Comparison of Five Methods of Crop Thinning in Pinot Noir and their Effects on Fruit Composition and Wine Quality

Final report for FNE18-885

Project Type: Farmer
Funds awarded in 2018: $14,871.00
Projected End Date: 03/31/2020
Grant Recipient: Beneduce Vineyards
Region: Northeast
State: New Jersey
Project Leader:
Michael Beneduce
Beneduce Vineyards
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Project Information

Summary:

The purpose of this research was to determine the most effective crop thinning techniques for Pinot Noir grown in the Northeast. We utilized five different crop thinning techniques in a large sample size of vines and compared their effects to a control, then made wine from each treatment and evaluated the final products. Measurements included primary grape chemistry, final wine chemistry, and professional wine scores and comments. Results were varied among the measured data, but indicated that two techniques (green harvest and Austrian method) were the most effective in driving overall ripeness in the grapes and resulting wine. The Austrian method, which involves trimming off the bottom 1/3 of each individual cluster, earned the highest wine score (92 pts) by a wide margin, indicating that the effects of this method may have led to an increase in wine quality. We shared this data with nearly growers, educators and industry professionals through published articles in Horticulture News, and presented to an audience of nearly 100 at a live presentation at Grape Expectations, an annual statewide symposium for wine & grape industry members.

Project Objectives:

The project intends to compare five methods of grape cluster thinning and their results as they relate to fruit composition, finished wine quality, and economic sustainability. This is information is directly applicable to all commercial vineyards seeking to grow economically sustainable, high quality Pinot Noir throughout the northeastern United States.

This will be accomplished through three main objectives:

Measuring crop load balance for each thinning technique.

Measuring the quality of the grapes resulting from each thinning technique using standard industry metrics.

Measuring the quality of the wine resulting from each thinning technique using standard industry metrics.

Introduction:

In a commercial vineyard, vine capacity and crop load are carefully balanced to obtain high quality wine grapes. This balance can vary greatly across varieties due in part to crop load differences. One of the highest value Vitis vinifera (European wine grape) varieties commonly grown in the Northeast is Pinot Noir. This cultivar consistently overcrops (over produces grapes in relation to vine capacity) and is notoriously sensitive to total crop load. Thus, any crop load management in Pinot Noir is likely to have significant impacts on fruit composition, wine quality, and the

economic sustainability of growing Pinot Noir in the Northeastern United States.

The crop loads on grape vines are managed through methods such as winter pruning, shoot thinning in early spring, irrigation, fertilization, and manual removal of portions of the crop once it has set fruit (cluster thinning). Of these methods, cluster thinning has been shown to be one of the most effective. This method allows for more uniform fruit ripening, consistent yields, and higher grape quality.

Cluster thinning typically occurs over a 3-4 week period from pea-sized berry stage up until veraison (color change) in wine grapes. Although cluster thinning has been shown to be effective, the timing, extent, and methods used to thin crops lead to drastic differences in labor costs, grape quality and final yield. On average, Beneduce Vineyards (similar to other wineries in the Northeastern United States) spends approximately 20 man hours to cluster thin one acre of grapes. Despite the benefits, oftentimes vineyards will limit their time spent on cluster thinning when it becomes too time consuming and cost prohibitive. Since Pinot Noir is typically a very high value grape, with consistent overcropping many of these same vineyards will at minimum cluster thin this variety.

Limited work has been done in the Northeastern United States to examine the effects of crop thinning on grape and wine quality. The goal of this project is to find the most effective method of crop thinning Pinot Noir to produce a consistently high quality crop that can be sold for economically sustainable prices. Secondarily, the results from this project will lend insight into a method of crop thinning that is best suited (both economically and through quality measurements) to a specific wine style or targeted price point which is essential in successfully cultivating this variety.

Cluster thinning has been used extensively to achieve high quality wine grapes and is a common technique used in commercial vineyards worldwide. Unfortunately, there are many variables that affect the efficacy of this technique. Climate and growing conditions have been shown to be key factors in the success of cluster thinning in obtaining higher quality grapes and wine, which necessitates conducting these trials in different growing regions. In addition, cultivar, timing, and levels of crop thinning are important components in the success of this method of crop load management and grape quality. Fruit Thinning in Wine Grape Varieties

Numerous levels of crop thinning have been tested throughout the worlds wine growing regions. Methods of crop thinning vary extensively in overall reduction in yield, typically ranging from

10-50% total crop reduction. The most appropriate timing for crop thinning is also a widely debated topic and can range from as early as fruit set to as late as veraison (color change). There is a great need to perform studies of the timing and methods of cluster thinning to begin to develop crop thinning guidelines for the North East.

A very limited number of studies on the comparison of the efficacies of different thinning methods have been performed in the Northeast region. To the knowledge of the author, the only published study on grape cluster thinning performed in New Jersey involved three levels of crop thinning at one vineyard in New Jersey (SARE Farmer Grant FNE11-708), on Cabernet Sauvignon and Cabernet Franc grape varieties. On a whole the results of this study were inconclusive. Although the crop load was managed and cluster weights were increased, grape quality metrics were only improved in 1 of the 3 years of the study, and no differences were observed in wine quality.

In addition to timing and level of cluster thinning, the cultivar of grapes has also been shown to have an effect on the level of improvement of grape and wine quality. In comparison to other cultivars studied in New Jersey, Pinot Noir is typically very sensitive to croploads and potentially better suited for a study to assess cluster thinning. This project will seek to investigate which thinning method is the most effective and determine the extent to which the quality of the grapes and wine improves using each technique.

Pinot Noir is typically an economically sustainable variety to grow in the Northeast because high quality versions often demand high wine prices (typically ranging from $15-50 per bottle). In addition to quality assessment, this study will investigate whether the added labor cost of cluster thinning (depending on the method) is likely to translate to an increase in bottle price large enough to offset the additional costs associated with this vineyard practice.

Various crop thinning methods have been utilized in the block of Pinot Noir at Beneduce Vineyards over the past 4 years, with varying results in fruit composition and wine quality. A more organized and documented trial for crop thinning would provide data-based conclusions about which is the superior method for achieving high quality fruit. This project seeks to determine the best method for crop thinning as it relates to creating an economically sustainable amount of very high quality Pinot Noir grapes destined for a wine with a bottle price of around $30. This study will expand upon the work previously done, in several ways in that it will encompass several more (potentially improved) cluster thinning methods, and in addition the cost benefit analysis of labor to thin and resulting wine quality and estimated wine price will be calculated and used to quantify the benefits of cluster thinning Pinot Noir grapes in the Northeast.

Description of farm operation:

We are a 50 acre farm that has been in business since 2009. We currently grow over 22 acres of wine grapes, among other crops, and produce wine from those grapes that is sold direct to the consumer for on and off-premise consumption. We dedicated a 0.8 Acre block of Pinot Noir to this experiment, which was originally planted in 2011.

Cooperators

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  • Megan Muehlbauer - Technical Advisor (Educator and Researcher)

Research

Materials and methods:

Field Site:
The test/demonstration plot for this experiment is located at Beneduce Vineyards, a River-Friendly certified farm in Hunterdon County, NJ. The property encompasses 51 acres of Quakertown Silt Loam soils with varying pockets of clay and gravel. The property contains 20 acres of mature, dry-farmed vineyards managed by Mike Beneduce, who holds a B.S. in Viticulture/Enology from Cornell University.

Background on the Pinot Noir portion of the Vineyard:
The study plot is comprised of approximately 0.8 acres of Pinot Noir clone #23 (Mariafeld) on 3309 rootstock. They were planted in 2011 with a first crop harvested in 2013. The vines are planted at 5’x10’ spacing, cane-pruned and trained in a vertical shoot positioning trellis system, all of which are common for high quality V. vinifera production in the region.

Field Layout/Experimental Design:
The Pinot Noir utilized for this study are planted in 10 contiguous rows, each 350’ in length and located on a gently sloping hill with southeastern exposure. Each of the different methods of thinning was performed on 2 randomly selected rows. 
Standard vineyard maintenance was performed on the experimental plot, as guided by the Cornell Wine Grape Production Guide for Eastern North America and the grower's own experience. This includes standard nutrition, weed and pest management, manual pruning, and various canopy management techniques typically associated with high quality V. vinifera vineyards including shoot thinning and positioning, desuckering, leaf pulling, etc.

Timeline of main components of the study:
January-March 2018: Winter pruning was completed in accordance with standard practices for the vineyard. Twenty plants per treatment row will be marked, and the wood from these cuttings was weighed and factored into an end of season crop load measurement.
July and August of 2018: Treatments/Cluster Thinning were performed. The treatments are described below. The total labor hours, total crop reduction, and overall yield for each treatment were recorded and will be used for the cost benefit analysis.

Treatment 1: Thin to 2 clusters/shoot at bunch close, with an attempt to select out rot hazards first and then remove any additional clusters on shoots containing more than two clusters.
Treatment 2: Thin to 1 cluster/shoot at bunch close, with an attempt to select out rot hazards first and then remove any clusters with shot berries or those that would impede airflow.
Treatment 3: Austrian method. For lack of a better term (and because the grower originally witnessed this practice on a visit to Austria) this method involves removing the bottom half of every cluster, rather than the selective removal of whole clusters. The Austrian growers felt that in addition to its effects on crop load, this method had the added advantage of reducing rot pressure through a shorter rachis, which allows the cluster to dry out faster after rain events.
Treatment 4: Green harvest to 1.5 clusters/shoot at veraison. This method involves selectively removing the most visibly unripe clusters (those with the least amount of color development) during veraison as a means of advancing the overall ripeness of the remaining fruit. Green clusters were removed, leaving behind those that have started veraison.
Treatment 5: Unthinned (control)- For this method, only a few clusters posing a severe rot hazard were removed, such as those growing around trellis wire or tangled in an adjacent cluster.

August/September 2018 and 2019 Harvest and Measurements:
The total fruit from each of the subplots were weighed, and utilized for total crop load measurements.
Representative samples from each treatment (after destemming and crushing) were analyzed using in-house laboratory equipment for the following metrics- Soluble solids, pH and Titratable Acidity.

Grapes from each treatment are being kept isolated throughout the winemaking practice but otherwise treated exactly the same. Grapes were hand-harvested, machine destemmed, fermented in open top fermenters with twice daily manual punchdowns, pressed, and transferred to separate but identical French oak barrel for aging and clarification. After aging, finished wines will be evaluated by chemical analysis through a TTB-certified laboratory such as Enartis Vinquiry. The wines will also be subjected to an expert tasting panel such as the Beverage Tasting Institute at the end of its maturation in oak.

Research results and discussion:

Row 1-2: Thin to 2 Clusters / Shoot
7/24: removed approximately 90 lbs per row. Tried to select out rot hazards first and then removed third cluster on any shoots that had it (very few). Average thinning time = 110 minutes/row. 

Total Harvest: 1,150 lbs = 3.6 tons/A
Avg. Cluster Weight= 145.6 g
Avg. Berry Weight:= 1.67g
Brix = 23.6 pH= 3.33 TA=8.2 g/L

Total Tannin - 0.95 g/L epicatechin equivalent

Total Pigment - 5.61 AU

BTI Score - 86 • Beneduce Vineyards (NJ) 2017 Treatment #4, Pinot Noir, Hunterdon County. Silver Medal  Panel Feedback: Muted. Notes of relish and dill. A bit leafy and stemmy, which can appeal to old world Pinot lovers, but in the meantime is taking away from the fruit that's already muted by more liberal use of oak. 

Row 3-4: Thin to 1 Cluster / Shoot
7/24: removed approximately 270 lbs per row. Prioritized rot hazards then selected any clusters with shot berries or those that would impede air flow. This seems like too much thinning for the amount of vegetation on the vines. Average thinning time = 160 minutes/row

Total Harvest : 900 lbs = 2.8 tons/A
Average Cluster Weight= 178.7g
Average Berry Weight= 1.69g
Brix = 23.4 pH= 3.42 TA=7.2 g/L

Total Tannin - 0.87 g/L epicatechin equivalent

Total Pigment - 5.87 AU

BTI Score - 86 • Beneduce Vineyards (NJ) 2017 Treatment #3, Pinot Noir, Hunterdon County. Silver Medal  Panel Feedback: Spa-like aromas, eucalyptus, lavender, etc. Less fruity, more restrained. The acid and harder tannins may need a year or two to settle down as it's quite bracing. 

Row 5-6: Control (Unthinned)
7/24: removed approximately 30 lbs per row of “hazard clusters”, i.e. those wrapped around wines or grown into each other that are certain to cause rot issues. Average thinning time = 35 minutes/row

Total Harvest: 1,510 lbs = 4.7 tons/A
Average Cluster Weight= 158.1g
Average Berry Weight=1.79g
Brix = 23.1 pH= 3.37 TA=7.4 g/L

Total Tannin - 0.87 g/L epicatechin equivalent

Total Pigment - 6.32 AU

BTI Score - 87 • Beneduce Vineyards (NJ) 2017 Treatment #1, Pinot Noir, Hunterdon County. Silver Medal  Panel Feedback: Nice varietal character. Earthy. Great structure. concentrated flavor. Perhaps there's aging potential? Pretty leafy right now, though some soft textural notes, too.

 

Row 7-8: Green Harvest to approx. 1.5 Clusters / Shoot
8/8: removed approximately 200 lbs per row of green clusters, leaving behind those that have started veraison. Average thinning time = 120 minutes/rowTotal Harvest: 1,040 lbs = 3.2 tons/A
Average Cluster Weight= 136.2g
Average Berry Weight=1.79g
Brix = 25.6 pH= 3.48 TA=7.5 g/L

Total Tannin - 0.85 g/L epicatechin equivalent

Total Pigment - 5.76 AU

BTI Score -87 • Beneduce Vineyards (NJ) 2017 Treatment #2, Pinot Noir, Hunterdon County. Silver Medal  Panel Feedback: Spicier, fruitier. Notes of cranberry. Great structure, great juiciness. Drink now or later. Lengthy. Toastier oak notes. Notes of pomegranate, toasted nut bread.

Row 9-10: Austrian Method Removing Bottom Half of All Clusters
7/25: removed approximately 180 lbs per row. Removed bottom 40% of all clusters which did a good job of spacing out remaining clusters and seemed to be a reasonable crop load. This method took the longest and also left some cut berries at the bottom of each cluster which we tried to rub out but may lead to rot issues down the road. This method also probably not suitable for tighter clustered clones of Pinot Noir or other tight clustered varieties because hard to get scissors into the clusters to make a clean cut. Might work very well on looser clustered varieties. Average thinning time =240 minutes/row

Total Harvest: 980 lbs = 3.1 tons/A
Average Cluster Weight= 114.1g
Average Berry Weight= 1.7g
Brix = 24.1 pH= 3.46 TA=7.8 g/L

Total Tannin - 0.83 g/L epicatechin equivalent

Total Pigment - 6.38 AU

BTI Score - 92 • Beneduce Vineyards (NJ) 2017 Treatment #5, Pinot Noir, Hunterdon County. Gold Medal  Panel Feedback: Meatier, savory. Notes of tomato. Sanguine, iron-like finish. Sort of the total package for the varietal growing in a cooler climate, with a rich fruit showing depth and also some exotic herbal qualities alongside brandied cherry and juicy citrus. 

 

Research conclusions:

Based on our observations in this experiment, it appears that there are marked differences in the chemistry of the grapes harvested from the different treatment methods. Evaluating the perfect ripeness metrics for grape harvest is a complicated task which must factor in, among many other things, the winemaker's intended style for the finished wine. However, in a cool climate region, crop thinning in grapes is typically undertaken in order to advance the ripeness of the remaining crop, and therefore the technique that seems to have been most successful at doing so was the "green harvest", with the "Austrian method" coming in a close second. After separate but identical vinification of the grapes from each treatment, the wines were bottled and sent to Beverage Tasting Institute (BTI), a third-party wine evaluation company, for assessment. BTI found the wine made from the "Austrian method" to have the highest quality, with a score of 92 points. Wine scores from reputable publications have been shown to increase the market value for such wines, though the correlation is not a linear one. Assuming the "Austrian method" wine was able to sell for $3/bottle more in comparison with wines made by the other methods, we found that the added labor costs associated with this more time consuming crop thinning method would be more than covered by the theoretical price increase. 

On our own farm, we have considered the results of this experiment and decided to change our crop thinning techniques from the earlier methods of crop thinning to the green harvest and Austrian method, as these seemed to be able to drive ripeness most successfully in our study. We expect that with the success of these two methods, we will be able to leave a larger crop and still achieve our target ripeness levels in most years. Increase yields directly translate to increased profitability, so we are very happy with the results of this study and expect it to have a significant effect on the profitability of our farm in the coming years. We have shared this experiment with the majority of the growers and educators in the state, and many growers expressed gratitude for the information and mentioned that they would love to see more experiments like this performed in our state. We have directed them all to the SARE website and encouraged them to design their own research projects and submit them for SARE grants in the future. 

Participation Summary
1 Farmer participating in research

Education & Outreach Activities and Participation Summary

2 Consultations
2 Curricula, factsheets or educational tools
1 Journal articles
1 Published press articles, newsletters
1 Webinars / talks / presentations

Participation Summary:

90 Farmers
10 Number of agricultural educator or service providers reached through education and outreach activities
Education/outreach description:

Hort_News_Article_Wine_Grapes

Article Published in Hort News, volume 99, Winter 2019.

2020-Grape-Expectations-Program

Five Methods of Crop Thinning In Pinot Noir and Their Effects on Fruit Composition and Wine Quality (1)

Powerpoint presented on February 29th at Grape Expectations, an annual statewide industry seminar sponsored by Rutgers University.

Learning Outcomes

90 Farmers reported changes in knowledge, attitudes, skills and/or awareness as a result of their participation
Key areas in which farmers reported changes in knowledge, attitude, skills and/or awareness:

This number is based on the amount of farmers in attendance for the Grape Expectations presentation of our SARE project. They were not surveyed, but since this was a novel study topic I assume that it represents a change in knowledge for all those who heard it.

Through our presentation we were able to increase growers' knowledge of the various crop thinning techniques available to the industry, the theories behind why they work, and the actual affects of each treatment on the grape chemistry and wine quality made from them. Many growers expressed surprise that the techniques led to such widely varied results, and several stated that they anticipate changing their thinning techniques in the coming season due to the information presented in our research.

Project Outcomes

15 Farmers changed or adopted a practice
Project outcomes:

This number is based on feedback I received after the presentation from other farmers interested in applying some of the crop thinning techniques discussed in our presentation. We received a lot of follow up questions from farmers who indicated that they would be trialing some of these techniques during the upcoming 2020 growing season. Growers were more engaged in the discussion of this presentation than any of the other topics discussed at the seminar, and we encouraged them to look into the SARE grant program to replicate our study or design their own experiments on their farms.

On our own farm, we have considered the results of this experiment and decided to change our crop thinning techniques from the earlier methods of crop thinning to the green harvest and Austrian method, as these seemed to be able to drive ripeness most successfully in our study. We expect that with the success of these two methods, we will be able to leave a larger crop and still achieve our target ripeness levels in most years. Increase yields directly translate to increased profitability, so we are very happy with the results of this study and expect it to have a significant effect on the profitability of our farm in the coming years. We have shared this experiment with the majority of the growers and educators in the state, and many growers expressed gratitude for the information and mentioned that they would love to see more experiments like this performed in our state. We have directed them all to the SARE website and encouraged them to design their own research projects and submit them for SARE grants in the future. 

Assessment of Project Approach and Areas of Further Study:

I think overall our study was very well designed and applied. We were able to quantify the results of the different thinning methods using both objective and subjective measurements that provided us with ample data to make conclusions with real world effects. The results were strong enough to convince us to change our current production methods in favor of two techniques explored in the study. As mentioned previously, we expect this to lead to an increase in yield and quality, both of which should translate to an increase profitability for our farm. 

As with many crops, grapes are hyper sensitive to small changes in soil, topography and climate. In order to ensure that the results noted were not unique to our farm, we would love to see the study replicated at several other vineyard sites throughout the state and region. Additionally, it would be very interesting to see the study replicated using different varieties, especially Chardonnay and Cabernet Franc, as these are two of the most widely grown varieties in the area and could potentially have significant impacts on the industry at large.

Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.