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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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How does delaying spur-pruning to the onset or after bud burst impact vine performance? Insights from recent studies

By Michela Centinari

Now that harvest is finally over and wines are tucked away in the cellar, it is time to prepare for the next year. One of the first concerns that many growers feel in a new growing season is that worry of spring frost and the associated potential risk of vine injury. In the spring of 2016, for example, an unusually warm March was followed by a very cold start to the month of April, which resulted in damaging frost incidences in some vineyards of the Mid-Atlantic region.

Susceptibility to frost injury increases with advanced phenological growth stage [1], therefore, growers and scientists have explored different techniques for delaying bud burst of grapevines to increase the chance of avoiding spring frost damaging events. Vegetable-based oils (e.g., Amigo oil) can be sprayed on the canes/buds during the winter to slow down bud de-acclimation and delay the resumption of vegetative growth in the spring [2; 3; study at Penn State]. Delaying pruning until late winter can also be used to delaying bud burst of vines growing in frost prone areas.

Canes of cordon-trained vines can be pruned to 2-3 node spurs late in the winter or even when apical buds begin to open to delay bud burst of basal buds. Due to the strong apical dominance of Vitis vinifera cultivars, apical buds of an unpruned cane tend to burst first, which inhibits development and growth of median and basal buds [4] (Figure 1).

Figure1. Spur pruning vines while the apical buds are bursting. Photo source: McGourty, The case for double—pruning. Practical Winery &Vineyard.

Figure1. Spur pruning vines while the apical buds are bursting. Photo source: McGourty, The case for double—pruning. Practical Winery &Vineyard.

What may happen if we wait until the onset of bud burst or even later to prune the vines?

Spur-pruning the vines when the apical buds of un-pruned canes are already open may not only delay bud burst of the basal nodes, but may also postpone other phenological growth stages such as bloom, fruit-set, or even veraison with potential consequences for vine yield and fruit chemical composition at harvest [4].

I recently read two articles on this topic published in the American Journal of Enology and Viticulture (Post-bud burst spur-pruning reduces yield and delays fruit sugar accumulation in Sangiovese in central Italy [5] ) and in Frontiers in Plant Sciences (Phenology, canopy aging and seasonal carbon balance as related to delayed winter pruning of Vitis vinifera L. cv. Sangiovese grapevines [6]).

The studies described in these articles aimed to assess if and how delaying winter spur-pruning of Sangiovese vines to the bud swelling stage or later, after bud burst, impacted the annual growth cycle of the vines and its productivity.

The studies were conducted in Italy and the researchers were specifically interested in assessing if vines pruned around or after bud burst exhibited a delay in grape ripening as compared to those pruned during the winter, resulting in lower sugar accumulation and higher acidity in the fruit at harvest. A steady trend of increased warming is, indeed, pushing some Mediterranean grape growing regions toward accelerated ripening [7], which could lead to excessive or overly fast sugar accumulation in the fruit, high alcohol in the wine, unacceptably low acidity, high pH, and also atypical grape flavors and aromas [5].

Although excessive or overly fast sugar accumulation may not be a problem in our region, it’s still important to understand if delaying winter pruning to extremes could be used to delay bud burst and reduce risk of frost damage, as well as the impact this practice may have on vine yield, and fruit and wine chemistry. This is a topic of further interest in light of changing climatic conditions and the potential increase of unpredictable weather patterns like early spring warming and late spring frosts [8].

Below, I will summarize the two previously mentioned studies emphasizing results which can be of interest to wine grape growers in our regions.

Both studies were conducted on mature Sangiovese (Vitis vinifera L.) vines. The first study was established in a commercial vineyard in central Italy, whereas the second study was conducted on vines growing outdoors in 10-gal pots at a research station in northern Italy. Groups of vines were assigned to different pruning treatments. Vines assigned to the standard grower practice treatment were spur-pruned to 2 basal nodes during the winter when buds were dormant. Vines assigned to the other treatments were spur-pruned at more unusual times from the bud swelling to full bloom (Figures 2 and 3A).

Figure 2. Phenological growth stages of the apical shoot at the time vines were pruned to 2-node spurs. *BBCH scale was used to assess phenological stages [9] in studies described below.

Figure 2. Phenological growth stages of the apical shoot at the time vines were pruned to 2-node spurs. *BBCH scale was used to assess phenological stages [9] in studies described below.

Did delaying vine spur-pruning to after bud-burst consistently delay the whole annual growing cycle?

Basal buds of Sangiovese vines spur-pruned when apical shoots were about 1.6″ long (called late pruning treatment; Figure 3A central panel) burst 17 days later than those of vines pruned in the winter, when buds were dormant (called standard pruning treatment; Figure 3A left panel). Pruning the vines even later, when apical shoots were about 4.7-5.5″ long (called very-late pruning treatment;  Figure 3A right panel) extended the delay in bud burst to 31 days as compared to vines pruned in the winter Unfortunately no phenology data were recorded for vines pruned at bud swelling stage (study 1).

The delay in phenological growth stage decreased over the season. For example, late-pruned and very-late pruned vines reached veraison 3 and 13 days, respectfully, after those pruned in the winter (Figure 3C). Shoots of vines pruned after bud burst developed later in the season under higher air temperature than those of vines pruned during the winter. Greater air temperature may have helped shoots of late- and very-late pruned vines to reach bloom and veraison in fewer days as compared to those pruned earlier [6].

By harvest the delay was fully off-set for the late-pruned vines: they reached the sugar level set for ripening (~ 19 ºBrix) three days before those pruned in the winter. Grapes of very-late pruned vines reached 19 ºBrix 6 days after those pruned in the winter.

Figure 3. Vine appearance at the time of pruning (A) and at bloom (B) and veraison (C). Note: standard winter pruning was taken as a reference for bloom and veraison. Photo courtesy Dr. Stefano Poni (professor of Viticulture, Universita’ Cattolica del Sacro Cuore, Italy).

Figure 3. Vine appearance at the time of pruning (A) and at bloom (B) and veraison (C). Note: standard winter pruning was taken as a reference for bloom and veraison. Photo courtesy Dr. Stefano Poni (professor of Viticulture, Universita’ Cattolica del Sacro Cuore, Italy).

Spur-pruning vines after bud burst significantly reduced crop yield compared to standard winter pruning

Vines pruned at bud swelling growth stage had similar crop weight, number of clusters per vine, and cluster weight than those pruned when buds were still dormant. Pruning vines after bud burst, however, reduced yield as compared those pruned during the dormant season. For example, late pruned vines (spur-pruned when apical shoots were about 1.6″ long; Figure 3A central panel) had 26% lower crop yield as compared to those of the standard pruning control group (spur-pruned before bud burst). Reduction of crop yield was related to lower cluster weight and lower number of berries per cluster. While there is not a clear explanation on why late-pruned vines had fewer berries per cluster, several hypotheses were presented including increased production of gibberellins during the initial flush of growth in the late-pruned vines [6].

Waiting even longer to prune the vines had a detrimental effect, reducing not only cluster weight but also the number of clusters per vine. For example, vines pruned to two basal nodes when the apical shoots were already flowering had no crop at harvest. When vines were pruned so late the basal shoots did not develop flowers and remained vegetative after pruning. I am not sure why any growers would want to wait until bloom to prune the vines, but it’s still interesting to see how such a drastic treatment may limit sources of carbohydrates for developing cluster primordia [5].

Although uncertainty still exists, the authors suggested that delaying spur-pruning until after bud burst, but not to extremes, may have the potential for reducing crop yield in high-yielding cultivars such as Sangiovese planted in specific regions of Italy. However, long-term field studies are necessary to assess if it is possible to calibrate winter pruning date for managing yield reductions and/or fruit maturation rate.

Did delaying vine spur-pruning to bud swelling stage or after bud burst consistently impact fruit chemistry?

The effect of the timing of spur-pruning on fruit composition at harvest varied between studies and with the extent of the pruning delay. For example, Sangiovese vines late pruned (apical shoots 1.6″ long) had higher total soluble solids (+ 1 °Brix), total anthocyanins and phenolics than winter-pruned vines. However, vines growing in a commercial vineyard (study 1) and spur-pruned to two basal nodes later in the season, when inflorescences of apical shoots were already swelling (Figure 3C), had lower sugar concentration (-1.6 °Brix) and higher TA (+1.8 g/L tartaric acid) than those pruned during the winter, but at the same time they also had higher anthocyanins and phenolic concentrations.  This result suggests that spur-pruning canes after bud burst may decouple the accumulation patterns of total soluble solids and anthocyanins, phenolic metabolites. This could be intriguing for growers trying to delay fruit sugar accumulation and acid degradation, while maintaining wine color, but on the another hand it could also come with a  reduction in crop yield, quantified to over 50% in this study [5].

Did delaying winter spur-pruning have negative carry-over effects on the following season?

Pruning vines at the bud swelling stage did not have negative effects on vine growth in the following year. It did not impact bud fertility (number of clusters per shoot) or winter carbohydrate storage, which is important for winter vine survival and following year resumption of growth. However, pruning the vines to two-nodes after bud burst, specifically when inflorescences of apical shoots were already swelling (Figure 3C), reduced bud fertility by 50% in the following year. Those vines were able to recover once standard winter pruning was applied again at the end of the study.

In conclusion:

These studies conducted on Sangiovese vines grown in Italy found that:

  • Winter spur-pruning can be applied up to bud swelling without adversely affecting vine yield, grape composition at harvest or bud fertility in the following year.
  • Vines pruned after bud burst show pronounced delay in shoot development at the beginning of the season, which increased as the pruning time was further delayed. Under the warm conditions of these studies the delay in phenological growth stage decreased or even disappeared over the season. This could be partially explained by the fact that late-pruned vines needed less time than vines pruned during the winter to reach maximum photosynthesis efficiency.
  • Delaying spur-pruning to after bud-burst may reduce vine yield, decrease sugar accumulation and bud fertility in the following year.

Delaying winter pruning of vines located in frost prone areas to the onset of bud burst or shortly after that may be used as frost avoidance technique. However, we need to further understand how a delay in shoot development and potentially a shorter growing season (number of days from bud burst to harvest) may impact fruit ripening, yield component, vine over-winter carbohydrate storages and susceptibility to winter cold temperatures, as well as the following year growth. The studies summarized here were conducted in a warm region with a growing season longer than many areas of Pennsylvania.  Further research is necessary to corroborate those results under our regional climatic conditions.

 

Literature cited

  1. Centinari M, Smith MS, Londo JP. 2016. Assessment of Freeze Injury of Grapevine Green Tissues in Response to Cultivars and a Cryoprotectant Product. Hortscience 51: 1–5.
  2. Dami I, and Beam B. 2004. Response of grapevines to soybean oil application. J. Enol. Vitic. 55: 269–275.
  3. Loseke BJ, Read PE, and Blankenship EE. 2015. Preventing spring freeze injury on grapevines using multiple applications of Amigo Oil and naphthaleneacetic acid. Scientia Hort. 193: 294–300.
  4. Friend AP, and Trought MCT. 2007. Delayed winter spur-pruning in New Zealand can alter yield components of Merlot grapevines. J. Grape Wine Res. 13: 157–164.
  5. Frioni T, Tombesi S, Silvestroni O, Lanari V, Bellincontro A, Sabbatini P, Gatti M, Poni S, Palliotti A. 2016. Post-bud burst spur pruning reduces yield and delays fruit sugar accumulation in Sangiovese in central Italy. J. Enol. Vitic. 67:419–425.
  6. Gatti M, Pirez FJ, Chiari G, Tombesi S, Palliotti A, and Poni S. 2016. Phenology, canopy aging and seasonal carbon balance as related to delayed winter pruning of Vitis vinifera cv. Sangiovese grapevine. Frontiers in Plant Sciences 7:1–14. Article 659.
  7. Jones GV, White MA, Cooper OR, and Storchmann K. 2005. Climate change and global wine quality. Climatic Change 73: 319–343.
  8. Mosedale JR, Wilson RJ, and Maclean IMD. 2015. Climate change and crop exposure to adverse weather: Changes to frost risk and grapevine flowering conditions. PLoS One 10:e0141218.
  9. Lorentz DH, Eichorn KW, Bleiholder H, Klose R, Meier U, and Weber E.1995. Phenological growth stages of thegrapevine (Vitis vinifera ssp. vinifera). Codes and descriptions according to the extended BBCH scale. Aust. J. Grape Wine Res. 1, 100–103.

Customer Survey Opportunity for Wineries

By: Kathy Kelley

My very first post for this blog focused on using surveys to learn about consumers’ tasting room experiences (http://bit.ly/1QMfEtu).  I described a few easy to use and free tools (e.g. SurveyMonkey.com, SurveyGuizmo.com) that can be used to create a questionnaire.

I feel very strongly about gathering input from consumers about their attitudes and behaviors pertaining to winery tasting rooms in the region and how tasting rooms can encourage repeat visits.  As you know very well, there is limited data available that describes the Pennsylvania wine consumer, impressions of their tasting room visits, and wine preferences.  Collecting this data is essential, as described in an article published by Brian Fletcher on the MarketingProfs.com website: “Market research…is essential to you and your brand’s long-term success…[it] will keep your brand afloat while companies who fail to make research a high priority drown” (http://bit.ly/1NerOZW).

Hence, I have decided to “put my money where my mouth is” and I am creating a survey that tasting room owners/operators can use to collect this valuate data.  But, wait, there’s more…

What I am offering

My offer includes not only the survey questions and gathering responses via my SurveyMonkey.com subscription, but I will also send a monthly summary to each participating tasting room that will contain responses specific to their operation.  Because of the potential number of survey responses, I will only be able to provide summary data.  Summary data for each question will look similar to the following image (shown just for demonstration purposes).

Dec_Kathy_summary question

Who might benefit

My thought is that this offer could help a variety of tasting rooms.  For example, those:

  • without a system in place to capture consumer sentiment,
  • who are collecting data from customers but would be interested in learning responses to these additional questions,
  • interested in collecting the data digitally,
  • unable to fully administer a customer satisfaction survey for one reason or another, etc.

Sample questions and limitations

The overall goal of this survey is for owners/operators to learn from visitors what tasting room aspects they find appealing and what components of the experience may need to be reevaluated and enhanced or amended.

I will be working on a draft of questions until the survey launches in late winter 2016, but I have a core list of questions that I feel will benefit a majority of tasting rooms.  They include:

  • date and time of day (morning, afternoon, evening) of their most recent visit to your tasting room,
  • who they visited the tasting room with,
  • if they participated in a tasting, educational event/tour, festival or activity, etc. when at the tasting room,
  • if they made a purchase and what they purchased,
  • how they would rate their overall tasting experience, interaction with tasting room staff, products available for purchase, visual appeal of the tasting room, etc. using scales (e.g. 1 to 5, 1 to 7),
  • their interest in events and activities that you have an interest/ability to offer in the future,
  • if they were a first time visitor, how they learned about your tasting room and what encouraged them to visit,
  • how to encourage repeat visits to your tasting room (e.g. collaboration/cross promoting with other businesses, tasting room only offerings and events), and
  • demographic, socio-economic status of the survey respondent (e.g. age range, sex), and similar questions (e.g. distance traveled from home to visit the tasting room, other businesses that they visited in the area).

After consumers submit their survey they will be directed to your tasting room website, or other URL that you specify.

While each tasting room is unique and I’m sure that it would be preferable for each to have a customized survey, the amount of time to craft several different surveys is beyond what I have available.  But, those willing to participate can chose to remove certain questions and I will work with them to create up to two questions that are specific to their operation.

How to proceed

This first effort will be more of a pilot test to:

  • determine demand for such a tool/service,
  • work out any issues that arise,
  • get a general idea if this is a benefit for tasting rooms, and
  • gage the amount of time I would need to devote to this project each month.

Since this is a new offering, and just with introducing a new good or service in your tasting room, I would like to trial this with 20 tasting rooms.  Though preference will be given to Pennsylvania tasting rooms, if space is available I am willing to include businesses located outside the Commonwealth.

You may indicate your interest in participating by filling out a short survey/online form by Friday, January 15, which you can access by clicking on this link: http://svy.mk/1O6VMfr

Questions ask for your contact information, URL for your tasting room website, location of your primary/main tasting room (if you have more than one), and whether you agree that:

  • you will participate in the pilot test for the entire duration (one year with an estimated start date in late winter) unless a situation occurs that causes me to end the study early,
  • you will be able to delete certain questions and add up to two questions (which I will help you create),
  • responses collected from your tasting room visitors will be kept confidential and that any reports (blog posts, presentations, and similar) developed will be the result of combining data collected from all participating tasting rooms, and
  • tasting room visitors who access the survey will first need to read a consent form and agree to participate in the study before responding to the customer satisfaction survey.

After the 20 tasting rooms have been selected and the final list of questions has been developed, each tasting room will receive a URL to their survey.  The URL can be posted on websites, distributed via email, printed on material that is distributed to tasting room visitors, and so on.

Potential benefits/opportunities that your participant will provide

If you have been reading the marketing blog posts published on this site, you know that researchers from Pennsylvania, New York, and New Jersey received funding from the USDA Federal State Marketing Improvement Program (http://1.usa.gov/1YkCPRw) to survey consumers residing in the three state about their wine purchasing and consumption habits.  Though we are still conducting surveys and analyzing data, you can read some of the results by clicking on this link: http://bit.ly/1IWfTRK.  Results from this study will further benefit the industry.

I hope that some of you will find this offer interesting and chose to participate.  I think that this is a great opportunity for tasting rooms to learn from visitors and for the wine and grape group at Penn State to learn about potential areas of wine marketing research.  In addition, with the group’s goal of providing information to the industry through Extension efforts, your participation will also allow us to help educate tasting rooms in the region about tasting room visitors’ needs, wants, and interests.  Our hope is that this consumer-based survey can help us tailor ways to help you improve your tasting-room marketing initiatives and increase foot traffic and sales.

If you would like to participate, please click on the following link and complete the survey by Friday, January 15th: http://svy.mk/1O6VMfr

Please contact me at kmk17@psu.edu if you have any questions.

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.

 

NE-1020… What? The Top 5 Industry Benefits Affiliated with the NE-1020 Variety Trial

By: Denise M. Gardner

What is NE-1020?

Since the start of my tenure at Penn State Extension, we have been routinely highlighting the data and research affiliated with the NE-1020 project. Many have asked what NE-1020 is, and others have asked “Why are you participating in this trial? What is the point?” All valid questions!

As we come to an end of another vintage season, I thought it would be an interesting experience to review the NE-1020 project and what it is contributing to PA industry members.

The NE-1020 variety trials are a multi-state collaborative project, initially co-funded by the previously existing Viticulture Consortium-East, that were designed to evaluate the viticultural characteristics and wine quality potential of several wine grape varieties, cultivars and clones. Variety selections at each vineyard plot were determined based on dormant and growing season climatic conditions and research standards (i.e. standard varieties such as Cabernet Sauvignon, that would be tested at each vineyard site to establish a baseline and commonality at each site for research findings). These standard varieties are commonly referred to as “core varieties.”

Penn State has 2 research vineyards: 1 in Biglerville, PA and 1 at North East, PA near Erie. Vineyards were designed in a randomized complete block (RCB) design, meaning that “panels” of 4 vines were established at random throughout the ~1 acre of vineyard land at each site. The primary purpose of the RCB design is to allow for statistical analysis and to remove any potential variability due to location in the vineyard. This design is often affiliated with the cost to manage the NE-1020 sites, as varying training systems for hybrids and vinifera are frequent within a single row of vines. Additional costs are often related to data collection for all 20 varieties planted at one site. “Core varieties” for the Biglerville site include Cabernet Sauvignon and Merlot while “core varieties” for the Erie site include Chambourcin and Vidal Blanc. These varieties are harvested and made into wine annually, regardless of vintage variation.

After 3-4 years of vineyard establishment, Penn State began harvesting wine grapes in 2011. What a year to begin harvest and data collection! (I can hear the small grunts of laughter as we recall the 2011 season.) This was also the first year that we began making wines for research purposes from these varieties. Thus, as of the 2014 harvest, this will be the 4th year that Penn State has brought the Pennsylvania industry research wines for evaluation.

As this is a co-funded project between a Specialty Crop Research Initiative grant led by Dr. Tony Wolf at Virginia Tech and the PA Wine Marketing and Research Board (WMRB), we have tried to find active ways to engage pertinence of this study to industry members.

SCRI Logo_Grape Wine Quality_RGB

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For example, one of the varieties that we have been evaluating includes Albarino, a white variety that is limited in Pennsylvania, and industry members get an opportunity to taste this wine every year at the WMRB Symposium.

The following notes the top 5 benefits affiliated with the NE-1020 project since I became involved with the study in 2011:

  1. Growing grapes and making wines annually has put Penn State viticulture and enology Extension personnel and researchers in touch with real vintage struggles felt by industry members. Prior to the establishment of the NE-1020 vineyard plots, there was limited focus on viticulture and enology research that could apply to the entire state. [I should note, however, that Penn State has had active research programs in Entomology and Plant Pathology that were, and still are, quite pertinent to the wine grape community in Pennsylvania and the Mid-Atlantic region.] The 2011 season was a perfect example in which the Penn State community committed to the NE-1020 project felt the effects of harvest season tropical storm and hurricane. While both sites were affected in different ways, we too dealt with low yields, increased disease pressure, and altered protocols for harvesting and wine production. It gave many members within the Penn State community some active speaking points to assist industry members. Other examples that pertain to this point include a greater awareness of enological issues, such as red wine color stability or dealing with heavy incidence of disease. These issues that are often iterated by industry members are also dealt with here at Penn State, and have been highlighted through processing and fermenting the NE-1020 varieties. This has led to point #2.
Botrytis disease pressure on Pinot Grigio grapes

Botrytis disease pressure on Pinot Grigio grapes

  1. Evaluating winemaking options to determine their effects on wine quality. Penn State Extension is actively listening to industry suggestions and applying enological questions they may have to our NE-1020 varietal study. In 2012, we began a series of yeast trials, which were tasted amongst industry members at the annual PA WMRB Symposium, based on suggestions made by industry members while I toured the state in 2011. Some of these yeast trials captured the interest of industry members, and a few people have altered some of their purchases based on the trials’ initial results. Additionally, red wine color stability was an issue that was brought to my attention through several regional visits in 2013. Therefore, we were able to design a few studies, with support from Lallemand and Enartis Vinquiry, to evaluate potential treatments that we have applied throughout the 2014 vintage year. These treatments are actively taking place, being evaluated and will be presented at the annual PA WMRB Symposium in 2015.
2014 Vidal Blanc juice trials to evaluate latent astrigency and aromatic retention

2014 Vidal Blanc juice trials to evaluate latent astrigency and aromatic retention

2012 Yeast Trials

2012 Yeast Trials

  1. The NE-1020 project allows us to record and evaluate micro-climates within Pennsylvania. One of the primary advantages of having 2 vineyard sites is being able to evaluate cultivar potential throughout regional differences within the state. This is actually one of the leading projects that I see as contributing to the definition of Pennsylvania’s regions and micro-climates. Tastings of those varieties that are planted at both Erie and Biglerville has led to a series of great industry discussions, questions, and future research trials. If you are interested in tasting some of these wines, please join us during the 2015 PA WMRB Symposium (in April at University Park, PA).
Penn State Biglerville vineyard site

Penn State Biglerville vineyard site during Fall harvest season

  1. The project initiated annual research winemaking and wine tasting at Penn State. At the 2012 PA WMRB Symposium, many industry members indicated that they had never tasted research wines before that day. I think this is a very valuable quality affiliated with the NE-1020 project. It has given Penn State the ability to produce research wines on an annual basis and develop a winemaking infrastructure. Research wines are never fully finished; the priority is to focus on varietal character in addition to physiological ripeness parameters (i.e. sugar and acid) during harvest and throughout production. Production for whites usually ends post-primary fermentation with a few rackings to get wines off of the lees. For reds, most wines are put through MLF before being placed in cold storage. Neither type of wine sees any oak treatment, fining, or filtration. This is done purposefully, with the intention that when industry members taste the wines, they can evaluate the particular treatment (whether it be vineyard or processing induced) and determine the wine’s potential (i.e. would it be good as is with little refinement, or should it go forward into an aging or oaking regime?). This concept of research winemaking and wine tasting is applied to many well-developed wine regions throughout the world and has helped progress the quality of wines in those particular regions.
NE-1020 wine tasting

NE-1020 wine tasting

  1. The NE-1020 project has allowed undergraduate students the opportunity to get real experience in viticulture and enology. I see Pennsylvania’s wine industry at the forefront of making great strides of progress in terms of wine quality. Much of this, I believe, starts with wine education. The NE-1020 project has provided a network that now involves undergraduate students to actively learn about wine, winemaking, grape harvesting, production methodology, wine sanitation, wine styles, and analysis. These experiences have led to a plethora of opportunities for our undergraduate students including internships or co-ops at wineries within and outside of Pennsylvania, wine research opportunities at large wine companies, and extracurricular learning for wine certifications. 2014 is the first year in which I see the investment in our student population directly benefiting the wine industry. Several students are now graduating, exploring “harvest hop” opportunities in other countries, and bringing their education and experience back to the Pennsylvania industry. A few students have been hired at Pennsylvania wineries for full-time positions, and aim to help improve the quality of PA-produced wines consistently. This is a direction that I hope to see advance and progress Pennsylvania as time moves forward, and it with great appreciation that I thank the wineries that have actively taught or hired students to progress their winemaking careers.
    Students working the 2011 harvest

    Students pressing grapes during the 2011 harvest

    Students participating in grape harvest

    Students participating in grape harvest

    Students conducting wine analysis during the 2012 harvest season

    Students conducting wine analysis during the 2012 harvest season

    Students hydrating yeast for inoculations during the 2013 harvest season

    Students hydrating yeast for inoculations during the 2013 harvest season

    Crushing and destemming during the 2014 harvest season

    Students crushing and destemming incoming grapes during the 2014 harvest season

     

     

     

     

    “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”

Introducing the Penn State wine & grapes graduate students’ team

By: Michela Centinari and her graduate student team

An exciting and rewarding part of my responsibilities as a faculty member is mentoring graduate students and helping them to achieve their career goals. This week I would like to take the opportunity to introduce three young and talented graduated students who have decided to focus their studies and research on wine grapes.

It is my pleasure to advise Maria Smith and to co-advise Annie Klodd and Laura Homich. Their backgrounds are diverse and they each bring something new and interesting to the table. They are working on research projects that will benefit the wine and grape industry, as well as advance our knowledge on several topics including:

  • Effect of crop load and intensity of pre-bloom fruit-zone leaf removal on yield components, disease incidence, cold hardiness, winter carbohydrates storage, and wine sensory perception.
  • Effect of the timing of fruit -zone leaf removal and cluster sunlight availability on grape and wine aroma profiles.
  • Impact of under-trellis cover crops on vine root distribution, morphological traits, soil nutrient and water availability in response to below-ground competition for resources and/or interference for space.
  • Effect of delayed bud–break on fruit ripening, yield components and wine sensory perception.
  • Physiological response to post-budbreak freeze events in Vitis vinifera and inter-specific hybrids winegrape varieties.

These collaborative research projects on wine grapes have strengthened ties among faculty and research staff members at the Penn State College of Agricultural Sciences, as well as fostered cooperative relationships with universities such as Cornell and Virginia Tech. Finally, I would like to point out that thanks to the students’ hard work and efforts, this fall, wine will be made from several research trials under the supervision of the Extension Enologist, Denise Gardner. This will allow industry members to assess if and how viticulture treatments imposed in the vineyard affected wine sensory perception.

Later this year the students will post updates about their research projects in this blog. This week I invited Annie, Laura and Maria to introduce themselves to the wine grape community:

 

Annie Klodd

Sep 2014_Annie

“Hi, my name is Annie Klodd, and I’m a 2nd-year Masters student in Plant Biology at Penn State, advised by Drs. David Eissenstat and Michela Centinari. I grew up on a 20-acre vineyard in Iowa, and once I outgrew my childhood distain for pruning in -10 degree winters, I developed a true passion for the US winegrape industry, particularly in the Midwest and mid-Atlantic.

My research aims at understanding how cover crops planted under the trellis affect grapevine growth, so we can make informed decisions about if and how to use cover crops in mid-Atlantic vineyards. In order to get to the bottom of that, we have to look beyond pruning weight and yield and dig deeper (no pun intended) into how cover crops affect the vine roots’ access to vital nutrients and water. My experiment is located at Virginia Tech’s Alson B. Smith Agricultural Research and Extension Center vineyard, where Tony Wolf’s team found that an under-trellis grass cover crop reduced vegetative growth and yield of Cabernet Sauvignon vines. To explore why, I am testing whether the resource demands of the grass tend to limit the water and nutrients available to the vine roots. So far, my data suggests that the shallow fescue roots limit the phosphorus available to the vine in shallow soil, and force the vine roots into deeper soil, where nitrogen and phosphorus are in tighter supply. To learn more about how the vines respond to nutrient limitation, I’ll spend the next few months in the lab testing whether the cover crop caused the vine roots to alter their anatomy or rely more on beneficial mycorrhizal fungi for the uptake of phosphorus.”

 

Laura Homich

Sep 2014_Laura 3 pics

“Hi, my name is Laura Homich, and I’m a first year Masters student in the Food Science Department under the direction of Dr. Ryan Elias and Dr. Michela Centinari. I began my exploration of enology and viticulture as an undergraduate Chemistry student at Penn State. Through my undergraduate research experience with Extension Enologist, Denise Gardner, I not only helped with processing and analysis of the NE-1020 varietal wine trials, but also worked on my own project investigating the effects of co-inoculation on wine quality of a high-acid, red hybrid, Chambourcin. I was given the opportunity to present my research findings at the 2014 PA Wine Marketing and Research Board Symposium, and at the 2014 American Society of Enology and Viticulture Conference.

My thesis work will explore the effects of viticulture practices on the rotundone content in Noiret grapes and wine. Rotundone is an aroma-impact compound found in the grape skin and is attributed to the black pepper notes most commonly associated with Australian Shiraz. Rotundone has been identified in an increasing number of Vitis vinifera cultivars, including Grüner Veltliner. Interestingly, approximately 20% of consumers are anosmic (the inability to perceive) to rotundone, while those who can detect this compound can identify it at concentrations as low as 16 ng/L in wine. Noiret is a hybrid variety suitable for growth in cool-climate regions and is known for its black pepper characteristics. This study will look at the effects of timing of fruit-zone leaf removal and cluster sunlight exposure on rotundone content at various time points across the grape ripening process. Through this project, I’m thrilled to learn about wine aroma analysis methods, to continue to gain experience in winemaking, and to obtain hands-on experience in the vineyard.”

 

Maria Smith

Sep 2014_Maria

“Hi, I am Maria Smith. I graduated magna cum laude in 2009 from Virginia Commonwealth University, with a B.S. in biology and minors in chemistry and Spanish. At VCU, I studied the molecular genetic basis of symbiotic relationships for nitrogen fixation in flowering plants. I received my M.S. in horticulture from Cornell University in 2013 working with Dr. Taryn Bauerle on the role of both above and belowground traits on invasive potential of woody plants. I recently moved from Washington, DC here to Penn State for a Ph.D. in viticulture with Dr. Michela Centinari.

Grapevine injury due to cold temperatures (winter and late spring) is a limiting factor to grape production in PA and other regions as well. The focus of my research centers on how canopy management practices impact vine cold hardiness and winter carbohydrate reserves in permanent organs. Additionally, I will be exploring the role varietal differences have in physiological responses to imposed frost events post-bud break in young vines. This work will be in conjunction with on-going projects at the PSU Lake Erie Regional Grape Research and Extension Center and the vineyard at Rock Spring experimental farm.”

 

 Acknowledgment

 We would like to especially thank our collaborators at Penn State (Bryan Hed, Denise Gardner), at Cornell University (Dr. Justine Vanden Heuvel), and at Virginia Tech University (Dr. Tony Wolf). Additionally, we would like to extension a special thank you to the PSU Lake Erie Regional Grape Research and Extension Center staff and Don Smith for their technical support.