Using canopy management to reduce fungicide use and improve fruit composition in white wine grapes

Final Report for LNE09-289

Project Type: Research and Education
Funds awarded in 2009: $178,311.00
Projected End Date: 12/31/2012
Region: Northeast
State: New York
Project Leader:
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Project Information

Summary:

This project was a collaborative effort among researchers, extension personnel, and local grape growers. Our goal was to develop, demonstrate, and implement grower-identified practices in vineyards that reduce fungicide use and improve wine quality, resulting in increased economic returns to wine grape growers and decreased environmental impact. Through collaboration with our grower-partners we introduced low-cost practices (such as leaf removal and shoot thinning) to potentially increase fruit quality and reduce the need for fungicide use. The project consisted of applied research comparing CM practices to control vines, on-farm demonstrations of each of the practices compared to traditionally-managed white vinifera canopies, wine tastings, presentations, articles in newsletters, and a webinar. We achieved our performance target of having 20 of approximately 65 vinifera grape growers adopt one new canopy management practice, resulting in one less fungicide application per season and increased returns of at least $60 per acre in wet years.

Introduction:

The grape and wine industries have an estimated value to the New York State economy of $3.3 billion. For over 100 years, the majority of acreage in NY State has been dedicated to juice grapes (i.e., Concord, Niagara). Increased international competition and decreased demand for these products has encouraged long-time growers to increase plantings of premium Vitis vinifera winegrapes. Additionally, many novice growers have started producing vinifera grapes in recent years. Despite its relative youth as a premium wine region, NY State has received several glowing reviews in the popular wine press, especially for the quality of its white vinifera wines such as Riesling, Gewurztraminer, and Chardonnay. The wine industry has recognized that its continued growth is dependent on consistently high-quality premium winegrapes available at competitive prices, and that these goals must be achieved in an economically and environmentally sustainable fashion.

The primary goal of this project was to develop, demonstrate, and implement grower-identified practices in NY vineyards that reduce fungicide use and improve wine quality, resulting in increased economic returns to wine grape growers. Currently, a minority of growers of white vinifera wine grapes (such as Riesling, Chardonnay) in the Finger Lakes (FL) and Lake Erie (LE) regions practice canopy management (CM) techniques. As a result, many white wine grape canopies are dense and shaded, with a high incidence of disease. The performance target of this project is to have 20 of approximately 65 vinifera grape growers in NY/Northwestern PA will adopt at least one new canopy management (CM) practice to improve fruit composition and lower disease pressure, resulting in at least one less fungicide application per season and increased returns of at least $60 per acre in wet years, due to reduced fungicide inputs and improved fruit composition.

CM is a catch-all term that involves a suite of practices commonly used in wine grape production, such as shoot thinning and leaf removal. In cool climates worldwide, one or more of these practices is generally used by premium wine grape growers to reduce cluster shading and disease incidence within the canopies of both red and white grape cultivars. Throughout the Northeastern USA, however, many growers use these practices on their red cultivars but not on their whites. This differentiation in practices can be attributed to a number of factors, including a belief that high-quality white wines can be produced without the additional labor costs of these practices.

NY/Northwestern PA growers of premium wine grapes can suffer significant economic losses due to mounting costs of production (2) and these high costs are borne in large part from the need for disease protection during our humid growing seasons, and the need for vine replacement in the spring as a function of our cold winters. While both of these appear on the surface to be determined by external environmental forces, they are in fact a function of local viticultural practices as well. Specifically, our wet growing seasons result in vigorous vine growth that, in whites, is often not alleviated by available CM practices. Additionally, these dense canopies result in unripened periderm on shoots (3), which results in higher levels of winter kill than in canopies with improved light penetration. As we talked with growers to assess needs and develop this proposal, a key theme was echoed by all: in order to implement CM practices, their cost must be justified by either reduced disease management costs or increased prices received for their grapes or finished wines.

Performance Target:

Twenty of approximately 65 vinifera grape growers in NY/Northwestern PA will adopt at least one new canopy management practice to improve fruit composition and lower disease pressure, resulting in at least one less fungicide application per season and increased returns of at least $60 per acre in wet years, due to reduced fungicide inputs and improved fruit composition.

Cooperators

Click linked name(s) to expand
  • Tim Martinson
  • Gavin Sacks
  • Todd Schmit
  • Wayne Wilcox

Research

Materials and methods:

The project consisted of the following components: initial in-person survey of grower practices; applied research comparing CM treatments on cv. Riesling; on-farm demonstrations by our grower-implementation team of CM practices, integrated in combinations; on-farm workshops, newsletters, and other educational opportunities such as wine tasting; and final project assessment.

During the initial year of the project, a comprehensive, replicated trial of CM practices was established on Riesling vines in a commercial vineyard. This trial compared leaf removal timing, leaf removal intensity, and shoot thinning intensity, and these treatments were evaluated for the duration of the project. Treatment impacts on vine vegetative growth (pruning weight, bud survival), yield (total fruit yield, cluster number, cluster size), canopy microclimate (enhanced point quadrat analysis), and spray penetration into canopies (using fluorescent dye) was quantified. Chemical analyses (sugars, acids, flavor and aroma compounds: monoterpenes, norisoprenoids, ethyl esters, acetate esters, TDN, B-damascenone, B-ionone, phenylethyl alcohol) of the wine and grapes was performed to rationalize sensory differences in the wines. Sensory analysis of wines was conducted by project participants in Geneva and Fredonia NY. Price points of wines were also estimated by participants.

To address the viticultural and economic efficacy of CM practices identified by the grower team, project farmers and extension faculty established and evaluated field-scale demonstrations of shoot thinning (timing, intensity); leaf removal (method, timing, intensity); and integration of the practices. At all sites, practices were evaluated for impact on yield, disease incidence, spray penetration, and fruit/wine quality. Practice costs were compared.

Research/extension faculty assisted the grower implementation team in evaluating outcomes. Results from multiple sites were disseminated to the wider community in newsletters and seminars. Adoption assessment was accomplished through grower visits and interviews.

Research results and discussion:

1) 50 growers attend 1 of 2 spring meetings (one in Finger Lakes, one in Lake Erie) to learn about impact of canopy management (CM) practices on fruit composition and disease management. Participants will discuss their goals in winegrape production, experience with CM, and how these practices might help them. May 2009. This milestone was met in May 2009 with 40 growers attending 1 of 2 spring meetings (25 growers in Finger Lakes, 15 growers in Lake Erie) about CM. Total growers in attendance was lower than we had hoped, potentially due to the fact that both meetings were held on days of favorable weather for field work in a season when few of those days existed.

2) 35 growers attend 1 of 2 field tours (one in each region) at a research/demonstration site. Grower implementation team demonstrates impact of CM on cluster light exposure and spray penetration. August 2009. This milestone was met in August 2009 when 42 growers attended a tour of the replicated CM study at White Springs vineyard in the Finger Lakes region. We were pleased that we had excellent grower turnout at the meeting due to strong interest in the information presented. At the meeting growers participated in an informal survey of CM practices, indicating that 14% (6 of 42) of growers practiced leaf removal or shoot thinning on their Riesling vines. Unfortunately due to a frost event early in the season in the Lake Erie region we were unable to maintain our grower sites (primary shoots killed by early frost), and as a result could not host a meeting in the Lake Erie region.

3) 30 growers attend 1 of 2 tastings (one in each region) to sample wines from grower CM research/demonstration sites, estimate price points of wines for use in economic analyses. Growers provide testimony about their experiences with CM the previous year, evaluate whether their goals were met, and discuss similarities/differences in results among sites. June 2010. This milestone was met in August 2010, when 34 growers (25 in Finger Lakes region, 9 in Lake Erie) attended tastings, sampled wines from grower demonstration sites, and estimated price points for use in the economic analysis. We combined the meeting for this milestone with that for milestone #4, and presented economic analyses based on the 2009 data from grower sites. A large proportion of growers were interested in testing CM practices based on wines tasted, we are currently working to get firm commitments from those growers.

4) 25 growers attend discussion of economic impact of CM practices, study data produced in collaboration with grower implementation team. Team members share economic analyses of practices at their sites. 20 participants agree to adopt at least one CM practice for next year; group discusses which practices might suit regions/sites. December 2010. This milestone was met in August 2010 as it was combined with Milestone #3 (see above).

In 2011, we knew of at least 15 growers who experimented with a CM practice, and heard through the grapevine of at least 5 other growers who were experimenting but did not identify themselves to us.

5) 20 growers who adopted at least one new practice attend discussion to verify outcomes (improved wine quality, reduced fungicide use, improved economic returns) and share information concerning success of specific CM practices. This milestone was met in August 2012 when we had a live wine tasting/webinar for the industry. Approximately 30 growers attended the two live tastings, and another 17 growers attended via webinar.

Participation Summary

Education

Educational approach:

Presentations to Industry:

Impact of canopy management practices on yield, fruit composition, wine quality, and consumer willingness-to-pay for Riesling wines. Finger Lakes Grape Growers conference, Waterloo NY, March 2011. 300 participants.

From Vine to Bottle: Making Decisions about Canopy Management. Webinar and wine tasting for SARE project, Geneva NY broadcast to Fredonia NY, 34 participants.

Comparing canopy management treatments via sensory analysis of wines. Outreach for SARE project, Geneva NY, August 2010. 25 participants.

Comparing canopy management treatments via sensory analysis of wines. Outreach for SARE project, Fredonia NY, June 2010, 9 participants.

Canopy management for high-quality 'Riesling'. Outreach for SARE project, Geneva NY, August 2009, 42 participants.

Newsletter articles:

From 2009 through 2011, we published fruit composition data from the replicated trial as well as some of our grower side-by-side trials in each Veraison to Harvest newsletter, which reach 600 industry personnel. Previous issues can be found here:
http://grapesandwine.cals.cornell.edu/veraison-to-harvest/

Additional articles:

Vignoles harvest: shoot thinning, training system, and botrytis. Veraison to Harvest #5, 2010.

Harvesting Riesling at White Springs. Veraison to Harvest #7, 2010.

No milestones

Additional Project Outcomes

Project outcomes:

Impacts of Results/Outcomes

At least 20 growers adopted new canopy management practices for wet seasons, resulting in increased returns of $50-60 per acre for those years (note there is potential for much greater returns, see economic analysis below). However, in drier years, growers are hesitant to use these practices due to their impacts on final wine quality and the consumers willingness-to-pay for the wines.

Economic Analysis

The economic analysis for this project was more in-depth than we originally planned, as Todd Schmit was able to conduct willingness-to-pay analyses for resulting wines from this project as a function of receiving an external grant. While leaf removal generally has little to no impact on yield of grapevines, we found that shoot thinning reduced yield in Riesling by generally about 11-14%. Variable costs of management were the same with the exception of an additional $42 per acre for shoot thinning, and $54 per acre for leaf removal (resulting in a combined total costs of $100 per acre for the combined practice). The price per ton to maintain constant net returns for the grower therefore had to increase by about 14% for shoot thinning, 1% for leaf removal, and 18% for the combined practice. Price per bottle then had to increase by $0.47 for shoot thinning, $0.03 for leaf removal, and $0.64 for the combined practice. The results of the willingness-to-pay analysis suggested that if growers were aware that the canopy management practices reduced the need for spraying, they would pay premiums ranging from $0.83-0.86 per bottle if they hadn't tasted the wines - which meant that the increased production costs would be covered. However, if they tasted the wines, the willingness-to-pay for the wine from the leaf removal treatment was $-0.91 per bottle, suggesting that consumers did not like the wine as well as the control when leaf removal was implemented in the vineyard.

In summary, if a savings on a botrycide was achieved with the practices (which it was in wet years), the potential increase in WTP if the consumers didn't taste the wine resulted in a significant net return per acre (as great as approximately $700 per acre)due to their willingness to pay a premium - but if they tasted the wine, that premium was lost.

Farmer Adoption

Our target was to have 20 of approximately 65 vinifera grape growers adopt at least one new canopy management practice to improve fruit composition and lower disease pressure, resulting in at least one less fungicide application per season and increased returns of at least $60 per acre in wet years. Through our interactions with growers we are confident that we have surpassed that target in 2013 due to the extremely wet growing season. (Our initial survey indicated that 14% of growers were using shoot thinning and/or leaf removal on white cultivars, our communications with growers indicate this to be greater than 30% this year). Growers who implemented CM practices on Riesling and Pinot gris report to us that they will have more fruit to sell this year due to reduced incidence of disease. However the complicated results of the economic analysis (with a lower willingness-to-pay for wines from leaf removal treatments once the consumer has tasted them) has made growers wary of implementing the practices every year.

Assessment of Project Approach and Areas of Further Study:

Areas needing additional study

The economics of implementation of the CM practices requires further study. While we had anticipated a reduction in production costs as a function of the application of one less fungicide, we also found that the CM practices impacted the willingness-to-pay of consumers for the resulting wines. We also did not account for potential loss of fruit (i.e., less product to sell) in really wet years (unfortunately the grower cooperator we worked with for the replicated trial had a top-notch spray program, so we only have estimates of losses from our other cooperators). Essentially, using these CM practices on white vinifera cultivars is a more complicated decision than we had anticipated. Our project made a strong contribution by clearly demonstrating that using the CM practices was adventitious in wet seasons, and that consumers would pay a premium for wines made from these practices if they knew they were "environmentally-friendly", but did not lay out a decision-making framework to assist growers in determining the appropriate course of action in a timely manner, considering all economic variables.

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.