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2017 PA Research Symposium Provides Research-Based Practicality for PA Grape Growers and Winemakers

By: Denise M. Gardner

The Pennsylvania Wine Marketing and Research Board (PA WMRB) annually awards researchers and graduate students grants to explore pertinent topics to the Pennsylvania wine industry.  For the 2016 – 2017 fiscal year, four projects were awarded industry-funded grants.  Results from these four projects will be presented at the 2017 Symposium, co-hosted by the PA WMRB, Penn State Extension, and the Pennsylvania Winery Association (PWA).

Registration is being organized through the PWA, and can be found here:

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This year’s Symposium, held on Wednesday, March 29th at the Nittany Lion Inn (University Park, PA) will only run in the morning and is packed with 5 sessions of information pertinent to both the enology and viticulture fields in Pennsylvania.  At the close of the Symposium a lunch will be provided for all attendees.

Guest Speaker has Enology and Tannin Focus

The WMRB Symposium key guest speaker is Dr. Catherine Peyrot des Gachons, Winemaker Consultant at Chouette Collective.  Dr. Peyrot des Gachons has assisted Pennsylvania wineries with enhancing their quality production for several years.  She will be speaking towards her tannin and wine aroma matrix research that she has been working on at the Viticulture and Enology Department through the University of Montpellier (France).

Dr. Catherine des Gachons, winemaker consultant, will be the key guest speaker at the 2017 PA Wine Marketing & Research Board Symposium.

Dr. Catherine des Gachons, winemaker consultant, will be the key guest speaker at the 2017 PA Wine Marketing & Research Board Symposium.

Tannins: Modulation of wine structure and aroma

From environmental factors on tannin biosynthesis to human interventions to modulate tannin content in wine what do we know and what can we do to modulate wine structure. Can this tannin content impact wine aroma?  The presentation will focus on few main points of interest with practical applications.

 

Enology-Focused Presentations

An additional enology-based presentation will feature Laurel Vernarelli, a graduate student in Dr. Ryan Elias’s lab within the Penn State Department of Food Science.  Laurel’s presentation will be an extension from Dr. Gal Kreitman’s work that was presented last year on predicting reductive off-odors in wines.  Laurel will explore the use of copper fining in wine production and the potential impact it may have on wine quality.  Given the prevalence of reductive off-odors, including hydrogen sulfide, and heavy reliance on copper fining, this topic should be of considerable interest to most wineries.

Laurel Vernarelli will give an update on treating reductive and hydrogen sulfide aromas/flavors with copper sulfate at the 2017 PA Wine Marketing & Research Board Symposium.

Laurel Vernarelli will give an update on treating reductive and hydrogen sulfide aromas/flavors with copper sulfate at the 2017 PA Wine Marketing & Research Board Symposium.

Reconsidering copper fining in wine

This presentation will include a brief overview of copper fining, along with the impact of reductive thiols and recent findings describing the effect that copper has in wine. A method for using immobilized copper materials in place of copper fining is described. Depending on the result obtained, winemakers can make informed decisions for use of alternative fining techniques when dealing with reductive issues.

 

Viticulture-Focused Presentations

For those with an interest in viticulture, this year’s program promises to deliver some key updates.  Bryan Hed, Research Technologist for the Department of Plant Pathology, will present his annual updates regarding disease management for Pennsylvania vineyards.  For those that are frequent blog followers, Bryan is a lead contributor to the important seasonal reviews.  These tend to be very popular posts for growers and his presentations are always informative and practical.  If you missed the 2016 seasonal reviews, you can find them here:

Bryan’s talk at this year’s Symposium is a continued study with results collected over 2 years, which helps initiate trends and suggestions useful towards growers.

Bryan Hed from Penn State University will review current disease management techniques for the vineyard at the 2017 PA Wine Marketing & Research Board Symposium.

Bryan Hed from Penn State University will review current disease management techniques for the vineyard at the 2017 PA Wine Marketing & Research Board Symposium.

Updates on Grape Disease Management Research

Fruit zone leaf removal can be a very beneficial practice in the management of harvest season bunch rot. Bryan will start his presentation by briefly reviewing the pros and cons of different timings of this practice. In addition, leaf removal by hand is very expensive and labor intensive, and with the increasing scarcity and rising cost of hand labor, mechanization is crucial to increasing cost effectiveness and adoption of this practice, no matter what the timing. Bryan will follow up with an in depth discussion of the progress made toward mechanizing an early, pre-bloom leaf removal and comparing its effectiveness over a variety of wine grape cultivars and training systems during the past two seasons.

 

Maria Smith, Ph.D. candidate in Dr. Michela Centinari’s lab, will discuss her research regarding early leaf removal in Gruner Veltliner vines.  Maria and Dr. Centinari have previously written a blog post pertaining to leaf removal strategies for Mid-Atlantic vineyards, which could act as an excellent primer to Maria’s presentation in March.  Her presentation will deliver two-years (2015, 2016) of data regarding the effects of early leaf removal and cluster thinning techniques on Gruner Veltliner vines.

Penn State Plant Science Ph.D. Candidate, Maria Smith, will discuss her research on early leaf removal and cluster thinning techniques for Gruner Veltliner at the 2017 PA Wine Marketing and Research Board Symposium.

Penn State Plant Science Ph.D. Candidate, Maria Smith, will discuss her research on early leaf removal and cluster thinning techniques for Gruner Veltliner at the 2017 PA Wine Marketing and Research Board Symposium.

Vine response and management costs of early leaf removal for yield regulation in V. vinifera L. Gruner Veltliner

Early leaf removal (ELR) and cluster thinning (CT) were applied and compared for yield regulation in Grüner Veltliner over the 2015 and 2016 growing seasons.  Early leaf removal was performed at two different times, trace-bloom and fruit-set. We compared the effects of ELR and CT on grape quality, vine health, and economic costs to un-thinned vines.

 

Finally, Dr. Michela Centinari will follow up with further results regarding sprayable products to reduce frost damage in wine grape vineyards.  Michela’s frost research has been a prominent topic at previous Symposiums, and is often featured here on the blog site.  While the updated results that will be presented at the 2017 Symposium have not yet been reported through Penn State Extension, please see some of her past blog posts pertaining to frost control and freeze damage in the vineyard:

Dr. Michela Centinari will discuss her current research findings pertaining to frost protection in the vineyard at the 2017 PA Wine Marketing & Research Board Symposium.

Dr. Michela Centinari will discuss her current research findings pertaining to frost protection in the vineyard at the 2017 PA Wine Marketing & Research Board Symposium.

Spray-on materials: can they reduce frost damage to grapevines?

Dr. Centinari will present results of studies conducted to test the efficacy of sprayable products as a low-cost frost protection strategy. Two materials Potassium-Dextrose-Lac (KDL) and a seaweed extract of Ascophyllum nodosum, were tested for their cryo-protective activity using a controlled-freezing technique on several grapevine cultivars.

 

We hope to see you there!

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All of the cool V&E Research Covered at the 2015 PA Wine Marketing & Research Board Symposium

April 22, 2015 marked the 4th annual PA Wine Marketing and Research Board (PA WMRB) Symposium, held at the Nittany Lion Inn in State College, PA. It was a very successful program, hosting over 86 industry members concurrently with the PWA’s Annual Conference, which was held on both April 21st and 22nd. To read more about the PA WMRB, please visit their website here.

In addition to their other tasks, the PA WMRB financially supports a series of research projects, in which topics vary from a multi-state variety trial to frost protection in the vineyard and into experimentation with sulfur-containing aromatic control in wines. All research topics have been identified as prevalent interests to, or “problem areas” for, Pennsylvania industry members, and results have applicability to all producers.

In an effort to expand awareness of the various research programs taking place at Penn State, the following researchers have summarized their talks from the 2015 Symposium. Most of this research is in their beginning stages, and will continue into the current vintage.

All researchers would like to thank the Pennsylvania grape and wine industry and PA WMRB for their continued support.

 

Clonal Selection and New Interesting Varieties for Pennsylvania

By: Diego Barison, NovaVine, Inc.

  • Two Italian white varieties that show potential for Pennsylvania’s growing region include Tocai Friulano and Moscato Giallo. Tocai Friulana is an early ripening variety, has potential for barrel aging from a winemaking perspective. Moscato Giallo tends to have a subdued aromatic profile compared to other Muscat varieties, but on years that Botrytis pressure is high, it will retain a higher crop yield. Moscato Giallo can be used to make still and sparkling wines.
  • Two Italian red varieties that show potential for Pennsylvania’s growing region are Lagrein and Toraldego. Both varieties are common in northern Italy. Lagrein has a good tannin structure and good acidity, which is preferred for red wine aging. Toraldego has been planted at a few vineyards throughout the Mid-Atlantic region.
  • For more information on grape varieties and clonal selection, you can visit NovaVine’s website.
  • Additionally, Vitibook, co-authored by Diego, is a valuable resource for vineyard owners throughout the U.S.

 

Cold Temperature Stress in Grapevine: Impact of Management Practices and Varietal Selection

By: Maria Smith

  • Cold stress is one of the biggest limiting factors to high quality wine grape production in Pennsylvania.
  • Two types of relevant cold stress in PA include
  1. Dormant-season cold injury
  2. Late spring frost injury
  • Current experiments that I am involved with to evaluate management practices and varietal selection on impacts of cold stress:
  1. Crop load regulation using early leaf removal and cluster thinning, evaluating 2 over-cropping varieties: Chancellor (hybrid) in 2014 and 2015, and Gruner Veltliner (vinifera) in 2015 and 2016.
  2. Variety evaluation in 2015 for tolerance and recovery from late spring frost event. Which includes 4 potted varieties: Marquette (hybrid), Le Crescent (hybrid), Riesling (vinifera) and Lemberger (vinifera). These varieties will be exposed to an artificial frost ‘event’ at 26.5-28°  The physiological response and recovery of vines will be monitored.

 

The Role of Copper in the Evolution of Sulfur Compounds in Wine

By: Gal Kreitman

  • In order to mitigate wine oxidation, reductive winemaking is becoming more commonplace.
  • Reductive winemaking preserves important varietal thiols which provide aroma characteristics of passionfruit, grapefruit, citrus zest, blackcurrant. Reductive winemaking also preserves reduced sulfidic odors such as hydrogen sulfide and methanethiol.
  • Winemakers commonly add copper to wine to remove the reduced odors which very quickly removes hydrogen sulfide and methanethiol.
  • Copper does have downsides as it doesn’t remove disulfides and thioacetates which can significantly contribute to reduced odors in wine.
  • Copper can also remove some of the beneficial varietal thiols.
  • Residual copper in wine post-bottling can actually lead to higher formation of reduced odors in wine and other redox mediated reactions.
  • My research goals are to elucidate the mechanism for copper-mediated thiol redox reactions, and provide winemakers with tools to have a better control over sulfur-containing aroma compounds.

 

Assessing Spotted Wing Drosophila Injury Potential on Grape Production

By: Jody Timer and Michael Saunders

Spotted wing drosophila (SWD), Drosophila suzukii, is an invasive vinegar fly that was introduced into the United States in 2008. It was introduced into Pennsylvania in 2010. S. suzukii is a highly polyphagous pest, whose serrated ovipositor allows it to lay its eggs on undamaged ripening fruit. Adult females can lay 100 to 600 eggs in fruit, as the fruit starts to color and sugar levels begin to rise. SWDs’ lifecycle consists of adults, eggs, larva (3 instars) and pupa overwintering as adults. They differ from other fruit flies because of the serrated ovipositor which allows them to infest intact fruit by laying eggs inside of the undamaged fruit. Damage is often not discovered until the fruit goes to market. SWD is considered a major problem in grape vineyards and damage to wine grape crops has been reported in many states.

Red traps containing yellow sticky cards, baited with apple cider vinegar and the new dual Trece lure have shown to be the most effective and easiest way to trap SWD. Trapping is the most efficient way to determine if SWD is in a vineyard, and also to determine when it is time to check the grapes for infestation. Trapping in Erie County has shown that the SWD are appearing earlier each year, and the numbers of insects captured in the traps is increasing with each subsequent year. The best way to check for infestation in the vineyard is to add crushed grape berries to salt solution: 1 cup water to ¼ cup salt and the larva will float to the top. Larva found in recently ripened fruit is most likely SWD. SWD was discovered from emergence studies on Concord, Chambourcin, Niagara, and Vidal. No-choice, 2-choice-and 4-choice studies were conducted on these four grape varieties. All varieties in the no-choice trials were infested with SWD. They showed a slight preference for Niagara grapes in the 2 and 4 choice testing. Research was done bagging clusters with net bags containing SWD. All clusters became infected with SWD after being bagged. Pesticides in three activity groups have shown efficacy against SWD. It is not recommended to spray unless you have a known infestation in your vineyard.

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Updates on Grape Disease Management Research

By: Bryan Hed

Early leaf removal and Botector for bunch rot control:

  • Bunch rot control = fruit wound control. Many factors cause wounds to fruit: birds, insects, powdery mildew, cluster compactness. We typically make great efforts to minimize the effects of all of these factors, with the exception of compactness.
  • Compactness creates wounds that cause direct fruit rot. Compactness also activates latent Botrytis infections, increases the effect of retained bloom trash in clusters on bunch rot development, and reduces pesticide penetration into clusters.
  • We have investigated many methods of reducing cluster compactness over the years, and early leaf removal has been the most consistently effective method. Mechanization of this method will improve its cost effectiveness and increase adoption.
  • Botector, a biological pesticide was compared to synthetic fungicides and early leaf removal for control of bunch rot disease on Chardonnay and Vignoles grapevines.
  • Botector was not effective in either trial, but fungicides and early leaf removal were equally effective at reducing bunch rot disease, when compared to the control. An integrated treatment of both fungicides and early leaf removal was the most effective treatment.

The effects of rainfall on fungicide (Mancozeb) residue retention.

  • Mancozeb is one of the most widely applied fungicides for grape disease control. We monitored the effects of rainfall on mancozeb residues on grapevine leaves.
  • Over two seasons, high pressure liquid chromatography (HPLC) and inductively coupled plasma mass spectrometry (ICP) were used to quantify mancozeb residues on grape leaves. Both methods were equally effective in year one, but ICP appeared to be more effective and consistent in year 2. As ICP is less expensive and samples are easier to store, its use for quantifying mancozeb residues may improve the accuracy and reduce the cost of this research.
  • In the field, the first inch of rain removes about 60-70% of mancozeb residue, the second inch 70-80%, and the third inch 80-90% of the mancozeb residue.
  • Future research will focus on bioassays to determine the efficacy of varying concentrations of rain challenged mancozeb residues for disease control and the need for subsequent fungicide applications.

 

Wine Marketing Strategies for the Mid-Atlantic Region

By: Abigail Miller

  • Social media is a conversational marketplace; not just two-way, it’s multi-way.
  • Two-thirds of core wine drinkers (those who drink wine about once a week) and 40% of marginal wine drinkers (those who drink wine less frequently) use the Internet in some form to get information about wine (Guenther, 2013).
  • At least 30% of survey participants felt that a Facebook Page was mandatory for a winery. Fifty-four percent of 21- to 24-year-olds, specifically, responded in this manner.
  • Though percentages for Instagram were lower, 18.3% of those 21- to 24-year-olds responded that this tool is mandatory.
  • Younger Millennials are the primary users of Instagram and winery tasting rooms should consider posting on this network to reach these consumers.
  • Websites for promoting products and promoting purchases should be also be a part of a winery tasting room’s repertoire.
  • Content for all outlets could focus on serving and pairing suggestions, coupons, promotions, and discounts, as well as other components that appealed to survey participants.

To read more about Abby’s study on social media preferences for wineries, please visit:

 

Evaluation of Cost Effective Practices for Reducing the Risk of Spring Frost Injury in Vineyards

By: Michela Centinari

Michela presented the main findings from of a project started in 2014 to evaluate the potential of low-cost strategies to reduce the risk of spring frost injury in grapevines. Specifically two spray-on materials currently used by grape growers across the country were tested for their ability to delay budbreak (Amigo oil, soybean- based oil) and provide frost protection to young grapevine shoots after budbreak (KDL, potassium dextrose lactose; Agro-K corporation). Briefly, Amigo oil caused higher levels of delay in bud-break in V.vinifera varieties (Riesling and Lemberger) than in the hybrids varieties (Noiret and Traminette) (Figure 1). Current research efforts are investigating if the different response observed among varieties may be related to the time of oil application. In the vinifera varieties the delay in budbreak was followed by a significant reduction in yield (about 40%), with no effect on fruit composition and wine chemical parameters. Since no frost occurred in Pennsylvania in 2014 the effect of KDL was tested on 1-bud cuttings using a temperature controlled chamber. Preliminary results were shown together with current research efforts which include: testing the effect of KDL on potted vines using a controlled temperature chamber, and at multiple vineyard sites in case a frost event will occur in the next few weeks.

Figure 1. Control and oil-treated Riesling vines (May 20, 2014).

Figure 1. Control and oil-treated Riesling vines (May 20, 2014).

 

The Effect of Acetaldehyde on Red Wine Color Stability and Astringency

By: Marlena Sheridan

  • Wine oxidation can be risky for wines due to side effects of oxygen exposure, but there are important benefits of oxidation for red wines.
  • Acetaldehyde, typically formed from oxygen integration, leads to beneficial effects on red wine color and mouthfeel by binding with tannins and anthocyanins.
  • Reactions with acetaldehyde form stable, polymeric pigments as well as modified tannins with lower perceived astringency.
  • Winemakers use oxygenation techniques (e.g., micro-ox, barrel aging) to form acetaldehyde in the wine, but this includes the risk of detrimental effects of oxidation instead of acetaldehyde formation.
  • Our work aims to evaluate the efficacy of exogenous acetaldehyde treatment of red wine on improving color stability and astringency. This work will be done in real and model wine systems to fully understand the effects of acetaldehyde on wine tannins.
  • Further detail and a description of completed work can be found in my blog post from April 24.

 

The 2014 NE-1020 Variety Trial Harvest: A Comparison of North East and Biglerville, PA

By: Michela Centinari & Denise M. Gardner

Michela Centinari gave an update on the 2014 viticulture performance for the V. vinifera and inter-specific hybrids winegrape varieties established at the two variety evaluation plantings located at the Lake Erie Regional Grape Research and Extension Center (LERGREC), North West side of PA, and at the Fruit Research and Extension Center (FREC) in the southern side of PA (Table 1). The two plantings were established in 2008 as part of the NE-1020 project, a multi-state project that was developed to 1) evaluate the viticultural characteristics and wine quality potential of grape cultivars and clones of economic significance throughout the eastern US; and to 2) characterize the viticultural and wine quality potential of emerging cultivars based on regional needs.

The presentation mostly focused on winter cold temperature injury sustained by the grapevines at the two sites and on the different ability of the varieties to adapt and recover to extreme cold conditions experienced in PA in the winter of 2013-2014.

At the Lake Erie (LERGREC) planting all the vinifera varieties experienced extensive winter injury. Bud, trunk injury and crown gall symptoms were observed in all the vinifera varieties. High incidence of vine mortality was recorded in Syrah, and Muscat Ottonel. Among the vinifera varieties Cabernet franc and Grüner Veltilner vines recovered the best; healthy suckers grew from above the graft union. Lower levels of winter injury were recorded in the Southern part of PA. The most significant winter injury was observed in Tannat (almost 100% bud mortality and vascular tissue damage at cane and trunk levels). The damage on the other varieties was mostly limited to primary buds, although some vines (mostly Syrah, Malbec) sustained vascular tissue damage and collapsed throughout the summer. As a consequence of primary bud damage varieties such as Malbec, Albarino and Cabernet Sauvignon produced very low crop yield.

Table 1. List of varieties and clone designation, when known, planted at the Lake Erie Regional Grape Research and Extension Center (LERGREC), North West side of PA, and at the Fruit Research and Extension Center (FREC) in the southern side of PA.

Table 1. List of varieties and clone designation, when known, planted at the Lake Erie Regional Grape Research and Extension Center (LERGREC), North West side of PA, and at the Fruit Research and Extension Center (FREC) in the southern side of PA.

  • In 2014, 6 varieties were fermented for winemaking trials, and discussed at the recent Symposium: Vidal Blanc (North East), Chambourcin (North East), Cabernet Sauvignon (Biglerville), Merlot (Biglerville), Albarino (Biglerville), and Cabernet Franc (Biglerville).
  • The primary trend noted with Albarino is the continued low yield, which has been annually estimated at under 2.0 tons/acre since 2011. In 2014, the estimated yield for Albarino was 0.57 tons/acre.
  • The Vidal Blanc underwent a pre-fermentation juice trial based on Jose Santos’s presentation in August 2014, which can be found here. Vidal Blanc was separated into three treatment groups: Control (Brown Juice), SO2 addition, and AST addition. Attendees at the PA WMRB Symposium had the opportunity to taste wines produced from these treatments.

 

Pre-Fermentation Juice Treatments in Vidal Blanc. All treatments treated with pectinase and 24-hour settling time in cold storage. Image shown after racking.

Pre-Fermentation Juice Treatments in Vidal Blanc. All treatments treated with pectinase and 24-hour settling time in cold storage. Image shown after racking.

Chambourcin Wines in 2013 Vintage Year Showing Red Color Intensity Differences Between 2 Vineyard Sites in PA.

Chambourcin Wines in 2013 Vintage Year Showing Red Color Intensity Differences Between 2 Vineyard Sites in PA.

In addition to the support of the PA Wine Marketing and Research Board, this material is based upon funding provided by the National Institute of Food and Agriculture, U.S. Department of Agriculture, under agreement No. 2010-51181-21599.

Investigating the Inadvertent Transfer of Vitis labrusca Associated Aromas to Vitis vinifera Wines

By: Jared Smith

Polymers, such as plastics used during winemaking, can scalp (uptake) aroma compounds from juice and wine.

Aroma scalping can lead to not only the loss of desirable aromas, but also the presence of unexpected aromas in wines due to desorption of the aromas from the polymers during subsequent processing. This could especially be an issue when equipment is shared for the processing of two completely different species of grapes (ex. V. vinifera vs. V. labrusca) that have vastly different aromatic profiles.

One potential way to help remove scalped aromas from your polymeric winemaking materials is through the use of ethanolic (80%) cleaning solutions at higher temperatures (75°C) for an extended period of time.

Updates on freeze injury in grapevines

By Michela Centinari

It seems like yesterday we were looking at the weather forecast and worrying about cold winter temperature events and the potential for grapevine injury. Now that it is finally starting to get warmer here in Pennsylvania, we may be faced with another threat: spring frost. A grape grower is never bored!

It was another cold winter in Pennsylvania, particularly harsh in the Lake Erie region (Figure 1). At the Penn State Lake Erie Regional Grape Research and Extension Center (LERGREC) temperatures bottomed out at about -21 °F (-30 °C) on February 16, 2015. Unfortunately several cold events (-13, -14 and -15°F) were recorded over the following ten days. On a ‘positive’ note, the week before these extreme cold events, temperatures were lower than normal, with daytime temperature highs well below freezing, except for one day (34°F). These temperatures may have provided a positive, reinforcing maintenance of the vines’ mid-winter cold hardiness [1]. Bryan Hed and the LERGREC’s crew have been checking the extent of bud and trunk damage on Concord and other hybrid varieties.

Figure 1. Daily maximum and minimum temperatures recorded at the LERGREC during the 2014-2015 dormant season.

Figure 1. Daily maximum and minimum temperatures recorded at the LERGREC during the 2014-2015 dormant season.

Information available on cold winter injury on grapevine

At the 2015 Mid-Atlantic Fruit and Vegetable Convention I reviewed the factors that can affect grapevine cold hardiness, explained how to assess bud, cane and trunk cold damage, as well as how to manage cold-injured vines. For information on grapevine cold injury you can refer to the Grapevine cold injury, end of the season considerations blog post and references within.

If you are looking for specific information on winter injury to vine phloem you can check this recent and comprehensive review: Viticulture and Enology Extension News, spring 2015, Washington State University written by Michelle Moyer (Assistant Professor and Viticulture Extension Specialist at Washington State University).

Percentage of winter injury does not equal percentage of crop loss

In March, I attended The Northern Grapes Project Symposium in Syracuse, NY. Tim Martinson (Senior Extension Associate at Cornell University) and Imed Dami (Associate Professor and Viticulture Extension Specialist at Ohio State University) highlighted that the percentage of bud cold damage does not always equal percentage of crop loss. The answer often lies in the pruning adjustment strategies adopted by growers. Dami reported that, despite 40% of bud winter damage, Marquette produced about 5 tons/acre in Ohio last year. Those vines were pruned to 5 bud-spurs (‘hedge pruning’) to compensate for winter injury [2]. .

Tim Martinson reported that last year many growers in the Finger Lakes region (NY) left more buds to compensate for winter injury experienced during the 2013-2014 winter. The growers left up to five-fold more buds than they would have done in a normal year. Many cane-pruned VSP vineyards were spurred to 5-6 bud spurs. It was a pleasant surprise that in 2014 widely planted V. vinifera varieties such as Riesling, Chardonnay, and Cabernet franc, came through better than was expected based on bud mortality estimates. I know that many growers prefer cane pruning, and I understand the reasoning behind that, but please take into consideration that cane pruning is not recommended following winter injury [3].

How to train suckers of cold injured vines?

Imed Dami recommends that growers “actively” train vines back to their original training system in the same season in order to resume production quicker. Therefore, instead of training suckers vertically (they can become extremely vigorous!) they should be trained horizontally along the fruiting wire. With extremely vigorous vines, four shoots should be selected and then two can be laid horizontally on the fruiting wire. With less vigor, two shoots can be selected and laid horizontally, one to each side. Then, shoots should be tipped to stimulate lateral shoot growth. Lateral shoots growing vertically and upward will become the future spurs next season [4]. Latent buds on the lateral shoots will develop like buds from primary shoots. As long as they are exposed to sunlight and clean from disease and insects, they should have the same cold hardiness as any other buds.

Here is a valuable video regarding pruning with regards to cold injured vines: https://www.youtube.com/watch?v=r1Yhv8Rw38o

A few words on spring frost

As we get close to bud-break, the threat of spring frost is approaching. In the spring of 2014, no frost damage was recoded in grapevines in Pennsylvania and hopefully we will have another frost-free spring. If you would like to get information about frost protection strategies you can check the following websites and newsletters. Unfortunately, there is no new exciting or infallible frost protection method. Site selection remains the best way to protect vines from frost injury.

To the often asked question: If my vine gets frosted, should I remove the injured shoots?

The answer is: “There’s not much of a point,” according to Tony Wolf, Professor and Viticulture Extension Specialist at Virginia Tech University. A detailed explanation on how to handle damaged shoots and potential consequences on yield production can be found at Viticulture Notes, Vol.25, May-June 2010

Testing the cryo-protectant properties of KDL

KDL (potassium dextrose lactose; Agro-K corporation, Minneapolis, MN, USA) is a potassium based fertilizer. According to the manufacturer’s literature, spraying KDL shortly before a frost event (24-48 hours) would increase the potassium and sugar levels within the plant and reduce the frost injury on young vine tissue. Although attractive to growers, there is not scientific literature that supports the effectiveness of this product in preventing/reducing frost damage. Numerous grower testimonials are available, but growers usually do not leave an ‘untreated’ control area where the material is not applied, which is critical in order to evaluate the efficacy of KDL as cryo-protectant.

A large scale study coordinated by Tim Martinson (Cornell University) and in collaboration with the Agro-K company (KDL manufacturer) has been set up this spring to evaluate the effect of KDL at several vineyard sites located in NY and PA. Penn State is a collaborating university that is helping to work with six commercial growers that agreed to participate in the study in addition to the Penn State LERGREC in North East, PA.

Figure 2. Setting up the KDL trial with Tim Martinson and growers in the Endless Mountain region, PA.

Figure 2. Setting up the KDL trial with Tim Martinson and growers in the Endless Mountain region, PA.

Although, I’m hopeful there will not be a spring frost that growers have to deal with, if we do end up with a spring frost during the 2015 growing season, this study will hopefully provide some useful recommendations for grape growers.

References cited

  1. Wolf T.K., 2015. Viticulture Notes. Vol. 30 supplement, 17 February 2015
  2. Dami, I.E. , Ennahli S., Zhang Y. (2012). Assessment of winter injury in grape cultivars and pruning strategies following a freezing stress event. American Journal of Enology and Viticulture, 63: 106-111.
  3. Dami, I.E. 2009. Ohio Grape-Wine Electronic Newsletter Vol.3: 2-5, 6 Feb 2009.
  4. Dami I.E., 2014.Ohio Grape-Wine Electronic Newsletter, Vol.25, 3 July 2014.

 

Harvest 2014: An update to studies on frost injury

By: Maria Smith

Since I arrived in August, we have been busy at work continuing to collect field data on our current studies. In addition, we have been developing a new study which takes an in-depth look at the role of canopy management practices have on vine cold hardiness.

Harvest 2014:

After weeks of intense anticipation, monitoring berry development, and fretting over weather, harvest has finally come for us at the Centinari lab. As of last week, our commercial plots with Lemberger, Riesling, Noiret, and Traminette used to study frost tolerance and avoidance have all been harvested (Fig 1, See: “Evaluate cost-effective methods to decrease crop losses due to frost injury”). If you recall, these plots were sprayed with KDL, a commercially available cryo-protectant, and Amigo oil, a product used to delay bud break.

Fig 1. Left: Lemberger at harvest (10/9/2014), Right: Riesling at harvest (10/16/2014)

Fig 1. Left: Lemberger at harvest (10/9/2014), Right: Riesling at harvest (10/16/2014)

Our preliminary observations show that the Amigo oil treatments had noticeably lower yield in both Lemberger (Fig 2) and Riesling (data not shown) grapes harvested. Despite the lack of frost this spring, we did see a 2 week delay in bud break in Lemberger and a 1 week delay in Riesling with Amigo oil treatments. We are currently checking to see if these differences can be attributed to factors such as the number of shoots per vine between the treatments and/or cluster weight. However, if Amigo oil is in fact the cause of a decrease in yield we should see similar results over multiple years. In the case that Amigo oil has an actual affect on yield, it would be prudent to perform an economic analysis to decide if the use of Amigo oil as a frost avoidance mechanism is worth the cost in decreased yield.

Figure 2.  Lemberger yield data, 2014

Figure 2. Lemberger yield data, 2014

Winemaking:

 Winemaking is a crucial component in determining what sort of impacts delaying bud break can have on the final product. Thanks to the help of Denise Gardner and a group of students in a winemaking and enology independent study class, we have had the opportunity to crush, press, and ferment our harvested research grapes into wine (Fig 3).

Figure 3.  Lemberger processing at the PSU Food Science Wet Pilot Plant

Figure 3. Lemberger processing at the PSU Food Science Wet Pilot Plant

In the initial juice, we have noticed an increase in Brix and TA between the Amigo oil and control treatments in Lemberger, though the Brix of all treatments in Riesling were similar (Table 1). We will be running additional detailed chemical analyses on frozen berry samples taken throughout ripening in the upcoming months.

Table 1.  Juice analysis – Brix, pH, TA of Lemberger and Riesling.  Riesling was chapitalized to 21 Brix.

Table 1. Juice analysis – Brix, pH, TA of Lemberger and Riesling. Riesling was chapitalized to 21 Brix.

Future work planned for analyzing the effects of Amigo Oil and KDL include:

  • Grape Brix, TA, pH on samples from veraison through ripening
  • Wine chemistry – Alcohol, SO2, and color density
  • Sensory attributes of wine
  • Prepare for year 2 KDL and Amigo Oil application

 

Winter 2014: New work on canopy management and cold hardiness:

 We have recently begun work on a second study in cold hardiness. Canopy management practices are often used to improve the microclimate of grapes within the fruiting zone by exposing clusters to increased light and airflow. Early leaf removal (ELR) has been shown to successfully reduce cluster compactness in tight-clustering varieties, thus reducing incidents of bunch rot (Hed et al., 2014). Another common canopy management practice, cluster thinning (CT), is used to reduce fruit load of overcropping varieties to improve grape and wine quality. However, these practices may also change carbon source-sink relationships with cluster thinning removing carbon sinks and ELR removing photsynthetically active leaves (source), which could potentially alter cold acclimation and hardiness in the vine. Using ‘Chancellor’ vines under 3 imposed canopy management treatments – low-intensity leaf removal, high-intensity leaf removal, and CT – and an un-treated control at the Lake Erie Regional Grape Research and Extension Center, we plan to:

  • Quantify non-structural starches and sugars associated with bud cold hardiness between Nov. 2014 and March 2015
  • Assess how canopy management practices affect grape and wine chemistry and wine sensory perception
  • Perform an economic analysis on the cost and return of canopy management practice implementation

 

Literature:

Head B, Ngugi HK, Travis JW (in press). Short- and long-term effects of leaf removal and gibberellin on Chardonnay grapes in the Lake Erie Region of Pennsylvania. American Journal of Enology and Viticulture. doi: 10.5344/ajev.2014.14034

 

Funding:Print

The investigation of grapevine frost treatments is made possible by the John H. and Timothy R. Crouch Program Support Endowment, an endowment founded and funded by the Crouch brothers, original owners of Allegro Winery in Brogue, PA.  Additional financial support is contributed by the Pennsylvania Wine Marketing & Research Board (PA WMRB).  It is with great appreciation to investigate these projects based on funds and interest provided by the Pennsylvania wine community.

 

Acknowledgments:

A big thanks to Don Smith for his technical support in our lab and Denise Gardner for her assistance in winemaking. Also, thanks to our wine grape grower collaborators. _________________________________________________________________________________________________

Maria Smith is a viticulture PhD student with Michela Centinari, specializing in cold stress physiology of wine grapes.

Evaluate cost-effective methods to decrease crop losses due to frost injury

By: Michela Centinari

To get ready for my first growing season as a research viticulturist at Penn State University, I met several times with Mark Chien and Denise Gardner and read through all of Mark’s newsletters from the last couple of years. In the past few months I also visited several wine grape growers across the State with the objective of understanding the challenges that the PA wine grape industry is facing. By talking with Mark, Denise and growers, I established that crop yield loss related to late spring freeze injury is one of the economic challenges to the continued growth and advancement of the PA wine grape industry. It was a big relief for many growers that the 2014 spring, after a challenging winter, did not contain a (significant) freeze event recorded after grapevine budbreak. However, the cold temperatures that often occur in late spring, at the very cold-sensitive stages of shoot development, can result in severe crop losses and vine injury comparable to a severe midwinter freeze.

Below is a brief explanation of current frost damage/protection research that I have been working on at Penn State.

What can be done to reduce frost damage in vineyards?
“The best time to protect an orchard (or vineyard) against frost is when it is being established” (Humpries W.J., 1914). Selecting a site with good air drainage is extremely important to reduce the risk of freeze/frost damage. However, many vineyards are located in less than ideal sites. Best management practices for vineyards located in frost vulnerable sites include:

  • choosing the appropriate training system and variety,
  • strategies for delaying budbreak (double or delayed pruning; chemical application),
  • leaving additional canes post pruning, and
  • mowing the inter-row grass [1].

The most effective frost protection methods (i.e. wind machines, helicopters, over-tree covers, heaters, and sprinkling irrigation) may require large investments and not every grower can justify the costs involved. To enhance the profitability of growing grapes in PA the development of frost protection strategies affordable to many growers is critical.

With this in mind, in collaboration with Ryan Elias and Denise Gardner, I’m currently evaluating the effectiveness of spray-on materials (KDL and soybean oil) on reducing the risk of frost injury. In addition, the effect of these materials on vine performance, juice composition and wine sensory characteristics is being evaluated.

Specifically, we are looking at two potential ways to decrease freeze injury in vine green tissues:

1) Increase freeze tolerance of vine green tissue:
If your vineyard is located in a frost prone area, you’ve probably heard about a foliar potassium fertilizer called KDL (potassium dextrose lactose; Agro-K corporation, Minneapolis, MN, USA). According to the manufacturer’s literature, spraying KDL shortly before a frost event (24-48 hours) would increase the potassium and sugar levels within the plant and reduce the frost injury on young vine tissue. Although attractive to growers, there is not scientific literature that supports the effectiveness of this product in preventing/reducing frost damage. Numerous grower testimonials are available, but growers usually don’t leave an ‘untreated’ control area where the material was not applied, which is critical in order to evaluate the efficacy of KDL as cryo-protectant.

Freeze events are not easy to study; they are unpredictable and often variable across a single site. Therefore, a large scale study was set up in collaboration with Cornell University (Tim Martinson and other extension agents) and the Agro-K company (KDL manufacturer) to evaluate the effect of KDL at 25 vineyard sites located in NY and PA. With regards to PA, 6 commercial growers agreed to participate in the study, in addition to the PSU Lake Erie Grape Research & Extension Center. In the absence of a frost event we were unable to gather any data for the 2014 year but we hope to test the same protocol again next year (2015).

Since, as mentioned, frost events are unpredictable I am also using a temperature control chamber to simulate a frost event. In the spring, KDL was sprayed on several grapevine varieties at the PSU research vineyard established at Rock Spring. After 24, 36, and 48 hours, canes with healthy growing shoots were excised and placed in the frost simulation chamber. Several ‘frost’ runs were conducted and I am now in the process of analyzing the data.

Parallel experiments on vinifera and hybrid grapevine varieties are being conducted by Jason Londo at the USDA-Cornell University.

2) Avoid frost injury by delaying budbreak
Delaying of budbreak is a way to reduce the risk of frost and is used mostly for grapevine varieties that break bud early and are at the highest risk of spring frost injury and subsequent crop losses. Studies conducted in Ohio, reported that application of soybean oils delay grapevine bud deacclimation and budbreak anywhere from 2 to 20 days depending on several factors including variety, timing and coverage. However, since grapevine cultivars respond differently to soybean oil applications, optimal strategies for their use need to be established for grapevine varieties grown under PA environmental conditions. Moreover, the effect of soybean oils on fruit composition and wine quality needs to be evaluated, since oil applications could delay fruit ripening, affect yields, fruit chemistry and wine sensory characteristics.

In March field trails were established at two commercial vineyards in Central PA. A soybean oil-based adjuvant, Amigo (Loveland Industries, Greeley, CO) was applied at a 10% concentration (v/v) to runoff with a backpack sprayer during the dormant season (Figure 1A). Amigo oil was applied on March 7 at vineyard “Site 1” on Traminette and Noiret vines, and on March 27 at vineyard “Site 2” on Riesling and Lemberger vines. Temperature sensors were installed in the fruiting wire of selected vines to continuously monitor air temperature throughout the growing season (Figure 1B and 1C).

In the spring, control vines (not-sprayed) and treated vines (sprayed with oil) were visually evaluated for budbreak. Budbreak was determined as stage five of the Eichorn and Lorenz (1977) scale of grapevine development. The grapevine growth stage is being periodically monitored and recorded to date.

Figure 1. A) Don Smith sprays Amigo oil at Happy Valley vineyard. B&C) Temperature sensors installed at the vineyard.

Figure 1. A) Don Smith sprays Amigo oil on grapevines. B&C) Temperature sensors installed at the vineyard.

The oil application caused various levels of delay in budbreak. At “Site 2,” budbreak delay of approximately 7 and 14 days was observed in the oil-treated Riesling and Lemberger vines, respectively, compared to the control (Figure 2). Looking at Figure 2 you will see how stage 5 (budbreak) was reached on May 13 for the control Lembeger vines and on May 29 in the oil-treated Lemberger vines. Although reduced, a phenological delay was still present at bloom (stage 23) in the Lemberger and Riesling oil-treated vines.

Figure 2. Growth stage of control and oil-treated Riesling and Lemberger vines.

Figure 2. Growth stage of control and oil-treated Riesling and Lemberger vines.

Pictures of Riesling vines were taken on May 20 (Figure 3) and July 9 (Figure 4). On May 20 the difference between oil-treated and control vines was striking. On July 9: both oil-treated vines and control vines showed fully developed and healthy canopies.

Figure 3. Control and oil-treated Riesling vines (May 20, 2014).

Figure 3. Control and oil-treated Riesling vines (May 20, 2014).

Figure 4. Control and oil-treated Riesling vines (July 9, 2014).

Figure 4. Control and oil-treated Riesling vines (July 9, 2014).

The delay in budbreak was much less pronounced in the Noiret at “Site 1” (figure 5). The delay in budbreak in the oil-treated vines was only of a couple of days. Traminette data have not yet been analyzed.

Figure 5. Growth stage of control and oil-treated Noiret vines.

Figure 5. Growth stage of control and oil-treated Noiret vines.

In agreement with previous work [2] our data suggests that varieties respond differently to soybean oil application. Varieties such as Noiret may need multiple oil applications in order to increase the delay in budbreak. Moreover, environmental conditions may also in part explain the different results obtained at the two sites. Finally, it is important to remember that multiple years of evaluation are needed in order to gather meaningful results and give growers reliable recommendations

What is left to do for the 2014 research season?

  • Measure Brix, pH and TA during grape ripening and at harvest to check if the delay in budbreak may cause an un-even fruit ripening.
  • At harvest collect yield data (number and weight of cluster per vine) and make wine from the Riesling and Lemberger control and oil-treated vines. Our final goal is to analyze if the oil application has any effect on wine chemistry and sensory perception.

 

Acknowledgments

 The project “Evaluation of cost effective practices for reducing the risk of spring frost injury in vineyards” is being funded by a Pennsylvania Wine Marketing and Research Board (PWMRB) grant.

Thanks to Don Smith for his technical support and help in field data collection.

 

Literature cited

[1]. Trought et al. (1999). Practical considerations for reducing frost damage in vineyards. Report to New Zealand winegrowers.

[2]. Dami, I. and B. Beam. 2004. Response of grapevines to soybean oil application. Amer. J. Enol. Vitic. 55: 269-275.