UNIVERSITY OF CALIFORNIA PUBLICATIONS. COLLEGE OF AGRICULTURE. AGRICULTURAL EXPERIMENT STATION. RESISTANT VINES AND THEIR HYBRIDS By E. H. TWIGHT. BULLETIN No. 148 (Berkeley, October, 1902.) SACRAMENTO: W. W. SHANNON, SUPERINTENDENT STATE PRINTING. 1903. BENJAMIN IDE WHEELER, Ph.D., LL.D., President of the University. EXPERIMENT STATION STAFF. E. W. HILGARD, Ph.D., LL.D., Director and Chemist. E. J. WICKSON, M.A., Horticulturist, and Superintendent of Central Station Grounds. W. A. SETCHELL, Ph.D., Botanist. ELWOOD MEAD, M.S., C.E., Irrigation Engineer. R. H. LOUGHRIDGE, Ph.D., Agricultural Geologist and Soil Physicist. {Soils and Alkali.) C. W. WOODWORTH, M.S., Entomologist. M. E. JAFFA, M.S., Assistant Chemist. (Foods, Fertilizers.) G. W. SHAW, M.A., Ph.D... Assistant Chemist. (Soils, Beet-Sugar.) RALPH E. SMITH, B.S., Plant Pathologist. GEORGE E. COLBY, M.S., Assistant Chemist. (Fruits, Waters, Insecticides.) LEROY ANDERSON, M.S.A., Animal Industries, San Luis Obispo. A. R. WARD, B.S.A., D.V.M., Veterinarian, Bacteriologist. E. H. TWIGHT, B.Sc, Diploma E.A.M., Viticultunst. E. W. MAJOR, B.Agr., Dairy Husbandry. A. V. STUBENRAUCH, M.S., Assistant Horticulturist and Superintendent of Substations. WARREN T. CLARKE, Assistant Field Entomologist. H. M. HALL, M.S., Assistant Botanist. C. A. TRIEBEL, Ph.G., Student Assistant in Agricultural Laboratory. C. A. COLMORE, B.S., Clerk to the Director. EMIL KELLNER, Foreman of Central Station Grounds. JOHN TUOHY, Patron, >• Coast Range Substation, Paso Robles. . Tulare Substation, Tulare. JULIUS FORRER, Foreman, R. C. RUST, Patron, ) >■ Foothill Substation, Jackson. JOHN H. BARBER, Foreman, ) S. D. MERK, Patron, J. H. OOLEY, Workman in charge, S. N. ANDROUS, Patron, ) i Pomona. >• Southern California Substation, - J. W. MILLS, Foreman, ) ( Ontario. V. C. RICHARDS, Patron, ) Y Forestry Station, Chico. T. L. BOHLENDER, m charge, ) ROY JONES. Patron, ) V Forestry Station, Santa Monica. WM. SHUTT, Foreman, ) The Station publications (Reports and Bulletins) will be sent to any citizen of the State on application, so long as available. RESISTANT VINES AND THEIR HYBRIDS. GENERALITIES REGARDING RESISTANT VINES. (Abstract from Bulletin No. 131, by F. T. Bioletti.) The most satisfactory method of combating phylloxera is the use of resistant vines, because it is applicable to all conditions and is the most economical in the end. A resistant vine is one which is capable of keep- ing alive and growing even when phylloxera are living upon its roots. Its resistance depends on two facts: first, that the insects do not increase so rapidly on its roots; and second, that the swellings of diseased tissue caused by the punctures of the insects do not extend deeper than the bark of the rootlets and are sloughed off every year, leaving the roots as healthy as before. The wild vines of the Mississippi States have evolved in company with the phylloxera, and it is naturally among these that we find the most resistant forms. No vine is thoroughly resistant in the sense that phylloxera will not attack it at all; but on the most resistant the damage is so slight as to be imperceptible. The European vine ( Vitis vinifera, L.) is the most susceptible of all, and all the grapes cultivated in California, with a few unimportant exceptions, belong to this species. Between these two extremes we find all degrees of resistance, which is expressed by a series of numbers ranging from 20, indicating the highest possible resistance, to 0, indicating the utmost susceptibility. The following table shows the resistance (according to Viala and Ravaz and other authorities) of some of the best known species and varieties: Comparative Resistance to Phylloxera. Species ( Wild Vines). Cultivated Varieties and Hybrids. Vitis rotundifolia 19 Gloire de Montpellier (Riparia). 18 Vitis vulpina (Riparia) 18 Riparia X Rupestris 3309 18 Vitis rupestris 18 Rupestris Martin _ 18 Vitis Berlandieri 17 Rupestris St. George 16 Vitis aestivalis .._ 16 Riparia X Solonis 1616 16 Vitis labrusca 5 Solonis _ 14 Vitis Californica 4 Lenoir .. 12 Vitis vinifera Isabella 5 The degree of resistance necessary for the production of good crops varies with the character of the soil. The resistance expressed by the numbers 16 to 20 is sufficient for all soils. A resistance of 14 or 15 is sufficient in sandy and moist, rich soils, where the vine can readily replace the rootlets as fast as they are destroyed. Fairly successful vineyards have been established exceptionally with vines having a 4 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION. resistance of less than 14, but as the vines become old the lack of resistance is generally shown by a weakening of the vine and a falling off of the crop. Many vineyards in the south of France grafted on Lenoir which formerly bore well, have now to be doctored with injec- tions of bisulfid. For this reason it is advisable to reject all vines with a resistance of 13 or under, especially as vines with greater resistance can now be obtained for practically all conditions. Resistant vines are of two kinds: (a) those which are grown for the grapes they produce, and (b) those which are useful only as stocks on which to graft the non-resistant varieties. The former are called " direct producers" the latter, " resistant stocks" (a) Direct Producers. — When the phylloxera commenced to destroy the vineyards of Europe, the natural attempt was made to replace them with the varieties of vines which had proved successful in the United States, where the insect was endemic. These varieties, however, all proved unsatisfactory. Some, like the Concord and the Catawba, were insufficiently resistant, and although they could be grown where the severe cold of winter impeded the prolificness of the phylloxera, they quickly succumbed in the milder grape-growing sections of Europe.* Most of them were poor bearers compared with the prolific European vines, and finally the character of their fruit differed so widely from what Europeans were accustomed to that there was little sale for the fruit, and the wine could compete with only the very poorest quality of Vinifera wines, and brought a very inferior price. A few of the varieties introduced during that first period are still grown to a limited extent in France, chiefly the Othello and the Lenoir. They are being gradually abandoned, however, as their crops are unsatisfactory, and in many localities can be maintained only by the aid of injections of bisulfid. For some years the search for a suitable direct producer was almost abandoned by practical men, the use of resistant stocks having been so fully successful. Lately, however, renewed efforts have been made and several new direct producers are being advocated and planted to some extent. The merit of these new varieties, however, is chiefly their resistance to Peronospora and Black Rot. Phylloxera-resistance is con- sidered of much less importance by their most ardent advocates, and indeed the advice is given to graft some of the best of these direct pro- ducers upon phylloxera-resistant stock. The main importance of these facts to California grape-growers is that they hold out hopes of perma- nent prosperity for the wine-making industry here, where, owing to the dryness of the climate, there is no likelihood of trouble from these serious fungous diseases of the grape, which threaten to make the grow- ing of Vinifera varieties impossible in many parts of Europe. *In California, these and other Labrusca varieties and hybrids resist very little longer than Vinifera vines. RESISTANT VINES. O (b) Resistant Stocks. — Though high resistance to phylloxera is essential in a grafting stock, there are other characteristics equally necessary. The Rotundifolia (Scuppernong), which has the highest resistance of any vine, is useless as a stock on account of the impossibility of grafting it with any Vinifera variety. This is due to a lack of affinity, which means a lack of similarity in structure and composition between the tissues of the stock and those of the scion. This lack, in extreme cases, results in an imperfect and temporary union, but when not excessive, only in a slight decrease of vigor. The affinity is not perfect between Vinifera varieties and any resistant stock, but in the case of Riparia and Rupestris is generally sufficient to insure permanence to the union, and the slight decrease of vigor consequent often results in an increase of fruitfulness. It is for this reason that certain varieties when grafted on resistant stocks, especially on Riparia, often bear larger crops than when grown on their own roots. Not all varieties of Vinifera have the same affinity for the same stock. For this reason it is desirable to be cautious about making new or untried grafting combinations on a large scale. Some varieties, such as Carignan, Petite Sirah, Clairette, and Cabernet Sauvignon, do excellently on all stocks; while others, such as Mondeuse and Gamay, do not make a very good union with any of the thoroughly resistant stocks. The Petit Bouschet and Cinsaut make very poor unions with any variety of Riparia, but do fairly well on Rupestris St. George. The Pinot Noir makes a vigorous growth upon Rupestris St. George, but bears much more proliflcally upon Riparia Gloire. Selection. — A very serious defect of many resistant stocks is a slender habit of growth. This is true of most of the vines found growing wild, and cuttings from such vines make poor grafting stock for the stout Vinifera varieties, which will produce a trunk four inches in diameter while the stock is growing only two inches. This is particularly true of the wild Riparias. For this reason great care has been exercised in selecting the stronger-growing forms, and at present we have selected Riparia varieties which almost equal Vinifera in the stoutness of their trunks. The best of these are the Riparia Gloire de Montpellier and the Riparia Grande Glabre, the first of which has given the best results in California. RESISTANT VINES AND THEIR HYBRIDS. By E. H. TWIGHT. If we study the conditions affecting the adaptation of resistant vines, we see that the amount of lime contained in the soil, the degree of com- pactness, the moisture, and the fertility of the land are the most important factors. The proportion of lime in the soil has been, in many countries and particularly in France, the greatest drawback in 6 UNIVERSITY OF CALIFORNIA — EXPERIMENT STATION. re-establishing vineyards on resistant stock. Happily, in California we do not have to contend with that part of the problem, as few soils con- tain enough lime to affect even the Riparias and Rupestris, that are among the first to suffer from excess of carbonate of lime. The compactness of the soil, generally due to the large proportion of clay it contains, is an obstacle to the good growth of many varieties of resistant stock; the roots do not penetrate easily, the ground is cold and often wet, and under such conditions the Rupestris and Riparia, for instance, do poorly. On the contrary, the Lenoir, Champini, Riparia X Rupestris No. 3306 and 101 u will do well in such locations, and the hybrids of Solonis X Cordifolia X Rupestris will do still better. The last-mentioned have a higher resistance to phylloxera than Lenoir and Champini. If we examine the probable cause for the special adaptation to heavy soils, we see that whereas the Riparia and Rupes- tris have light, thin, hard roots very much ramified: on the contrary the varieties adapted to such soils have strong, fleshy roots, less ramified, with a heavier hair system on the rootlets. When in excess, the moisture in the soil affects the vine by checking the growth of the root system. Plants growing in a very moist place may have a vigorous aerial growth, but the root system is generally weak; such a plant will suffer greatly if for some reason the supply of moisture should fall below the average. The root system in a dry exposure will always be much more vigorous, as the plant has to send its roots lower down to find the water it needs. On the other hand, a moist soil will help a vine in its fight against phylloxera, and under such conditions some stocks, though inferior in absolute resistance, may do fairly well. As a general rule, the Solonis and its hybrids are very good in wet soils. The fertility of the soil is a condition of adaptation that we must not overlook: A Riparia or a Solonis will turn yellow and look sick in a soil where a Rupestris would do fairly well. This does not mean that a Rupestris will not do better in a good soil than in a poor one, but simply that it is more rustic in its adaptation. VARIETIES OF RESISTANT STOCK. We give below the adaptation of the principal varieties of resistant vines used as grafting stock or as parents in the making of hybrids. (Riparia, Rupestris, Candicans, Cordifolia, Monticola, Arizonica, Cali- fornica, Berlandieri.) Vitis riparia. — The V. riparia (see title-page) is very resistant to phylloxera (18).* The grafts made on this stock are fructiferous, vigorous, and advanced in maturity. All varieties root readily from ♦Resistance to the phylloxera is indicated by figures on the scale of 20 points. RESISTANT VINES. / cuttings and from grafted cuttings; they also take easily from field grafts. This stock has often been over-boomed, and planted in many localities where it could never grow; and from these failures some people have jumped to the conclusion that the stock is of no value. But when we consider that in France alone, seventy-two per cent of the vineyards that have been replanted are on Riparia roots, we readily see that the failures must be due to the ignorance of the conditions of adaptation. Riparias do not grow well in dry locations; they must have a good loamy soil, the best being clayey-siliceous alluvions; a deep, cool, fertile PLATE 1. Vitis Rupestius St. George. Showing on the right the natural fold of the leaves along the mid rib, and on the left the bracket-shaped petiolar sinus. soil, not too wet. The two varieties mostly used are the Riparia Gloire de Montpellier and the Riparia Grande Glabre. Vitis rupestris. — This vine, shown in Plate 1, is found in its wild state in open places along hillsides and ravines in the arid eastern part of the region, growing in gravels and in decomposed rocks. From this natural 8 UNIVERSITY OF CALIFORNIA — EXPERIMENT STATION. habitat we may see that it will be well adapted to light gravelly soils, hillsides, and sandy soils. It is very resistant to phylloxera (16-18). The Rupestris vines have a larger trunk than the Riparias and show, after grafting, less difference between the scion and stock. The cuttings root easily, but not quite as well as those of Riparias; the rooting can be aided by scratching the bark of the lower part of the cutting on a short-tooth iron comb. The returns in bench-grafting are about the same as those obtained with Riparia. As the Rupestris cuttings sucker very much, it is of great importance to suppress carefully the eyes on PLATE 2. Vitis Candicans. Mustang Gkape. Showing the entire orlobed leaves with the limb convex on the upper face. Three of the leaves are turned over, showing the very thick, white felt on the under face of the leaves. the stock when bench-grafting. Of the two varieties that are mostly used, the Rupestris Martin is possibly a little better adapted to dry locations. The Rupestris St. George, though well adapted to gravelly hillsides and light soils, has proved also, in the last few years, to be a vigorous grower, even in lands where the water-table is close to the surface several months in the year. (Letter from Prof. L. Ravaz.) Vitis candicans. — The V. candicans, or Mustang grape (Plate 2), found in its wild state in Texas and Arkansas, grows generally on bottom RESISTANT VINES. 9 lands and along rivers, but it is also found in very dry locations; in these, however, its growth is not as vigorous. It does best in alluvial soils, but its large roots enable it to grow well in heavy clays. This variety is hard to grow from cuttings, but is very valuable in hybridization. Vitis cordifolia. — This vine is adapted to the same class of soils as the V. riparia; it is very highly resistant to phylloxera, and does fairly well in heavy soils; it has been also used to great advantage in creating hybrids. PLATE 3. V. Arizonica. Vitis arizonica. — This vine (Plate 3) is found mostly in Arizona and New Mexico, while numerous hybrids of Arizonica X Californica exist in the region where both varieties grow wild. It grows well from cuttings, is nearly as resistant as Rupestris, and ought to be studied carefully. In adaptation it would hold a place between the Riparia and the Rupestris. 10 UNIVERSITY OF CALIFORNIA — EXPERIMENT STATION. Vitis monticola. — This vine has only a limited range -of distribution in Texas, where it is found on lands similar to those where the Rupes- tris grows, but containing generally a high percentage of lime. It comes next to the Berlandieri as a resistant to chlorose, which is caused by excess of lime in the soil. This stock is a very good element in hybrid- izing, and may turn out to be very valuable as a direct grafting stock. Vitis calif ornica. — The wild native vine of California; it has a resistance to phylloxera too low to be of much use. Vitis Berlandieri. — This vine is found in Texas, New Mexico, and Mexico, growing on limestone ridges, where it resists excessive drought and heat. The quality of resistance to lime would not be of much interest in California, but it may prove to be a very valuable stock in heavy, dry soils, as probably its large fleshy roots will allow it to penetrate readily. Though the Berlandieri does not grow well from cuttings, its hybrids have not that drawback. From these few remarks on the principal resistant stocks we may see that the range of adaptation of each variety is rather narrow. This observation led the nurserymen and the experiment stations in the countries mostly interested, to try to obtain, by hybridizing, new varieties having a wider range of adaptation. This has been done with two different objects in view. Some simply crossed the American resistant varieties to obtain new grafting stocks having a larger range of adaptation; we will call these Americo X American hybrids. Others tried to cross the American resistant stocks with the Vinifera-producing varieties, to obtain a resistant direct producer; we will call these Vinifera X Americans. So far the latter have only succeeded in making some good grafting stocks, the bearing qualities of the Vinifera not being transmitted. AMERICO X AMERICAN HYBRIDS. Mr. Munson, in the United States, and a great number of scientists in Europe (Couderc, Millardet, Grasset, Foex, Ravaz) have created a large number of new hybrids, some of the most promising of which we will review. Riparia X Rupestris. — This group is probably one of the most inter- esting. Among the varieties selected as the best at present we find Nos. 3306 and 3309 of Couderc and No. 101 u of Millardet. They are very resistant to phylloxera, root easily from cuttings, and give a high percentage of good grafts. The trunk increases rapidly in size, so that there is little difference between stock and scion; the fructification after grafting is good and regular. The range of adaptation is a combination RESISTANT VINES AND HYDRIDS. 11 of that of Riparia and of Rupestris; Nos. 3306 and 101 u being also able to do well in soils a good deal more compact in nature than those suitable for either of the parents; No. 3309 stands drought well. Solonis X Riparia. — These hybrids are well known for the heavy- bearing character they communicate to their grafts. The affinity is very good and they are particularly well adapted to wet lands. While adapted to the same soil-conditions mentioned above for the Solonis, they have a much higher resistance to phylloxera than the latter. The best known are Nos. 1615 and 1616 (Couderc). Solonis X Cordifolia X Rupestris. — These have great vigor, which they hold from the Cordifolia X Rupestris, while they take some of the characters of the Solonis in moist locations. They have proved very valuable in heavy moist clays. No. 202* of Millardet and Grasset is among the best. Riparia X Cordifolia X Rupestris (No. 106 8 ). — Is very similar to the last group regarding its vigor, but is adapted more particularly to very arid locations, where it has proved superior even to the Rupestris Martin. It will probably be of great value in some of our adobe lands. Berlandieri X Riparias. — These hybrids have been studied in France, mainly to create a stock having the resistance of the Berlandieri to chlorose, and the easy rooting of the Riparias. Some of the selections have given very satisfactory results (157, 420, 34E). The Berlandieri hybrids are very productive after they have been grafted. The roots are very strong and both surface and deep roots are abundant; as we said before, this hybrid may prove to be very valuable in stiff, dry soils. VINIFERA X AMERICAN HYBRIDS. Lenoir. — Though the question of the origin of the Lenoir is not very well settled, it probably comes in this group of Vinifera X American. The Lenoir has a great affinity for the Viniferas, so that when grafted in the field it gives very good results. It does not root as well from cuttings and does not bench-graft as well as the Riparias and Rupestris, but still gives satisfactory results. The resistance to phylloxera is not high (12-13), which is too low unless it is planted in a soil perfectly adapted to its growth. In rich soils, fertile, and with plenty of moisture, it does very well, but these are also good Riparia soils. When the soil becomes compact, then the Lenoir would do better than the Riparia. But for these heavy lands we have to-day such varieties as the Solonis X Cordifolia X Rupestris, the Riparia X Cordifolia X Rupestris, the Riparia X Rupestris 101 u , which are far superior to the Lenoir in resistance, and ought therefore to receive the preference. 12 UNIVERSITY OF CALIFORNIA — EXPERIMENT STATION. Mourvedre X Rupestris or Mataro X Rupestris is a very fine selection of Vinifera X American; the 1202 grows well in all soils from a chalky land to a deep alluvial one. It has been found quite resistant to phylloxera, and particularly well adapted to heavy clay soils. Bourrisquou X Rupestris and Carignane X Rupestris have also a large range of adaptation, but are specially adapted to dry locations. Aramon X Rupestris (1 and 2) are found to do splendidly in clay soils of medium fertility and in soils underlaid with clay. We have a great many of these soils in California, and this stock may prove to be of great value. The roots are superficial, like those of the Riparias, but they are large and fleshy. MUNSON HYBRIDS. Mr. Munson has created, in recent years, a great many hybrids of Americo X Americans and of Vinifera X Americans; some of these are quite promising, but the local results that have been published at different times can not be taken as final proof of their value. We have not yet sufficient data to give personal observations on these, but will give the opinion of Professors Viala and Ravaz, the French viticultural authorities, on some of the Munson resistant stocks. Vitis champini (Candicans X Rupestris). — Can be divided in two groups: the glabrous and the tomentose. The glabrous group has a resistance of 14, the tomentose of 12. They are harder to grow from cuttings than the Rupestris, but have the advantage of being good growers in heavy clays and of having large wood. Their low resistance is, however, a grave objection, especially when we have some varieties that do just as well in the same locations and which are much more resistant. Candicans X Monticola (Gwyn, Sanford, Belton).— The latter is prob- ably the best; it has a resistance of 16, is very vigorous, has a large trunk, does well in compact soils, and has large wood, but does not grow well from cuttings. Novo-Mexicana. — This is probably a Candicans X Riparia X Rupes- tris. The Solonis, Moobetie, Hutchison, and Doaniana are some of the varieties of this group. They are adapted to Solonis soils; that is, rich, with plenty of moisture. They do well in lands that are rather wet and salty (alkali). They grow well from cuttings and have good-sized wood. The resistance to phylloxera is not first class, but is sufficient in soils well adapted to them. In lands not well adapted, they suc- cumb rapidly to the attacks of the insect. The Hutchison is more vigorous and resistant; the Solonis and Doaniana less so. RESISTANT VINES AND HYBRIDS. 13 RESPECTIVE VALUE OF AMERICO x AMERICANS AND VINIFERA x AMERICANS. We have seen that in both of these groups of hybrids we may find some varieties that are well adapted to our special conditions; in both, we find a good resistance to phylloxera in the selected stock. Which of these should we plant in our vineyards? It may be said in a general way that the Americo X American hybrids, as well as the ordinary American grafting stocks, make the Vinifera scions that are grafted on them bear more heavily than they would if they were on their own roots. They come into full bearing earlier, and generally the fruit will ripen a few days earlier. But the variety of Vinifera grafted on these roots does not reproduce exactly the type it represents when on its own roots: the grapes may be larger, but there is a slight difference in the flavor and the per cent of sugar. The Vinifera vines grafted on Vinifera X American hybrids retain better their original qualities and have a better affinity between stock and scion. The heavy bearing of the vines grafted on Americans or on Americo X American will exhaust the land sooner; so that fertilizing will have to be resorted to earlier, and it is a known fact that heavy fertilization affects the quality of the grapes. From these remarks we may conclude that the American resistant stock and their hybrids will probably be favored by those who look to quantity more than to quality; while for the fancy wine grapes and the better grades of table and raisin grapes the Vinifera X American resistant stock will be chosen. The choice between the two groups is mainly an economic question. A warning must be given regarding the selection of the stock. We find hundreds of thousands of hybrids of each kind, but only very few have been carefully selected. Because the Riparia X Rupestris 3306 or 3309 are good, it is by no means a reason for any " Riparia X Rupestris" to be equally good. The number of the selection is as important, and in fact more important, than the name of the stock.