The grape is best conserved as a raisin. Canning is seldom practiced with this fruit. A raisin is a dried grape. Tree-fruits are evaporated as by-products, but the raisin is a primary product. This is a difference worth noting; for with tree-fruits the cream of the crop goes to the fresh fruit market, while with the grape the entire crop of raisin varieties may go into the cured product. The raisin industry is dependent on a sunny and rainless climate and hence in America is confined to the grape regions of certain parts of California. In this state, raisin-making is a rich resource of the grape-grower, the annual output now averaging well above 200,000 pounds, grown on 120,000 acres of land, and having a market value of $10,000,000. Fresno County, California, produces nearly 60 per cent of the output of the state and the city of Fresno is the center of the industry. The raisin industry does not stand alone in California, as some raisin grapes, notably Muscat of Alexandria, are good dessert sorts and are also much used for wine and brandy. Only the first crop of the variety named is used for raisins, while practically all of the second crop each season is made into wine and brandy.
Raisins proper are mostly made from the Muscat of Alexandria, although other large, white, sweet grapes are sometimes used. Sultana raisins, naturally seedless, are made from Sultanina and the Sultana. The dried currants of commerce are made from grapes, and of these California produces small quantities from White Corinth.
The following account of raisin-making is given by Husmann:
"In the raisin districts grapes are ripe by the middle of August, the season often lasting into November. The average time necessary for drying and curing a tray of raisins is about three weeks, depending on the weather, the earliest picked grapes drying in ten days and the later ones often taking four weeks or more.
"The method of drying is very simple. The bunches are cut from the vines and placed in shallow trays 2 feet wide, 3 feet long, and 1 inch high on which the grapes are allowed to sun-dry, being turned from time to time by simply placing an empty tray upside down on the full one and then turning both over and taking off the top tray. After the raisins are dried they are stored away until they are packed and prepared for shipment. Some of the larger growers, in order not to run so much risk in drying on account of rain, and also to enable them to handle the crop fast enough, have curing houses, where the curing is finished after having been partially done outside."
Dipping and scalding raisins.
"The operation of dipping and scalding is designed to accomplish several purposes, namely, to cleanse the fruit, to hasten its drying, and to give the dried fruit a lighter color. In dipping and drying, the fruit, immediately after being cut from the vines, is either dipped in clear water to first rinse it of particles of dust and other foreign matter, or it is taken direct to the scalder and immersed in a boiling alkaline mixture called 'legia' (lye) until the grapes show an almost imperceptible cracking of the skin, the operation consuming perhaps from one-fourth to one-half of a minute. This dipping calls for skill on the part of the operator, the duration of the emersion depending on the strength and temperature of the mixture and the condition of the fruit. Desiccation follows the scalding process, which is accomplished on trays in the sun, the same as undipped raisins cured entirely by solar heat. On account of the scald they cure rapidly, and the fruit is also often of lighter color when cured.
"The following formula has been used for Sultana and Sultanina grapes at Fresno:
"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 1-1/2 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."
Classes of raisins.
"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 2-1/2 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 deg. 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 deg. 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.
BY-PRODUCTS OF GRAPE INDUSTRIES
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.
DOMESTIC USES FOR GRAPES
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.
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 aestivalis; 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.
Improvement by selection.
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.
New varieties from sports.
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.
HYBRIDIZING THE GRAPE
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.
How to hybridize.
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.
Choosing the parents.
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.
RESULTS OF GRAPE-BREEDING
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.
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.
Berckmans Bertha Cottage Croton Delaware Diana Etta Janesville Lady Washington Lutie Moore Early Poughkeepsie Pocklington Prentiss Rochester Senasqua Winchell
CLASS II. Clusters marketable; moderately compact or loose.
Agawam Brilliant Brown Catawba Champion Chautauqua Clinton Colerain Concord Dutchess Early Victor Elvira Empire State Fern Munson Hartford Iona Isabella Isabella Seedling Jefferson Jessica Lady Mills Missouri Riesling Perkins Rommel Triumph Ulster
CLASS III. Clusters unmarketable.
Brighton Canada Dracut Amber Eumelan Geneva Hayes Lindley Noah Northern Muscadine Vergennes
CLASS IV. Self-sterile. No fruit develops on covered clusters.
America Aminia Barry Black Eagle Clevener Creveling Eldorado Faith (?) Gaertner Grein Golden Hercules Jewel Massasoit Maxatawney (?) Merrimac Montefiore Requa Salem Wyoming
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.
Blooming dates of grapes.
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
===================================================================== VERY MID- VERY EARLY EARLY SEASON LATE LATE -+ -+ -+ -+ -+ - Agawam * America * August Giant * Bacchus * Barry * Beacon * Bell * Berckmans * Black Eagle * Brighton * Brilliant * Brown * Campbell Early * Canada * Canandaigua * Carman * Catawba * Champion * Chautauqua * Clevener * Clinton * Colerain * Columbian Imperial * Concord * Cottage * Creveling * Croton * Delago * Delaware * Diamond * Diana * Downing * Dracut Amber * Dutchess * Early Victor * Eaton * Eclipse * Eldorado * Elvira * Empire State * Etta * Eumedel * Eumelan * Faith * Fern Munson * Gaertner * Geneva * Goethe * Gold Coin * Grein Golden * Hartford * Headlight * Helen Keller * Herbert * Hercules * Hicks * Hidalgo * Hosford * Iona * Isabella * Janesville * Jefferson * Jessica * Jewel * Kensington * King * Lady Washington * Lindley * Lucile * Lutie * McPike * Manito * Martha * Massasoit * Maxatawney * Merrimac * Mills * Missouri Riesling * Montefiore * Moore Early * Moyer * Nectar * Niagara * Noah * Northern Muscadine * Norton * Oporto * Ozark * Peabody * Perfection * Perkins * Pierce * Pocklington * Poughkeepsie * Prentiss * Rebecca * Regal * Requa * Rochester * Rommel * Salem * Secretary * Senasqua * Stark-Star * Triumph * Ulster * Vergennes * Winchell * Worden * Wyoming * =====================================================================
RINGING GRAPE VINES
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.
Ringing without harm to the plant depends much on the way in which the vines have been pruned. For instance, if the vines are pruned to the two-arm Kniffin method, the ringing of bark should be done from both arms just beyond the fifth bud. Thus, the ten buds left on the vine produce enough leaf surface to supply the food necessary to keep the vine in vigorous condition. When the four-arm Kniffin method is used, the two top arms only are ringed, and even so three or four buds must be left on each for renewals. Whatever the method of training, it will be seen from these examples that some unringed wood must be left to the vine with which to supply leafy shoots to support the vine. Some growers ring their vines only every other year, thus giving them an opportunity to recover from whatever loss of vigor they may have sustained in the season of ringing.
Several other considerations are important in ringing: First, the vines must not be permitted to carry too large a crop. Again, the amount of fruit on the ringed portion of the vine must depend on the amount of leaf surface not only of the plant but of the ringed arms, each ringed arm acting somewhat independently so far as its crop is concerned. If too many clusters are left on the ringed arms, it always follows that the fruit is inferior and often worthless. Lastly, all fruit between the rings and the trunk must be removed, for it does not mature properly and so adds only to the drain on the plant's vitality.
As to the results, it is certain from the experiments that have been conducted and from the experience of grape-growers, that the maturity of the fruit is hastened, and berries and bunches are larger when the ringing has been done intelligently. Many growers hold that fruit produced on ringed vines is never quite up to the mark in quality and in firmness of fruit. There seems to be a difference in opinion about this falling off in quality, however, although unquestionably, choice sorts, as Delaware, Iona and Dutchess, suffer more or less in quality. It is commonly agreed, also, that varieties, the fruits of which crack badly, as the Worden, suffer more from cracking on ringed than on unringed vines.
Experiment and experience prove that the best results of ringing are obtained if the work is done when the grapes are about one-third grown. Of course the exact time depends on the season and on the variety. The operation is variously performed and is easily done with a sharp knife, but when large vineyards are to be ringed the grower ought to provide himself with some simple tool. Paddock, in the bulletin previously mentioned, pictures two of these tools and these are reproduced in Fig. 52.
In conclusion it must be said that it is doubtful whether the gains attained by ringing offset the losses. The practice is chiefly of value only when exhibition clusters of grapes are wanted or when it is necessary to hasten the maturity of the crop. Always, however, the work must be performed with intelligence and judgment or the losses will offset the gains.
In some localities bagging is considered an essential to profitable grape-growing. The bags serve to protect the grapes against birds. In some grape regions vineyards suffer more from the depredations of robins and other birds than from all other troubles. Grapes bearing small berries and having tender pulp and those which shell most readily from the stem suffer most. Of standard sorts, Delaware is probably more enticing to robins than any other variety. There is only one way of preventing damage to grapes from birds and that is by bagging the clusters.
Bagging is also an effective means of protecting the grape from several fungi and insects. In home plantations or small commercial vineyards, bagging the bunches often eliminates the necessity of spraying for fungi and for most of the insects that trouble the grape. Because of the warmth afforded by the bags, bagged grapes ripen a little earlier and are of somewhat higher quality than those not bagged. Grapes bagged are protected from early frost, thus prolonging the season. Grapes that have been protected from the elements during the summer are more attractive than those exposed to the weather, since the fruits are free from weather marks and present a fresh, bright appearance, which puts them in a grade above unbagged grapes. Bagging often enables the grower to sell his crop as a fancy product.
Grapes are bagged as soon as the fruits are well set, the sooner the better if protection against fungi is one of the purposes. Under no circumstances, however, should the clusters be bagged while in blossom. A patent bag made for the purpose may be purchased or, serving equally well, the common one and one-half and two-pound manila bags used by grocers prove satisfactory. One of the patent bags which is known as the Ideal Clasp Bag has a metal clasp attached to the top for securing the bag in place over the cluster. In using the grocer's bag, before it is put in place the corners of both the top and bottom are cut off by placing several bags on a firm level surface and using a broad-shaped chisel. Cutting off the corners of the top enables the operator to close the bag neatly over the cluster, while cutting off the corners of the bottom furnishes a means of escape for any water that gets in the bag. In putting the bag in place, the top is pinned above the lateral from which the bunch hangs, and must not be fastened about the small stem of the cluster, as the wind blowing the bag almost invariably breaks the cluster from the vine. The largest pins to be purchased in dry-goods stores are used in pinning the bags. The bags remain until the grapes are picked. Wet weather does not injure bags and seemingly they grow stronger with exposure to sun and wind.
The cost of the bags and the work of putting them on is no small item. To secure the best results, the work must be done at the period between the dropping of the blossoms and the formation of the seeds, when the grapes are about the size of a small pea. This is a busy time for the grape-grower, which adds to the cost. When the work is conducted on a large scale, the cost is about two dollars a thousand bags, this figure covering both the cost of bags and labor. Women do the work more expeditiously than men and soon become very skillful in putting on the bags. Despite the trouble and cost of bagging, growers seeking to produce a fancy product find that the expenditure proves profitable.
WINTER-PROTECTION OF GRAPES
With a little care as to winter-protection, grapes may be grown profitably in northern regions where, without protection, the vines are killed or injured by low temperatures. Indeed, it is little short of amazing how well grapes can be grown in northern regions where nature wears a most austere countenance in winter, if hardy early sorts are planted in warm soils and situations, and the vines are covered in the winter. Occasionally one finds grapes grown profitably in commercial vineyards in the northern states in regions where protection must be given to prevent winter-killing, the extra work of giving protection being more than offset by the high price received in local markets for the fruit.
In all locations in which winter-protection must be given, several other precautions are helpful or even necessary. Thus, cultivation must cease early in the season, and a cover-crop be sown to help harden and mature the vines. The grapes, also, must not be planted in soils rich in nitrogen, and nitrogenous fertilizers must be applied with care. The pruning should be such as does not induce great growth. These simple precautions to hasten maturity often suffice in climates where the danger of winter-killing is but slight, but where danger is imminent the vines must be covered either by wrapping or by laying down. Wrapping with straw may suffice for a few vines, but when many vines are to be protected, laying them down is cheaper and much more effectual.
By laying down is meant that the vines must be placed on the ground and there be protected by earth and snow or other covering. It is obvious that to protect thus, the vines must receive special training; otherwise the trunks may be too stiff for bending. Some method of training must be chosen in which renewals may be made rather frequently from the ground so that if the trunks become large, clumsy and unpliable, a more manageable trunk can be trained. If the provisions for renewal are kept in mind, any one of the several methods of training grapes explained in Chapter VIII on training may be used.
Laying down must be preceded by pruning, after which the arms and trunk are loosened from the wires and bent to the ground. Bending is facilitated by removing a spade full of earth from the side of the vine in the direction in which the vine is to be bent. The trunk is then laid on the earth and sufficient soil placed on it to keep it in place on the ground. If the danger of winter-killing is great because of the tenderness of the variety or the austerity of the climate, it often becomes necessary to cover the whole plant lightly with earth. Small growers often make use of coarse manure, straw, corn-stalks or similar covering, in which case the vines are held on the ground by fence-rails or other timbers; but protecting with material that must be brought into the vineyard is expensive and not more satisfactory than earth.
The vines can be put down at any time after the leaves drop and before the earth begins to freeze. It is more important that the vines be taken up at the proper time in the spring. If uncovered too early and cold weather follows, injury may result and more harm be done than if the vines had not been covered. On the other hand, if the earth is permitted to remain too long, foliage and vine are tender both to sunshine and frost. A grape-grower in New York who has had much experience in laying down vines in a vineyard of some thirty or forty acres says that the work may be done at a cost of $6 an acre at the average wage paid for farm-labor. It must be expected in a large plantation, no matter how well the work of covering is done, that occasionally a trunk will be broken, making it necessary to graft the vine if a shoot does not spring up from below the break.
RIPENING DATES AND LENGTH OF SEASON FOR GRAPES
Every grape-grower should know when his varieties may be expected to ripen and the length of season that they will keep. The commercial fruit-grower by all means should have this information. It is not sufficient that he know only roughly at what season his varieties ripen; for, to take the turn of the market, he must know exactly when a variety will ripen and how long it will keep. He needs this information, also, that he may distribute his labor better throughout the picking season.
Unfortunately, the data as to ripening time given by originators and introducers of varieties are not always reliable. This untrustworthiness of data is readily accounted for in several ways: First, growers do not generally agree as to when grapes are ripe nor as to how long they are fit to eat. Again, much confusion as to when varieties ripen and how long they will keep arises from the fact that grapes ripen at different times in different places, and it is difficult for the grape-grower in Maine to make allowance in season for varieties, the time of ripening of which is given for Maryland. There are also other causes than the seasonal differences in grape regions for variability in ripening time; thus, some soils are warmer and quicker than others, and on these grapes ripen earlier. Application of nitrogenous fertilizers may delay the period of ripening somewhat. Grapes ripen perceptibly earlier on old plants than on young ones. Lastly, every vineyard in a particular region has its own particular climate caused by the lay of land, nearness to water, air currents and altitude which cause small differences in ripening.
The following table taken from Bulletin No. 408 of the New York Agricultural Experiment Station gives the ripening dates of grapes at Geneva, New York. It is necessary that the reader know something about the conditions affecting the ripening time at Geneva. The latitude is 42 deg. 50' 46". The altitude is 525 feet above sea level. The vineyard lies a mile west of a relatively large body of water. The soil is a cold heavy clay which must delay ripening time somewhat. The land is level. The data are given as an average for three seasons, 1913-1915.
The figures given for "weeks in common storage" cover a variable number of years, but for all varieties three or more years. The grapes, after being picked, were at once placed in common storage in a room on the second floor of a building. There conditions were not ideal, and no doubt the season of storage would have been prolonged somewhat had the fruit been kept in a better storage-room.
TABLE V.—SHOWING THE RIPENING TIME OF GRAPES
===================================================================== WEEKS IN COMMON VERY MID- VERY STORAGE EARLY EARLY SEASON LATE LATE - - - Agawam * America * Barry 28 * Beacon 7 * Bell 8 * Berckmans 21 * Black Eagle 18 * Brighton 20 * Brilliant 11 * Brown 6 * Campbell Early 12 * Canada 17 * Canandaigua 20 * Carman 17 * Catawba 21 * Champion 6 * Chautauqua 10 * Clevener 13 * Clinton 21 * Colerain 8 * Columbian Imperial 7 * Concord 8 * Cottage 5 * Creveling 16 * Croton 23 * Delago 25 * Delaware 15 * Diamond 10 * Diana 17 * Downing * Dracut Amber 9 * Dutchess 23 * Early Ohio * Early Victor 11 * Eaton 6 * Eclipse 7 * Eldorado 17 * Elvira 18 * Empire State 24 * Etta 15 * Eumelan 17 * Faith 11 * Fern Munson 11 * Gaertner 17 * Geneva 22 * Goethe 18 * Gold Coin 10 * Grein Golden 12 * Hartford 8 * Headlight 8 * Helen Keller 26 * Herbert 27 * Hercules 13 * Hicks 10 * Hidalgo 12 * Hosford 6 * Iona 13 * Isabella 11 * Janesville 13 * Jefferson 18 * Jessica 12 * Jewel 12 * Kensington 19 * King * Lady Washington 16 * Lindley 27 * Lucile 9 * Lutie 4 * McPike 7 * Manito 7 * Martha 10 * Massasoit 16 * Maxatawney 12 * Merrimac 31 * Mills 29 * Missouri Riesling 6 * Montefiore 9 * Moore Early 6 * Moyer 9 * Nectar 10 * Niagara 10 * Noah 10 * Northern Muscadine 9 * Norton 7 * Oporto 12 * Ozark 11 * Peabody * Perfection 8 * Perkins * Pierce * Pocklington * Poughkeepsie 15 * Prentiss 16 * Rebecca 18 * Regal 16 * Requa 30 * Rochester 7 * Rommel 10 * Salem 27 * Secretary 25 * Senasqua 13 * Stark-Star 10 * Triumph 15 * Ulster 21 * Vergennes 28 * Wilder 11 * Winchell 6 * Worden 6 * Wyoming 9 * =====================================================================
The grape-grower must know the gross structure and the habits of growth of the plants properly to propagate, transplant, prune and otherwise care for the grape. Certainly he must have knowledge of the several species from which varieties come if he is to know the kinds of grapes, understand their adaptations to soils and climates, their relation to insects and fungi, and their value for table, wine, grape-juice and other purposes. Fortunately, the botany of the grape is comparatively simple. The organs of vine and fruit are distinctive and easily discerned and there are no nearly related plants cultivated for fruit with which the grape can possibly be confused. Botanists, it is true, have dug pitfalls for those who seek exact knowledge as to the names and characters of the many species, but, fortunately, each of the cultivated species constitutes a natural group so distinct that the grape-grower can hardly mistake one for another in either fruit or vine.
PLANT CHARACTERS AND GROWTH HABITS OF THE GRAPE
A grape plant is a complex organism with its many separate parts especially developed to do one or a few kinds of work. The part of a plant devoted to one or a group of functions is called an organ. The chief organs of the plant are the root, stem, bud, flower, leaf, fruit and seed. Flowers and leaves, it is true, develop from buds and the seeds are parts of the fruits, but for descriptive purposes the vine may well be divided into the parts named. These chief organs are further divided as follows:
Root-crown: The region of the plant in which root and stem unite. Tap-root: The prolongation of the stem plunging vertically downward. Rootlets: The ultimate divisions of the root; usually of one season's growth. Root-tips: The extreme ends of the rootlets.
The roots of some species of the grape are soft and succulent as those of V. vinifera, while the same organs in other species, as in most American grapes, are hard and fibrous. They may also be few or numerous, deep or shallow, spreading or restricted, fibrous or non-fibrous. The structure of the root thus becomes important in distinguishing species.
Stem or trunk: The unbranched main axis of the plant above ground. Branches or arms: Main divisions of the trunk. Head: The region from which branches arise. Old wood: Parts of the vine older than one year. Canes: Wood of the current season. Spurs: Short pieces of the bases of canes; usually one or two nodes with a bud each. Renewal spurs: Spurs left to bear canes the following year. Shoots: Newly developed succulent stems with their leaves. Fruit-shoots: Flower and fruit-bearing shoots. Wood-shoots: Shoots which bear leaves only. Laterals: Secondary shoots arising from main shoots. Water sprouts: Shoots arising from adventitious buds. Suckers: Shoots arising from below ground. Nodes: Joints in the stem from which leaves are or may be borne. Internodes: The part between two nodes. Diaphragm: The woody tissue which interrupts the pith at the node. Bloom: The powdery coating on the cane. Tendril: The coiled, thread-like organ by which the vine grasps an object and clings to it.
Species of grapes have very characteristic vines. A glance at a vine enables one to tell the European grape from any of the American grapes; so, also, one is able to distinguish most of the American species by the aspect of the vine. Many varieties of any species of grape are readily told by the size and habits of the plant. Size of vine is rather more variable than other gross characters because of the influence of environment, such as food, moisture, light, isolation and pests; yet, size in a plant or the parts of a plant is a very reliable character when proper allowances are made for environment.
The degree of hardiness is a very important diagnostic character in determining both species and varieties of grapes and very largely indicates their value for the vineyard. Thus, the varieties of the European grape are less hardy than the peach, while our American Labruscas and Vulpinas are as hardy as the apple. The range of varieties as to hardiness falls within that of the species, and cultivated varieties hardier than the wild grape are not found. Grapes are designated in descriptions of varieties and species as hardy, half-hardy and tender.
Habit of growth varies but little with changing conditions and is thus an important means of distinguishing species and varieties and not infrequently stamps the variety as fit or unfit for the vineyard. Habit of growth gives aspect to the vine. Thus, a vine may be upright, drooping, horizontal, stocky, straggling, spreading, dense or open. The vine may grow rapidly or slowly and may be long-lived or short-lived; the trunk may be short and stocky or long and slender. These several characters largely determine whether a vine is manageable in the vineyard. Productiveness, age of bearing and regularity of bearing are distinctive characters with cultivated grapes. The care given the vine influences these characters; yet all are helpful in identifying species and varieties and all must be considered by the grape-grower.
Immunity and susceptibility to diseases and insects are most valuable diagnostic characters of species and varieties of grapes. Thus, species differ widely in resistance to phylloxera, the grape-louse, to the grape leaf-hopper, the flea-beetle, berry-moth, root-worm, powdery-mildew, downy-mildew, anthracnose and other insect and fungous troubles of this fruit.
The structure of the bark is an important distinguishing character for some species, but is of little importance in identifying the variety and has no economic value to the fruit-grower. In most species of grapes, the bark has distinct lenticels and on the old wood separates in long thin strips and fibers; but in two species from southeastern North America, the bark bears prominent lenticels and never shreds. Smoothness, color and thickness are other attributes of the bark to be noted.
Canes of different species vary greatly in total length and in length of internodes. They vary also in size, in number and in color, while the shape in some species is quite distinctive, being in some round, in others angular and in still others flattened. The direction of growth in canes, whether sinuous, straight or zigzag, is an important character. Nodes and internodes are indicative characters in some species, being more or less prominent, angular or flattened, while the internodes are long or short.
The diaphragm distinguishes several species of grapes. The cane contains a large pith and this in most species is interrupted by woody tissue, forming a diaphragm at the nodes. In the Rotundifolia grapes the diaphragm is absent, while in several other American species it is very thin and in still others quite thick. The character of the diaphragm is best observed in year-old canes. In studying the diaphragm, notice should be taken also of the pith, which is very variable in size.
Young shoots of the grape offer a ready means of distinguishing species and varieties through their color and the amount and character of the pubescence. Shoots may be glabrous, pubescent or hairy and even spiny.
The tendril is one of the organs most used in determining species and varieties of grapes. In some species, as V. Labrusca, there is a tendril or an inflorescence opposite nearly every leaf, continuous tendrils. All other species have two leaves with a tendril opposite each and a third leaf without a tendril, intermittent tendrils. To study this organ it is necessary to have vigorous, healthy, typical canes. Tendrils may be long or short, stout or slender; simple, bifurcated or trifurcated; or smooth, pubescent or warty.
The number of inflorescences borne by species is an important character in some cases. All species, excepting V. Labrusca, average two inflorescences to a cane, but V. Labrusca may bear from three to six inflorescences, each in the place of a tendril opposite the leaf.
Bud: An undeveloped shoot. Fruit-bud: A bud in which a shoot bearing flowers originates. Wood-bud: A bud in which a shoot bearing only leaves originates. Latent bud: A bud which remains dormant for one or more seasons. Adventitious bud: A bud arising elsewhere than the normal position at a node. Eye: A compound bud. Main bud: The central bud of an eye. Secondary bud: The lateral bud of an eye.
Buds of different species of grapes vary greatly in time of opening as they do somewhat in varieties, so that the time the buds begin to swell is a fine mark of distinction. The angle at which the bud stands out from the branch is of some value in determining species. Differences in color, size, shape, position and amount of pubescence of buds must all be noted in describing grapes. The scales of the buds vary more or less in size and in thickness.
Staminate: Having stamens and not pistils; a male flower. Pistillate: Having pistils and not stamens; a female flower. Dioecious: Said when the stamens are on one plant and the pistils on another. Polygamous: Said when flowers on a plant are in part perfect (having both stamens and pistils) while others are staminate or pistillate. Hermaphrodite: Said of a flower having both stamens and pistils. Fertile: Said of a flower capable of bearing seed without pollen from another flower. Sterile: Said of a flower without or with abortive pistils. Perfect: Said of a flower having both stamens and pistils. Imperfect: Said of a flower wanting either stamens or pistils. Peduncle: The stalk of a flower-cluster. Pedicel: The stalk of each particular flower.
The time of bloom is an easy mark of distinction between several species of grapes and helps to distinguish varieties in a species as well. Most species of grapes bear fertile flowers on one vine and sterile flowers on another and are, therefore, polygamous-dioecious. Sterile vines bear male flowers with abortive pistils so that, while they never produce fruits themselves, they usually assist in fertilizing others. Fertile flowers are capable of ripening fruits without cross-pollination. Vines with female flowers only are seldom found. In most species of the grape, plants with sterile flowers and those with complete flowers are found mixed in the wild state, but usually only the fertile plants have been selected for cultivation. Plants raised from seeds of any of the species, however, furnish many sterile vines.
The degree of fertility of blossoms is also a fine mark of distinction in species and varieties of the grape. Fertile vines are of two kinds in most species. The flowers on one kind are perfect hermaphrodites, while in the other kind the stamens are smaller and shorter than the pistil and eventually bent down and curved under. The two kinds of stamens are shown in Figs. 53 and 54. These may be called imperfect hermaphrodites since they are seldom as fruitful as the perfect hermaphrodites unless fertilized from another plant. Examined with a microscope, it is found that self-sterile plants usually bear abortive pollen and that the percentage of abortive pollen grains varies greatly in different varieties. The upright or depressed stamen does not always indicate the condition of the pollen, since there are many instances in which upright stamens bear impotent pollen and occasionally the depressed stamens bear perfect pollen.
Blade: The expanded portion of the leaf. Lobe: The more or less rounded division of the leaf. Sinus: The recess or bay between two lobes. Petiole: The leaf-stalk. Petiolar sinus: The sinus about the petiole. Basal sinuses: The two sinuses toward the base of the blade. Lateral sinuses: The two sinuses toward the apex of the blade.
The size, shape and color of the leaves are quite distinctive of species and more or less so of varieties, if allowances are made for variation due to environment. The lobing of leaves is a very uniform character in most species, some having lobes and others having entire leaves. The upper surface of the leaf in some species is smooth, glossy and shiny and in others is rough and dull. The lower surface shows similar variations and has, besides, varying amounts of pubescence, down and bloom. In some species the down resembles cobwebs. The number, size and shape of the lobes are important in distinguishing both varieties and species, as are also the petiolar, basal and lateral sinuses. As in most plants, the margins of the leaves, whether serrate, dentate or crenate, are often distinguishing characters. The petiole in different species varies from short to long and from stout to slender. Lastly, the time at which the leaves fall is often a good distinguishing mark.
Peduncle and pedicel: Defined as in flower. Brush: The end of the pedicel projecting into the fruit. Base: The point of attachment of bunch or berry. Apex: The point opposite the base. Bloom: The powdery coating on the fruit. Pigment: The coloring matter in the skin. Quality: The combination of characters that makes grapes pleasant to the palate, sight, smell and touch. Foxiness: The rancid taste and smell of some grapes which are similar to the effluvium of a fox.
Of all organs the fruit is most responsive to changed conditions and hence most variable. Yet the fruits furnish most valuable characters for determining both species and varieties. Size, shape, compactness and the number of clusters on a shoot must be noted. Coming to the berry, size, shape, color, bloom, adherence of stigma to the apex and adhesion of fruit to the pedicel are all of value. Difference in adherence of the skin to the pulp separates European from all American grapes. The thickness, toughness, flavor and pigment of the skin have more or less value. The color, firmness, juiciness, aroma and flavor of the flesh, as well as its adherence to seed and skin, are valuable marks in describing grapes. All species and varieties are well distinguished by the time of ripening and by keeping quality. The color of the juice is a plain and certain dividing line between some species and many varieties.
Beak: The narrow prolonged base of the seed. Hilum: The scar left where the seed was attached to the seed-stalk. Chalaza: The place where the seed-coats and kernel are connected. Raphe: The line or ridge which runs from the hilum to the chalaza.
Seeds are accounted of much value in determining species. The size and weight of seed differ greatly in different species, as they do also in varieties of any one species. Thus, of native grapes, Labrusca has the largest and heaviest seeds and Vulpina has the smallest seed, while those of AEstivalis are of medium size and weight. The shape and color of seed offer distinguishing marks, while the size, shape and position of the raphe and chalaza furnish very certain marks of distinction in some species.
THE GENUS VITIS
The genus Vitis belongs to the vine family (Vitaceae) in which most botanists also put the wood-vines (Ampelopsis), of which Virginia creeper is the best-known plant. The genus Cissus, to which belong many southern climbers, is combined with Vitis by some botanists. Vitis is separated from Ampelopsis and Cissus by marked differences in several organs, of which, horticulturally at least, those in the fruit best serve to distinguish the group. Species of Vitis, with possibly one or two exceptions, bear pulpy edible fruits; species of Ampelopsis and Cissus bear fruits with pulp so scant that the berries are inedible. Vitis is further distinguished as follows: The plants are climbing or trailing, rarely shrubby, with woody stems and mostly with coiling, naked-tipped tendrils. The leaves are simple, palmately lobed, round-dentate or heart-shaped-dentate. The stipules are small, falling early. The flowers are polygamo-dioecious (some plants with perfect flowers, others staminate with at most a rudimentary ovary), five-parted. The petals are separated only at the base and fall off without expanding. The disk is hypogynous with five nectariferous glands which are alternate with the stamens. The berry is globose or ovoid, few-seeded and pulpy. The seeds are pyriform and beak-like at the base.
SPECIES OF AMERICAN GRAPES
The number of species of grapes in the world depends on the arbitrary limits set for a species of this fruit, and knowledge of the genus is yet too meager to set these limits with certainty. Indeed, the men who have made grape species have seldom been able to outline the habitats of their groups with much certainty. In habitat, it should be said, grapes are confined almost wholly to temperate and subtropical regions. However, the grape-grower is not much concerned with species of grapes other than those that have horticultural value. Of these, in America, there are now ten more or less cultivated either for fruit or for stocks. The following descriptions of these ten species are adapted from the author's The Grapes of New York, published in 1908 by the state of New York (Chapter IV, pages 107-156).
CONSPECTUS OF CULTIVATED SPECIES OF VITIS
A. Skin of mature berry separating freely from the pulp. B. Nodes without diaphragms; tendrils simple. 1. V. rotundifolia. 2. V. Munsoniana. BB. Nodes with diaphragms; tendrils forked. C. Leaves and shoots glabrous at maturity and without bloom; tendrils intermittent. D. Leaves thin, light, bright green, generally glabrous below at maturity except perhaps in the axils of the veins with a long or at least a prominent point and usually long and sharp teeth or the edge even-jagged. E. Leaves broader than long; petiolar sinus usually wide and shallow. 3. V. rupestris. EE. Leaves ovate in outline; petiolar sinus usually medium to narrow. 4. V. vulpina. DD. Leaves thick, dull colored or grayish-green, often holding some close, dull pubescence below at maturity, shoots and leaves nearly always more or less pubescent when young; the teeth mostly short. 5. V. cordifolia. 6. V. Berlandieri. CC. Leaves rusty or white tomentose or glaucous blue below, thick or at least firm. D. Leaves flocculent or cobwebby or glaucous below when fully grown. 7. V. aestivalis. 8. V. bicolor. DD. Leaves densely tomentose or felt-like beneath throughout the season; covering white or rusty white. E. Tendrils intermittent. 9. V. candicans. EE. Tendrils mostly continuous. 10. V. Labrusca. AA. Skin and pulp of mature berry cohering. (Old World.) 11. V. vinifera.
1. Vitis rotundifolia, Michx. Muscadine Grape. Bull Grape. Bullet Grape. Bushy Grape. Bullace Grape. Scuppernong. Southern Fox Grape.
Vine very vigorous, sometimes, when without support, shrubby and only three or four feet high; when growing in the shade often sending down aerial roots. Wood hard, bark smooth, not scaling, with prominent warty lenticels; shoots short-jointed, angled, with fine scurfy pubescence; diaphragms absent; tendrils intermittent, simple. Leaves small, broadly cordate or roundish; petiolar sinus wide, shallow; margin with obtuse, wide teeth; not lobed; dense in texture, light green color, glabrous above, sometimes pubescent along veins below. Cluster small (6-24 berries), loose; peduncle short; pedicels short, thick. Berries large, globular or somewhat oblate, black or greenish-yellow; skin thick, tough and with a musky odor; pulp tough; ripening unevenly and dropping as soon as ripe. Seeds flattened, shallowly and broadly notched; beak very short; chalaza narrow, slightly depressed with radiating ridges and furrows; raphe a narrow groove. Leafing, flowering and ripening fruit very late.
The habitat of this species is southern Delaware, west through Tennessee, southern Illinois, southeastern Missouri, Arkansas (except the northwestern portions), to Grayson County, Texas, as a northern and western boundary, to the Atlantic Ocean and the Gulf on the east and south. It becomes rare as one approaches the western limit but is common in many sections of the great region outlined above, being most abundant on sandy, well-drained bottom lands and along river banks and in swampy, thick woodlands and thickets. The climate most suitable for Rotundifolia is that in which cotton grows, and it thrives best in the lower portions of the cotton-belt of the United States.
The fruit of Rotundifolia is very characteristic. The skin is thick, has a leathery appearance, adheres strongly to the underlying flesh and is marked with lenticel-like russet dots. The flesh is more or less tough but the toughness is not localized around the seed as in the case of Labrusca. The fruit and most of the varieties of the species are characterized by a strong, musky aroma and are lacking in sugar and acid. Some varieties yield over four gallons of must to the bushel. Wine-makers are divided in opinion as to its value for wine-making, but at present the most promising outlook for Rotundifolia varieties is as wine, grape-juice and culinary grapes. Rotundifolia does not produce fruit suitable for shipping as dessert grapes chiefly because the berries ripen unevenly and when ripe drop from the cluster. The common method of gathering the fruit of this species is to shake the vines at intervals so that the ripe berries drop on sheets spread below the vines. The juice which exudes from the point where the stem is broken off causes the berries to become smeared and gives them an unattractive appearance. Owing, however, to the tough skin, the berries do not crack as badly as other grapes would under the same conditions, but nevertheless they are not adapted to long-distance shipments. Under reasonably favorable conditions, the vines attain great age and size and when grown on arbors, as they often are, and without pruning, they cover a large area.
Rotundifolia is remarkably resistant to the attacks of all insects and to fungal diseases. The phylloxera do not attack its roots and it is considered as resistant as any other, if not the most resistant of all American species. The vines are grown from cuttings only with difficulty and this prevents the use of this species as a resistant stock. However, under favorable circumstances, and with skillful handling, this is a successful method of propagation. Under unfavorable circumstances, or when only a few vines are desired, it is better to depend on layers. As a stock upon which to graft other vines, this species has not been a success. There is great difficulty in crossing Rotundifolia with other species, but several Rotundifolia hybrids are now on record.
2. Vitis Munsoniana, Simpson. Florida Grape. Everbearing grape. Bird Grape. Mustang Grape of Florida.
Vine slender, usually running on the ground or over low bushes. Canes angular; internodes short; tendrils intermittent, simple. Leaves smaller and thinner than Rotundifolia and rather more circular in outline; not lobed; teeth open and spreading; petiolar sinus V-shaped; both surfaces smooth, rather light green. Cluster with more berries but about the same size as in Rotundifolia. Berry one-third to one-half the diameter, with thinner and more tender skin; black, shining; pulp less solid, more acid and without muskiness. Seeds about one-half the size of those of Rotundifolia, similar in other respects. Leafing, flowering and ripening fruit very late.
The habitat of V. Munsoniana is central and southern Florida and the Florida Keys. It extends south of the habitat of Rotundifolia and blends into this species at their point of meeting. Munsoniana appears to be a variation of Rotundifolia, fitted to subtropical conditions. It is tender, not enduring a lower temperature than zero. In the matter of multiplication, it differs from V. rotundifolia in that it can be propagated readily from cuttings. Like Rotundifolia it is resistant to phylloxera.
3. Vitis rupestris, Scheele. Mountain Grape. Rock Grape. Bush Grape. Sand Grape. Sugar Grape. Beach Grape.
A small, much branched shrub or, under favorable circumstances, climbing. Diaphragm thin; tendrils few, or if present, weak, usually deciduous. Leaves small; young leaves frequently folded on midrib; broadly cordate or reniform, wider than long, scarcely ever lobed, smooth, glabrous on both surfaces at maturity; petiolar sinus wide, shallow; margin coarsely toothed, frequently a sharp, abrupt point at terminal. Cluster small. Berries small, black or purple-black. Seeds small, not notched; beak short, blunt; raphe distinct to indistinct, usually showing as a narrow groove; chalaza pear-shaped, sometimes distinct, but usually a depression only. Leafing, blossoming and ripening early.
This species is an inhabitant of southwestern Texas, extending eastward and northward into New Mexico, southern Missouri, Indiana and Tennessee to southern Pennsylvania and the District of Columbia. Its favorite places are gravelly banks and bars of mountain streams or the rocky beds of dry watercourses. This species is rather variable both in type and growth. It was introduced into France at about the same time as Vulpina, and the French vineyardists selected the most vigorous and healthy forms for grafting stock. These pass under the various names of Rupestris Mission, Rupestris du Lot, Rupestris Ganzin, Rupestris Martin, Rupestris St. George and others. In France, these varieties have given particularly good results on bare, rocky soils with hot, dry exposures. In California, Rupestris does not flourish in dry locations, and as it suckers profusely and does not take the graft as readily as Vulpina and AEstivalis, it is not largely propagated.
The clusters of fruit are small, with berries about the size of a currant and varying from sweet to sour. The berry is characterized by much pigment under the skin. The fruit has a sprightly taste wholly free from any disagreeable foxiness. Rupestris under cultivation is said to be very resistant to rot and mildew of the foliage. The vine is considered hardy in the Southwest. The attention of hybridizers was attracted to this species over thirty years ago, and various hybrids have been produced of great promise for grape-breeding. The root system of Rupestris is peculiar in that the roots penetrate at once deeply into the ground instead of extending laterally as in other species. Like those of Vulpina, the roots are slender, hard and resistant to phylloxera. The species is easily propagated by cuttings. The vines bench-graft readily but are difficult to handle in field grafting.
4. Vitis vulpina, Linn. (V. riparia, Michx.). Winter Grape. River Grape. Riverside Grape. Riverbank Grape. Sweet-scented Grape.
Vine very vigorous, climbing. Shoots cylindrical or angled, usually smooth, slender; diaphragms thin; tendrils intermittent, slender, usually bifid. Leaves with large stipules; leaf-blade large, thin, entire, three- or lower ones often five-lobed; sinuses shallow, angular; petiolar sinus broad, usually shallow; margin with incised, sharply serrate teeth of variable size; light green, glabrous above, glabrous but sometimes pubescent on ribs and veins below. Cluster small, compact, shouldered; peduncle short. Berries small, black with a heavy blue bloom. Seeds two to four, small, notched, short, plump, with very short beak; chalaza narrowly oval, depressed, indistinct; raphe usually a groove, sometimes distinct. Very variable in flavor and time of ripening.
Vulpina is the most widely distributed of any American species of grape. It has been discovered in parts of Canada north of Quebec and from thence southward to the Gulf of Mexico. It is found from the Atlantic coast westward, most botanists say, to the Rocky Mountains. Usually it grows on river banks, on islands or in upland ravines. Vulpina has always been considered of great promise in the evolution of American grapes. It can hardly be said that it has fulfilled expectations, there probably being no pure variety of this species of more than local importance, and the results of hybridizing it with other species have not been wholly successful. Attention was early turned to Vulpina because of the qualities presented by the vine rather than those of the fruit, particularly its hardiness and vigor. However, both of these qualities are rather variable, although it is only reasonable to suppose that in such a widely distributed species, plants found in a certain region would have adapted themselves to the conditions there present; thus, it should be expected that the northern plants would be more hardy than those from the South, and that the western prairie forms would be more capable of resisting drouth than those from humid regions. It is, consequently, impossible to say what conditions best suit this species. It may be said, however, that Vulpina is adapted to a great variety of soils and locations; vines have withstood a temperature of 40 to 60 degrees below zero and they show equal ability in withstanding the injurious effects of high temperatures in the summer. On account of its habit of early blooming, the blossoms sometimes suffer from late frosts in the spring.
While Vulpina is not a swamp grape and is not found growing under swampy conditions, it is fond of water. In the semi-arid regions always, and in humid regions usually, it is found growing along the banks of streams, in ravines, on the islands of rivers and in wet places. It is not nearly so capable of withstanding drouth as Rupestris. Vulpina likes a rather rich soil, but in France has been found to do poorly on limestone land and calcareous marls. The French tell us, however, that this is a characteristic of all our American grapes, and that Vulpina is more resistant to the injurious effects of an excess of lime than either Rupestris or AEstivalis.