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

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.