Curation of the UC Davis Viticulture Herbarium, Saving and Invaluable Teaching and Research Resource

Funding was requested to curate the UC Davis Viticulture Herbarium, which consists of two main collections. The first collection is the original viticulture herbarium, ca. 1000 specimens dating from 1885 to the 1920s (pre-prohibition era), which document an impressive number of the wine grape cultivars grown in California at that time (collected from both vineyards and agricultural stations). The second collection is that of Harold P. Olmo and his assistant Albert Koyama; their specimens were collected between the 1930s and the 1960s and document the grape cultivars that they collected from a number of countries in Europe, the Middle East, Asia, and South, Central, and North America (including California).

Herbarium specimens consist of a dried and pressed plant sample mounted on paper and a label, which includes information on the name of the plant, the location and date of collection, and the collector?s name. At the time this project was funded, the folders (and associated labels) of the original viticulture herbarium were crumbling, and we were in danger of losing the label information stating the cultivar name and location and date of collection. In addition, the collections of Olmo and Koyama had never been labeled or mounted on paper, and we were in danger of losing their collection information, due to the advanced ages of their collectors.

The project was carried out at the UC Davis Herbarium between October 2000 and March 2001. Kate Borland proved to be an excellent person to carry out the project. In curating the Olmo and Koyama collection, she communicated effectively with Olmo and Koyama, deciphered their collection notebooks, checked species and cultivar names in the appropriate literature resources, typed collection data for nearly 2,000 specimens into our Access label-generating database, generated the labels on archival-quality paper, and placed the new labels with the correct specimens. The Olmo and Koyama specimens still require mounting onto archival paper. For the original viticulture herbarium, Kate cut the original labels off their crumbling folders, xeroxed them onto archival-quality paper, and placed the new labels with the specimens. Undergraduate students then glued the new labels onto archival folders and placed the pressed specimen into the folders, securing them with linen tape. We did not glue these specimens, so that they can be used easily be future researches for both morphological and molecular studies.

PDF: Curation of the UC Davis Viticulture Herbarium, Saving and Invaluable Teaching and Research Resource

Development of Grape Rootstocks with Multiple Nematode Resistance

Rootstocks currently available for nematode resistance have either inappropriate horticultural characteristics (such as the inducement of excessive vigor in scions leading to poor production and quality) or they have insufficient resistance against aggressive nematode strains and species. Several species of plant-feeding nematodes are present in most vineyards, however few rootstocks have resistance to more than one species.

Sources of resistance to root-knot and dagger nematodes have been detected in several Vitis species. Crosses made among these species in 1989, 1993 and 1994 were screened first for rooting characteristics and then sequentially against three nematode species: the root knot nematode (Meloidogyne incognita race 3), a strain of root-knot nematode that overcomes the resistance of Harmony rootstock (Meloidogyne arenaria), and the dagger nematode (Xiphinema index).

We have selected several candidate rootstocks with strong resistance to the individual nematode species, and some with broad resistance to two or more of the nematode species. Candidate selections will progress to field trials for testing of resistance durability and horticultural characteristics in the coming year. Screening of candidate selections against other nematode species, and against combinations of nematode species, will proceed in greenhouse trials.

Rootstock candidates evaluated in these studies are selected from Dr. Walker’s rootstock breeding program. This report addresses the nematode screening, not the breeding and horticultural components of that program.

PDF: Development of Grape Rootstocks with Multiple Nematode Resistance

Rootstock Interactions with Cultural Practices

This project covers three objectives. It evaluates the interaction of rootstock with increased buds retained at pruning at the Oakville Experimental Vineyard, the performance of rootstocks with several in-row spacings under non-irrigated conditions at the Oakville Experimental Vineyard and the interaction of nine rootstocks with potassium application in Merlot with Chalk Hill Vineyards.

The response of cordon trained Cabernet Sauvignon on 110R, 101-14, and 5-C rootstocks to a wide range of pruning levels was evaluated to examine the interaction of rootstock and pruning formula. Rootstock had no effect on the measured components of fruit composition at harvest. Maturities varied in response to pruning level with a significant interaction between pruning and spacing. Closer spacing resulted in a steeper decline in maturity with incremental increases in bud number. This was especially evident for vines planted on 5C. Pruning level influenced components of yield that depend on shoot number: clusters per vine and total yield. It had no independent effect on components that depend on bud fruitfulness: clusters per shoot and cluster size. Significant interactions arose between pruning and rootstock on the number of berries per cluster and final cluster weight. Cluster weights tended to increase with increasing pruning levels on 5-C and decrease with increasing pruning levels on 110R. Berry size was reduced at high bud numbers on 101-14 and 110R.

In 2000, the in-row spacing treatments had yields of 3.22, 4.07 and 4.44 kg m-1, for the 1.0, 1.6 and 2.2 meter spacing, respectively. The differences in yield was attributed to the numbers of berries per cluster with the 1.0, 1.6 and 2.2 m treatments having 120, 130 and 133 berries cluster-1, respectively. There were no differences in berry weight. The four-year average also showed that yield was lower at the 1.0 m spacing than the 1.6 and 2.2 m spacing treatments, 2.49, 3.15 and 3.20 kg m-1, respectively. The lower yield of the 1.0 m spacing was attributed to both smaller berries and fewer berries per cluster. In 2000, there was no effect of rootstock on yield for those vines pruned to equivalent buds per vine. Likewise, the components of yield, berry weight, cluster weight and berries per cluster did not differ. These results are consistent with the cumulative four-year averages.

At the Chalk Hill Merlot site yield in 2000 was equal to the four-year mean at 8.5 kg vine-1. However, when the effect of the potassium fertilizer treatment is taken into account we see a different picture. Yields for vines receiving potassium fertilizer were slightly higher (0.4 kg vine-1). Indeed, yield has been higher for vines receiving potassium fertilizer for all but the first year. In the last two years, 1999 and 2000, the increased yield has been approximately 1.5 kg vine-1. The yield increase has been largely accomplished through an increase in cluster number arising from an increase in shoot number. The vines have been pruned as was appropriate for each vine therefore, the increase in shoot number represents an increase in perceived capacity.

PDF: Rootstock Interactions with Cultural Practices

Field Evaluation of Wine Grape Rootstocks

This project continues rootstock evaluation for winegrape performance in a wide range of coastal and foothill production areas, and in sites which are infested with phylloxera, nematodes or both, or which have important site/soil conditions or limitations. This project includes sites in Amador, Napa, San Luis Obispo, Sonoma, Mendocino and Monterey Counties. At all sites we see significant differences in the performance of the rootstocks that will lead us toward more informed better rootstocks decisions.

Two sites in Amador County both have Zinfandel as the scion variety. These sites not only represent our on Zinfandel sites but the only ones in the granitic soils common to the Sierra Foothills. The first site is unique in that it is a non-irrigated site. We have reported data from this site since 1995. In terms of relative yield performance, we have seen that over time 1103P has distanced itself from the other rootstocks and 3309C has fallen behind. The second trial contains 14 rootstocks. The 2000 yield data followed the 7-year trend and 5BB had the greatest yield and O39-16 the least. The yield difference was driven by differences in both berries per cluster and cluster number.

At our Cabernet Sauvignon rootstock trial in Mendocino County we are able to look at the effect of the nematodes and their populations often increases over time. The highest yielding rootstock found in 2000 as well as in the multi year data was 110R with 8.6 and 13.4 kg vine-1 respectively and the lowest in 2000 and in the multi-year data was 101-14 with 1.8 and 5.8 kg vine-1 respectively. The 2000 data we present in our report will be coupled with nematode population data that will be collected this spring and another year of performance data in 2001.

In our report we present data from 5 sites where 2000 was the first or second year of data collection. These vineyards are all young and during the initial years of data collection we need to look at year-to-year data to establish developmental stability. Yield and pruning weight data in subsequent years will be used to establish developmental stability. Three sites are located in the Napa Valley. The first site is Merlot located mid-valley near the Silverado Trail, with well-drained, quite cobbly soil. This is only the second year in which we have collected data in this trial. For the two remaining Napa Valley sites, Chardonnay in the Carneros region and Cabernet Sauvignon near Calistoga, and 2000 was the first year of data collection. Data from two additional first year sites is also reported. One is a non-irrigated Pinot noir site in San Luis Obispo County that showed quite a bit of yield variability and lastly we have a Chardonnay site in Sonoma County. All of these sites represent opportunities to collect rootstock data from new varieties and/or conditions and will add significantly to our rootstock knowledge base.

PDF: Field Evaluation of Wine Grape Rootstocks

Development of Grape Rootstocks with Multiple Nematode Resistance

Rootstocks currently available for nematode resistance have either inappropriate horticultural characteristics (such as the inducement of excessive vigor in scions leading to poor production and quality) or they have insufficient resistance against aggressive nematode strains and species. Several species of plant-feeding nematodes are present in most vineyards, however few rootstocks have resistance to more than one species. Sources of resistance to root-knot and dagger nematodes have been detected in several Vitis species. Crosses made among these species in 1989, 1993 and 1994 were screened first for rooting characteristics and then sequentially against three nematode species: the root knot nematode {Meloidogyne incognita race 3), a strain of root-knot nematode that overcomes the resistance of Harmony rootstock {Meloidogyne arenaria), and the dagger nematode (Xiphinema index). We have selected several candidate rootstocks with strong resistance to the individual nematode species, and some with broad resistance to two or more of the nematode species. Candidate selections will progress to field trials for testing of resistance durability and horticultural characteristics in the coming year. Screening of candidate selections against other nematode species, and against combinations of nematode species, will proceed in greenhouse trials. Rootstock candidates evaluated in these studies are selected from Dr. Walker’s rootstock breeding program. This report addresses the nematode screening, not the breeding and horticultural components of that program.

Field Evaluation of Wine Grape Rootstocks

This project continues rootstock evaluation for winegrape performance in a wide range of coastal and foothill production areas, and in sites which are infested with phylloxera, nematodes or both, or which have important site/soil conditions or limitations. This project includes sites in Amador, Napa, San Luis Obispo, Sonoma, Mendocino and Monterey Counties. At all sites we see significant differences in the performance of the rootstocks that will lead us toward more informed better rootstocks decisions. Two sites in Amador County both have Zinfandel as the scion variety. These sites not only represent our on Zinfandel sites but the only ones in the granitic soils common to the Sierra Foothills. The first site is unique in that it is a non-irrigated site. We have reported data from this site since 1995. In terms of relative yield performance, we have seen that over time 1103P has distanced itself from the other rootstocks and 3309C has fallen behind. The second trial contains 14 rootstocks. The 2000 yield data followed the 7-year trend and 5BB had the greatest yield and 039-16 the least. The yield difference was driven by differences in both berries per cluster and cluster number. At our Cabernet Sauvignon rootstock trial in Mendocino County we are able to look at the effect of the nematodes and their populations often increases over time. The highest yielding rootstock found in 2000 as well as in the multi year data was 110R with 8.6 and 13.4 kg vine” respectively and the lowest in 2000 and in the multi-year data was 101-14 with 1.8 and 5.8 kg vine’1 respectively. The 2000 data we present in our report will be coupled with nematode population data that will be collected this spring and another year of performance data in 2001. In our report we present data from 5 sites where 2000 was the first or second year of data collection. These vineyards are all young and during the initial years of data collection we need to look at year-to-year data to establish developmental stability. Yield and pruning weight data in subsequent years will be used to establish developmental stability. Three sites are located in the Napa Valley. The first site is Merlot located mid-valley near the Silverado Trail, with well-drained, quite cobbly soil. This is only the second year in which we have collected data in this trial. For the two remaining Napa Valley sites, Chardonnay in the Carneros region and Cabernet Sauvignon near Calistoga, and 2000 was the first year of data collection. Data from two additional first year sites is also reported. One is a non-irrigated Pinot noir site in San Luis Obispo County that showed quite a bit of yield variability and lastly we have a Chardonnay site in Sonoma County. All of these sites represent opportunities to collect rootstock data from new varieties and/or conditions and will add significantly to our rootstock knowledge base.

Rootstock Interactions with Cultural Practices

This project covers three objectives. It evaluates the interaction of rootstock with increased buds retained at pruning at the Oakville Experimental Vineyard, the performance of rootstocks with several in-row spacings under non-irrigated conditions at the Oakville Experimental Vineyard and the interaction of nine rootstocks with potassium application in Merlot with Chalk Hill Vineyards. The response of cordon trained Cabernet Sauvignon on 110R, 101-14, and 5-C rootstocks to a wide range of pruning levels was evaluated to examine the interaction of rootstock and pruning formula. Rootstock had no effect on the measured components of fruit composition at harvest. Maturities varied in response to pruning level with a significant interaction between pruning and spacing. Closer spacing resulted in a steeper decline in maturity with incremental increases in bud number. This was especially evident for vines planted on 5C. Pruning level influenced components of yield that depend on shoot number: clusters per vine and total yield. It had no independent effect on components that depend on bud fruitfulness: clusters per shoot and cluster size. Significant interactions arose between pruning and rootstock on the number of berries per cluster and final cluster weight. Cluster weights tended to increase with increasing pruning levels on 5-C and decrease with increasing pruning levels on 11 OR. Berry size was reduced at high bud numbers on 101-14 and 11 OR. In 2000, the in-row spacing treatments had yields of 3.22, 4.07 and 4.44 kg m”1, for the 1.0, 1.6 and 2.2 meter spacing, respectively. The differences in yield was attributed to the numbers of berries per cluster with the 1.0, 1.6 and 2.2 m treatments having 120, 130 and 133 berries cluster’1, respectively. There were no differences in berry weight. The four-year average also showed that yield was lower at the 1.0 m spacing than the 1.6 and 2.2 m spacing treatments, 2.49, 3.15 and 3.20 kg m”1, respectively. The lower yield of the 1.0 m spacing was attributed to both smaller berries and fewer berries per cluster. In 2000, there was no effect of rootstock on yield for those vines pruned to equivalent buds per vine. Likewise, the components of yield, berry weight, cluster weight and berries per cluster did not differ. These results are consistent with the cumulative four-year averages. At the Chalk Hill Merlot site yield in 2000 was equal to the four-year mean at 8.5 kg vine”1. However, when the effect of the potassium fertilizer treatment is taken into account we see a different picture. Yields for vines receiving potassium fertilizer were slightly higher (0.4 kg vine’1). Indeed, yield has been higher for vines receiving potassium fertilizer for all but the first year. In the last two years, 1999 and 2000, the increased yield has been approximately 1.5 kg vine”1. The yield increase has been largely accomplished through an increase in cluster number arising from an increase in shoot number. The vines have been pruned as was appropriate for each vine therefore, the increase in shoot number represents an increase in perceived capacity.

Field Evaluation of Wine Grape Rootstocks

Napa 4 was lost when the plot was night machine-harvested in error. Napa 5 was determined to be too immature to yield acceptable data in 1999. A revised Final Report will be submitted when the additional data is available. Amador 1. Fox Creek. The 1999 data slightly favored putative drought resistant rootstock 1103P over the rootstock 3309C more so than the long term average (1995-1999, Table 3b). However, none of the yield components individually were significantly different enough to account for the observed yields. Thus the site variability which has manifested itself in this trial before continues to show. Amador 2. Sutter Home. Yields in 1999 were about at the long term average, 1994-1999. The 1999 data followed the 6-year trend with 5BB having the greatest yield and 039-16 and 101-14 having the least. There were differences in cluster number, berries per cluster and berry wt contributing to the yield differences. Napa 3. Duckhorn Vineyards. This is a new trial near the Silverado Trail, mid-valley with well-drained, quite cobbly soil. The 1999 data (Table 4) show that 3309C is out-yielding other rootstocks by 0.5 to 1.3 kg per vine. Napa 4. Oakville Experimental Vineyard. Teleki 5C, 225 Ruggeri and 1103P lead the yield column while S04 and Kober 125AA are among the lowest yielding. Berries per cluster and berry wt are the yield components playing the most important role, although the component clusters per shoot also is involved. Shoot wt (relating to shoot length) is dramatically different varying from a low of 35 g (S04) to 110 g (1103P), resulting in dramatic differences in pruning wt, from a low of 1.4 kg/vine (101-14Mgt) to a high of almost 4.0 (1103P).

Grape Phylloxera Life Tables: Relevance of Whole Grapevine and Soil

A critical aspect of a pest’s biology is the way plant and environmental factors influence growth of populations. For grape phylloxera, our laboratory work has demonstrated the immense potential this pest has for population growth. However, surveys of actual populations on field vines has shown that such potential is not met and phylloxera population growth varies during the vine’s growing season. On susceptible vines, populations peak midsummer and then for unexplained reasons decline thereafter until a second peak occurs after-harvest. Populations are low in winter because low temperatures prevent insect activity. The purpose of the present research was to do life-table experiments to understand why populations decline midsummer. We set up phylloxera populations on roots while the roots were still attached to field vines and separated the insects from the soil environment by encasing them and then-feeding sites in Petri dishes. We then looked at these test populations at 3-5 day intervals and measured survival, developmental rate to the adult stage, and fecundity over a 45-day assay period. This experiment had a detached root control?that is, roots that were detached from the same test vine were infested and placed in Petri dishes in the ground adjacent to the attached-root Petri dishes. These insect life-table experiments were done three times, once at the vegetative, post-veraison, and post-harvest periods. The most striking result confirmed previous findings that attached roots have about a 2- to 8-fold inferior performance in comparison with detached roots from the same vine held under identical conditions. Since the soil was not in contact with the insects during this experiment, this finding was not due to a direct soil effect; the effect was either due to vine physiology or a soil factor mediated by vine physiology. The second striking finding was that the ability of the vine to support phylloxera changes markedly during the growing season and the major cause of the change is a factor causing phylloxera mortality prior to the insect’s 3rd instar. This is the time the insect is inducing the plant to form the gall. So, the cause of this mortality may be a toxin or a physiological factor inhibiting gall formation. With regard to nutritional factors, our data are not yet complete?a portion of the analyses being done by the DANR analytical laboratory are yet to be received. But so far the data suggest that involvement of nutritional factors is limited. In addition, greenhouse experiments in progress with rootstock cultivars will discover whether similar patterns are seen in plants with strong phylloxera resistance. These results will be available for the final report. Based on these results we are proposing new work to determine the relative role of gall formation, toxins and nutrition in the natural field mortality. In composite these findings are important for understanding vine susceptibility and resistance. Farmers will use them for managing infested vineyards prior to replanting and plant breeders will use them for producing better adapted rootstocks.

Inheritance of Resistance to Phylloxera in Fland F2 Populations of Grape

Approximately 1,170 of the 1,540 seed from the controlled crosses to create population 1 were germinated from June until August. About 980 plants completed germinating and were planted in 2Vi” pots and then inoculated when they were one month old. They were evaluated in January, 2000 and only one plant was found infected with phylloxera. The poor results may have been due to the small seedling roots. The seedlings have been re-potted and inoculated again. For population 2, cuttings were taken from 950 plants in the field. Four leafy cuttings per plant were mist propagated for a total of 3,800 cuttings. All cuttings that rooted were transplanted to 2V4″ pots and inoculated with phylloxera eggs at that time. The first cuttings were taken June 21 and the last cuttings taken August 12, 1999. The rooted cuttings have much stronger roots than plants started from seed and it seems easier for the phylloxera to become established on them. Good phylloxera infection was obtained for the crosses 1 to 9 resulting in good evaluation of resistance and susceptibility. Poor results were obtained for crosses 15 to 20 because they were inoculated after the first of September. Plants were inoculated again after their evaluation to fully test their resistance and eliminate the possibility of escapes. The occurrence of phylloxera on the roots is positive identification of susceptible individuals. There was good correlation between the tests conducted in the 6″ pots and the 2Vi” pots. Susceptible parents generally produce susceptible offspring except when Kober 5BB was the resistant parent. Based on this progeny test, Kober 5BB has the highest level of resistance that is passed to its offspring. Because of the low number of individuals in certain crosses, they were repeated this spring. A total of 237 seed were produced from the four crosses made. They have been stratified and are ready for planting. Work on molecular markers was not started. The resistant/susceptible nature of the seedlings needs to be determined first.