Vineyard Sprays to Improve Ripening in Merlot (in collaboration with VT) (2017)

This study examines the impact of different desiccation sprays on the resulting juice and wine chemistry of Merlot. 8 rows of Merlot from the same block were divided into 4 pairs, each pair of rows receiving a different treatment. The following treatments were performed: 1) Control (no spray), 2) RG 1950 spray in collaboration with Dr. Mizuho Nita, where rows were sprayed 4 times weekly, over four weeks, starting from veraison, 3) VT Tech Dehydration spray in collaboration with Dr. Bruce Zoecklein, where rows were treated on the fruit zone at approximately 19 degrees Brix using a 2% solution of methyl esters of fatty acids in a 2% solution of potassium carbonate in water, and 4) Sugar Express (Miller Chemical) Spray (4-10-40 Nitrogen-Phosphate-Potash), where rows were treated on the full canopy at approximately 19 degrees Brix at 10 lbs/acre. All other viticultural and winemaking practices were equal. Grapes were harvested on September 20, after processing musts were inoculated with D21, and each fermentation received a 16 day maceration. The two VT sprays had the greatest impact on Brix and Average Berry weight during ripening. Fluctuations are due to rain events around September 2 and September 6. The VT sprays produced juice with higher Brix, although the Zoecklein spray had higher TA and the RG 1950 had lower TA. Wine chemistry showed higher ethanol for these two sprays, higher TA and tartaric acid for all three sprays, and lower levels of lactic acid. Color intensity was increased by the desiccation sprays. Anthocyanins were slightly lowered for the VT sprays, although polymeric anthocyanin was increased for these sprays. Tannin showed slight increases for these sprays as well. These phenolic differences, however, were not very great.

Overall, the desiccation sprays had a tendency to lower the Herbaceous character of the wines. Overall Aromatic Intensity and Body tended to be increased by the Zoecklein spray, although RG 1950 also had a slight tendency to increase Body. These two sprays also had a slight tendency to increase Fruit Intensity, although this was weak. In general, the control wine was more similar to the Sugar Express treatment, and the two Virginia Tech desiccation sprays were more similar to each other. Preference trends were hard to determine, but the Sugar Express treatment tended to be less preferred. The two Virginia Tech desiccation sprays were perhaps slightly more preferred control when considering that these two wines were fairly similar to each other. These results suggest that desiccation sprays may be a valuable tool in Virginia winemaking, and studies like these merit more rigorous analysis, especially with regard to sensory attributes of the wines. These studies should be continued to be repeated, on multiple varieties over multiple vintages.

Read Full Report (PDF)

Vineyard Sprays to Improve Ripening in Cabernet Franc (in collaboration with Bruce Zoecklein) (2017)

This study examines the impact of vineyard desiccant sprays on grape ripening and wine quality in Cabernet Franc. A block of Cabernet Franc was divided so that part of the block was backpack-sprayed with a desiccant spray (2% solution of methyl esters of fatty acids in 2% solution of potassium carbonate in water) provided by Bruce Zoecklein. The spray treatment occurred when the grapes had reached approximately 19 Brix (September 22, 2017) and clusters were coated until dripping with spray. Grapes were harvested on September 28 and were processed identically. Wines were pressed after 11 days of maceration. Cluster weight, total anthocyanins, and tannin were decreased in sprayed fruit. Brix was increased and acidity was decreased in sprayed fruit as well. Alcohol and potassium were higher in the sprayed wine, and acidity was lowered. Color, tannin, and polymeric anthocyanin were also higher in the sprayed wine, in spite of opposite trends being seen in this regard with the grapes. Overall, these wines were found to be significantly different. There was a tendency for the desiccated wine to have higher Body. Desiccated wines had a slight tendency for higher Acidity and Astringency, and lower Fruit Intensity. However, more sensory studies are needed to confirm these trends. There may have been a very slight preference for the non-desiccated wine. In the future, more studies should be performed on fruit desiccation, as it has potential to be a useful tool in Virginia grape growing. These studies should include the timing of desiccation sprays before harvest.

Read Full Report (PDF)

The Impact of Trellising on Ripening and Quality in Merlot (2017)

Different trellising systems can have a large impact on canopy sun exposure, leaf area:fruit ratios, and yields. Different trellising systems also have different labor requirements for proper management. Determining which trellising system is best for a given site, on a given variety, is therefore very important. This study examines the difference between two training methods – VSP and Scott Henry – on resulting juice and wine quality. Merlot (clone 181) was planted in 2000 and trained as Scott Henry. In 2017, every other row of this block was converted to VSP. All vineyard treatments were identical, with leaf pulling on east side of vine after fruit set. Grapes were harvested on the same day, and all fermentation practices were identical between treatments. There were not many differences in juice and wine chemistry, except for slightly lower tartaric acid in the Scott Henry wine and decreased acidity. Tannin may have been slightly lower in the Scott Henry wine as well. Overall, these wines were not found to be significantly different, but perhaps would have been at more lenient p levels. Descriptive analysis was not completely consistent between tastings. Preferences slightly favored the VSP trellis, but this was not strong. This study should be repeated over multiple years on different grape varieties. More careful attention should be paid to viticultural parameters, such as leaf area to fruit weight ratios, and yield parameters.

Read Full Report (PDF)

The Impact of Different Leaf Pulling Treatments in Cabernet Franc (in Collaboration with Cain Hickey) (2017)

This study examines the impact of different leaf pulling regimes on ripening in Cabernet Franc. Grapes received either: 1) No leaf pulling, 2) Standard leaf pulling (leaf pulling before mid-June on East side of vine), 3) pre-bloom leaf pulling (May 17, both sides of vine), 4) post fruit-set leaf pulling (June 2, both sides of vine), 5) Mechanical leaf pulling (May 26, post fruit-set, both sides of vine), 6) bagged clusters (July 22). Grapes were harvested on the same day. All other treatments were identical. Mechanical Leaf Pulling and Post-Fruit Set Leaf Pulling had the smallest average berry weight (no data is available for the bagged clusters). Pre-bloom leaf removal saw the greatest increase in average berry weight, but this was not significant when compared with No Leaf Pulling and Post-Fruit Set. Yield per vine was significantly lower on the pre-bloom leaf removal compared to No Leaf Pulling and Post-Fruit Set, but Brix was significantly higher. This yield difference likely resulted from the significantly lower cluster weight in the Pre-Bloom treatment, as well as the lower number of berries per cluster and the lower number of clusters per vine found in the leaf pulling treatments. The Pre-Bloom and Post-Fruit Set treatments spent much more time at critical temperatures between 35-40°C than the No Leaf Pulling treatment, due to greater exposure of the grapes. The Pre-Bloom treatment was overall cooler than the Post-Fruit Set treatment, possibly because of the decreased berries per cluster and thus looser cluster architecture allowing for better air flow and cooling.

Leaf pulling always increased tannin, quercetin, and anthocyanin concentration in grapes, with the greatest concentration of tannin in the Pre-bloom Leaf Removal and anthocyanin and quercetin in the Post-Fruit Set Leaf Removal. Leaf-pulled juice tended to have less malic acid and lower YAN. In general, TA and color was higher in finished wine with leaf pulling, with the greatest increases seen in post-fruit set leaf pulling. Caftaric acid, gallic acid, quercetin, tannin, and anthocyanin were generally increased by leaf pulling, with the most profound differences found in pre-bloom and post-fruit set leaf pulling. Bagged clusters showed much lower color and tartaric acid.

Due to the complexity of this project, the Mechanical Leaf Pulling and Bagged treatments were not tasted. Overall, descriptive results for these wines were inconsistent between tastings. Wines which had received leaf pulling were generally more preferred by judges, with preferences generally being for early leaf pulling regimes. This study should be repeated several times in order to further validate these results. It should also be performed on different grape varieties, at different sites, and on different trellising systems. More rigorous descriptive work should be performed on these projects, as well.

Read Full Report (PDF)

The Impact of Bloom Leaf Removal vs Veraison Leaf Removal (2017)

This study examines the impact of leaf pulling at either bloom or at veraison. The goal was to have looser clusters and smaller berries from pre-bloom leaf removal. A block of Cabernet Sauvignon (planted 2006) was divided so that every other row was a different treatment. One row had the four-most basal leaves removed at 30% bloom (mid-May), exposing the entire fruiting zone. Continuous passes were made to ensure fruit zone exposure throughout the season. Every other row had leaves removed at the start of veraison, in mid-August. Grapes were harvested and processed at the same times, and all other vineyard and winemaking treatments were identical between treatments. Each wine received a 6-day cold soak, and 25 days of total maceration. Grapes from prebloom leaf removal had lower TA, malic acid, and tartaric acid, with a similar pH to the control. Tannin was higher in grapes with pre-bloom leaf removal, but anthocyanins were lower. Pre-bloom wine chemistry was similar except for slightly lower acidity. Color intensity and tannin was also slightly increased in the pre-bloom wine, although these differences were not very pronounced. For the triangle test, of 19 people who answered, 6 people chose the correct wine (32%), suggesting that these wines were not significantly different. In general, of those who answered correctly, no preference trends could be seen between wines. For the descriptive analysis, there were no strong trends for the descriptors used in this study. Most descriptive results were mixed, but Pre-bloom leaf pulling may have had slightly lower Acidity and higher Body. It also may have had slightly less Herbaceous/Green  character, but these trends were weak. These results suggest that pre-bloom leaf removal may not always have as large of an impact as is often seen. This practice should be performed more at different sites, on different varieties, and in different vintages (perhaps rainier vintages which may benefit more from this kind of leaf pulling regimen). 

Read Full Report (PDF)

The Impact of Crop Management Timing on Wine Quality (2017)

This study examines the impact of the date of cluster thinning on juice and wine chemistry. The goal was to attempt to dilute the impact of potassium uptake during veraison by cluster thinning at later dates, in order to keep the pH lower. A block of Cabernet Franc was cluster thinned either pre-veraison (around Mid-August), halfway through veraison (around the end of August), and post-veraison (first or second week of September). Every third row received one of these treatments, so that treatments were evenly dispersed throughout the block to minimize variation. All grapes were harvested on the same day, and all other treatments between each juice and wine lot were identical. The later the clusters were dropped, the higher the average berry and cluster weight. The later the clusters were dropped, the lower the Brix and phenolic compounds. YAN was slightly higher in later cluster thinning sweeps. In general, wine made from later cluster dropping had slightly less ethanol, and slightly higher TA and tartaric acid. Color intensity was decreased with later cluster thinning, as were most phenolic compounds. Thus, earlier cluster thinning tended to enhance grape “ripeness” characteristics. For the descriptive analysis, there was a strong tendency for the 50% veraison treatment to have higher Herbaceous/Green character (LSD=0.43). There was a slight tendency for this wine to also have higher Bitterness. Pre-veraison cluster thinning may have had higher Fruit Intensity. Post-veraison cluster thinning may have had slightly lower Overall Aromatic Intensity and Astringency. In general, the wines which were cluster thinned at 50% veraison were most preferred. These results suggest that the beneficial impacts of cluster thinning prior to veraison on chemistry may not be beneficial towards flavor profiles. However, this study should be repeated over multiple vintages, at different sites, and with different grape varieties to better understand how this timing of cluster thinning affects a Virginia appellation.

Read Full Report (PDF)

The Effect of Canopy Area on Ripening and Wine Quality (2017)

This study examines the impact of canopy height and ripening on wine quality in Merlot. Three sets of five rows of Merlot were hedged to different heights in mid-June: 52 inches (High canopy), 44 Inches (Medium canopy, normal height), and 36 inches (Short canopy). All other vineyard treatments were identical. Not much additional shoot growth occurred after hedging. Grapes were harvested on August 25 and processed into separate T Bins. All other treatments were identical. Juice Brix was slightly higher for the short canopy compared to the higher canopy. This may have been due to a seeming resistance to rain dilution seen in the short canopy vine compared to the medium and higher canopy vines. The ethanol, TA, color, and tannin increased with decrease in canopy height, and pH decreased with canopy height. Overall, descriptive analysis had difficulty distinguishing the wines consistently. The short canopy treatment tended to have slightly more Bitterness and Overall Aromatic Intensity. The short canopy wine also exhibited some slight reduction relative to the other two wines, which may have influenced results. Fruit Intensity and Astringency tended to vary between wines between tastings. In general, the high canopy wine tended to be the most preferred. Future studies should examine how bud fruitfulness and yield are impacted by multiple vintages of heavy hedging, pick fruit at different times depending on which treatment is deemed “optimally” ripe, and hedging shoots when they reach their designated height to try to force lateral growth. More studies are needed to confirm the trends seen in this study, as well.

Read Full Report (PDF)

The Impact of Bagging Grape Clusters on Grape Ripening and Quality (in Collaboration with VT) (2017)

This study examines the impact of bagging grape clusters during the growing season on grape and wine flavor, chemistry, microbiology, and phenolics. The vineyard uses organic grape growing practices, and the goal of this project was to see if bagging grape clusters would improve disease resistance without negatively impacting grape and wine quality. The bags used were 19x27cm white paper bags with micropores. Corot Noir grapes in one block experienced 4 treatments: 1) not bagged, 2) bagged at pea-sized berries, 3) bagged at berry touch, and 4) bagged at veraison. Because of a prediction of reduced disease incidence in bagged clusters relative to unbagged clusters, and because unbagged, rotting clusters were going to be dropped during the season, green harvesting of the treatment clusters was undertaken on lagging blooming clusters at berry set in order to attempt to keep crop levels similar between treatments. Lagging clusters were also not bagged on treatment rows. Control and treatment grapes were harvested 2 days apart from each other, and the 3 treatments were combined into one must to ferment. Both control and treatment musts received a 10% saignee, both were inoculated with Renaissance Ossia yeast, and all other treatments between wines were equal. Both bins received 2 weeks extended maceration. Bagging clusters might have reduced incidence of black rot, with the earlier bagging treatments being more effective; however, more intensive work is needed to confirm this. The grape treatments generally exhibited slight increases in berry weight and cluster weight, as well as increases in malic acid, pH, and YAN. Juice and wine chemistry was not much impacted, except that acidity was lowered in the bagged treatment. Bagging clusters lowered the microbial content of the juice, although wine was not much impacted. All phenolic and color parameters, in grape and wine, were either reduced or did not change as a result of bagging. 64% of people were able to distinguish the wines in triangle testing, suggesting a statistically significant difference between them (p<0.001). Of those who correctly distinguished between the wines, there was not a major preference for one wine over the other, perhaps slightly favoring no bags. There were strong trends for the unbagged treatments to have higher Overall Aromatic Intensity and higher Acidity. There was a slight tendency for Fruit Intensity to be higher in the unbagged treatments as well.

Read Full Report (PDF)

Central Virginia Cabernet Franc Terroir Investigation (2017)

The purpose of this study is to evaluate the difference in wine quality and chemistry based on vineyard site and winemaking style using Cabernet Franc grapes grown in and around the Monticello Wine Trail appellation. This purpose was achieved through comparing the impact of growing area on wine style (by comparing how wines from different vineyard sites taste when produced by the same winemaker) as well as comparing different winemaking stylistic impacts on grapes from different regions (by tasting grapes from the same region being produced by different winemakers). Three winemakers traded their grapes to each other and fermented each other’s grapes according to their own stylistic practices. The results of this study suggest that winemaking practices are able to substantially impact many of the vineyard effects on wine chemistry. Wines produced at Veritas tended to be positively correlated with Tannin and either negatively correlated to Total Anthocyanin, or not correlated with Anthocyanin (Veritas Winery Veritas Grapes). Wines produced at Early Mountain Vineyards, on the other hand, were generally correlated to Total Anthocyanins and negatively correlated to Tannin. Horton winery tended to produce wines which were in-between the Veritas and Early Mountain wines, in many of these regards. Overall, these results suggest that while vineyard site places some boundaries on the chemical qualities of wine, chemical qualities can be easily driven by winemaking practices. However, vineyard site tended to have the greatest impact on sensory characteristics. Early Mountain grapes tended to have more Herbaceous and Acidic qualities, and Veritas grapes tended to have higher Fruit Intensity and Astringency. Horton grapes tended to have higher Overall Aromatic Intensity. However, winemaking practices were able to alter these sensory characteristics in some cases, so that there was not a simplistic division of vineyard sites into certain flavor profiles. Most parameters were not dominated by either winemaking or vineyard site, but a mixture of both was seen. In the future, many more studies should be performed, with more statistical rigor.

Read Full Report (PDF)

Harvest Decisions Based on Grape Phenolic Development (Enartis) (2017)

This study examines the ability to judge when grapes are harvest-ready by monitoring phenolic development over time. Cabernet Franc grapes began being sampled weekly starting on September 1 for a number of chemical and phenolic parameters. Enartis then made a harvest recommendation for September 22 (First Pick) based on comparing phenolic and chemical profiles over time. This decision was based on declining anthocyanin and phenolic values occurring in the grapes, with a desire to pick while these values were near their peak. The winemaker monitored grapes based on in-house chemistry values, seed coloration, and hang time, and picked another portion of the block on October 4 (Second Pick). Because the chemistry was different between juices, the second pick juice received more tartaric and malic acid additions. All other treatments were the same, except for a possible non-addition of Lafase HE Grand Cru to the second pick must. Wines were pressed off after 18-19 days. Grape ripening tended to follow classic ripening curves, exhibiting increasing Brix and a positive sigmoidal pH ripening curve. Average berry weight and water content peaked and then declined, due to dehydration. Phenolic content tended to peak and decline as well, and this occurred after the berry weight and water content began to decline. The first pick, based on phenolic ripeness, had lower alcohol. The differences in lactic acid may have been due to different malic acid additions between treatments. The first pick wine had slightly higher tannin and anthocyanin and much higher quercetin glycosides, but slightly lower color. However, this wine received Lafase HE Grand Cru, whereas the second pick wine may not have received this enzyme. This may have altered the results in this regard. Overall, sensory analysis suggests that these wines were significantly different. There tended to be a preference for the earlier picked wine, but this preference was tasting-dependent. Descriptive analysis was inconsistent between tastings, and no conclusions can be drawn with regard to this. Due to this inconsistency, this study should be repeated multiple times to help gauge the impact of picking based on phenolic parameters on sensory qualities in wine. Additionally, the use of Lafase HE Grand Cru in one wine and perhaps not in the other could have further confounded these results, suggesting that this study should be repeated. However, the idea behind this technique of monitoring ripening may serve to be a useful guide to picking in Virginia, to harvest while phenolic levels are maximized before they begin to decrease.

Read Full Report (PDF)

Clonal Assessment of Cabernet Franc (2017)

This study examines the clonal differences between Cabernet Franc clones 214 and 327. Grapes were harvested separately on October 4, 2017. Must was inoculated with ES488 and was pressed off after around 18-19 days of maceration. Both wines received the same additions, and all other treatments were identical between wines. Clone 327 tended to have higher berry weight and cluster weight, although yield was slightly lower. Grape chemistry suggests that clone 214 had lower tannin and phenolics, but slightly higher anthocyanins. Juice and wine chemistry did not differ too much. Clone 214 wine tended to have slightly higher phenolic parameters, although these differences were weak. It is possible, then, that although Clone 214 had lower levels of phenolic compounds (except anthocyanin), phenolic compounds were more extractable from these grapes. However, Clone 214 received an addition of Lafase HE Grand Cru which Clone 327 may not have received, and this may have impacted the results as well. Overall, the wines were not found to be significantly different via triangle testing. Descriptive analysis did not yield any consistent trends between tastings. There may have been a slight preference for Clone 327, but this was weak. More work should focus on the sensory and chemical differences between wines produced from these clones, but more work should also be done to better distinguish viticultural characteristics between these wines, as well.

Read Full Report (PDF)

The Impact of Soil Conductivity on Petit Verdot Ripeness and Wine Quality in VSP Trellising (in collaboration with Bubba Beasley) (2017)

This study attempts to quantify the impact of soil conductivity on VSP-trained Petit Verdot juice and wine chemistry, as well as on the sensory qualities of wine. Soil conductivity was determined by EM mapping performed by Bubba Beasley, in order to find areas of low and high conductivity within the vineyard block. The low conductivity soil had a low rock content, and the high conductivity soil had high rock content (75%, shale). Then, fruit from each conductivity region was harvested on the same day but kept separate and destemmed into two T Bins: One for low conductivity fruit, and the other for high conductivity fruit. Fermentations were punched down twice per day, and all other treatments between wines were identical. Yield and viticultural parameters suggest an ESVC:CW index of 1.2 for both the low conductivity and high conductivity. Acidity and potassium was higher in the high conductivity juice. Indeed, soil pH was found to be negatively correlated to petiolar potassium and positively correlated to fruit pH. Petiolar potassium was also found to be positively correlated to juice potassium. Wine made from higher conductivity grapes had higher acidity and lower potassium. The high conductivity treatment had slightly lower anthocyanin and tannin measures. These results, overall, suggest that the lower conductivity wine had generally “riper” characteristics. These results would not be expected, as the higher conductivity soil (with higher rock content) would be expected to have less total available water in the soil for the grapevines to use. It would be more expected, therefore, that the high conductivity vine would have had less water, and thus potentially more “ripe” chemistry characteristics. Overall, the wines were not found to be significantly different at tastings. There may have been a slight preference for the low conductivity wine, but if so it was very weak. There were slight tendencies for the high conductivity treatment to have higher Acidity and Bitterness, and slightly lower Body. These further suggest a less “ripe” wine was produced at the high conductivity block. This study should be repeated over multiple vintages in order to determine whether these results are replicable.

This study should be read with its companion study in Ballerina trellising.

Read Full Report (PDF)

The Impact of Soil Conductivity on Petit Verdot Ripeness and Wine Quality in Ballerina Trellising (in collaboration with Bubba Beasley) (2017)

This study attempts to quantify the impact of soil conductivity on ballerina-trained Petit Verdot juice and wine chemistry, as well as on the sensory qualities of wine. Soil conductivity was determined by EM mapping performed by Bubba Beasley, in order to find areas of low and high conductivity within the vineyard block. The low conductivity soil had lower soil rock content (10%, channers), and the high conductivity soil had higher rock content (50%, shale). Then, fruit from each conductivity region was harvested on the same day but kept separate, and destemmed into two T Bins: One for low conductivity fruit, and the other for high conductivity fruit. Fermentations were punched down twice per day, and all other treatments between wines were identical. Average berry weight and cluster weight were slightly higher in the high conductivity treatments. Yield and viticultural parameters suggest an ESVC:CW of 1.7 and 1.9 for the low conductivity and high conductivity, respectively. Juice Brix and potassium was lower, and acidity and nitrogen were higher in the high conductivity treatment. These differences transferred through to wine chemistry. The high conductivity treatment seemed to have lower levels of phenolic compounds, and lower color. These results, overall, suggest that the lower conductivity wine had generally “riper” characteristics. These results would not be expected, as the higher conductivity soil (with higher rock content) would be expected to have less total available water in the soil for the grapevines to use. It would be more expected, therefore, that the high conductivity vine would have had less water, and thus potentially more “ripe” chemistry characteristics. Overall, these wines were not found to be significantly different in triangle testing. No preference trends could be seen. Additionally, descriptive analysis results were inconsistent between tastings, and no general trends can be seen except perhaps that the high conductivity wine had slightly lower Body. In the future, this study should be repeated over multiple vintages, on different grape varieties, and at different sites.

This study should be read with its companion study in VSP trellising.

Read Full Report (PDF)

The Impact of Agrothermal Systems Heat Blast Treatments on Grape Ripening, Wine Chemistry, and Wine Quality in Virginia (2017)

The aim of this experiment was to determine measurable differences of grape quality by utilizing Heat Blast technology used to treat wine grapes. A block of Petit Manseng was divided into two separate sections. One section was treated with heat blast delivery to the canopy and fruiting zones using an Agrothermal Systems XT heat system. The other section was not treated with this technology. The treatment block was treated 1 to 4 times per month depending on stage of growth, with the treatment regime starting around veraison. The majority of treatments were near veraison. Chemical spray regimes were the same between treatments. All other vineyard and winemaking treatments between grapes were equal. Acidity and potassium was slightly lower in the heat-treated grapes. Quercetin and tannin slightly increased in grapes, whereas catechin slightly decreased. Wine chemistry was not very much affected except for lower malic acid levels in the heat treatment. The tannin content of wine with heat treatment was slightly higher for most compounds. Overall, these wines were not found to be significantly different. There was a very slight tendency for the Control to have higher Tropical Fruit intensity, Fruit Intensity, and Body. No major preference trends could be seen between wines. In the future, more studies should be performed with Agrothermal heat treatment and its impacts on fruit chemistry. These studies should look into multiple grape varieties, as well as closely monitor disease progression. The use of Agrothermal heat treatment in conjunction with different vineyard spray regimes should be investigated as well. Although more studies are needed to confirm this, these preliminary results suggest that heat treatment may be a beneficial tool for East Coast viticulture.

Read Full Report (PDF)

Leaf Pulling on One vs Two Sides of Petit Verdot Vines (2017)

This study examines the impact of leaf pulling on one vs both sides of the vine in Petit Verdot. Petit Verdot vines (clone 400, planted 2012, 9x4 spacing, ESVC/CW index of 2.4) from the same block were split so that all vines received leaf pulling on the east side at flowering, and one portion of the vineyard received leaf pulling on the west side as well at veraison. Grapes were harvested on the same date, and all winemaking practices were identical between treatments. Must was inoculated with D80, Enzyme CX was added, punched down twice per day until fermentation was complete, and then switched to one punchdown per day during extended maceration (25 days maceration time, total). Juice chemistry was similar between treatments, although leaf pulling on one side resulted in higher alcohol content and lower acidity. Color and anthocyanin were not much impacted by treatments. Seed tannin indices (catechin, epicatechin, and gallic acid) may have been slightly lowered with leaf pulling on both sides. Tannin may have slightly decreased by this treatment, as well. The sensory results suggest that the two wines were significantly different. No strong trends could be seen for the descriptors used in this study,  although Acidity seemed to be lower in the one sided leaf pulling wine. No major preference trends could be seen between treatments. This study should continue to be performed over multiple years, in different regions, as well as on different grape varieties.

Read Full Report (PDF)

Sauvignon Blanc Clonal Investigation (2016)

This study examines the clonal differences between Sauvignon Blanc FPS 1, FPS 18, ENTAV 376, and ENTAV 241 planted in the same year in the same vineyard block. Grapes were harvested and pressed on the same day but kept separate, and all treatments between lots were kept the same. Yields were different between some clones, and the FPS clones tended to have higher malic acid and YAN. Clone 241 tended to have lower acidity and higher pH than the other clones, and the opposite trend was observed for FPS 1. Wines produced from FPS 1 and ENTAV 376 had the highest levels of 3-MH. Descriptive analysis found several differences between clones. Wine made with ENTAV 376 was highest in most sensory descriptors, and most people preferred Clone 376. However, these differences may not all be clonal, but could be due to variations between fermentations. As such, this study should be repeated in order to determine if clone 376 is truly much more aromatically intense.

Read Full Report (PDF)

The Effect of Timed Nitrogen and Sulfur Sprays on Sauvignon Blanc (2016)

This study examines the impact of timed Nitrogen and Sulfur sprays on the sensory and chemical attributes of Sauvignon Blanc. A mix of Nitrogen and Sulfur sprayed at 20% veraison and at 50% veraison were applied to 2 out of four segments of a vineyard block. The other segments were unsprayed. The grapes were harvested and processed identically. After racking off of gross lees, the lees were harvested, combined, and centrifuged to create a centrifugate juice (a mix of the lees from the control and sprayed grapes). No major chemical differences were found between the control and treated juice and wines, except that pH was slightly higher. The sprayed wine had a slightly higher level of 3-MH. However, the wine made from the combined lees centrifugate had the highest level of 3-MH and lower levels of 3-mercaptohexylacetate. Additionally, this wine had a longer lag phase during fermentation compared to the other two. Judges were generally able to distinguish between the unsprayed and sprayed treatments, and there was a tendency for the sprayed treatment to be preferred and the centrifuged treatment to be least preferred. The sprayed wine had slight tendencies to have higher Overall Aromatic Intensity, Herbaceous/Green character, and Varietal Character. There were slight trends for the centrifuged wine to have lower Tropical Fruit and Varietal Character than the other treatments, and higher Herbaceous/Green character. These tendencies were all very weak, however.

Read Full Report (PDF)

The Effect of Leaf Removal at Bloom vs Leaf Removal at Veraison on Ripeness (2016)

This study examines the impact of removing the 4 most basal leaves from Cabernet Sauvignon vines at 30% bloom. One section of a vineyard block was not leafed at bloom, while another section underwent this leafing treatment. Both treatments received leaf-pulling at veraison. All other vineyard and fermentation practices were the same. Leaf removal at bloom appeared to slightly reduce berry weight, cluster weight, Brix, and yield. Grape phenolics and TA were slightly increased by bloom leaf removal. Wine produced with leaf removal at bloom had lower ethanol, color intensity, and tannin. Judges did not find the wines to be significantly different, and there were no strong preference trends for either wine. Early leaf removal may have had a very weak tendency to increase Overall Aromatic Intensity. The lack of differences are likely due in part to the particular vintage (weather events may have equalized the treatments) and in part due to vegetative growth reducing the effectiveness of the bloom leaf removal. More studies need to be performed in this area in order to draw more conclusions.

Read Full Report (PDF)

The Effect of LalVigne Mature Foliar Spray on the South Side of Merlot Vines (2016)

This study examines the impact of LalVigne Mature Foliar Spray (ScottLabs) on ripeness and the chemical and sensory qualities of the South side of Merlot vines planted East-West. Every other row of a block of Merlot was sprayed at 5% veraison and 10 days later following the LalVigne spray protocol with a tunnel recycle sprayer, allowing for a treatment of sprayed Merlot and a treatment of unsprayed Merlot. Both treatments were harvested only from the South side of the vine (afternoon side) and processed identically and on the same day, but kept separate. All other treatments between projects were identical. The LalVigne spray slightly decreased tannins and anthocyanins in the grape berries. Caffeic acid was higher in wine from grapes treated with LalVigne. Tannin was also increased in wine from grapes sprayed with LalVigne, but anthocyanins were decreased. Triangle sensory testing revealed no significant differences between wines, and there was no strong preference for either wine. The sprayed wines tended to exhibit greater Fruit Intensity, but this was not a strong tendency.

Read Full Report (PDF)

The Effect of LalVigne Mature Foliar Spray on the North Side of Merlot Vines (2016)

This study examines the impact of LalVigne Mature Foliar Spray (ScottLabs) on ripeness and the chemical and sensory qualities of the North side of Merlot vines planted East-West. Every other row of a block of Merlot was sprayed at 5% veraison and 10 days later following the LalVigne spray protocol with a tunnel recycle sprayer, allowing for a treatment of sprayed Merlot and a treatment of unsprayed Merlot. Both treatments were harvested only from the North side of the vine (morning side) and processed identically and on the same day, but kept separate. All other treatments between projects were identical. The LalVigne spray slightly increased tannins and anthocyanins in the grape berries, but lowered cluster weight (although not berry weight). Anthocyanins were decreased in the wine from grapes treated with the LalVigne spray. Triangle sensory testing found significant differences in the wines (p<0.05), although there was not much of a preference for one wine over the other. No major descriptive sensory trends can be seen.

Read Full Report (PDF)