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.
Performing a cost benefit analysis for each thinning technique, where industry information will be used to assign values to grape and wine quality and compare the results to labor and associated costs for each method.
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.
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.
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.
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
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
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
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
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
While the wine is still too young to evaluate for organoleptic qualities, the results clearly indicate that not only did the 5 treatments results in a wide range of overall crop yields but they also affected the physical ripeness of the resulting grapes in what appears to be a statistically significant manner. From a visual and sensory perspective, the grapes from the “green harvest” treatment were superior, though it remains to be seen if this will translate into higher finished wine quality. From an economical perspective, the relative differences in treatment applications could add up to labor costs with meaningful differences in a commercial vineyard. The yields per treatment will almost certainly have strong economic implications for the grower, which will be confirmed once an evaluation of the finished wine and expected price per bottle is attained.