STEPHEN J. KREBS

PHYLLOXERA BIOLOGY AND LIFE CYCLE The phylloxera, Daktulosphaira vitifoliae (Fitch), (: Homoptera: ), is an aphid-like that attacks the roots and the leaves of in the genus . It was first described in 1854 from in New York State by Asa Fitch, who named the insect Pemphigus vitifolii. It was then reclassified into the genus Phylloxera (Mayet, 1894) but because the grape phylloxera differs morphologically from other phylloxera species it was re-assigned to its own genus. Outside the , Viteus is an accepted synonym for the older term Daktulosphaira. Numerous other names appear in the literature (Russell, 1974). The basic biology of phylloxera was established in the 1870s by C. V. Riley, State Entomologist in Missouri (Riley, 1871, 1872, 1873, 1874, 1876). He found that in its native North American range and in other summer-humid climate areas, phylloxera has a complex life cycle, feeding on both the root system and the aerial portion of the (Figure 1). The root feeding forms are all oviparous parthenogenic females. Some of the eggs these females produce are pre-destined to become winged adults. In their fourth instar the alates emerge from the soil and molt to the winged type. In this form they are highly mobile (Riley, 1876). The winged adult, which does not feed, lays eggs that hatch into male and female . These males and females, which also do not feed, molt four times, mate and produce the so-called winter egg. Only fundatrix females hatch from the winter eggs, their feeding inducing galls to form on the vine leaves. They develop and lay eggs which will produce females. The offspring of the fundatrix females eventually exit from the galls to form new galls. Some may return to the soil to live on the roots. Infestations are spread by both the movement of the winged form above ground in regions where they are fertile, and by the crawler form, a first instar female that can move short distances above or below ground (Riley, 1874) or, when they are above ground, short or long distances in wind (Granett, personal communication, 1995). Riley confirmed that the insect damaging vines in and California was the same phylloxera native to the eastern United States (Riley, 1872; Appleton, 1880; Ordish, 1987). He also confirmed that American Vitis species were resistant to phylloxera and were seldom killed by the insect (Riley, 1880). In California and other dry-summer climates, the phylloxera life cycle is truncated. The insect is found on the roots as an oviparous parthenogenic female. The development of the winged form is often observed under these growing conditions, but it is not known to be fertile and therefore no sexual forms or winter egg is produced and there is no leaf-galling. The lack of the sexual cycle is thought to limit the genetic diversity of the phylloxera population (Davidson and Nougaret, 1921). 2 S- PHYLLOXERA Daktulosphaira vitifoliae (Fitch)

WINTER EGG

SEXUAL FORMS 2/ TO LEAVES

LEAF WINGED GALLIN FORM

C WLER DISPERSAL TO OTHE

DI SPERSAL TO OTHER LEAVES AND TO ROOTS NYMPH 41 WITH FORMING ROOT WINGPADS SWELLING CYCLE

CRAWLER D SPERSAL TO OTHER ROOTS

Phylloxera is the most serious insect pest of the grapevine. The active root stage of the insect is known as the radicole and its feeding results in the formation of nodosity and tuberosity root swellings. Several parthenogenic female radicole generations are produced during the active growth of the vine. Crawlers of the radicole form migrate above and below ground to the roots of other vines. The overwintering root form is called a hibernant and does not feed. The emerging nymph with forming wingpads becomes the winged migratory adult female, called an elate. The sexual forms develop from eggs laid by the alate. Mating of the sexual forms produces the winter egg, which hatches into the fundatrix female. The fundatrix migrates to new leaves in the spring and feeds on the leaf tissue, causing leaf galls to form. The egg of the fundatrix hatches into the gallicole female, which forms additional galls and several more parthenogenic generations are produced during the active growth of the vine. The gallicole may migrate to other leaves, or to roots where a new radicole cycle is initiated.

(Illustration © 1994 by R. Krebs James. Text ° 1994 by S. Krebs.) 3

Phylloxera may damage grapevine roots by feeding on either new root tips or on older root tissue. Feeding on new root tips causes a small gall called a nodosity to develop at the feeding site. Feeding on older roots causes the formation of an abnormal roughened swelling called a tuberosity. The formation of tuberosities is more serious because it leads to the decomposition and death of the damaged root (Millardet, 1892).

Phylloxera damage to the roots of the grapevine results in a general weakening and the eventual death of susceptible plants. Vegetative symptoms include reduced cane growth, short internode length, an absence of actively growing shoot tips in the spring and premature leaf fall. Crop is reduced because the berries are small and few clusters are produced. The symptoms become increasingly severe over several seasons. In the field, a circular pattern of decline radiating from the point of first infestation may occur (Riley, 1874; Bioletti, 1901; Davidson and Nougaret, 1921; Husmann, 1910).

In phylloxera coevolved with the indigenous Vitis species. The resistance developed by some American Vitis species limits the root damage caused by the insect. Different levels of resistance to both leaf and root damage are found among the Vitis species (Riley, 1874; Millardet, 1892; Viala and Ravaz, 1903; Boubals, 1966). has susceptible roots but is resistant to leaf galling (Wapshere and Helm, 1987). It is the species from which most commercial grape cultivars have been selected. Accidental importation of phylloxera led to the catastrophic destruction of V. vinifera vineyards throughout Europe, California and most other world viticultural regions in the late nineteenth century (Stevenson, 1985; Ordish, 1987). It is the most important insect enemy of the grapevine worldwide.

PHYLLOXERA INTRODUCTION INTO EUROPE AND ELSEWHERE The introduction of phylloxera into Europe probably occurred on American vines used in and hybridizing experiments for the control of powdery mildew (oidium), , which had been accidentally brought into Europe in the mid-1800s from North America (Hewitt, 1988). The knowledge gained from this work was later applied to the control of phylloxera (Ordish, 1987).

Phylloxera was found on the roots of grapevines in southern France in 1868 (Planchon, et al., 1868). Based on vine decline symptoms that had been previously noted there, the actual introduction into France probably occurred in the Rhone Valley around 1862. The insect spread very rapidly and soon had devastated the industry in much of the country (Stevenson, 1980). 4

In other European countries, phylloxera was found at about the same time. In Portugal, the first discovery of the pest occurred in 1862. It had spread through the Douro region by 1872 and was found in most other districts by 1880 (Bleasdale, 1880; Morrow, 1973). In Spain, the discovery of phylloxera occurred in 1876 in the Mediterranean district of Malaga and infestation had become general in the country by 1888. In Italy, phylloxera was probably present by 1870. In Germany, the first damage occurred in 1875 (Ordish, 1987). In Great Britain, phylloxera was discovered in 1867 (Stevenson, 1985). Other European countries infested with phylloxera include Turkey, Austria, Hungary, Switzerland, , Greece, Cyprus and Yugoslavia (Branas, 1962; Daris, 1970; Ordish, 1987). In Asia, phylloxera is present in Korea and in Japan. In Central America, the insect is found in Mexico (Anonymous, 1975).

Phylloxera was also introduced into viticultural regions of the Southern Hemisphere in the nineteenth century. The insect was first detected in Australia in 1875 (Adcock, 1914; Buchanan, 1987). The introduction into New Zealand occurred in 1885 (Dry and Smart, 1982a, 1982b; Smart and King, 1983). In South Africa, phylloxera was discovered in 1886 and is now widely distributed throughout the grape growing regions of that country (De Klerk, 1972). In South America, phylloxera is present in Peru, Brazil and Argentina (Anonymous, 1975). Olmo (19xx) believes it to be native to Venezuela.

Phylloxera created severe economic and social displacement as production declined (Eichel, 1975; Stevenson, 1980; de Blij, 1983; Ordish, 1987; Unwin, 1991). Expensive insecticide applications were devised to control the insect. Carbon bisulfide was the most effective material tested, but its application was labor-intensive and the effects were short-lived. Repeated treatments were therefore required. Many other purportedly insecticidal materials were also recommended, including coal tars, manures, and various fanciful decoctions. None of these were successful in the control of the insect (Bleasdale, 1880). Quarantine methods were generally ineffective in controlling the spread of phylloxera. Growers were warned to practice careful sanitation whenever moving from one vineyard to another, because the insect is readily transported on harvesting bins, on nursery stock and in contaminated soil that becomes attached to vineyard equipment and workers' clothing. The small size of the pest makes detection difficult (Fodx, 1902; Viala and Ravaz, 1903). PHYLLOXERA INTRODUCTION INTO CALIFORNIA Phylloxera was first found on the roots of grapevines in the Sonoma Valley in 1873, at the center of the young industry. It was to this location that many Vitis cultivars had been introduced before being taken to other growing regions in the state (Pinney, 1984). As early as 1860, growers had noted vines with symptoms of phylloxera injury (Appleton, 1880). University of California reports proposed an introduction date of 1858 (Davidson 2 5 and Nougaret, 1921) or 1852 (Smith and Stafford, 1955). The insect may have been brought into California directly from the eastern United States (Davidson and Nougaret, 1921), from contaminated sites in Europe (Bioletti, 1901) or on the roots of the V. vinifera cultivar Mission (Criolla) imported from Mexico (Granett, personal communication, 1994). Multiple introductions from these sources may have occurred. Soon after the discovery of phylloxera in Sonoma Valley, the insect was found in adjacent regions. By 1880, damage to vineyards had become so serious that the California State Legislature passed an act that created the Board of State Viticultural Commissioners and mandated that the University of California develop a department of viticulture. The phylloxera problem was a primary focus of their activities (Borg, 1991).

Both the Board and the University published information on the insect and documented the rapid spread of the infestation. By 1900, phylloxera was present in all grape growing areas north of the Tehachapi Mountains (Bioletti, 1901). The rapid spread of the insect caused severe economic damage to the wine industry in the state (Sullivan, 1981, 1982). Phylloxera has never become a problem in Southern California vineyards, probably because the soils are generally sandy there and inland areas may be too hot for the pest (Granett, et al., 1992).

EARLY CONTROL PRACTICES At first innumerable methods were proposed for the control of phylloxera (Bleasdale, 1880; Wetmore, 1880). The Board of State Viticultural Commissioners in California published summaries of the most important work on the insect at that time. Hundreds of articles were listed that describe the biology, damage and incidence of phylloxera, and possible control practices. Many of these practices involved the application of some material that was purported to have insecticidal properties. The inaccessibility of the insect on the roots made this approach largely impractical. The most successful methods proposed included the planting of grapevines on sandy soils, carbon bisulfide soil treatments, the use of water for vineyard submersion during the winter dormancy period and the use of resistant .

DEVELOPMENT OF PHYLLOXERA-RESISTANT ROOTSTOCKS From 1885, the use of American Vitis vines for phylloxera-resistant rootstocks became the focus of control efforts. American vines were evaluated in Europe for phylloxera resistance and viticultural performance. By comparing the relative development of nodosities and tuberosities on grapevine roots infested with phylloxera, it was found that V. riparia, V. rupestris and V. berlandleri and their hybrids were sufficiently resistant to phylloxera for use in commercial vineyards (Millardet, 1892). Some crosses were made using the susceptible V. vinifera in an attempt to develop direct producer vines that did not require resistant rootstocks. 6 (Millardet, 1892; Fogx, 1902; Viala and Ravaz, 1903). In California, grape growers began to use the resistant vines developed in Europe. The first rootstocks planted in California were Lenoir and Herbemont, which are natural hybrids between V. vinifera and American vines (Munson, 1885). These two rootstocks were quickly destroyed by phylloxera. The native grape V. californica was used as a for a short time (Hilgard, 1885a, 1885b, 1886, 1887), but was discarded because of its insufficient phylloxera resistance (Hayne, 1897). Growers also planted unselected seedlings of V. riparia and V. rupestris. Many of these seedling rootstocks had insufficient resistance and were killed by the insect (Hilgard, 1886). Other failures occurred because rootstocks were not well adapted to particular soil conditions (Hilgard, 1887). It became clear that scientific evaluation of rootstocks for California vineyards was essential (Hayne, 1897; Bioletti, 1906; Husmann, 1910).

ROOTSTOCK EVALUATION IN EUROPE AND ELSEWHERE During the late 1800s and early 1900s, thousands of hybrid rootstock cultivars were developed and tested by European breeders, mainly in France (Fogx, 1902; Viala and Ravaz, 1903). The genus Vitis is highly heterozygotic (Olmo, 1976) and phenology is not predictable, so it is necessary to test rootstocks under field conditions before satisfactory recommendations can be made. The results of early French rootstock evaluations and the nature of both specific rootstocks and of general parentage combinations have been summarized by several authors (Hayne, 1897; Fogx, 1902; Viala and Ravaz, 1903). While confirming that the suitable Vitis species for rootstock use were V. riparia, V. rupestris, V. berlandieri and

their hybrids, they warned against the use of V. vinifera -American Vitis rootstock hybrids. Although rootstocks with V. vinifera parentage may be selected which are vigorous, grow on a wide range of soils and are easily propagated, their resistance to phylloxera tends to be unstable. Numerous failures of such rootstocks are cited (Fogx, 1902; Viala and Ravaz, 1903) and the authors state unequivocally that only rootstocks of pure American Vitis parentage can contain a stable resistance to phylloxera. In France, the use of some V. vinifera-American Vitis hybrid rootstocks declined. The V. berlandieri x V. vinifera hybrid rootstock cultivars 41B and Fercal are still widely used there (Galet, 1979; Pongracz, 1983). The low or unstable phylloxera resistance of V. vinifera-American Vitis rootstock hybrids has been confirmed for many rootstock cultivars by field research trials (Bioletti, 1908; Bioletti, et al., 1921; Jacob, 1938; Loomis, 1943; Jacob, 1944; Lider, 1958a), commercial vineyard experience (Bioletti, 1906, 1908, 1920; Perold, 1927; Galet, 1956; Dalmasso, 1968; Galet, 1979; Pongracz, 1983) and in laboratory rating studies (Boubals, 1966; Pastena, 1976; De Benedictis and Granett, 1991). 7 Extensive rootstock testing has been conducted in many other grape growing regions. In Australia, New Zealand and California the V. vinifera-American Vitis hybrid rootstocks have been widely planted (Hardie, 1977; Clarke and Pollock, 1981; Pongracz, 1983; Smart and King, 1983; Whiting, et al., 1987; Whiting, 1991; Southey, 1992). This practice is now changing in these locations.

ROOTSTOCK EVALUATION IN CALIFORNIA At first, California grape growers were completely dependent on rootstock testing performed in Europe, because most of the phylloxera-resistant rootstocks available in California were developed by European breeders (Hayne, 1897). After early failures in the reconstitution of phylloxerated vineyard sites, scientific field trials in California were established to determine which rootstocks were best suited to the soil and climate conditions peculiar to the state. The first United States Department of Agriculture rootstock trials in California were started in 1902 (Husmann, 1910). Over four hundred V. vinifera fruiting varieties and almost three hundred rootstock cultivars were tested in several locations. The rootstocks were inoculated with phylloxera to determine resistance and rated according to their effect on yield and vigor in the scions. The trials continued until 1939 (Husmann, et al., 1939). The AxR#1 rootstock was one of a group of rootstocks recommended in 1910 because it was resistant to phylloxera and induced high vigor and high yield in scion varieties grafted onto it (Husmann, 1910). A similar recommendation for AXR#1 was repeated in succeeding U.S.D.A. reports from these trials (Husmann, 1915, 1930; Husmann, et al., 1939). Additional U.S.D.A. rootstock trials were established in the 1930s at Oakville in the Napa Valley and at Fresno. Both sites were infested with phylloxera. In these trials, rootstocks were judged according to their effect on vigor, yield and fruit quality. Despite its earlier recommendation, AxR#1 was not included in these U.S.D.A. rootstock tests. No reason for this omission was given in the reports of the trials (Snyder and Harmon, 1948; Harmon, 1949; Harmon and Snyder, 1952, 1956; Snyder and Harmon, 1956).

The first University rootstock trial was started in 1900 at the Moffit Vineyard in St. Helena in the Napa Valley. In a report on this trial, Bioletti (1908) stated that all the rootstocks tested were vigorous, although there is no mention of the phylloxera status of the test site. He recommended St. George for dry soils and AxR#1 for compact or wet soils, stating that AxR#1, unlike other V. vinifera-American Vitis hybrids, has sufficient resistance to phylloxera. He also discussed the failure of AxR#1 in some South African vineyards. He suspected the failures were caused by overcropping, but indicated that no really satisfactory explanation for the death of vines there had been proposed. 8 The University began testing rootstocks in 1911 at Davis and at Kearney, measuring the effect of rootstock on scion variety vigor and yield in specific rootstock-cultivar combinations. In 1921, AxR#1 was recommended for limited use by the University because it had produced high yields and high vigor in some of the scion varieties tested. It apparently had good phylloxera resistance, although no mention of phylloxera conditions at the test locations is included in the report (Bioletti, et al., 1921). Starting in 1929, Jacob established University rootstock trials in presumably phylloxerated commercial vineyards, using the most promising stocks from previous tests. Jacob used the V. rupestris St. George rootstock as a standard of comparison at all of these cooperative rootstock trials. He chose this rootstock because it was the most widely planted rootstock in California at that time and because it was considered resistant to phylloxera. Jacob published recommendations for AxR#1 prior to his death in 1949, based on good scion vigor and yield in his trials. He noted that AxR#1 does not have high phylloxera resistance compared to other rootstocks. However, AxR#1 performed well in the trials in spite of its low phylloxera resistance. Jacob felt that no satisfactory rootstock was available for dry conditions, so he reluctantly recommended St. George for these sites (Jacob, 1938, 1944, 1947; Jacob and Winkler, 1950). After the death of Jacob, University rootstock studies were continued by Lider. Rootstock rating criteria were expanded to include several fruit quality factors in addition to vigor and yield. By the mid-1950s, University viticulturists had recommended AxR#1 as an all-purpose phylloxera-resistant rootstock while noting that its phylloxera resistance was relatively low compared to other rootstocks. It became the most widely planted rootstock in the north coast winegrape regions of the state. The St. George rootstock recommendation was continued for dry sites (Lider, 1957, 1958a, 1958b, 1958c, 1959; Lider and Sanderson, 1959; Kasimatis and Lider, 1962; Lider, 1964; Kasimatis and Lider, 1972; Lider, et al., 1973; Kasimatis and Lider, 1981). In 1978 data collected from six of the University rootstock trials established between 1935 and 1941 showed that the AxR#1 vines in these trials were still performing well. The authors were clearly concerned with the possible failure of this rootstock. Although the low phylloxera resistance of AxR#1 was noted, they continued to recommend it for planting in the phylloxerated vineyard soils of California (Lider, et al., 1978). PHYLLOXERA BIOTYPES Insects of a single species may differ in reproduction, survival and development, behavior, host preference and other traits. The term biotype has been used broadly to describe such variations within a species (Russell, 1978). When an insect biotype is partially or completely isolated reproductively from other members 32 9 of the species as a result of adaptation to a particular host, the more specific term host race is used. It may be impossible to distinguish host races morphologically from other insects of the same species (Diehl and Bush, 1984). Biotypes are common in other aphid species (Eastop, 1973; Russell, 1978). The complex life cycle and its long coevolution with Vitis should produce biotypes in phylloxera as well (Riley, 1874; Fergusson-Kolmes and Dennehy, 1991, 1993; Hawthorne and Via 1994). Since phylloxera may injure or destroy susceptible vines, host races are of concern to grape growers. In order to perform well over the normal lifetime of a vineyard a rootstock must have stable resistance to any possible host races. If a genetic weakness in a rootstock permits a new host race to arise, the potential for economic damage is great.

The existence of phylloxera biotypes has been demonstrated in many different locations. As early as 1914, Burner claimed that both morphologically distinct races of phylloxera and strains of the insect that utilized specific rootstock hosts were present in Germany (Burner, 1914). The occurrence of morphologically different phylloxera biotypes has not been substantiated, but the existence of host races has been demonstrated in tests with various rootstocks (Becker, 1988). In South Africa, a new host race on the roots of vines developed around 1912. At first, the AxR#1 rootstock was destroyed by phylloxera only in certain districts and not in others. This failure was initially attributed to dry and infertile soil conditions. When the decline eventually spread to all vineyard districts in South Africa, selectively killing only vines planted on AxR#1, it was clear that a new phylloxera host race had arisen on that rootstock (Perold, 1927; De Klerk, 1979). Host races of phylloxera occur also with the leaf galling form of the insect. In , seven local phylloxera populations were collected from leaf galls and placed on the leaves of several Vitis cultivars. The differential leaf galling reaction that occurred with the cultivars tested showed that at least two phylloxera biotypes existed there (Stevenson, 1970).

The occurrence of host races in France was confirmed in a laboratory root segment study using phylloxera populations obtained from the roots of the V. vinifera cultivar and rootstock cultivars 41B and 3309 (Song and Granett, 1990). These phylloxera populations were tested on the roots of V. vinifera cultivar Cabernet Sauvignon and the rootstocks 41B, 3309 and St. George. The authors concluded that host races existed because differences in survivorship were found among the populations. This result was in contrast to findings in California with phylloxera biotypes A and B, which differed in fecundity and in developmental rate, but not in survivorship (Granett, et al., 1985). This could 33 10 indicate variations in rootstock resistance mechanisms. Evidence of phylloxera host races was discovered in a potted vine experiment conducted in New Zealand. Phylloxera populations from Germany and New Zealand were placed onto the roots of the V. vinifera cultivar MUller-Thurgau and five rootstock cultivars. Leaf galls, root nodosities and root tuberosities occurred with MU ller-Thurgau. Although leaf galls and root nodosities were produced on rootstock cultivar 420A, root tuberosities, which cause root death and vine decline, did not occur. These results indicate that a host race suitable for those vines was present among the phylloxera populations used in the experiment (King and Rilling, 1985, 1991). In Ohio, separate leaf gall populations of phylloxera from the cultivars and Concord were tested on the leaves of both cultivars. The Clinton phylloxera colonized only the leaves of Clinton, while the Concord phylloxera colonized the leaves of both cultivars, indicating that these were separate biotypes. Other cultivars exposed to the Clinton and Concord phylloxera populations were susceptible to only one of the biotypes. The differences between the two phylloxera biotypes were consistent with electrophoretic tests (Williams and Shambaugh, 1987), although multiple populations of each biotype were not tested. In a trial conducted at Cornell University, phylloxera populations were collected from wild vines from a broad section of the eastern United States. In laboratory root segment tests using the V. vinifera cultivar Cabernet Sauvignon, some of these insect populations could not survive. Those that did survive were also tested with AxR#1 root segments. Some of these populations were more successful on the roots of AxR#1 than on the roots of Cabernet Sauvignon. The researchers concluded that biotypes in eastern phylloxera populations differ from phylloxera found in California. Additional root segment tests and potted trials comparing twelve New York phylloxera populations with California phylloxera biotype A confirmed that different biotypes existed in the two states (Fergusson-Kolmes and Dennehy, 1991, 1993). The existence of phylloxera host races adapted to specific rootstock cultivars was demonstrated in an experiment that used phylloxera from the roots of wild and cultivated grapevines. Life tables were developed for wild grapevine phylloxera populations by culturing the insects on AxR#1 and Cabernet Sauvignon roots. Overall performance by these phylloxera populations on AxR#1 was equal to or greater than their performance on Cabernet Sauvignon roots. When these phylloxera populations were cultured on the roots of AxR#1 and Cabernet Sauvignon, the phylloxera from commercial vineyards showed greater overall performance on Cabernet Sauvignon than the phylloxera from wild grapevines. Phylloxera from commercial vineyards had greater performance on Cabernet Sauvignon than on AxR#1. There was no difference between the 11 performance of the phylloxera from the wild vines and the commercial vineyards on AxR#1. The results of these trials indicated that there is genetic variation among phylloxera populations and that phylloxera in commercial vineyards has adapted to the particular cultivars used by growers (Hawthorne and Via, 1994).

In California, only the root form of phylloxera occurs. A 1964 University of California test for the presence of phylloxera biotypes was conducted using V. vinifera x V. (Muscadinia) rotundifolia hybrids. Phylloxera was collected from five sites in the state and grown on the roots of these vines to determine if phylloxera biotypes existed. No evidence of different California biotypes was found in this experiment (Davidus and Olmo, 1964).

More recently, a series of experiments has demonstrated that at least two phylloxera biotypes are present in California vineyards. These biotypes have been designated phylloxera biotypes A and B, and are identified by their differential ability to colonize the AxR#1 rootstock. Research now in progress on phylloxera populations collected from the roots of other rootstock cultivars indicates that many more host races exist in the state and that biotypes A and B actually each consist of a number of genetically distinct strains (Granett, personal communication, 1994).

In the first experimental report on phylloxera biotype B in California, the decline of vines grafted on the AxR#1 rootstock caused by a phylloxera infestation in a Rutherford, Napa Valley vineyard was investigated. Laboratory root segment studies using V. vinifera cultivar Cabernet Sauvignon and the rootstocks AxR#1 and St. George indicated differences in developmental rate and fecundity between the two biotypes. In the laboratory, Cabernet Sauvignon was a suitable host for both phylloxera biotypes. The AxR#1 rootstock was a suitable host only for biotype B. The St. George rootstock did not support either biotype (Granett, et al., 1985). Field trials to determine rootstock resistance were started in 1984 at the Rutherford vineyard. Further root segment tests confirmed the host suitability of AxR#1 for biotype B (Granett, et al., 1987).

Laboratory tests demonstrated that two AxR#1 selections (AxR#1-01A and AxR#1-05) were both suitable hosts for biotype B. A field survey of biotype distribution conducted in fifteen counties in the state found only biotype A and biotype B. However, this result occurred because only own-rooted V. vinifera and vineyards grafted on AxR#1 were included in the study, and therefore only host races relative to the AxR#1 rootstock were collected. (Granett, et a/., 1991).

In a more extensive survey of California vineyards, 118 phylloxera colonies were collected from vineyards grafted to the AxR#1 rootstock. When these phylloxera populations were reared on AxR#1 12 root segments in the laboratory, again only phylloxera biotypes A and B were detected. From bioassays the authors concluded that for California phylloxera there is a common ancestral type, and that biotype B resulted from a mutation in biotype A (De Benedictis and Granett, 1991). FAILURES OF THE AxR#1 ROOTSTOCK The rootstock cultivar AxR#1 was developed by the French grape breeder Victor Ganzin in 1879 from a cross between the V. vinifera cultivar Aramon noir and the V. rupestris selection Rupestris Ganzin (Pongracz, 1983). Ganzin believed that all of his Aramon-V. rupestris hybrids had complete immunity to phylloxera (Millardet, 1892). Viala and Ravaz (1903) found that tolerance was the actual resistance mechanism of these hybrids in France. One of the first reported failures of this rootstock occurred in 1909 in Sicily, where it was killed by phylloxera. Researchers there concluded that AxR#1 lacked phylloxera resistance in that region (Richter, 1909; Rossi, 1954). A major failure of AxR#1 occurred in South Africa during the period of 1900 to 1925. The damage was initially ascribed to a lack of phylloxera resistance on poor soils (Cillie, et al., 1920) or overcropping (Bioletti, 1908). However, large phylloxera populations were noted on the roots of AxR#1 even in very fertile soils. The failure was then attributed to a new phylloxera host race in South Africa (Perold, 1927). At this time V. vinifera- American Vitis rootstocks were disappearing from other viticultural regions and the recommendation of AxR#1 in South Africa was withdrawn (van Niekerk and Theron, 1927). The use of AxR#1 continued only in California, Australia and New Zealand (Pongracz, 1983). The first failure of the AxR#1 rootstock in California was detected in 1983 near Rutherford in the Napa Valley and at a few other sites. Testing showed that biotype B phylloxera was present at these sites (Wolpert, 1988). The spread of biotype B to other AxR#1 vineyards has been rapid. By 1993, over 16,000 acres in the north coast districts had become infested (Weber, 1994). SOIL EFFECTS ON ROOTSTOCK PERFORMANCE The effect of soil type on phylloxera infestation was noted soon after the insect appeared in Europe. By 1874, it was discovered that vines growing in sandy soils low in clay in southern France were not affected by the insect, even though the surrounding region was generally infested (Bleasdale, 1880). It is believed that in soils with a high clay content, small passages are created when the soil dries and shrinks. This permits the insect to move along vine roots and to migrate through the soil. Soils with a sand content over sixty percent do not support phylloxera populations in the field. (Nougaret and Lapham, 1928; Smith and Stafford, 1955). 13 Soil conditions also directly affect the growth of the vine. Rootstock performance as related to soil depth, fertility and moisture content has been widely documented (Fogx, 1902; Viala and Ravaz, 1903; Bioletti, 1906, 1908; Bioletti, et al., 1921; Nougaret and Lapham, 1928; Galet, 1979; Pongracz, 1983). Many reports have indicated that rootstocks with relatively low phylloxera resistance perform well on very deep, moist, fertile soils. Under conditions of favorable soil type where these observations were made, apparently the vines produce enough root growth to mitigate phylloxera damage (Twight, 1903; Bioletti, 1908; Bioletti, et al., 1921).

WATER EFFECTS ON ROOTSTOCK PERFORMANCE The role of water in the management of phylloxera and phylloxera damage may be separated into two general effects. The first is a direct effect on the insect by the exclusion of air from the soil. The second is the indirect effect on phylloxera by the role water plays in vine stress and growth.

Vineyard submersion during the dormant season was used successfully in the nineteenth century to control phylloxera. However, this method is not widely applicable because it can only be used in level vineyards planted on dense soils where large amounts of water are available. A long period of submersion is required because phylloxera is well adapted to wet soil conditions (Bleasdale, 1888; Mayet, 1894; Hayne, 1897; Fo6x, 1902). The use of irrigation to relieve water stress and enhance vine growth is a widely practiced viticultural technique. The effect of optimum water availability on vine growth, crop yield and wine quality has been extensively studied (Neja, et al., 1977; Freeman, et al., 1979; Freeman and Kliewer, 1983; Kliewer, et al., 1983; Matthews and Anderson, 1987; Matthews, et al., 1987; Grimes and Williams, 1990). Summer irrigation to reduce phylloxera damage was used successfully in some early French studies (Herrison, 1888). However, failures of summer irrigation were also reported. In 1869, Faucon found submersion useful but felt that summer irrigation was ineffective. In 1878, Cornu and Mouillefert found summer irrigation had no beneficial effect (Mayet, 1894). In the San Joaquin Valley region of California, Twight reported that V. vinifera-American Vitis rootstocks with a relatively low phylloxera rating performed well in moist, rich soils because the vine could grow additional rootlets to replace those damaged by the insect (Twight, 1903). Bioletti reported similar success in the San Joaquin Valley, where he felt resistant rootstocks were not needed in fertile phylloxerated soils that could be irrigated (Bioletti, 1920). Referring to vine decline in the Santa Clara Valley in California, Davidson and Nougaret found that water stress limited the ability of roots to regrow, but warned against 14 excessive irrigation that could promote rot (Davidson and Nougaret, 1921). Jacob stated that rootstocks with low inherent phylloxera resistance could be used if irrigation could be applied (Jacob, 1938). Winkler reiterated this concept in his viticulture textbook (Winkler, et al., 1974).

The performance of AxR#1 appears to be closely related to soil moisture content. In general, University of California publications recommended AxR#1 only for valley sites with deep soils well-supplied with moisture. The rootstock was never recommended for use on dry or shallow soils, in part because of its low phylloxera resistance. Jacob stated that there had never been a case of insufficient resistance with AxR#1 on irrigated sites in the San Joaquin Valley. He predicted that if the rootstock were to succumb to phylloxera the failure would occur on non-irrigated sites (Jacob, 1938, 1944). Lider repeatedly mentioned that the low phylloxera resistance of AxR#1 is mitigated by soils with a high moisture content (Lider, 1957, 1958a, 1958b). Winkler made a similar statement about AxR#1 in his text (Winkler, et al., 1974). Stafford and Doutt specified that AxR#1 performs well only on irrigated soils (Stafford and Doutt, 1974).

A recent article has suggested that phylloxera infestation is a symptom of water stress rather than a direct cause of vine decline (Helm, et al., 1991). This conclusion is in opposition to the findings reported in the vast literature on the insect. Unfortunately, the experimental design of this trial was flawed because no control treatment was included in the potted vine study, from which the authors made their conclusion. The lack of a control made it impossible to separate the effect of water stress from the effect of phylloxera injury. Field study data were contradictory.

OBJECTIVES OF THIS TRIAL (Krebs--Dissertation) The decline of Northern California vineyards planted with the AxR#1 rootstock has been rapid since phylloxera biotype B was first discovered. During this same time, the area has experienced a prolonged drought. In addition, many vineyards have experimented with reduced water application to enhance wine quality. There is a great deal of anecdotal information in the literature that relates the relative phylloxera resistance of rootstocks to soil moisture (Jacob, 1938, 1944; Lider, 1957, 1958a, 1958b; Winkler, et al., 1974; Stafford and Doutt, 1974). However, there is a lack of experimental work to substantiate these claims. The purpose of this trial is to determine the effect of different phylloxera biotypes and different levels of water stress on the relative phylloxera resistance of the AxR#1 rootstock. From a practical standpoint, the use of additional irrigation to reduce phylloxera damage would offer a positive economic alternative to delay vineyard replanting with other rootstocks. 15

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Sullivan, C.L., 1981. How Vitis vinifera got its roots. Redwood Rancher Country, Vintage Issue:16-20. Sullivan, C.L., 1982. Like modern Edens: Winegrowing in Santa Clara Valley and Santa Cruz Mountains 1798-1981. California History Center, Cupertino, California. Twight, E.H., 1903. Resistant vines and their hybrids. California Agricultural Experiment Station Bulletin 148. University of California. 26

Unwin, T., 1991. Wine and the vine. Routldege, London and New York. van Niekerk, S.W. and C.J. Theron, 1927. American stocks: investigation of grafted vines. Department of Agriculture Bulletin 10. Union of South Africa. Viala, P. and L. Ravaz, 1903. American Vines, translation of the Second Edition by R. Dubois and E.H. Twight. Freygang-Leary Company, San Francisco. Wapshere, A.J. and K.F. Helm, 1987. Phylloxera and Vitis: an experimentally testable coevolutionary hypothesis. American Journal of Enology and Viticulture, 38:216-222.

Weber, E., 1994. 1993 phylloxera survey results. Vineyard Views, February 25, 1994. University of California Cooperative Extension, Napa. Wetmore, C.A., 1880. The wild vines of California and Arizona. First Annual Report of the Board of State Viticultural Commissioners. State of California, Sacramento, 1880:44-59. Whiting, J.R., 1991. Phylloxera and rootstock experiences. Practical Winery and Vineyard, 11:23-26. Whiting, J.R., G.A. Buchanan, and M.E. Edwards, 1987. Assessment of rootstocks for wine grape production. Proceedings of the Sixth Australian Wine Industry Technical Conference, July 1986, Adelaide, Australia, 1987. Williams, R.N. and G.F. Shambaugh, 1987. Grape phylloxera (Homoptera: Phylloxeridae) biotypes confirmed by electrophoresis and host susceptibility. Annals of the Entomological Society of America, 81:1-5. Winkler, A.J., 1938. The effect of climatic regions. Wine Review, 6:15-17. Winkler, A.J., J.A. Cook, W.M. K1iewer and L.A. Lider, 1974. General Viticulture, second edition. University of California Press, Berkeley, California. Wolpert, J., 1988. Phylloxera and the use of AxR#1 rootstock in California vineyards. A statement of the Phylloxera Task Force, University of California, Davis.

5 U BiO/Ag PERIODICALS ROOM UNIVERSITY OF CALIFORNIA COOPERATIVE EXTENSION

.Tor people who earn a living in land cape horticulture— or are about to . . .

VOLUM • NUMBER 4 • NOVEMBER 1990

SPOTTED LEAVES ON VA PHYLLO

By C. S. Koehler, Department of Entomology, UC Ber

Three times this summer, samples of heavily spotted leaves of valley oak were received — one each from Stanislaus, Contra Costa and Yolo County. The cause of the spotting Is an oak phylloxera. The insect family Phylloxeridae consists of small, aphid-like creatures. The best known member of this family is the grape phylloxera, which nearly wiped out the industry 100 years ago, following the accidental introduction of the insect An: from North America. Fig. I. Phylloxera adults, nymphs, and eggs on the urturside of Phylloxera have been known a valley oak leaf. for many years to occur on responsible for the current "outbreak" is oak in California, yet they have never unknown. Conversation with an attracted attention as pests. Whether entomologist in Victoria, B.C., climatological factors, or the disclosed the occurrence of high introduction of a new species, Is numbers of an oak phylloxera on Garry oak there. Insects from the Contra Costa and Yolo County sample have been sent to a USDA phylloxera specialist for identification.

Fig. 2. Spotting of a portion of valley oak leaf by phylloxera.

sieseetwer Nalemoserammeassweessete The University of California, In compliance with Titles VI and VII of the Civil Flights Act of 1964, Till. IX of the Education Amendments of 1972, Sections 503 and 504 of the Rehabilitation Act of 1973, and the Age Discrimination. Act of 1975, does not discriminate on the basis of race, religion, color, national origin, sex, mental or physical handicap or age In any of Its programs or activities, or w:In respect to any of its employment policles, practices, of procedures. Nor does the University of California discriminate on the basis or ancestry, 'sexual orientation, marital status, citizenship, medical condition (as defined In Section 12928 of the California Government Code), or because Individuals are special disabled veterans or Vietnam era veterans (as defined by the Vietnam Era Veterans Readjustment Act of 1974 and Section 12940 of the California Government Code). Inquiries rogardin3 this policy may be addressed to the Affirmative Action Director, University of California, Agriculture and Natural Resources, 300 Lakeside Drive, 8th Floor, Oakland, CA 94612.3560. (415) 9870097. from "Alternative Rootstock Update" April 1991, Napa, CA. (ASEV Publication, Davis, CA.

Characteristics of Vitis species commonly used in rootstock breeding.

V. rupestris— from , the mid - west once into , now restricted to the surrounding states to the east and the north: OK,'AK, TN, MO. Found near rocky and sandy streams, not found in very dry sites. Excellent phylloxera resistance, good rootability and graftability.

V. riparia — ranges from south central Canada to Texas and cast to the Atlantic. Usually associated with river or streamside habitats. No apparent drought resistance, but excellent phylloxera resistance, rootability and'graftability.

V. bcrlandicri — from the limestone hills of central southwestern Texas, well adapted to limestone soils and drought, although also grows in "moist" sandy soils. Excellent phylloxera resistance, very hard to root and propagate.

V. champion— a vigorous species from central and southwestern Texas found in dry chalky limestone soils. •Excellent lime and drought tolerance although does receive some summer water and associated with dry strearnbeds. Good root knot nematode tolerance, moderate co good phylloxera tolerance. Roots and propagates less well than rupcsrris and riparia, but better than berlandiert V. longii (Solonis, more correctly acerifolia) -- from northwestern to central Texas into AK, NM and OK, usually associated with gullies. Very vigorous, good to moderate phylloxera tolerance and better nematode resistance. Very vigorous species and is used in hybrid combinations.

Muscadinia rotund ifolia (V, zotundifolia)-- south to southeastern US, usually found on higl-y ground in moist, but welt-drained shady locations. Apparently a nonhost to most of what ails vinifera-- including soil-borne and foliar pests. Woody!cuttings do not root, only green grafts with Ms species and produces mostly sterile hybrids with Vitis species.

The three major groups of rootstock hybrid combinations. Group 1. V. bcrlandicri x V. riparla Examples are — 5A, SBB, 5C, 8B, 125AA, SO4, 33 EM, 420A, Cosmo 2 and 10.

These hybrids are crosses between a difficult to root species with good i drought tolerance and a readily propagated and grafted species from wet habitats. Most of these stocks grow vigorously when given ample water or When grown in wet habitats. The bcrlandicriadds lime tolerance, and riparia adaptation to cool wet climates.' It is thought that several of these stocks are "dcv igorating", however, whcn grown in areas with ample water or irrigation this effect may not be seen. In general, these stocks were designed for northern European growing conditions.

I Prepared by M.A. Walker for "Alternative Rootstock Update", April 30, 1991, Napa, CA.

S2_

Group 2. V. bcrlandicri x V. rupestris Examples are — 99R, 1 10R, 140Ru, 775P, 1103P.

These hybrids arc also crosses between a difficult to root species and an easily propagated species. Bcrlandicri and rupcstris are both adapted to drought stress and rootstocks produced from them arc adapted to sites where water is limited. These rootstocks produce shoots with greater numbers of laterals and reduced overall growth compared to the bcrlandicri x riparia stocks. In general, the bcrlandicri x rupcstris stocks were designed for southern European, Mediterranean growing conditions in non-irrigated vineyards.

Group 3. V. riparia x V. rupcstris Examples are — 3306C, 3309C, 101-14 Mgt, and Schwarzmann.

These hybrids root and graft well, but have moderate to poor tolerance to lime and little adaptation to drought stress. In general they reduce vigor, but are not well adapted to Mediterranean growing conditions and prefer fertile deep soils.

THREE PHYLLOXERA RESISTANCE RATING SCALES

Viala and Ravaz scale of phylloxera resistance in Vitis species and select cultivars. Viala, P. and Ravaz, L. 1903. American Vines. Their adaptation, culture, grafting and propagation. Translation of the 2nd Edition by Dubois, R. and Twight, E.H. Freygang - Leary Co., San Francisco. pp 197-200.

Viala and Ravaz claim that species or vines with ratings of 16 - 20 were adequately resistant to phylloxera for use in all soil types, ratings of 14 and 15 were sufficient for sandy and damp c.olis and below 13 had insufficient resistance and "should be totally discarded from vineyards".

20 Immunity (their term not mine) 19 rotundifolia 18 cordifolia, rupcstris, arizonica, riparia, rubra, ripariax rupcstris 17 bcrlandicri, monticola, bcrlandicrix riparia, bcrlandicrix rupestris 16 rupcstris St. George (du Lot), acstivalis, 15 mustangensis (candicans), cinema 14 lincccumil, champinli, longii (solonis) 13 doaniana 12 glabrous champinil, Jacquez (Lenoir) 10 Elvira 6 Othello S labrusca 4 Catawba 3 Delaware, Concord, coignetiac 2 Rulander (Pinot noir), amurensis 1 Ungi blanc 0 Cabernet Sauvignon

There is no information on how these values were determined, presumably from field observations . In addition, there is no indication that a wide range of selections from each species was tested to determine phylloxera resistance variability within that species. Viala and Itavaz tested many American and French hybrids, but few rootstocks.

Boubals scale of phylloxera resistance in Vitis. Boubals, D. 1966. Etude de la distribution et des causes de la resistance au phylloxera radieole chez les Vitacees. (A study of the distribution and causes of resistance to radicicolou, phylloxera in the Vitaceac) Ann. Arnelior. Plantes 16(2):145-184. Boubals' scale is based on root studies from phylloxera infested vines grown in pots. He assessed the formation Of tubcrositics on the roots and subsequent decay or necrosis. Tuberosities are phylloxera induced gall-like swellings that occur on roots with peridcrm (roots that arc becoming woody). Nodositiesare phylloxera induced swellings that occur near the root tips. Tuberosities are always found with nodosities, but nodosities can occur alone and are found on phylloxera resistant species. Boubals recommends that only rootstocks with phylloxera resistance ratings of 0 or 1 be used.

Class 0 - no indication of phylloxera activity on the roots of the plant. Examples - rotundifolia, some riparia, rupestris, berlandieriand cordifolia, 420A, 779P, 1616C. Class 1 - from a series of inoculated plants one or two tuberosities appear, and signs of necrosis on the roots. Examples riparia, rupestris, berlandieri, cordifolia,3306C, 3309C, 101 - 14 Mgt, 33EM, 5BB, SC, SO4, 8B, 157-11, 161-49, 775P, 1103P, 140Ru, 99R, 110R, 41B, AXR#2, 44-53 Mal., Salt Creek.

Class 2 - several tuberosities in chains, or a few tuberosities but with definite necrosis of the root. Examples - labrusca, mondcola, some selections of riparia, rupcstris, berlandieri, 333EM, AXR#1, AXR#9, Catawba, Dog Ridge. Class 3 - large portion of the roots are destroyed, decomposed as a result of phylloxera feeding. Examples - arizonica, girdiana, vinifera, some labrusca, 1613C.

This study was based on potted vines and European biotypes of phylloxera. Boubals' study tis. • some of the phylloxera resistance variability in Vitis species - selections of rupestris can be seen in Classes 0, 1 and 2.

Pastena list of phylloxera resistance Pastena, B. 1976. Trattato di Viticoltura Italian. pp 379-403. Edagricola, Bologna. 1051 pp.

Pastena's scale is based on potted vines and Italian phylloxera. He also scored phylloxera damage to the roots. 10 is absolute resistance, S is "tolerable" resistance, and 0 is completely susceptible. An interesting aspect of his study is the variable susceptibility to phylloxera seen in vinifcra cultivars.

10 rotundifolia 9 riparia, bcrlandieri, and cordifolia 8 rupestris, 779P, 420A, 41B (?), 7 St. George, 1103P, 140Ru, 110R, 775P, 41B (in Palermo), I447P 6 3306C, 3309C, 225Ru, SO4, 5BB, 161-49, 157-11, 1045P, 44 - 53 5 Solonis, Jacqucz 4 AXR#1, several hybrid direct producers 2 to 3 several vinifera cultivars: Tannat, Nocera, Olivetta, Carigmane, Sangiovese, Barbera, Trcbbiano dorato, Sauvignon, Grecanico 1 hybrid direct producers (many S.V. numbers, some Seibcl 0 vinifera and more hybrid direct producers.

S CI CHARACTERISTICS OF VITIS SPECIES USED FOR ROOTSTOCKS

RIPARIA — Habitat — moist sites near streams/rivers, high humidity, variable soils but usually lots of organic matter and apparently fertile, not well-adapted to limestone sods. Not Found in dry areas, either in terms of soil water or humidity/rainfall. Found form the

RocLv Mountains to the Atlantic, from Canada to TX. Propagation — roots and grafts well Pest resistance — highly resistant to phylloxera feeding on roots, but leaves are heavily galled_ Susceptible to weak resistance to nematodes (dagger and root knot).

Phenology — goes dormant earlier than the other species and appears to induce/hasten maturity in scions. Roots — very thin, tough, fibrous, well-branched, shallow meandering and weakly penetrating.

RUPESTRIS — Habitat — rocky Midwestern to TX stream beds with standing water near the crown, but well oxygenated. Probably not very fertile sites due to excessive leacning and open rocky soil. Does poorly on limestone soils. Propagation — roots anc grafts well. Pest resistance — resists phylloxera although perhaps at lesser levels than riparia_ Susceptible to nematodes. Phenology — early bud break, early maturity, no dramatic effect on scions. Roots — tough, deep penetrating, branching and thicker than riparia with greater presence of larger roots.

BERLANDIERI — Habitat — with broad leafed , not jumper, on limestone bluffs of central TX in relatively dry areas. Trees in these areas appear stunted, likely due to the lime content of the soil and the availability of nutrients. Grows well in Davis so root system well adapted to non-lime soils. Propagation — roots and grafts poorly. Pest resistance — good phylloxera resistance, some selections have resistance to root knot nematodes. Phenology — late budbreak and late maturity, not used as a rootstock.

Roots — strong thick deeply penetrating, little or no branching, taste-astringent not pungent.

CHAMPINII — Habitat — wooded areas in limestone areas of central TX, in sandy creek beds. Sod appears well leached, without abundant organic matter. Cyclical moisture patterns, but hot and dry for much of the year. Propagation — varies but cultivated rootstocks root at poor to moderate rate and graft if rooted. Pest resistance — disputable to unknown phylloxera resistance not known if durable, good resistance to root knot, variable for dagger. Phenology — average budbreak and dormancy. Roots — wiry, deep, very penetrating.

LC)NGII (acerifolia)— Habitat — dry gullies and ravines in west TX into NM. Associated plants are juniper and mesquite. Not necessarily associated with limestone but grows in limestone areas. Dry areas except for infrequent, but abundant rainfall. Sandy soil leached and dry with little organic matter. Propagation — roots and grafts well. Pest resistance — good resistance to root knot nematodes, some to dagger. Phylloxera resistance judged to be moderate, not known if durable. Phenology — early budbreak, average leaf fall. Roots — slender branching, very wiry and deeply penetrating.

ROTUNDIFOLIA — Habitat — wooded areas of south east. Acidic soils, relatively high organic matter. Not found in overly wet or dry areas. Propagation — will not root or graft from dormant cuttings, roots and grafts from green cuttings, but long term compatibility is unknown. Pest resistance — seems to resist all soil pests of vinifera. Phenology — almost evergreen in the south, ate budbreak and leaf fall in Davis. Roots — [thick, little branching, intensely pungent taste.

Prepared by M. Andrew Walker for UNEX course "Assessing Vine Nutrition: New Problems. New Solutions", December I I, 1993, University of California, Davis- VINIFERA — Habitat — vanes from wooded areas and strea.rnside locales of western and central Europe to dry hillsides of the Middle East and central Asia. Excellent tolerance to drought and calcareous soils. Propagation — roots and grafts very well. Pest resistance — some resistance to root knot nematodes, and some tolerance to fanleaf. Susceptible to phylloxera ... appears to act as a dominant trait and lead to decline to rootstocks with vinifera in parentage AXR#1, 1202C, 41B, 043-43, Jacquez (Lenoir), Fa:rich hybrids, Freedom?, Harmony? 1613C? Phenology — varies but average in comparison with the species. Roots — branching, medium thickness, penetrating.

ROOTSTOCK PARENTAGE GROUPS Riparia — Riparia Gloire de Montpellier — much like the species. Induces low vigor in scions, and early maturity. Needs ample moisture and not adapted to dry soils or water- stressed sites. Shallow fibrous root system. Poor nematode resistance, very high phylloxera resistance, good rooting, lime susceptible, suited for deep moist fertile foams with good drainage. Provides early ripening and a tendency to overbear has been observed.

Rupestris — St. George — much like the species, has apparent drought tolerance due to massive root system, but does not do well in shallow soils under drought stress. Phylloxera resistance is not as strong as riparia, seems to support a relatively high population on the roots_ Phylloxera resistance studies using potted plants in some countries have concluded that resistance may not be great enough (Whiting found substantial numbers of nodosities on St. George) but no case of field failure exists. Moderate to high vigor, poor nematode resistance, high phylloxera resistance, excellent rooting, on well-drained non-restricting soils provides drought tolerance. Has problems with bearing on vigorous sites and small clustered varieties. Moderate to poor yields, high K juices with high pH.

Riparia x Rupestris Schwarzmann (sometimes called Teleki in West Australia)— moderate vigor, good nematode resistance (root knot and dagger), high phylloxera resistance, moderate lime tolerance, good rooting, should not be used where summer drought is common. Easy to propagate can have high K uptake, recommended where drought and high juice pH arc not a problem.

101-14 — low to moderate vigor, moderate nematode resistance, high phylloxera resistance, moderate lime tolerance and good rooting, similar to riparia with shallow, well branched root system needs deep moist soil. Tolerates wet spring conditions in France, but susceptible to water-logging in Australia. Promotes early maturity.

3309C — moderate vigor, low root knot resistance, good resistance to phylloxera, moderate lime tolerance, good rooting, does not tolerate saline or thy soils. Recommended for replanting on well-drained shallow soils with low fertility. Said to have deep rooting with well-branched roots.

Berlandleri x Riparia Teleki SC — moderate vigor, moderate nematode resistance, strong phylloxera resistance, excellent rooting, moderate lime tolerance, cool region rootstock used in Germany. Not suited to warm irrigated areas, yields well where cooler except where drought is a problem, moderate vigor and low pH juice, recommended for most areas except where drought is a problem (Whiting). Shallow well-branched root system. French

S 3

find SO4 confers higher vigor to the scion other problems include later maturity, susceptible to Mg deficiency and waterberry, not for use in fertile soil.

5BB — low to moderate vigor, moderate nematode resistance, very high phylloxera resistance, excellent rooting, well suited to moist compact soils, used to Europe as dual purpose nematode/phylloxera stock and warrants further testing here on that basis. Whiting found a few tiodosities in his potted vine studies. Relatively high vigor and yielded well in some dry sites (confirmed by preliminary Wolper% data). Shallow well- branched root system.

4204 — low to moderate vigor, low to moderate nematode resistance, high phylloxera resistance, poor to moderate rooting, shallow well-branched root system, well suited to poor heavy textured soils, tolerates dry conditions but not waterlogging, may over crop in early years. Whiting found it survived in water-logged soils, but not recommended in Australia (too weak and low yields).

Berlandieri x Rupestris — 110R — moderate vigor, low to moderate nematode resistance, high phylloxera resistance, moderate rooting, drought tolerant. Scions develop slowly then bear large crops of excellent quality, wet poorly drained soils should be avoided. More roots and thicker roots, not quite as deep as St. George. Whiting found a few nodosities in his potted vine studies. Vigor has ranged from low to high in different trials (as have yields). Australian 110R has vein necrosis and may effect experiences with low vigor and low pH juice.

140Ru — high vigor, high phylloxera resistance, low nematode resistance, moderate to fair rooting, but have been problems with grafting, excellent drought tolerance. Root system is like St. George. Late maturity and susceptible to wet feet, not advised for fertile sites. Very deep growing roots, and well-branched.

1103P — moderate to high vigor, moderate nematode resistance, high phylloxera resistance, moderate rooting, good drought tolerance but not susceptible to water logging, moderately tolerant of salt. Roots deeply like St. George. Late maturity not for use in fertile sites.

Champinii — Ramsey — low dagger and high root knot and phylloxera resistance, moderate lime tolerance, poor rooting, well suited to coarse textured low fertility soils, susceptible to Zn deficiency. Recommended for sandy soils. Problems with high vigor and K in some varieties, but not as problematic or as vigorous in cooler areas. Phylloxera resistance may not be durable and has been rated differently.

Dog Ridge — very high vigor, same characters as Ramsey, suited to very coarse textured and infertile soils, Ramsey easier to manage.

(Longil x Othello) x Dog Ridge — Freedom — moderate to high vigor, questionable phylloxera resistance (nociosities have been found in pot studies), high root knot and moderate dagger nematode resstance. Can have high pH and K problems in high vigor areas, but grows with only moderate vigor in cooler sites.

Harmony — moderate to high vigor, questionable phylloxera resistance, good nematode resistance, lower yields and vigor than Freedom. Both stocks designed for saady soils in the Central Valley. S 4

Longii x Riparia 1616C — tow to moderate vigor, but Davis 1616C is different from French selections. Shallow well - branched rooting, and sensitive to drought. Early maturing, resists phylloxera_ Should act much like a more vigorous Riparia Gloire.

Vinifera x Rotundifolia — 039-16 — high vigor, high resistance to dagger nematode, does not prevent transmission of fanleaf virus, scions on this rootstock seem to prevent the decreased set effects of fanleaf degeneration. Good phylloxera resistance in lab and field, durability unknown. 043-43 is showing effects of phylloxera decline in some areas.

Howell — A rootstock cultivar that possess root characteristic resulting in deep soil penetration, a positive hydrotropism, and is efficient in uptake of water and nutrients required for growth will not limit the growth habit and physiology of the scion cultivar.

References Delas, J.J. 1992. Criteria used for rootstock selection in France. In: Rootstock Seminar: A Worldwide Perspective. Am. Soc. Enol. Vitic. pp1-14. Cialet, P. 1979. A Practical Ampelography. L.T. Morton, translator. Cornell Univ. Press, Ithaca. 248p. Galet, P. 1988. Cdpages et Vignobles de France. Tome 1. Les Vignes Americaines. 2nd Edition. Charles Dehan, Montpellier. 553p. Hardie, W.J. and Cirami, R.M. 1988. Grapevine rootstocks. pp 154-176. In: Viticulture. Vol. 1. Resources. B.G. Coombe and P.R. Dry. eds. Winetitles, Adelaide. 211p Howell, G.S. 1987. Vitis rootstocks. In: Rootstocks for Fruit Crops. R.C. Rom and R.F. Carlson eds. J. Wiley and Sons, New York, pp451-472. Munson, T.V. 1909. Foundations of American Grape Culture. T.V. Munson and Son, Denison TX, reprinted in 1975 Denison Public Library. 252p. Pongrdcz, D.P. 1983. Rootstocks for grape-vines. David Philip Pub., Cape Town. 150p. Southy, J.M. 1992. Grapevine rootstock performance under diverse conditions in South Africa. In: Rootstock Seminar A Worldwide Perspective. Am. Soc. Enol. Vitic. pp27-51. Van Zyl, J.L. 1988. The grapevine root and its environment. Republic of South Africa Dept. Agricult, Water Supply Tech Comm. no. 215. 146p. Viala, P. and Ravaz, L. 1903. American Vines: their adaptation, culture, grafting and propagation. R Dubois and E.H. Twight, translators. Freygang-Leary Co., San Francisco. 299p. Whiting, J.R. and Buchanan, G.A. 1992. Evaluation of rootstocks for phylloxera infested vineyards in Australia. In: Rootstock Seminar. A Worldwide Perspective. Am. Soc. Enol. Vitic. pp15-26.

SS e i-±t1

ri. ~ ipaz ia

•

e./P rnotnitairr. "riativo river bitty %ream ' Parentage and breeder of grape rootstocks available to some degree in California. Compiled by M.A. Walker. for the Proceedings of the Rootstock Seminar: an International Perspective. Reno. NV June 24. 1992 Rootstock Parentage Breeder Riparia Gloire riparia Viala, PortalisiMontpellier, 1860's St. George rupestris Sijas of Montpellier. 1860's 187G rupestris Neustadt (1297) Salt Creek (Ramsey) champinii Species selection (Munson?) = 1900 Dog Ridge champinii Munson selection 1900 3306 C riparia x rupestris Couderc 1881 3309 C nparia x rupestris Couderc 1881 101-14 Mgt riparia x rupestris Millardet 1882 Schwarzmann riparia x rupestris Sthwarzmann, 1891 44-53 Malegue riparia x (cordifolia x rupestris) Malegue 106-8 Mgt riparia x (cordifolia x rupestris) Millardet 1882 44R berlandieri x rupestris Richter ? 57R berlandieri x rupestris Richter 99R berlandieri x rupestris Richter 1889 110R bedandieri x rupestris Richter 1889 140 Ruggeri berlandieri x rupestris Ruggeri, 1897 775 Paulsen berlandieri x rupestris Paulsen, 1894 779 Paulsen berlandieri x rupestris Paulsen, 1894 1103 Paulsen berlandieri x rupestris Paulsen, 1895 1447 Paulsen berlandieri x rupestris Paulsen, 1896 Vivet 15 rupestris x berlandieri ? from Neustadt SO4 berlandieri x riparia Teleki group 4A, 1896 8B berlandieri x riparia Teleki, 1896 5A berlandieri x riparia Teleki, 1896 93B berlandieri x riparia Kober from Teleki SA 5C berlandien x riparia A. Teleki, from 5A, 1922 125AA berlandieri x riparia Kober from Teleki SA? 161-49 C berlandien x riparia Couderc 1888 157-11 C berlandieri x riparia Couderc 1889 33 EM berlandieri x riparia Foes 1899 *34 EM berlandieri x riparia Foes 1899 420 A Mgt berlandieri x riparia Millardet, 1887 225 Ru berlandieri x riparia Ruggeri, 1897 Cosmo 2 berlandieri x riparia Cosmo from 8B, 1931 Cosmo 10 berlandieri x riparia Cosmo from 8B, 1931 *Boemer riparia x cinerea Boerner released by Becker 1988 41 B vinifera x berlandieri Millardet 1882 333 EM vinifera x berlandieri Foes 1883 Vidal 1 vinifera x berlandieri? Vidal IT? Eves 13-5 probable yin x berland Fernandez de Bobadilla, 1943 AXR#1 vinifera x rupestris Ganzin, 1879 AXR#2 vinifera x rupestris Garvin, 1879 AXR#9 vinifera x rupestris Gamin, 1879 1202 C vinifera x rupestris Couderc, 1883 93-5 C vinifera x rupestris Couderc, 1889 1045 P berlandieri x AXR#1 Paulsen. 1895 Fercal (bed x yin) x 333 EM Pouget/Ottenwaelter, 1983 *Gravesac 161-49C x 3309 C Pouget/Ottenwaelter, 1985 196-17 Castel 1202 x Riparia Gloire Castel, late 1800's 216-3 Castel solonis x nip (1616 x St. Geo) Castel, 1880's 1616 C solonis x riparia Couderc 1881 1613 C solonis x Othello (labxripxvin) Couderc 1881 Lenoir (Jauquez) Bourquiana (nest x cin x vin) Harmony 1613 C x champinii Weinberger/Harmon, 1966 Freedom 1613 C x champinii Weinberger/Harmon, 1967 VR 039-16 vinifera x rotundifolia Olmo, 194, patent 1988 VR 043-43 vinifera x rotundifolia Olmo, 1948, patent 1988 171 -6 rufotomentosa x vinifera Lider, 1966 * not available in CA The Myth of Universal Rootstock wiv\er vivte,5 4 ,1 (61-70( LUCIE T. MORTON

"GRAPEGROWERS always have tended to ing the characteristics of only three of these are suited to warm climates and are contra- believe that there is a universal rootstock which species provides a good base for understanding indicated in areas with short growing seasons. will serve in all situations, and that all one most commercial rootstocks. Rupestris roots and grafts very easily. By far needs to do is remember a name or number. He the most widely cultivated pure rupestris stock . A native of Texas, is mainly preoccupied with vigor (indication of is Rupestris St. George. In France, St. George phylloxera resistance) and resistance to lime- Berlandieri has a long vegetative cycle and is (or du Lot) currently is losing ground to the one of the latest maturing. It has good induced chlorosis." Berlandieri-rupestris crosses (110 R, 99 R), So said a Burgundian in 1930 while resistance to phylloxera and very good especially in dry areas. resistance to lime-induced chlorosis — its most reviewing the rise and fall of various rootstock There are so many variables involved with varieties in the Cote d'Or since the 1880s. This important virtues in Europe. Pure Berlandieri vines are very difficult to root; hybridiza- choosing a rootstock that is very handy to have sort of wishful thinking is as apparent now as it tion with other species was necessary to a sort of "vintage chart" for reference. The was then. In fact, the U.S. is a good example of following basically is a compendium of where, until very recently, Rupestris St. develop lime-tolerant stocks which would root well enough for commercial propagation. Vitis information found in European literature. George and AxR 1 in the West and 3309 Like a vintage chart, it is designed only to give Couderc in the East were accepted as universal vinifera vines also have a naturally high tolerance for lime. The most lime-tolerant an overall impression and, naturally, there are stocks. exceptions and qualifications. The blank spaces Crapegrowers already face a challenge rootstocks which also are phylloxera-resistant are both vinifera-Berlandieri crosses: 41 B indicate insufficient information. The Cali- choosing, cultivating and defending the (Chasselas x fornia reader will need to fill in on AxR 1, 1202 fruiting varieties above ground; it is no Berlandieri) and 333 E. M. (Cabernet Sauvignon x Berlandieri). C, 1613 C, and Dog Ridge since these varieties wonder they prefer to minimize the com- are not used commercially in Europe. plexities of subterranean viticulture. Although Although most American vineyard soils are there is no "universal" rootstock, only a on the acid side, and lime tolerance is not a When contemplating roostock qualities, it is fraction of the thousands of varieties developed concern, many important commercial stocks helpful to remember the following: since the phylloxera crisis are of commercial are Berlandieri crosses (S.O. 4, 5 BB, 99 R, Vigor. It is not always a virtue. Excess importance. 1103 P). rootstock vigor can cause poor fruit set in the The majority of today's stocks were scion (fruiting variety). Excess vigor may developed at the turn of the century and— Vitis riparia. Widely distributed east of the sometimes, in the case of very productive modifications by heat treatment and clonal Rockies into Canada, riparia is for cool varieties, be controlled through leaving extra selection notwithstanding—their behavior is climates. It is the earliest maturing of the fruiting buds at pruning. However, in less becoming increasingly familiar. With so many native species, has excellent cold resistance, productive scions, this can lead to over- factors influencing the performance of root- prefers rich, humid soils and often is found cropping and early vine demise. Vigor can stocks they need to be examined in many along riverbanks. Riparia roots and grafts very delay ripening, which often is undesirable. different situations before their capabilities easily and has excellent resistance to phyl- Furthermore, vigorous vegetative growth is and idiosyncracies can be clearly understood. loxera. Riparia basically contributes quality, linked with increased bunch rot. Ironically, in its native United States, the not quantity, to its progeny because of its low vigor and early maturity. Balance between fruit quality and quantity phylloxera root louse has been far less always is important. When selecting a destructive than abroad. In the East, native rootstock, remember that some vineyards American varieties and French hybrids can be Riparia Gloire de Montpelliei- is the only profit from a reduction in vigor and profit is grown on their own roots. The spread of commercial, pure riparia rootstock used today. the operative word. Effect on maturity. phylloxera in California has been very slow Since Riparia Cloire has very low vigor, it is As discussed, this is an important considera- and many vineyard areas are free of it. used only where early ripening is desired for tion in the table grape industry and in cold In France, on the other hand, phylloxera table grapes or where early wood maturity is climates. destroyed over six million acres of vines before Rooting and grafting. It has been essential for winter survival. Rtparia-Berland- said with some cynicism that rootstock varieties 1900. France for a time was one huge rootstock ieri crosses are quite vigorous, although less so trial and, in fact, still is. Since America's need are chosen by the nurseries and not the than the Berlandteri-rupestrls crosses. universities. It is true that nurseries need to was less pressing, Americans profited from the . A Midwestern species, V. operate profitably and consumers lean towards early French rootstock findings. Today France rupestris behaves more like a self-supporting bargains. Consider the case of 110 R and St. has 28 approved rootstock varieties and since bush than a clinging vine. With its strongly George. World War II there has been a considerable vertical root system, rupestris seeks water and evolution in their relative popularity. minerals in deep soils. St. George produces more meters of wood The first and most important step in under- per hectare, roots better, and bench grafts standing rootstocks is to study their parents, Like Berlandieri, rupestris has a long more successfully than 110 R. Since 110 R costs the native American species of Vitis and vegetative cycle with late maturity. Therefore more to produce, it costs growers more, and occasionally Vitis vinifera. Fortunately, know- rupestris and Berlandieri-rupestris rootstocks this is where the dilemma arises. For example, 24 WINES & VINES (0 1 a Napa grower needs to replant an old cooler, rainier areas are riparia relatives quite Why St. George? vineyard formerly planted on St. George. He at home in wet conditions. Baffled by the standard recommendation in has read somewhere that 110 R might be better California of St. George for dry, non-irrigated than St. George in shallow, dry soils. He must Droughty. This is slightly trickier because hillside vineyards—a direct contradiction of decide whether future yields will justify from the above comments about wet soils one European views—a review of the literature increased planting cost and the risk of trying a would figure that St. George would be very was in order. new stock. drought-resistant. The Europeans consistently There are three excellent publications on The answer depends on the particular site. give St. George a poor drought rating. This is phylloxera-resistant stocks in California: The important point here is that just because a due in part to the often shallow soil conditions Bioletti, et. a., 1921; Husmann, et. a., 1939; rootstock is readily available, roots and grafts in Europe where the deep-rooting St. George is and Lider, 1958. In addition, Lider, Ferrari, easily, and produces vigorous young plants stymied in its search for water. and Bowers presented an update on graft does not mean it is the best stock for a site in Heavy (clay). While heavy soils with a high combinations at a 1975 enology convention. the long run. The history of St. George in percentage of clay often are associated with All of these are well worth scrutiny by California is a case in point. poor drainage and never have been considered experimentally-minded, rootstock-conscious optimal for vineyards, they nonetheless are Californians. So as not to get lost in a thousand Soil conditions: used for many none-vine related reasons. An variables, it is prudent to choose one question Wet. Some vines are not happy with wet apparent difference in rootstock response to and stay with it. The question here is: why feet. This often takes care of itself since heavy soils is worth considering. recommend Rupestris St. George for shallow, generally rootstocks recommended for warm dry, hillside vineyards? climates (rupestris and family) do not like Nematodes. While no stock is totally The Bioletti report of 1921 was not the humid soils and are not usually subjected to resistant to nematodes, some stocks are more source of this recommendation. Based largely them. Similarly, many suitable stocks for tolerant than others. on French sources, but also on his experience to

European Rootstock Chart

Variety Origin Effect on Rooting Grafting SOIL CONDITIONS Vigor Maturity Bench Field Wet Droughty Heavy Nematodes

Rupestris rupestris xxxx delay good good good poor poor poor Some St. George tolerance

99 Richter Berlandieri xxxx delay fair poor good poor fair O.K. good rupestris tolerance

110 Richter Berlandieri xxxx delay poor fair good good O.K. some tolerance rupestris 1103 Paulsen Berlandieri xxxx delay good good good O.K. good O.K . x rupestris 140 Ruggeri Berlandieri xxxx delay fair fair good poor good x rupestris Aramon Rupestris vinifera xxxx delay very gd good good O.K. no x tolerance Ganzin No. 1 rupestris 1202 Couderc vinifera xxxx delay good fair good O.K. x rupestris 41 B vinifera xx advance poor poor good poor fair O.K. no x Millardet et de Grasset Berlandieri tolerance 1613 Couderc Candicans xxx good good good O.K. some vinifera tolerance riparia labrusca

1616 Couderc candicans - xx advance good fair good - poor good riparia tolerance

Dog Ridge rupestris- xxxx advance poor good candicans tolerance (Berland.) Riparia Gloire riparia x advance very gd very gd very gd O.K.poor poor some de Montpellier tolerance

57874 _co Berlandieri xxx advance good fair good O.K. poor O.K. good riparia tolerance Berlandieri xxx advance good fair poor O.K. good-Germany O.K. good 5 BB Kober x riparia poor-France tolerance 420 A Berlandieri xx advance fair fair good O.K. fair O.K. some x Millardet et de Grasset riparia tolerance riparia xxx fair poor good O.K. poor no 161-49 x tolerance Couderc Berlandieri

riparia xxx advance good good good poor poor-good poor no 3309 Couderc x rupestris tolerance 101-14 riparia xx advance good good good poor some x Millardet et de Grasset rupestris tolerance

APRIL, 1979 25 L? era indications of trouble have tended to be this is because "phylloxera resistance may be a 14111141111 confirmed. prime criterion in its choice as a stock." Lider Husmann, et. al , 1939. This bulletin has a had an excellent reason for not recommending 13-column chart summarizing data concerning 1202 C and AxR 1 for shallow, dry hillsides in 411 72 vinifera varieties with 69 rootstock varieties spite of their good performance in trials. These from 10 vineyards; complete data sheets would varieties are vinifera-rupestris crosses which, have taken 200 pagesl Fortunately for the while starting off brilliantly in France, computerless inquirers only one vineyard eventually failed completely there because of ' 171-1 suffered from severe drought. The Elk Grove insufficient resistance to phylloxera. If the (Sacramento Co.) vineyard was irrigated at the vinifera-rupestris stocks were considered insuf- first plantings, but never thereafter and the ficiently resistant to phylloxera in shallow soils average rainfall of 14 inches was hardly elsewhere in the world, there was no reason to 4474711 generous. suppose they would succeed in California. Record of seven principal stocks with ten A review of this rootstock performance Lider, Ferrari, and Bowers (1975). Astudy of scions. The work was done by Bioletti. would not sell one on St. George. It was rootstock trials from 35-40 years old shed light date, he says of St. George: "It succeeds in all surpassed in overall performance by five on the question of the longevity of vinif era- good soils provided they are deep, well- varieties: 1202 C, 1613 C, AxR 1, Constantia rupestris stocks in California. However, the drained, and sufficiently supplied with water. (a rupestris seedling), and 101-14 C. There was interest here is in St. George on a shallow, In shallow soils underlaid with impervious some variation among different scion varieties, non-irrigated site in Napa County planted in hardpan, rock, or clay, it usually fails. It is but in no instance was St. George best at Elk 1936; the scion is Zinfandel: well thought of in Algeria although It suffers in Grove. dry seasons." However, iri the summary of all results in all Stock Crop yield Stock Crop yield ' Commenting on the results of his trials at the vineyards, St. George emerges among the (kg/vine) (kg/vine) Davis and Kearney, Bioletti stated: top stocks. The basis for the rating is based on 1940-52 1975 "The low rating of Rupestris St. George in vigor and not on yield. According to the this table is remarkable. The crops yielded by authors, the ratings represent "an optical 1202 C 6.8 3309 C 9.6 its grafts have averaged only about half of rating given to each vine at the end of the 420 A 6.4 420 A 8.3 those of the best stocks. This stock is used much yearly growing season and indicate the relative AxR 1 6.2 1202 C 7.7 more than any other in California. It is growth of each variety when grafted on several 3309 C 5.7 St. George 3.7 sometimes claimed that the light bearing of rootstocks under conditions existing at the St. George 3.8 AxR 1 (not avail) vines on St. George roots is due to the excessive vineyard designated." vigor of the stock and that the crops increase In this study vigor is accepted as the This table brings up a number of questions with age and can be improved by longer unqualified indicator of success, although concerning the other varieties, (420A bears „pruning. This may be true in some cases but vigorous vegetative growth does not necessarily looking into, for instance), but the perfor- most of the evidence of our investigations correspond with high crop levels. As the mance of the "universal" St. George speaks for points the other way. For most of the varieties authors say, "the more vigorous stocks have itself. It would seem that on the question of tested and for conditions similar to those of shown wide adaptibility ... these investiga- planting St. George on shallow, dry sites, the Davis, the St. George is, as a stock, tions have eliminated many of the weaker and Europeans and Californians are in accord: undoubtedly inferior to several others. poorer stocks." It could be argued that some of don't. "... At Davis, the crops on only two stocks these "weaker" stocks, while not being "all- When Europeans ask why American cars are were as large as those of the ungrafted vines. purpose" would be very useful in certain so big and inefficient, I reply that we have a big The Davis vines were somewhat stinted in the situations. country, big roads, and (had) cheap gas. When matter of water and these comparatively small According to Husmann, the more important asked why Californians use AxR 1 which is not crops probably indicate a greater sensitiveness stock varieties, in order, were: 1202 C, 1613 phylloxera resistant, I reply that they have to drought on the part of grafted vines." C, St. George, Constantia, Dog Ridge, AxR 1, deep, rich soils, irrigation, and lazy phylloxera. The above is a visual summary of Bioletti's and Monticola x Riparia 188.15 Cl. However, just as someone faced with scarce results. Later studies have not confirmed some The next , bulletin in my files concerning gasoline and difficult parking would abandon of his conclusions (based on three years rootstocks in California is "Vineyard Planting big cars, a grower faced with scarce water and cropping at Davis and six years at Kearney). It Stock" by H. E. Jacob (1944), and here were a heavily phylloxerated vineyard would do is unfortunate that these trials were premature- the first recommendations of St, George for dry well to abandon "universal" stocks. ly discontinued. However, on the matter of St. conditions. Jacob mentions only five root- Dry farmers are not the only one who could George in very dry conditions, these early stocks: St. George, AXR 1, 1613 C, Dog Ridge benefit from a less universal approach to and Salt Creek, the latter two considered rootstocks. A premium California winegrower experimental. This is not a bulletin giving once said at a dinner party that he planned to research data and the above are described pull out his Malbec because it would not set. ORDER WITS PAPERS NOW! because they were then the most commercially When asked what stock it was on he said, "AxR Important. 1, probably." I mumbled something about the Jacob stated, "St. George is the standard French grafting Malbec on 420 A and changed Last call for papers developed phylloxera-resistant stock for wine grape the subject. for the 1978 Wine Industry varieties on non-irrigated soils in the coastal While rootstocks hardly make for sparkling valleys of California. Under these conditions it party conversation, they are an important part Technical Seminar at Monterey, of the industry and can affect significantly California. is recomended, and used almost to the exclusion of all others." That St. George was long-term economic returns. used is understandable; that it was "recom- Plantings on a rootstock different from the A few copies still are available. mended" is not. "universals" is like putting money into the stock To Lider (1958). This bulletin is especially exchange instead of a savings account: It may get your own copy send your or may not pay off. There are no easy answers check ($11.00 in the U.S. and interesting because it is an excellent example of the complexities, unknowns and inconsistencies and no stock will be perfect in every respect. $12.50 elsewhere) to: which abound in rootstocks. Lider concluded There is a great deal of conflicting information that St. George was not the most suited variety both here and abroad ; this means one should to the coastal valley vineyards and that the check as many sources and vineyards as WITS, Attn. Secy J. L. Jacobs possible to get a better perspective. 46 Seventh Avenue "experimental" AXR 1 was the most vigorous and productive. In fact, he noted that AxR 1 San Francisco, CA 94118 (Ed. Note: In addition to being Wines & Vines and 1202 C produced higher yields on the Eastern Correspondent, Morton is a consulting drier, shallower, soils in the trials. He also viticulturist with a degree in viticulture from Name pointed out that while 99 R was slower to Montpellier in France. The bibliography for Address develop, at maturity it outperformed St. this article is available upon request. She has George. translated Pierre Calet's Precis d'Ampel- Although he said there is a place for St. ographic Partique into English; it has been George on shallow, nonirrigated soils, he said published by Cornell University Press). 26 WINES & VINES Keynote paper

Myth of the universal rootstock: the fads and facts of rootstock selection

Lucie T. Morton and Louise E. Jackson Respectively, Viticulturist PO Box 208, Broad Run, Virginia 22014 Botanist Branch of Western Regional Geology, U.S.G.S. ih 345 Middlefield Road, Menlo Park, California 94025 United States of America

Abstract Understanding the importance and relative merits of Ecology of Vitis species: role of genotypes grape vine rootstocks is no easy task. The native Ameri- Commonly used grape rootstocks are the result of can Vitis species that are parents to most commercial root- hybridising several wild North American grape species stock varieties are totally unfamiliar in appearance and (Table 1). Three main species have been used and each is "personality" to most grapegrowers outside the ranks of adapted to a unique set of environmental conditions in its grape geneticists and ampelographers. In many of the native habitat. Here we describe the growth strategy that world's vineyards, grafting Vitis vinifera scions to phyllox- allows each of these species to survive in their respective , era resistant stocks has been routine for nearly a century. environments. Understanding the ecology of these root- In other areas, the spread or threat of phylloxera is rela- stock progenitors is the first step in assessing how well a tively new. Even in France, however, where the majority rootstock will do in a given vineyard. of today's commercial rootstocks were developed before 1900, there has been a continual evolution in rootstock Table 1. Common rootstocks listed by parentage. plantings and recommendations. In this paper we explore Riparia Riparia Gloire de Montpellier (Portalis) the factors involved in understanding why grapevine root- Riparia, Berlandieri SO 4, 5 A, 5 BB, 5 C, 8 B, 34 E.M., 125 AA, stocks differ from each other and how these differences 225 Ru, 420 A, 157-11 C, 161-49 C, RSB 1, might affect the performance of fruiting vines grafted on Cosmo 2 & 10, Craciunel 2 & 71 them. Riparia, Labrusca Vialla Riparia, Rupestris 3306 C, 3309 C, 101-14 Mgt, Schwarzmann Riparia, Vinifera 143 A, 143 B Introduction Rupestris Rupestris du Lot (St. George) Rootstocks are one weapon grape growers have against Rupestris, Berlandieri 57 R, 99 R, Prosperi Super 99 R, 110 R, 140 an array of vineyard problems relating to climate (short RU, 775 P, 779 P, 1103 P, 1447 P growing season, cold winters, excessive rain, drought) and Rupestris, Vinifera AXR 1 (ARG 1), 93-5 C ("XX"), 1202 C Berlandieri, Vinifera 41 B, 333 E.M., Fercal soil conditions (high pH, salt, phylloxera, nematodes, exces- Complex ( 2 species) 44-53 M, 1613 C, 1616 C, 1045 P, 196-17 Ca, sive fertility or infertility). It is important to prioritise one's 216-3 Ca, 4010 Ca, Dog Ridge, Golia, Grezot needs in a rootstock, because rarely does one rootstock ful- 1, Harmony, Salt Creek (Ramsey), Tampa fill all the desired requirements equally. The opportunity to select a rootstock does not present itself often and Vitis rupestris Scheele requires serious thought when it does. Unlike pruning, V. rupestris grows in dry sunny sites which have periodic spraying, trellising, or even choosing a fruiting variety, there rain. It is found in rocky places, sandy gulches, heads of is no changing or modifying a rootstock once it is planted. ravines or along dry water runs (Ravas 1902). Before exten- Rootstock performance is extremely site dependent and sive grazing of the surrounding prairies, its distribution results for a given stock/scion combination are bound to once extended into non-forested areas. Although this differ from region to region. Growers in new vineyard areas habitat description suggests that it survives well under dry must extrapolate information generated in foreign sites. conditions, this species, in fact, appears to be very sensi- Much useful literature about rootstocks is not in English tive to drought. V, rupestris can be considered a drought and what practical advice there is can be sometimes con- avoider rather than a drought tolerator. It manages to tap flicting and often confusing to a grower with the simple a deep water supply with its plunging root system. Under question, "What is the best rootstock for my vineyard?". conditions of low water availability, its roots must be able The simple answer would be, "there isn't one; there are to grow down to water deep in the soil profile. Otherwise, several," but in what follows we will examine what should if there is severe drought, or an impenetrable hard pan, be considered in order to make some reasonable choices. this plant will die (Munson 1909). When drought begins, Familiarity with three Vitis species is essential before the V. rupestris hastily loses the leaves at the base of its shoots (almost) invisible (Freeman and Smart 1976) world of sub- and this also happens to V. vinifera scions grafted to V. terranean viticulture begins to make sense. rupestris: leaves dry out, berries wither up and the size and quality of the crop is lowered (Ravas 1902).

Proceedings Second international Cool Climate Viticulture and Oenology Symposium, Auckland, New Zealand. January 1988. 25

OLi Myth of the universal rootstock

V. rupestris may have difficulty controlling water balance a short period with early budbreak and early fruit and because of its narrow vascular vessels (Rives 1925). He sug- wood maturation. Although a shortened growth span gests that once the water supply becomes depleted, or that would decrease the total production by the plant each year, heat, light, or wind creates high evaporative demand, the it ensures completion of growth, fruit and wood ripening vascular system, can no longer keep up with transpiration before the onset of winter cold. and this causes leaves to die. Its bushy structure, with numerous short, upright shoots and many adventitious Yids berlandieri Planchon buds is better suited to periodic flushes of growth due to V. berlandieri is a species of calcareous and dry soils in alternating drought and rain fall during the growing sea- central and southwestern Texas and into tropical Mexico son than would be a climbing vine with a single main stem. (Viala 1889; Galet 1979). These are arid areas which do Leaf characteristics of V. rupestris such as thick paren- receive some summer rain in the form of thunder showers. chyma layers, glabrousness and sunken stomata indicate V. berlandieri is adapted to extremely hot and dry condi- adaptation to high light conditions, but not necessarily to tions, and rarely is it found in fertile or non-calcareous soils drought, e.g. no thick cuticle, heavy pubescence, or ,tomen- (Viala 1889). In southwest Texas, it grows along streams, tum for light reflection. but also on hillsides and hill tops (Munson 1909). V. rupestris has a very long vegetative cycle with early V. berlandieri is a climbing vine, not a shrub or a creep- budbreak and late fruit and wood maturation. Under ing vine. In exposed hillside sites, it climbs into small, natural conditions, especially before grazing restricted it shrubby trees, live oaks for example, and along stream- from deep richer prairie soils and confined it to drier forest banks, into tall trees bordering the water (Viala 1889). It openings too poor for the establishment of trees, its strategy is a vigourous climber with ribbed, soft and easily broken might be best described as opportunistically making shoots. Wood ripens late. Leaves are medium sized, shiny vigourous growth during periods of high water and nutrient above and cobwebby below. The felty-woolly hairs on the availability, then reducing activity during drier periods. growing tips may be reflective protection against intense Thus, while it is not really drought adapted, it can survive heat and light while the young leaves are beginning to a long growing season with periodic dry spells as long as emerge. soils are deep enough to maintain a continuous water Vitis berlandieri has a high root to shoot ratio (Ravas supply. 1902). Whereas mature rootstocks of V. riparia, V. rupes- tris, and 3309 Couderc (riparia x rupestris) may produce Vitis riparia Michaux 12-30 tons/ha of roots, hybrids of V berlandieri can have V. riparia is a trailing or climbing vine in the forests of 50-60 tons/ha (Galet 1983). V. berlandieri has fleshy, strong eastern North America, from Texas to Virginia and north roots that plunge downwards at almost the same angle as to Canada. It is a forest species, usually growing in shade, V. rupestris, 25-35 degrees (Galet 1983). in moist soils, or along the edges of streams. Rain occurs Compared to V. rupestris, V. berlandieri can be classi- throughout the summer, and its restriction to moist habitats fied as a drought tolerator. Unlike V. rupestris, which dies ensures that it experiences little fluctuation in water avail- back under stress, V. berlandieri maintains a climbing ability during the growing season. Compared to V. rupes- growth habit and keeps green leaves under drought condi- tris, its environment is more predictable, less prone to tions, and growth and fruit maturation occur during the drought, and its growth strategy is better adapted to low most severe part of the summer. Drought tolerance must light conditions, and to a shorter, cooler growing season. be achieved in part by its large, deep root system. Phenol- V. riparia tends to grow upward seeking light, and ogy in this species is very late. produces very long shoots with a large amount of wood. Although V. berlandieri is adapted to maintain activity Its leaves are well-adapted to shade but have little ability and survive during a long, hot growing season, it can toler- to resist drought. They are large and broad; stomata are ate extreme cold during winter (23 degrees below zero cen- even with the epidermis (not sunken) and the parenchyma tigrade; Viala 1889). Its success in cooler temperate regions layer is thin (Ravas 1902). Trunks are slim and weak. V. is limited, however, because its growth cycle is so long and riparia has lower root weights than V. rupestris (Branas late that there is not enough time for fruit and wood matu- and Vergnes in Galet 1983). Riparia Gloire also has a less ration to occur, especially in moist rich soils. plunging root system, and roots have higher angles of geotropism (75 to 80 degrees) compared to 20 degrees in Water and nutrient uptake Rupestris du Lot (Guillon 1905 in Galet, 1983). The roots of different rootstocks have morphological In one study, V. riparia was the only species to produce and physiological differences that result in different abili- less root material than shoot material (Ravas 1902). The ties to take up water and nutrients. Their roots explore very vigourous shoot growth in V. riparia may be due to different soil zones (Harmon and Snyder 1934; Champag- the fact that the plant exports little of its photosynthate nol 1984) and deeper roots give them access to greater back down to the roots, and instead, allocates it to new moisture supply. Stomatal characteristics of the leaves are shoot growth. The growth strategy of V. riparia is conser- also related to rootstock type. On rootstock hybrids that vative and is oriented to long term survival of upwardly are V. riparia x V. rupestris hybrids, stomatal densities, size mobile shoots. and rates of stomatal conductance are higher than in V. In its native habitat, V. riparia can count on adequate rupestris x V berlandieri or V. riparia x V rupestris hybrids soil moisture and nutrient supply. Thus it partitions most (Scienza and Boselli 1981). Rootstocks can impart drought of its growth to long-lived, woody stems that allow it to resistance to the leaves of their scions in a similar fashion climb towards light. Another adaptation to temperate (Carbonneau 1985). ,P colder climates is that its growing season is confined to The absorbancy of certain minerals, e.g. N, K, Ca, Mg, Myth of the universal rootstock

P, varies both among rootstocks and among V. vinifera and maturity can be delayed. scions. Rootstocks have a significant affect on N concen- When vegetative vigour is very high, serious problems tration at bloom (a factor in fruit set/shatter), but not at arise. Rives (1971) describes some of these: "The conse- veraison. Stocks which absorb the most K, 44-53 M and quences are a high incidence of post-bloom abor- SO 4, absorb the least Mg. When these rootstocks are used tion or whole bunch abortion, an overall decrease in foliage with Mg demanding scions such as Grenache or Cabernet efficiency due to mutual shading and to the blocking of Sauvignon, the result is a problematic Mg deficiency and photosynthesis from the premature closing of the stomata associated problems (Boulay 1982). Not only do recent under the water stress caused by the very increase in leaf studies into the influence of rootstock on mineral uptake area, the build-up within the canopy of a micro-climate contribute to future refinements on rootstock choices, but which is highly favourable to disease especially bunch rot they be useful in interpreting past rootstock trials, espe- (Botrytis cinerea) while the density of the canopy makes cially where soil composition is known. it harder for the sprays to reach their targets properly." Ideally, measurements of the rate of vegetative growth Hormones rather than amount of vegetative growth would be the Plant hormones (growth substances) regulate source-sink preferred way to evaluate vegetative vigour. With growth relationships. The control of the routing of metabolites and rates, changes in vigour at various parts of the season could nutrients to target areas are important in determining the be determined, e.g. between the pre-bloom, bloom and relative rates and amounts of vegetative and reproductive fruit-maturation stages, or between periods of high and growth. Three important plant hormones (cytokinins, gib- low water availability. Rate measurements, however, berellins, and abscisic acid) are produced in roots yet they demand large amounts of time and they use a lot of des- control growth processes such as shoot initiation, shoot tructively harvested material. Measurements of standing elongation and flowering. Likewise hormones, e.g. auxin, crop at the end of a growing season are more realistically synthesised in shoots can affect root growth. Lefort (1978) achieved in the vineyard. makes the analogy of the root as orchestra conductor con- trolling in particular the equilibrium between the Cold hardiness path and the vegetative path. Growers in cool climates are especially vulnerable to the It seems odd to hear of certain rootstocks, which never negative effects of excessive vine vigour. Not only can the see the light of day, referred to as more "fruitful" than rootstock affect wine quality each year. if ripening is others. However, research into the role of cytokinins, sup- delayed, but it can be a critical factor in winter survival. plied by the roots at the time of bud burst, shows that In the cool Finger Lakes region of New York, stocks with flower formation in primordia is a cytokinin- V. berlandieri parentage such as 5 BB and 5 C have tended controlled process (Mullins 1980). It has been shown that to produce undesirable, rank growth. On the other hand, rootstocks have more influence on the scion during the first V. riparia x V. rupestris stocks such as 3309 C and 101-14 part of the vegetative cycle. At veraison the fruiting vari- have had less vegetative vigour and therefore been more ety becomes the dominant influence (Lefort 1978). satisfactory (Pool 1987). On the other hand, in the lime- Biochemical research will ultimately tell us much more than stone soils of Germany, 5 BB and other V riparia x V, ber- we now know about how and when rootstocks influence landieri hybrids are the leading rootstocks (Ambrosi and such things as fruitfulness and vigour. Becker 1978). Differences in soil fertility are one factor of course and the other is scion variety. In the temperate cli- Vigour mate and generally fertile soils of Virginia, Cabernet Sau- Rootstocks clearly have a role in determining the vigour vingnon/5 BB or Merlot/5 BB are a poor combination due of their grafted scions. Yet, the relationship is poorly under- to excessive vegetative growth and subsequent winter injury. stood. We can confine the term "vegetative vigour" to White Riesling/5 BB however is acceptable. growth of above-ground non-reproductive structures of the grapevine: shoots and wood. In so doing, we separate it Influence of viruses from sexual reproductive vigour, growth of According to Rives, all rootstock trials before the 1970s and grape clusters, and also from root growth. were flawed due to uncontrolled virus infection. Differing An increase in vegetative vigour means that the amount performances among the rootstocks may have been due of leaf and shoot material increases, and the number and more to their relative degeneration than to other factors size of both active and dormant meristems increases (Rives 1971). Recent studies have also shown how variable (Branas 1974, p. 254). Associated with increased vigour is clonal selections of the same fruiting variety can be, an increase in auxin, a plant hormone that prolongs the independent of virus status, a fact which further compli- period of cellular expansion and allows the extension of cates statistics drawn from early trials (Whiting and Hardie the young parts of the shoot. Chlorophyll and chloroplasts 1981). in the leaves also increase. Vigorous shoots have more leaves Studies of rootstock varieties have shown differences in and they branch more strongly and profusely. It is as if tolerances to virus and virus-like diseases: fan-leaf, leafroll, one apex of the plant cannot use all the energy and and stem pitting in particular. For instance, the V. riparia resources available, so other apices join in the activity. x V. rupestris crosses were much more susceptible to fan- Increased vegetative vigour often gives an increase of leaf then the V. riparia x V. berlandieri crosses (Egger et reproductive vigour, for example, more floral buds are al., 1985). This might be one reason that SO 4 seemed like initiated (Champagnol 1984, p.32). But adverse phenolog- such a superior stock for a time in Europe. Today, however, ical consequences can also result, e.g. the vegetative period SO 4 (very sensitive to Mg deficiency and prone to thyllo- of growth can be maintained for a longer time. Veraison sis) is being replaced in some areas such as Bordeaux,

Proceedings Second International Cool Climate Viticulture and Oenology Symposium, Auckland, New Zealand. January 1988. 27 Myth of the universal rootstock

France, with clean stock of some of the old standards stock decisions based on the latest fad or simplistic tradi- including 3309 C, 101-14, and Riparia Gloire (Anon. 1980; tion. Ironically, it is often the "investment package" which Boulay 1982). The University of California at Davis has dictates how many acres must be planted each year, regard- recently released several V vinifera x V. rotundifolia hybrid less of whether the optimal rootstock/scion combination rootstocks reportedly immune to fan-leaf virus vectors: is available. more testing will reveal what other properties they might After reading nearly 200 sources by 125 authors on the have and impart to their scions. subject of grapevine rootstocks, it is clear that there is no Mistaken identities single "universal" rootstock. There is however, a plurality an individual of venerable universal stocks which have withstood the test Mistaken identities for rootstocks can be on of time and are right now under the competent eye (and level where the nursery erroneously delivers the wrong HPLC!) of leading viticultural scientists. With the follow- material or on a national level such as happened in Aus- ing seven rootstocks all developed before the turn of the tralia when 34 E.M. was incorrectly called 161-49 C (Goss last century, a travelling salesman would have something 1981). Or in California where the identities of 99 R and to offer nearly every grape grower in the world: Riparia 110 R were reversed (Alley and Olmo 1981). If results of Gloire, 420 A, 3309 C, 5 BB, 110 R, 41 B, and Dog Ridge. a rootstock trial seem way out of line, it is not .unreasona- Cool climate growers should select from the riparia family ble to question the naming of the stock involved as a pos- at hand, or select from more then a dozen others obtaina- sible explanation. On an individual level, it is always safer ble by special order. to field graft when possible to allow for checking trueness to type. Literature cited On an international level, it is interesting to note the Alley, C.J., and Olmo, H.P. Letters to the Editor. Am. J. Enol. Vitic. 36: many names that the V. riparia x V. berlandieri Tbleki see- last page (1981). dlings have taken on over the years as various clones have Ambrosi, H. and Becker, H.(Eds.). Der deutche Wein. 364 pp. Grafe and been selected: 5 A, 5 BB, 5 C, 8 B, SO 4, 125 AA, Cosmo Unzer Verlag, Munchen (1978). 2 & 10, Craciunel 2 and 71, to name a few. After so much clonal selection in various countries, there is some debate Anonymous. Les Porte-Greffes de la Vigne dans le Bordelais et le Ber- about the exact ampelographic characteristics of some cul- geracois. 25 pp. Chambre d'Agriculture de la Gironde, Bordeaux (1981). tivars using these names. When the author found a male Boulay, H. Absorption differenciee des cepages et des porte-greffes en "SO 4" vine with the leaf morphology of normally female Languedoc. Prog. Ag. Vit. 99: 431-4 (1982). 5 BB (a colleague suggested calling the anomalous vine "SO B"), she began to wonder how mixed the population Branas, J. Viticulture. 990 pp. Dehan, Montpellier (1974). of vines under the names "5 BB" and "SO 4" might be in Carbonneau, A. The early selection of grapevine rootstocks for resistance the US and elsewhere. to drought. Am J. Enol. Vitic. 36: 195-8 (1985). Influence of commerce There is no question that rootstock cultivars which are Champagnol, F. Elements de la Physiologie de la Vigne et de Viticulture Generale. Champagnol, Montpellier (1984). easy to root and graft are also more economical to produce. Such stocks are far more widely planted than their inher- Egger, E., Borgo, M., and Antoniazzi, P. Tolleranza de portainnesti della ent value warrants. For example, the planting of Rupestris vite ad alcune malattie virali o virus-simili. Riv. Viti. Enol. 38: 302-7 (1985). du Lot in dry regions instead of the superior 110 R can Ferris, H. Quantitative aspects of the development of Meloidogyne arenaria be directly attributed to the latter's poor rooting and medi- larvae in grape vine varieties and rootstocks. J. Nematol. 11: 168-74 (1979). ocre grafting qualities (Galet 1979). Also there is a tendency to favour stocks which produce Freeman, B. M., and Smart, R.E. Research Note: A root observation strong early growth over those that take longer to get estab- laboratory for studies with grapevines. Am. J. Enol. Vitic. 27: 36-9 (1976). lished. This can be a mistake because often the "slow- Galet, P., A Practical Ampelography, L. T. Morton (trans.). 248 pp. Cornell starters" are actually the best producers in the long gun. University Press, Ithaca, (1979). Growers must be patient when ordering new rootstock- scion combinations and be willing to pay more for rare Galet, P. Precis de Viticulture. 584 pp. Dehan, Montpellier (1983). or difficult to propagate stocks. Nurseries faced with new Goss, 0. and Cameron, I.J. Rootstocks beat nematodes in grapevines. J. rootstock cultivars need to study ways to increase their per- Ag. West. Aust. 22: 34-5 (1981). centage of successful grafts; chances are the "new" stock for them is common in another country. Harmon, F.N., and Snyder, E. Grape root distribution studies. Am. Soc. Universal rootstocks? Hort. Sci. 32: 370-73 (1934). In a previous article (Morton 1979), the reasons for Lefort, P.L. Les relations quantitatives entre porte-greffes et greffons. In: differing opinions between the U.S. and French literature Grapevine Genetics and Breeding, lleme Symposium International sur on the drought tolerance of Rupestris St. George (du Lot) ('Amelioration de la Vigne, pp 303-8, Institut National de la Recherche Agronomique, Paris (1977). were examined. What emerged was that St. George was being recommended for dry sites by default: for secondary Lider, L., Ferrari, N.L., and Bowers, K.W. A study of longevity of graft reasons having nothing to do with its drought resistance. combinations in California vineyards. Am. J. Enol. Vitic. 29: 18-24 (1978). It further became clear that a thorough review of rootstock Morton, L.T. The Myth of the Universal Rootstock. Wines & Vines. April: trials in California might show other stocks worthy of con- 24-6 (1979). sideration there (Lider et al., 1978). Vineyards are just too expensive these days to make root- Muffins, M.G. Growth regulators and the genetic improvement of Myth of the universal rootstock vines. In: Webb, A.D., Ed. Grape and wine centennial symposium proceed- ings; 1821 June 1980; Davis, CA: University of California, Davis, CA: 1437 (1982).

Munson, T V. Foundations of American Grape Culture. 252 pp. T.V. Mun- son & Son, Denison, Texas (1909).

Pongracz, D.P. Rootstocks for Grape-vines. 150 pp. David Philip, Cape Town (1983).

Pool, Robert M. Rootstock and winter hardiness. Vineyard & Winery Management. July/Aug: 40 (1987).

Ravas, Louis. Les Vignes Americaines: Porte-Greffes et Producteurs- Directs. 376 pp. Coulet et Fils, Montpellier (1902).

Rives, L. Recherches sur les deperissements de'certains hybrides greffes. Revuede Viticulture. LXII-1603: 221-7 (1925).

Rives, M. Genetique et amelioration de la vigne. In: Sciences et Tech- niques de la Vigne. Riberau-Gayon, J., and Peynaud, E. (Eds.). pp 171-219. Dunod, Paris (1971).

Scienza, A. and Boselli, M. Frequence et caracteristiques biometriques des stomates de certains porte-greffes de vigne. Vitis. 20: 281-92 (1981).

Viala, P. Une Mission Viticole en Amerique. 387 pp. Camille Coulet, Montpellier (1889).

Whiting, J.R., and Hardie, W.J. Yield and compositional differences between selections of grapevine cv. Cabernet Sauvignon. Am. J. Enol. Vitic. 32: 212-8 (1981).

Proceedings Second International Cool Climate Viticulture and Oenology Symposium, Auckland, New Zealand. January 1988. LIST OF ROOTSTOCK EFFECTS ON WINE QUALITY Yield -- vine's capacity balance between vegetation & fruit (hormonal influence) number of clusters per shoot number of berries per cluster size of berries condition of berries at harvest (water uptake) -- yield in turn affects: ripening time due to crop load sugar/alcohol levels acid :valance tannin content color quality factors:concentration, complexity

Canopy size (Vigor): from vigor (N uptake?) from more or less laterals from water uptake from balance of vegetation & fruit (hormones) canopy shading in turn affects: rot mildew pH/potassium malic acid herbaciousness

Chemical composition of fruit N uptake K uptake Ca uptake others? chemical composition affects rate of fermentation stability color flavor

Vegetative cycle (Phenology) -- bud fruitfulness affected by temperature flower date vie a vis spring frost? ripening date before or after rains ripening in warmer or cooler conditions

Vine longevity -- better pest & disease resistance better winter hardiness less "burn out?" (SO 4, AXR?) reasons unknown (3309?) Older vines mean -- better economics if grape variety is certain more consistent wine character more complex wine

2 L GROTROP/C ANGLKS

14 0 g6e 9° 160 ' go' /8D° oa • 0 200 "a,or' o° 0 0 RUPESTRIS RIPARIA EUIRLANDIERI

The technical choice of a rootstock is mainly based in the growing habits of the roots; some are deep growing, others are shallow growing. Those different characteristics are known as the •Geotropic angles' of the roots. Under the influence of gravity, the roots follow an oblique direction which differs for each variety. They form with the vertical, an angle that is very important to know because it provides you with very useful information about the growing habits of the root systems and, therefore, their adaptation to the different soil types. The varieties whose roots grow close to the vertical are drought tolerant. The varieties whose roots grow close to the horizontal are sensitive to drought. Thus, if you have a shallow soil with a poorly drained subsoil, you should use a variety of rootstock with a shallow growing pattern.

-10 *Are Hold la.1/Pege 2

Vitis riparia grows naturally in areas where there is ample moisture, such as along streams. Many of the stocks with V. riparia as a parent reflect this need for moist soils and do not perform well under dry conditions.

Vitis rupestris grows in regions with hot, dry summers - often in rocky soils where its roots can grow deep in search of water. This ability to withstand drought is reflected in many of the hybrids which have V. rupestris as a parent.

Vitis Berlandieri grows in high limestone soils. It is quite resistant to a nutritional disorder which most grapes experience in such soils. Chalky, high limestone soils are common in Europe so V. Berlandieri was used to breed its lime tolerance into resulting hybrid stocks.

ACIDIC SOIL TYPE WELL DRAINED WELL DRAINED BADLY DRAINED PH 4.0-5.0 HUMID SOIL DRY SOIL WET IN SPRING RARELY SANDY 101.14 1103P. 3309C 101.14 FOUND 1616C 44.53 1616C RARELY SANDY GRAVEL RIPARIA GLOIRE 1103P. 3309C RIPARIA GLOIRE FOUND 101-14. 3309C 44.53.420A 3309C. 1103P 420A 1616C 1 103P CLAYEY GRAVEL RIPARIA GLOIRE 1103P 3309C RIPARIA GLOIRE 44-53. 110R 101-14. 420A 420A. 101-14 3309C. 1103P 140R 3309C. 1103P 44.53 RARELY SANDY LOAM RIPARIA GLOIRE I 103P 44-53 RIPARIA GLOIRE 101-14 3309C 1616C, 44.53 FOUND 3309C. 420A 3309C. 1103P 1103P LOAM RIPARIA GLOIRE 420A. 3309C RIPARIA GLOIRE 44-53. 3309C 101-14 I615C 10114.44.5344-53 101-14 110R. 140R 420A. 3309C 1103P 1103P. 44.53 1103P CLAYEY SANDY RIPARIA GLOIRE 1103P. 44.53 RIPARIA GLOIRE 44-53. I I OR 101-14. 420A 3309C 1616C 14OR 3309C 1103P CLAY LOAM RIPARIA GLOIRE 1 103P. 44.53 RIPARA GLOIRE 1616C. 101.14 3309C 1616C 44-53. 110R 140R 3309C. 420A 1103P CLAY RIPARIA GLOIRE 103P. 44-53 NON•ViTICuLTURAL 44-53. 14OR 101-14. 1103P SOIL 1616C

1- I

HERRICK GRAPEVINES 1450 S. LANE CA 94574 (707) 967-8000 FA (707) 963-7930 ortouom. ADAPTATION FoltlylioxepA .. NEMATODE BEST SOIL PARENTAGE VIGOR _ 0100T-KNOT) ADVANTAGES DISADVANTAGES ROOTSTOCK RESISTANCE , - RESISTANCE : T° WET- . E *SISTANCE CLAY SOIL.,

Prefers deep fertile soils. Can do well in Riparia Gloire / Low High Deep/Fertile Doesn't do well in sandy soils or arid sites. V. ripana Low Yes Poor high density plantings. Gloire de Montpellier

/ Deep, Uniform Prefers deep soils and is considered a high Not good for shallow soils or areas known Saint George V. rupestris High Yes Poor Moderate Moderate Rupestris du Lot Loam vigor rootstock. to have nematodes.

V. riparia x Deep Well Does best in deep fertile soils, good for high Very low tolerance of nematodes, sensitive 3309 Courderc Moderate Yes Susceptible Low High V. rupestris Drained density planting. to drought.

V. riparia x Loam/Good Low tolerance of lime, can suffer from Moderate High Can do well in high magnesium soils. 44-53 Malegue (V.cordifolie x Moderate Yes Unknown Fertility magnesium deficiency. V. rupestrts)

Low / 101-14 Miliprdet Et V. riparia x Yes Susceptible , r y .. ft Best rootstock for heavy clay soils. Needs Irrigation in dry areas. De Gra&et V. rygestris .. Moderate t: r. ,‘. ;, :t. - Al V. rtparia ic, '.: L , / , ,. , ' ... Not drought tolerant. Not much resistance yell- - it Moderate ow/Modest Nigh ertile Does well in deep, fresh, fertile soils. Schwarnbann V. niiiestris" Moderate to fan leaf. ..---,-.

420A Millardet Et V. berlandieri x Low Yes Moderate Moderate Fertile Low vigor excellent for close spacing. Difficult to root, needs sufficient water. De Grasser V. riparia a q s

, VW,: . 1 , ■), D V. berlandieri x Ii.' _.:. refstance phyllox nd Oppenheim #4 / High •ii:z Clef *lot diteght n Moderate Yes Moderate nematodes, tde 51Gne stills. SO4 V. riparia it

V. berlandieri x Does well in clay soils, broad nematode Vulnerable to phytophthora, not for arid High Yes Good - Low Moderate Clay Loam 5BB Kober V. riparia resistance. plantings.

V. berlarlieri x Early ripening, does well in clay soils, 5C Teleki High Yes Moderate Low High Clay Not drought tolerant. V. riparia Phylloxera resistant, nematode resistant.

V. berlandien x Susceptible to rootknot and dagger 1103 Paulsen High Yes Susceptible High High Loam, Lime Drought tolerant, hillside sites work W. V. rupestris nematodes.

V. berlandieri x Moderate Recommended for hillside or dry farmed Not recommended for deep fertile soils, can 110 Richter High Yes Susceptible High Moderate V rupestris Fertility areas. show potassium deficiency on heavy soils.

Very vigorous, recommended for hillside or Not recommended for deep fertile soil. Shallow DDrought V. bertandieri x Susceptible High Moderate shallow drought prone soils. Tolerant of Moderate resistance to rootknot nematode 140 Ruggeri Very High Yes Prone V. rupestris relatively high active lime. reported.

Sandy Low Excellent nematode resistance. Does best 11313 C x High Questionable High Moderate/High Low Not recommended for fertile soils . Freedom V. champinli Fertility in coarse textured soils with low fertility. ROOTSTOCK VARIETIES • ACTIVE LIME RESISTANCE • SOILS ADAPTATION

Active lime Varieties resistance Soils adaptation and aptitudes

Very vigourous, has some resistance to salt. tt is not recornmanded for humid soils and its resistance to drought depends RUPESTRIS DU LOT 14 Wo on the soil and climate conditions. He grows in siliceous and clayey soils. Excellent resistance to Phylloxera.

RIPARIA GLOIRE DE MONTPELLIER 6 % Prefers fresh, humid soils. Sensitive to drought conditions. Excellent resistance to Phylloxera.

3.309 COUDERC Vigourous rootstock in fresh, deep soils, sensitive to drought and also not recommanded for humid, poorly 12 % drained soils. Excellent resistance to Phylloxera.

RIPARIA 101-14 MILLARDET ET DE GRASSET 14 % This variety does well in fresh, clay soils. More vigourous than Riparia Gloire but less vigourous than 3.309 C. X RUPESTRIS 44-53 MALEGUE 9-10 % Resistance to Fanleaf degeneration and to drought. Suffers from magnesium deficiency. Good resistance to Phylloxera.

196-17 CASTEL 6 % Variety very resistant to drought. It does well in fresh, sandy and acid soils. It resists to salt.

Vigourous. Good resistance to Phylloxera. Does not tolerate salt. Sensitive to dry conditions. 99 RICHTER % 17 Some resistance to nematodes. BERLANDIERI 110 RICHTER 17 % Vigourous. Good resistance to drought. Somewhat resistance to nematodes. X RUPESTRIS 1103 PAULSEN 17-18 % Vigourous. Adaptability to clay-lime soils with fresh, humid subsoils. Good resistance to salt. Recommended for very dry conditions.

140 RUGIERI 32 % Very vigourous. Hardy variety used in dry, limy soils. Resistance to Phylloxera.

Vigourous rootstock. Suits to humid, clay soils. Not recommended for very dry conditions. SO4 17-18 % Good resistance to nematodes.

Slighty more vigourous than Riparla Gloire. Good resistance to Phylloxera. Not a good choide for dry conditions. 420A MILLARDET ET DE GRASSET 20 % It prefers fresh, fertile soils. 161-49 COUDERC 25 % Vigourous rootstock. It is not recommanded in drought conditions. RIPARIA It is susceptible to nematodes. Excellent resistance to Phylloxera. X BERLANDIERI Vigourous rootstock. 5B8 KOBER is suited to humid, clay soils but is not recommanded in extremely dry 5BB KOBER 20 % conditions, Good resistance to nematodes.

Aptitudes very similar to those of 5BB KOBER, with an earlier maturing. 5C TELEKI % 20 It may interest those cultivating the vine at high altitude or in northern regions.

RSB1 20-22 % Vigourous rootstock. Aptitudes very similar to those of 5 BB KOBER. Good resistance to Phylloxera.

VIMIFERA 41B MILLARDET ET DE GRASSET 40 % + Exceptionally high resistance to lime. Its resistance to Phylloxera is sufficient, but not absolute. There is no X resistance to salt ; and his foliage must be protected against downy mildew. BERLANDIERI FERCAL 40-45 % + Sensitive to magnesium deficiency. Good resistance to Phylloxera and nematodes. HYDRIDE DE This is a fairly weak variety which should be grow in humid soils. It is mostly used 1616 COUDERC in The 5 tiliy 'oils along the CANOICANS 11 % coasts. Good resistance to nematodes and Phylloxera. WYBRIDE GRAVESAC (161-49 C. X 3.309 C.) 20 % Used in sandy, gravely, slightly acid soils. Excellent resistance to Phylloxera. COM PLEXE