen.
Grape pollen does not keep well and an effort should be made to have it as fresh as possible. The work of pollination is best performed in bright, sunny weather when the pollen is very dry. As may be seen from the foregoing statements, tools and methods are of less importance than care in doing the work. The only tool absolutely necessary is a pair of forceps, although a hand-lens is often helpful. Bags for covering the flowers should be just large enough and no larger. A bag to cover the pollen-producing flower may well be an ordinary manilla bag sufficiently large to amply cover the flower-cluster. It is helpful, however, to have a light transparent oiled bag through which one can see the condition of the anthers. It is desirable that the bag for the female flower be permitted to remain until the fruits ripen as a protection against birds and fungi. It must, therefore, be of larger size. While the bags are still flat, a hole is made near the opening through which a string is passed which can be tied when the upper end of the bag is squeezed about the cluster.
Very much depends on the immediate parentage in hybridizing grapes. Some varieties when crossed produce much higher averages of worthy offspring than others. There is so much difference in varieties in this respect that to discover parents so endowed should be the first task of the grape-breeder. Fortunately, considerable work has been done by several experiment stations in breeding grapes, and their accumulated knowledge, together with that from such workers as Rogers, Ricketts, Campbell and Munson, furnishes beginners with good starting points. There is no way possible of discovering what the best progenitors are except by records of performance. Very often varieties of high cultural value are worthless in breeding because their characters seem not to be transmitted to their progeny and, to the contrary, a good-for-nothing variety in the vineyard is often valuable in breeding.
From present knowledge it does not appear that new characters are introduced in plants by hybridizing. A new variety originating from hybridization is but a recombination of the characters of the parents; the combination is new but the characters are not. Thus, one parent of a hybridized grape may contribute color, size, flavor and practically all the characters of the fruit, while the other parent may contribute vigor, hardiness, resistance to disease and the characters of the vine. Or these and other characters in the make-up of a new grape may be intermingled in any mathematical way possible. The grape-breeder must make certain that one or the other of the parents possesses the particular characters he desires in his new grape.
It is now known that the characters of the grape, in common with those of other plants, are inherited in accordance with certain laws discovered by Mendel. The early workers in grape-breeding did not know of these laws and could not take aim in the work they were doing. Consequently, hybridization was a maze in which these breeders often lost themselves. Mendel's discoveries, however, assure a regularity of averages and give a definiteness and constancy of action which enable the grape-breeder to attain with fair certainty what he wants if he keeps patiently at his task. The grape-breeder should inform himself as to what Mendel's laws are, and on the work that has been done on the inheritance of characters of the grape. A technical bulletin published by the State Experiment Station at Geneva, New York, and another from the North Carolina Station at Raleigh give much information on the inheritance of characters in certain grapes, and further information can be secured by applying to the United States Department of Agriculture at Washington for literature on the subject.
The grape-breeder can hope to progress only by making many combinations between different varieties and growing large numbers of seedlings. He should extend his work to all varieties which show promise in the breeding of grapes for the particular purpose he has in mind. The seed may be saved and planted as directed in the chapter on propagation. Unless he desires to make scientific interpretations of his results, weak seedlings should be discarded the first year, and a second discard may be made before the young plants go in the vineyard. The breeder will soon discover that he can tell fairly well from the character of the seedlings whether they are of sufficient promise to keep. Thus, if the number of leaves is small or if the leaves themselves are small, the vine is of doubtful value; if the internodes are exceedingly long, the prospect is poor; slenderness of cane, if accentuated, does not promise well; on the other hand, great stoutness and very short internodes are not desirable indications. Through these and other signs, the breeder will come quickly to know which vines should eventually go to the vineyard.
There are now 2000 or more varieties of grapes of American origin, all produced within approximately a century. It is doubtful whether any other cultivated plant at any time in the history of the world has attained such importance in so short a time from the wild state as American grapes. It would seem that almost every possible combination between species worth considering has been made. Through hybridization, species and varieties have become so mixed that the grape-breeder cannot now work intelligently with these gross forms and must work with characters rather than with species and varieties which are but combinations of characters. Great progress, it is true, has been made in the past in breeding grapes in America, but the work has been wholly empirical and extremely wasteful. Many varieties have been called, but few have been chosen. With the new knowledge of breeding and with the experience of past workers, progress should be made with greater certainty. From what has been done and from work now under way, it is not too much to say that we shall soon be growing grapes everywhere in America, and kinds so diverse that they will meet not only all purposes to which grapes are now put, but also the demand for better grapes made by more critical consumers.
MISCELLANIES
There yet remain several phases of grape-culture essential to success, none of which quite deserves a chapter and none of which properly falls into any of the foregoing chapters. The subjects are not closely related, are by no means of equal importance, yet all are too important to be relegated to the limbo of an appendix and are, therefore, thrown into a chapter of miscellanies.
The blooming of the vine had little significance to the grape-grower, the blooming period being so late that grapes are seldom caught by frost, until the discovery was made that many varieties of grapes are unable to fertilize themselves, and that failure of crops of these varieties was often due to the self-sterility of the variety. Until this discovery, the uncertainty attending the setting of the grape in these varieties was one of the discouragements of grape-growing. Following investigations of the self-sterility of the tree-fruits, an investigation of the grape showed that the vines of this fruit are often self-sterile. This knowledge has in some degree modified the planting of all home collections and has more or less affected the plantings of commercial sorts.
Varieties of American grapes show most remarkable differences in the degree of self-fertility. Many sorts fruit perfectly without cross-pollination. Others set no fruit whatsoever if cross-pollination is not provided for. Most varieties, however, are found in groups between the two extremes, neither self-fertile nor self-sterile. Figure 51 shows staminate and perfect clusters on one vine. Some varieties show no variation in the degree of self-sterility or self-fertility; others behave differently in regard to these characters under different environment. Now and then the widest variations are to be found in a variety in respect to self-fertility.
Following the lead of Beach at the New York Agricultural Experiment Station, several workers have made careful studies of the self-fertility of the grape, and now the cultivated varieties of native grapes are divided into four groups in accordance with the degree of self-fertility. Class I includes self-fertile varieties having perfect or nearly perfect clusters; Class II includes self-fertile varieties having clusters loose but marketable; Class III includes varieties which are so imperfectly self-fertile that the clusters are generally too loose to be marketable; Class IV includes self-sterile varieties. The following is a list of commonly cultivated grapes classified according to the divisions just given:
CLASSIFICATION OF GRAPES ACCORDING TO SELF-FERTILITY
Class I. Clusters perfect or varying from perfect to somewhat loose.
Class II. Clusters marketable; moderately compact or loose.
Class III. Clusters unmarketable.
Class IV. Self-sterile. No fruit develops on covered clusters.
In the main, the cause of infertility, as with other fruits, is the impotency of pollen on the pistils of the same variety. There are a few cases in which pollen does not seem to be formed abundantly, but these are very few. There are a few cases, also, in which the pistil does not become receptive until after the pollen has lost its vitality; these, however, are very few. In a greater number of cases the pollen is found defective. However, dismissing all of these as the exception, the rule is that self-sterility is due, as has been said, to the lack of affinity between pollen and pistils produced on the vines of some varieties.
Nature is helpful to the grape-grower in giving a guide to self-fertility. The length of stamens is a fairly safe indication of self-fertility. All grapes which are self-fertile bear flowers with long stamens, although the latter are not a sure sign of self-fertility, as a few varieties with long stamens are self-sterile. On the other hand, short or recurved stamens are always associated with complete or nearly complete self-sterility.
The remedy for self-sterility is inter-planting. Only the varieties named in Classes I and II in the foregoing classification should be planted alone. The sorts named in Classes III and IV must be planted near other sorts which bloom at the same time in order that their flowers may be cross-pollinated.
It is evident that the grape-grower must have some knowledge of the relative time that grapes bloom, if he is to plant intelligently to secure cross-pollination. The following table, taken from Bulletin 407 of the New York Agricultural Experiment Station, shows the blooming time of grapes at that Station. Variations due to location and season must be expected, but within the bounds of the regions in which these grapes are grown variations will be slight. When this table is used for other regions than New York, it must be borne in mind that the farther south, the longer the blooming season; the farther north, the shorter the season.
From three years' records, the average length of blooming season for grapes was twenty days, nineteen days in 1912 and 1914 and twenty-two days in 1913. The first date in the average year of 1912 was June 14, while for 1914, it was June 7:
Table IV.—Showing Blooming Time of Grapes
The ringing of woody plants is a well-known horticultural practice. Three objects may be attained by ringing: unproductive plants may be brought into bearing by ringing; the size of the fruits may be increased and thereby the plants be made more productive; and the maturity of the fruit may be hastened. In European countries, ringing has long been practiced with all tree-fruits and the grape, but in America the operation is recommended only for the apple and the grape and with neither fruit is ringing widely practiced. Experiments carried on at the New York Agricultural Experiment Station by Paddock, as reported in Bulletin 151 from this Station, show that ringing may well be practiced by grape-growers under some conditions. Since Paddock's experiments, and possibly to some extent before, the grape has been ringed to produce exhibition fruits or a fancy product for the market.
Ringing consists in taking from the vine a layer of bark around the vine through the cortex and bast of the plant. The width of the wound varies from that of a simple cut made with a knife to a band of bark an inch in diameter. The operation is performed during that period of growth in which the bark peels most readily from the vine, the period of greatest cambial activity. The term "ringing" is preferred to "girdling," a word sometimes used, since the latter properly designates a wound which extends into and usually kills the plant.
The theory of ringing is simple. Unassimilated sap passes from the roots of the plant to the leaves through the outer layer of the woody cylinder. In the leaves this raw material is acted on by various agents, after which it is distributed to the several organs of the plant through vessels in the inner bark. When plants are ringed, the upward flow of sap is continued as before the operation, but the newly made food compounds cannot pass beyond the injury, and therefore the top of the plant is supplied with an extra amount of food at the expense of the parts below the ring. The extra food produces the results noted.
It turns out in practice that ringing is usually harmful to the plant, as one might expect from so unnatural an operation. Injury to the plant arises from the fact that parts of the vine are starved at the expense of other parts; and because, when the bark is removed, the outer layers of the woody cylinder dry out very quickly and thus check to some extent the upward flow of sap through evaporation from the exposed wood. Thus, not infrequently, the plant's vitality is seriously drained. Nevertheless, vineyards may be found in which ringing has been extensively practiced many seasons in succession and which continue to yield profitable crops, the growers having learned to perform the work of ringing so as to injure the vines but little.