On March 5, 2019, Penn State researchers and Extension personnel presented research findings and provided five-minute overviews of upcoming studies at the 2019 Wine Marketing & Research Board Symposium, held in conjunction with the Pennsylvania Winery Association Annual Conference.
In this post, we have included short summaries of what each presenter discussed during their session along with a PDF/access to their presentation.
Under-vine cover crops: Can they mitigate vine vigor and control weeds while maintaining vine productivity?
Presented by Michela Centinari, Assistant Professor of Viticulture, Suzanne Fleishman, Ph.D. Candidate, and Kathy Kelley, Professor of Horticultural Marketing and Business Management
Michela, Suzanne, and Kathy discussed research conducted at Penn State related to the use of under-vine cover crops as a management practice alternative to herbicide or soil cultivation. Michela reviewed potential benefits of under-vine cover crops, such as reduction of excessive vegetative growth, weed suppression, and reduced soil erosion. She showed how the selection of cover crop species depends on the production goals of a vineyard, climate, vine age, and rootstock. Suzanne presented results from her research project. She is investigating above- and belowground effects of competition between a red fescue cover crop and Noiret grapevines, comparing responses between vines grafted to 101-14 Mgt vs Riparia rootstocks. Surveys will be administered to Pennsylvania grape growers and wine consumers in the Mid-Atlantic region. Growers will be asked to respond to questions about interest in using cover crops and benefits that could encourage their use. The consumer survey will focus on learning whether cover crops use would impact their purchasing decision and if they would be willing to pay a price premium for a bottle of wine to offset additional production costs.
Impact of two frost avoidance strategies that delay budburst on grape productivity, chemical and sensory wine quality.
Presented by Michela Centinari, Assistant professor of Viticulture
Crop losses and delays in fruit ripening caused by spring freeze damage represent an enormous challenge for wine grape producers around the world. This multi-year study aims to compare the effectiveness of two frost avoidance strategy (application of a food grade vegetable oil-based adjuvant and delayed winter pruning) on delaying the onset of budburst, thus reducing the risk of spring freeze damage. Our objectives are to: i) evaluate if the delay in budburst impacts grape production and fruit maturity at harvest, as well as chemical and sensory wine properties; ii) elucidate the mechanism of action of the vegetable oil-based adjuvant through an examination of bud respiration and potential phytotoxic effects; and iii) assess the impact of the two frost avoidance strategies on carbohydrate reserve storage and bud freeze tolerance during the dormant season.
Toward the development of a varietal plan for Pennsylvania wine grape growers.
Presented by Claudia Schmidt, Assistant Professor of Agricultural Economics, and Michela Centinari, Assistant Professor of Viticulture
Claudia Schmidt is a new Assistant Professor of Agricultural Economics with an extension appointment at Penn State. Claudia used the opportunity of the symposium to introduce herself to the industry. In her presentation, she first gave an overview on what and where Pennsylvanians buy their wines and spirits. She then talked about the research needed to develop a varietal plan for the Pennsylvania grape and wine industry to match existing and future grape production and variety suitability with anticipated consumer demand. The immediate next steps on her research agenda are to develop a baseline survey of grape production in Pennsylvania and, in collaboration with Michela Centinari, region specific cost of production of grapes.
Survey for grapevine leafroll viruses in Pennsylvania: How common is it, and how is it effecting production and quality?
Presented by Bryan Hed, Research Technologist
This is a continuing project funded by the PA Wine Marketing and Research Board, that has focused on the determination of the incidence of grapevine leafroll associated virus 1 and 3 (the two most economically important and widely distributed of the leafroll viruses) in commercial vineyard blocks of Cabernet franc, Pinot noir, Chardonnay, Riesling, and Chambourcin, across the Commonwealth. Over two years, the survey has shown that grapevine leafroll associated viruses 1 and/or 3, were present in about a third of the vineyard blocks examined. Infection of grapevines by grapevine leafroll-associated viruses can have serious consequences on yield, vigor, cold hardiness, and most notably fruit/wine quality. Bryan also discussed a second phase of the project, anticipated to continue for at least another two years within 6 vineyard blocks of Cabernet franc, identified in the survey. In these vineyards, we plan to plot the spread of these viruses, examine and report their effects on grapevine vegetative growth, yield, and fruit chemistry, and characterize the influence of inter- and intra-seasonal weather conditions on virus-infected grapevine performance.
Integrating the new pest, spotted lanternfly, to your grape pest management program.
Presented by Heather Leach, Extension Associate
Spotted lanternfly (SLF) is a new invasive planthopper in the Northeast U.S. that threatens grape production. Heather covered the basic biology, identification, and current distribution of SLF. She also presented on the economic impact of SLF in the grape industry and ways to manage SLF in your vineyard. SLF can feed heavily on vines causing sap depletion in the fall which has resulted in death of vines, or failure of vines to set fruit in the following year. While biological controls such as pathogens and natural enemies along with trapping and behaviorally based methods are being researched, our current management strategy relies on using insecticides sprayed in the vineyard. Heather showed results from the 2018 insecticide trials conducted against SLF, with efficacy from several products including bifenthrin, dinotefuran, thiamethoxam, carbaryl, and zeta-cypermethrin. You can read more about the results from this trial here: https://extension.psu.edu/updated-insecticide-recommendations-for-spotted-lanternfly-on-grape
Five-minute research project overviews
Impact of spotted lanternfly on Pennsylvania wine quality.
Presented by Molly Kelly, Extension Enologist
The Spotted Lanternfly (SLF) presents a severe problem both due to direct damage to grapevines as well as their potential to impact wine quality. Insects are known to produce or sequester toxic alkaloid compounds. The objectives of this study include characterizing the chemical compounds in SLF and production of wines with varying degrees of SLF infestation. We can then provide winegrowers with recommendations for production of wine from infested fruit. Toxicity studies will be conducted to determine the levels of toxic compounds in finished wine, if any, using a mouse bioassay.
Exploring the microbial populations and wild yeast diversity in a Chambourcin wine model system.
Presented by Chun Tang Feng, M.S. Candidate, and Josephine Wee, Assistant Professor of Food Science
In Dr. Josephine Wee’s lab, we are interested in the microbial population and diversity associated with winemaking. When it comes to wine fermentation, not only are commercial yeasts involved in this process, but also many indigenous yeasts. Our research goal is to isolate the wild yeasts and assess their feasibility of wine fermentation. We are expecting to explore the unique yeast strains from local PA which are able to make a positive impact on wine flavor.
Rotundone as a potential impact compound for Pennsylvania wines
Presented by Jessica Gaby, Post-Doctoral Scholar and John Hayes, Associate Professor of Food Science
This study will examine Pennsylvania consumers’ perceptions of rotundone with the goal of determining whether a rotundone-heavy wine would do well on the local market. This will be examined from several different perspectives, including sensory testing of rotundone olfactory thresholds, liking and rejection thresholds for rotundone in red wine, and PA consumer focus groups. The ultimate aim of the study is to determine the ideal concentration of rotundone in a locally-produced wine that would appeal to PA consumers.
Defining regional typicity of Grüner Veltliner wines
Presented by Stephanie Keller, M.S. Candidate, Michela Centinari, Assistant Professor of Viticulture, and Kathy Kelley,
Grüner Veltliner(GV) is a relatively new grape variety to Pennsylvania, and while climatic conditions are favorable to its growth, the Pennsylvania wine industry is still becoming familiar with the varietal characteristics of GV grown and produced throughout the state. This study focuses on defining typicity of Pennsylvania-grown GV wines. Typicity is described as the perceived representativeness of a wine produced from a designated area, and defining typicity can improve wine marketing strategies. This study uses multiple experimental sites across the state to create wines from a standardized vinification method. The wines will be analyzed using both instrumental and human sensory methods.Surveys will be administered to Pennsylvania grape growers and white wine consumers in the Mid-Atlantic region. Growers will be asked their interest in growing GV and what perceived and real barriers may impact their decision to grow the variety. The consumer survey will focus on understating how to introduce them to a wine varietal they may be less aware of and what promotional methods may encourage them to purchase the wine.
Boosting polyfunctional thiols and other aroma compounds in white hybrid wines through foliar nitrogen and sulfur application?
Presented by Ryan Elias, Associate Professor of Food Science, Helene Hopfer, Assistant Professor of Food Science, Molly Kelly, Extension Enologist, and Michela Centinari, Assistant Professor of Viticulture
The quality of aromatic white wines is heavily influenced by the presence of low molecular weight, volatile compounds that often have exceedingly low aroma threshold values. Polyfunctional varietal thiols are an important category of these compounds. This project aims to provide research-based viticultural practices that could lead to increases in beneficial varietal thiols in white hybrid grapes. The expected increase in overall wine quality will be validated both by measuring the concentrations of these desirable compounds (i.e., thiols) in finished wines using instrumental analysis and by human sensory evaluation, thus providing a link between the viticultural practice of foliar spraying and the improvement of overall wine quality.