Tag Archive | harvest

Assessing grape maturity for harvest planning

By Dr. Michela Centinari, Assistant Professor of Viticulture, Department of Plant Science

If just one adjective was chosen to describe the 2018 growing season to date, many of us might suggest ‘rainy.’ In many Pennsylvania regions, grape growers faced persistent rainfall for the majority of the summer. For example, in central PA, State College has had an accumulation of 29 inches (737 mm) of rainfall for the months of April through August.  Growers really had to be on top of their fungicide spray schedule and canopy management plans to minimize the risk of disease so that fruit will be healthy at harvest time. Recently, Bryan Hed and Jody Timer wrote blog posts that provided recommendations for late-season downy mildew control (late season downy mildew control)and insect problems (late season insect problems). While the weather forecasted for harvest season is weighing heavily on the minds of many grape growers, a post-veraison task critical for a successful harvest is collecting grape samples to measure the progression of fruit maturity.

This article provides a brief review on what fruit ripeness parameters you should measure and how to collect berry or cluster samples to best assess fruit maturity. While this information could be particularly useful for new grape growers approaching their first vintage, experienced growers should review the information to ensure that they are using the best techniques for collecting representative fruit samples.

Harvest decisions

Grapes are typically harvested when they reach desired fruit quality parameters (e.g., sugar content, pH, flavor, color) which vary depending on the wine type or style the winemaker aims to produce. Grapes should be sampled periodically until harvest to monitor how parameters associated with fruit maturity (e.g., sugar, pH, organic acids, flavors) evolve through the ripening season. However, there are many other factors involved in selecting a harvest date, which may or may not directly relate to optimal fruit maturity. These factors include:

  • Fruit health condition (is the fruit deteriorating due to rot or other disease or insect damage?),
  • disease and insect pressure,
  • short and long-range weather forecasts,
  • available labor,
  • space available at the winery to process the grapes, and
  • type or style of wine that will be made.

What fruit ripeness parameters to measure

The evaluation of the overall fruit ripeness involves quantitative parameters (sugar content, pH, titratable acidity) but also measurements that go beyond analytical techniques(berry sensory analysis).

Quantitative measurements to determine grape ripeness:

The information reported below is adapted and summarized from the factsheet Determining grape maturity and fruit sampling written by Dr. Imed Dami, Ohio State University.  To access the entire document click the following link Determining grape maturity and fruit sampling.

Sugars, organic acids, and pH are the primary indicators of technological or commercial grape maturity, which is different from physiological maturity that occurs at or soon after veraison when seeds are ready to germinate.

Sugars: Sugars, specifically glucose and fructose, are the main soluble solids in grape juice. Sugar content is typically measured in degree Brix (°Brix); 1 degree Brix corresponds to 1 gram of sugar per 100 grams of grape juice. Desirable levels of sugar content are typically between 18 and 24ᵒBrix, depending on grape variety and wine style.

Sugar level is relatively easy to measure in the vineyard with a handheld refractometer (Figure 1). However, sugar content is not always related to an accumulation of flavor compounds. Even within the same variety, the desired varietal flavor can be reached at different sugar level in different vintages. Similarly, two varieties might have the same sugar level, but one might have fully developed varietal flavors, while the other may not.

Screenshot 2018-09-07 07.08.06Figure 1. Handheld refractometer used to measure soluble solids (sugars) content.

Organic acids: Titratable acidity (TA; sometimes referred to as total acidity) indicates the total amount of acids in the grape juice. The two major organic acids in grapes are tartaric and malic acids. TA is determined by titration of the juice sample with a standardized solution of sodium hydroxide (NaOH).  The amount of NaOH used to neutralize the acid in the juice is used to calculate juice TA.

Screenshot 2018-09-07 07.08.21

Although acid levels at harvest vary across vintages and varieties, they generally fall between 0.6 and 0.8 grams of titratable acids / 100 mL of juice (or 6 – 8 g/L of juice).

pH: pH (power of Hydrogen) measures the strength of acidity, which is the reactivity of H+ ions in the juice solution. pH is generally measured with a pH meter. Typically, the lower the pH the higher the acidity in the juice; however, there is no direct relationship between TA and pH. It is possible to find juice (or wine) with high pH and high TA. Generally, white grapes are harvested at a lower pH than red grapes (white varieties = pH of 3.1 to 3.3; red varieties = 3.3 to 3.5).  High pH levels (> 3.70) can negatively influence wine microbial and physical stability.

Berry sensory analysis:

It is a good exercise for growers and winemakers to periodically monitor fruit ripeness (e.g., development of flavor, color) both visually and using sensory evaluation of the berry skin, pulp, and seeds separately. Berry sensory analysis may seem difficult at first, but you can easily master the technique with some practice and good record keeping.

The procedure involves putting berries in your mouth, crushing them gently to press out the juice, and evaluating its sweetness and acidity. The next step is to separate the seeds from the skin and place them in your hand for visual observation (green seed = immature seed; brown seed = mature seed; Figure 2). Lastly, crush the berry skin and put it on your cheeks to assess the degree of astringency. For more detailed information refer to the following article written by Dr. Joe Fiola, University of Maryland:  Evaluating grape samples for ripeness.

Screenshot 2018-09-07 07.07.56

Figure 2. Seed – visual and taste evaluation (Photo credit: Denise Gardner)

You can learn more about berry sensory analysis techniques and protocols available by reading Berry sensory analysis, written by Dr. B. Zoecklein, Virginia Tech University, and Assessing ripeness through sensory evaluation, written by Dr. Mark Greenspan.

One way to quantify and record subjective fruit ripeness criteria is to use a scorecard, one of which has been developed by The Ohio State University.  You can find the scorecard on page 2 in the article: Determining grape maturity and fruit sampling.

When to start sampling grapes and how often

You should begin sampling grapes after veraison, and increase how often you sample as harvest approaches (i.e., from every other week to weekly to every couple of days).

How to collect a representative sample

Before you start walking down your vineyard rows, it is important to understand your vineyard’s variability in order to collect samples that are representative of the entire vineyard, which can effectively assist with your harvest scheduling-decisions.

Variation within a vineyard can be due to soil characteristics, topography, vine age, etc., which creates differences in vine growth and subsequent ripening. Make sure to collect a separate sample from each area of your vineyard that produces vines with different growth. The number of samples to collect depends on the vineyard size, but also on the level of variation in growth, disease, and other stress amongst vines. A higher level of variation amongst vines will require a greater number of samples.

Sampling technique

Every vineyard manager or winemaker has a preferred method for collecting grape samples.  While some might prefer to collect whole clusters, others prefer to collect individual berries from multiple clusters and combined them into one sample for each block (Figure 3).

Screenshot 2018-09-07 07.07.46Figure 3. Berry samples collected around veraison (Photo credit Don Smith).

Each sampling method has its own pros and cons; however, regardless of the technique you decide to adopt it is critical to:

  • Avoid sampling from edge rows, vines at the beginning or end of the row, or ‘unusual’ vines.
  • Collect ‘random’ samples and avoid looking at the cluster when sampling. Although subconsciously, we tend to preferentially collect good looking, large, and sun-exposed clusters, as well as the ripest berries. This can lead to an overestimation of the actual sugar content of the whole fruit biomass used for winemaking.
  • Collect berries or clusters from both sides of the vine and from shoots at all positions on the vines (near the trunk, middle of the cordon/cane, end of the cordon/cane) and across the entire fruiting zone of the vine. Select clusters from basal and distal nodes, but not from clusters that you will not harvest, such as those from lateral shoots.
  • Collect the sample from a large number of vines. For example, if you collect 100 berries per vineyard block, they should be from at least 20 clusters from 20 different vines.
  • Be consistent. Use the same standardized protocol throughout the season and across seasons. If possible, the same person should do the sampling each time.
  • With berry sampling, it is also important to collect berries from all parts of the cluster: top, center, bottom, front, and back. Sampler bias can favor berries collected from the top and bottom of the cluster, missing, or underrepresenting the central region of the cluster.

It is also important to remember that:

  • The larger the sample the more accurate the measurement will be. For example, if you collect individual berries you need 2 samples of 100 berries to be within +/- 1.0 °Brix accuracy level at harvest. To improve accuracy and be within +/- 0.5 °Brix of actual sugar at harvest you need to collect 5 samples of 100 berries.  If you are sampling clusters, 10 clusters are required to be within +/- 1.0 °Brix.  The number of samples also depends on vineyard variability.
  • Weather condition might affect the values of fruit ripeness parameters. Try to collect your samples at the same time of the day each time you collect the berries.

Process the sample

Samples should be processed within 24 hours of collecting them. Until you are able to process them, store berries in sealed plastic bags and clusters in a container/bucket, and keep the fruit in a refrigerator.

You can crush the berries in a clear plastic bag and visually check to see that all of them have been crashed, or you can use a food mill or another piece of kitchenware. After crushing the fruit, filter the juice using a cheesecloth, coffee filter, or paper towel.

We encourage PA wine grape growers to share their experience with grape sampling; what works for them and what doesn’t.


Useful References

Evaluating grape samples for ripeness

Determining grape maturity and fruit sampling




Further Pre-Harvest Cellar Preparations to Consider

By: Denise M. Gardner

Last week, we reviewed scheduling bottling operations and pre-ordering harvest supplies in the month of July in order to open up space in the cellar and save financial resources on free-shipping promotions, respectively: July Pre-Harvest Planning in the Cellar

This week, we’ll review a few extra considerations as the cellar prepares for the up-coming harvest season.

What wine components will you measure in grapes/juice?

At minimum, each incoming lot of grapes or juice should be analyzed for:

  • Brix,
  • pH,
  • titratable acidity (TA), and
  • yeast assimilable nitrogen (YAN).

For grapes and juice, refractometers are quick tools that can provide a quick reference for the sugar concentration of grapes and juice.  Once primary fermentation is underway, it is best to switch to hydrometers to measure the drop in sugar concentration, as alcohol can interfere with sugar concentration readings when using a refractometer.

Using a hydrometer to monitor primary fermentation is preferred over the use of a refractometer due to the fact alcohol content interferes with a refractometer’s readings. Photo by: Denise M. Gardner

The pre-harvest time period is a good time to ensure that pH meters and all titration supplies are working properly.  Ensure the pH electrode is working properly and that there are plenty of [fresh] calibration standards and buffers to sustain the production through harvest.  For titrations, it is a good idea to replenish sodium hydroxide.

YAN analysis can be accomplished enzymatically or by Formol titration.  Both come with challenges and require some experience and expertise to run efficiently and effectively.  With enzymatic analysis, new enzyme kits are typically required for the current year’s harvest.  Purchasing these kits right before harvest could be a time saver for when fruit arrives. For more information on YAN analysis, please refer to:

Having protocols for each analysis that will be run in-house ready for incoming lab assistants or harvest interns can also save time and energy during the harvest season.

Check chemical expiration dates and re-order supplies where needed.  In July, some suppliers may offer discounts or promotions, like free shipping.

If the winery is able to run analyses like free/total sulfur dioxide by aeration oxidation, volatile acidity by cash still, or Rippers, it may be imperative to update chemicals for the up-and-coming harvest season.  Chemicals like hydrogen peroxide (H2O2) and Iodine have a limited shelf-life that will not be reliable if purchased the previous year.

If the winery is using a microscope, make sure that the microscope is working properly and not in need of any repairs.  Update the lab’s record books with images of relevant microorganisms that may help lab personnel better identify any problem microflora in juice or wine.  The use of a microscope can be a great tool to assess the quality of incoming fruit or help determine problematic fermentations.

For wineries that distribute samples to certified laboratories, stock up on sample bottles and any supplies that you would need to take representative samples during the harvest season.  Some labs will pre-distribute sample bottles to the winery free of charge.

Stock up on sample bottles before harvest begins to efficiently collect required juice/wine samples that will be shipped to a laboratory. Photo by: Denise M. Gardner

Bring Quality Control Standard Operating Procedures (SOPs) Up-to-Date

Standard Operating Procedures (SOPs) are step-by-step plans that detail a winery’s production steps and/or lab analyses.  The development and integration of SOPs can be time consuming, especially considering it can be challenging to effectively document a winemaker’s communications on production steps.  However, wineries can build SOP policies over time, especially during moments of downtime in the cellar.

The evaluation of production-based prior to harvest can ensure that all employees are aware of production decisions, proper safety practices, and preparation steps for harvest.  Properly trained employees prior to the onset of harvest guarantee a smoother work-flow system and lays out production expectations before crunch time.

For wineries that run analysis in-house, SOPs or protocols can be developed for each analysis and general laboratory practices.  If you need a reference for lab protocols, Enartis USA (Vinquiry) provides a series of examples: http://www.enartis.com/us/tools/wine-analysis

Going through laboratory SOPs with employees prior to harvest can help guarantee training for all employees whose primary focus will be in the lab during harvest.  This may save time and effort during the harvest season when it may not be possible for upper management to train other employees.

When an SOP notebook or database has been developed, each employee should be aware of the SOPs, how to access them, their purpose, and have a general idea on what they include to ensure that production runs smoothly year round.

Visiting the Vineyard

If the winery is contracted with growers, it is a good idea to form an established, working relationship with the growers.  Now is the time, before harvest, to have regular vineyard walk-throughs, evaluate the fruit, and discuss harvest expectations for incoming fruit.  Talk about ripening expectations and taste the berries with growers so that they get a good sense for the sensory evaluation of the fruit.

Berry sensory analysis developed by the L’Institut Coopertif du Vin (ICV) in France can be a powerful learning tool for both growers and vintners, and could be a consideration for commercial wineries.

Additional Resources

“Harvest Preparation” by Dr. Muli Dharmadhikari http://www.extension.iastate.edu/NR/rdonlyres/173729E4-C734-486A-AD16-778678B3E1CF/73932/HarvestPreparation.pdf

“Monitoring the winemaking process from grapes to wine: techniques and concepts” by Patrick Iland, Nick Bruer, Andrew Ewart, Andrew Markides, and John Sitters.  ISBN: 978-0-9581605-6-8

“Winemaking Problems Solved,” Edited by Christian E. Butzke.  ISBN: 978-1-4398-3416-9

Lab Analysis Protocols by Enartis USA: http://www.enartis.com/us/tools/wine-analysis

July Pre-Harvest Planning in the Cellar

By: Denise M. Gardner

If you are a wine producer in the northern hemisphere, harvest may feel quite far away.  However, given that it is now the month of July, it will be here before we all know it.

Harvest season is just around the corner! Photo by: Denise M. Gardner

The month of July is a great time to start preparing a few essential pre-harvest tasks including getting a bottling schedule ready, especially if bottling operations have not yet begun, and ordering harvest supplies.   This blog post will focus on these two tasks.

Prepare and Enact a Bottling Schedule

New grapes are about to flood your winery with juice and future wine.  Now is the time to review inventory within the cellar and determine what has to be moved and what has to be bottled before harvest begins.

Freeing up previous years’ inventory by moving it into bottle will free up tank, barrel and storage space for this year’s incoming fruit.  It makes for a much easier transition if all of the wines that need bottling are bottled before harvest season starts.  Bottling during harvest is not only chaotic, but it tires employees, pulls resources from the incoming product, and may lead to harvest decisions that may be regretted later.

Always make sure to get bottled wines properly stored and away from any “wet areas” on the production floor.  If possible, bottled wines should have a separated storage area within an ideal environment that is physically separated from production.  From there, stored wines can be moved into retail space when needed.

For more information on how to get wines prepared for bottling, please visit our previous posts:

Bottling comes with its own set of challenges and risks, but several analytical tests can help put a winemaker’s mind to ease regarding bottle stability. Photo by: Denise M. Gardner

Ordering Fermentation and Lab Supplies

Many suppliers and wine labs offer free shipping in July, which can especially be useful for wineries that are not geographically close to a winery supply store-front.  Planning ahead and determining what fermentation supplies will be needed in August, could save extra money.  Not to mention, having supplies on hand during the busy processing season can be a big stress relief.

Winemakers should also take the time to look at new fermentation products and assess the previous year’s needs in order to adequately supply for the up-and-coming harvest.  Keeping an annual inventory of purchases can be helpful to isolate regular needs.

Things to consider purchasing include:

  • Yeast
  • Fermentation Nutrients
  • Malolactic Bacteria
  • Enzymes
  • Yeast Hulls
  • Salts for Acid Adjustments
  • Tannins
  • Pectic Gums and/or Inactivated Yeast Products
  • Fining Agents
  • Oak Alternatives or Barrels
  • Sanitizing Agents

While new yeasts are released frequently, being constructive about the production’s fermentation needs can help isolate what yeasts are needed for the upcoming harvest.  I typically recommend that all vintners have at least 5 strains on hand for harvest: 2 reliable strains that will get through primary fermentation with little hassle, 1 strain that can be relied upon for sluggish or stuck fermentations, and 2 strains for specialty needs (e.g., sparkling or fruit wine/hard cider production) or experimental use.

Select and purchase your yeast strains in July to take advantage of free-shipping promotions. Photo by: Denise M. Gardner

Fermentation nutrients should be a must-have for all wineries to help minimize the risk of hydrogen sulfide.  Always double check nutrient requirements for yeast strains purchased.  In general, wineries will need hydration nutrients (e.g., GoFerm), complex nutrients (e.g., Fermaid K), and diammonium phosphate (DAP).

For more information on why YAN is important and how yeasts utilize nitrogen during primary fermentation, please visit the following blog posts:

If you need further step-by-step instructions on how to determine adequate nutrient additions during primary fermentation, please visit our Penn State Extension fact sheet: Wine Made Easy Nutrient Management during Fermentation

Sometimes hydrogen sulfide will arise in a wine by the time primary fermentation ends despite all preventative care.  Making sure there are adequate supplies on hand, such as copper sulfate and PVI/PVP can save time in the future.  Also make plans for ways that the production can reserve fresh lees.  PVI/PVP is a fining agent that can help reduce metals like residual copper, but fresh lees will also help reduce the perception of hydrogen sulfide aroma/flavor and residual copper in the wine.  Having a plan for retaining and storing lees during harvest season can save time during challenging situations that develop through the end of harvest and into the winter’s storage season.  A fact sheet on copper screens and addition trials can be found at the Penn State Extension fact sheet: Wine Made Easy Sulfur-Based Off-Odors in Wine.

I also like to make sure we have supplies on hand in case of heavy disease pressure come harvest.  This includes things like Lysozyme, beta-gluconase, pectinase or other clarification enzymes, and fermentation tannins.  Lysozyme can help reduce lactic acid bacteria levels while beta-gluconase can assist clarification problems associated with Botrysized wines.  For further information on how to manage high-disease pressured fruit, please visit the Penn State Extension website on Fermenting with Botrytis or Managing Sour Rot in the Cellar.

Double check the storage requirements for all materials purchased before and after the product is opened.   It’s important to store all of those supplies in the winery properly as it will ensure their efficacy by the time the product is needed.

Preparation for Harvest – Considerations in the Winery

By: Denise M. Gardner

Well, the time is here – harvest season!  And if you haven’t geared up already, it is now crunch time.

In my travels across the state, I am seeing a lot of good things in the vineyard, which makes me eager for the 2016 crop to come into the winery where it can be made into wine.  While the drought has impacted a large portion of the state, I’m also seeing good color, tannin, and flavor development in fruit, and am hoping for a nice 2016 vintage.  This picture of ripening Pinot Grigio from the Endless Mountains region shows just how far along the fruit is coming into its developed stage.

Pinot Grigio grapes surpassing veraison and moving into their full ripening stage. Photo by: Denise M. Gardner

Pinot Grigio grapes surpassing veraison and moving into their full ripening stage. Photo by: Denise M. Gardner

With all that work that went into a good growing season, please don’t forget that harvest is also about taking the care and time required to make a clean, quality wine.  Otherwise, all of that hard work in the vineyard may be lost in the wine!  While taking a few short cuts here-and-there can be appealing during the busy harvest season, some short cuts can detrimentally impact final wine quality or even lead to flaws when things like cleaning and sanitation steps are forgotten or minimally implemented in the cellar.

The following blog post will review a few practical steps that winemakers and the cellar crew can take now in order to prepare for the first lot of incoming fruit in an effort to try to minimize stress and chaos during a hectic time of year.

1. Order your harvest materials

While “free shipping” July has passed, if you haven’t ordered your harvest supplies yet, now is the time to do it.  Take a few hours and figure out what you will need to get through harvest.  This includes anything from sugar and acid to yeast and malolactic bacteria.  Don’t forget your sanitizers.  There is a PSU Wine Made Easy Fact Sheet that gives a more thorough list of supplies you should make sure to have in the winery and properly stored for use prior to the start of harvest.

2. Get last year’s wines bottled

It goes without saying that getting last year’s inventory moved into bottles will free up tank, barrel and storage space for this year’s incoming fruit.  It makes for a much easier transition if all of your wines that need bottling are bottled before harvest season starts.  Bottling during harvest is not only chaotic, but it will tire your employees (and you!) and may lead to harvest decisions that may be regretted later.

Always make sure to get your bottled wines properly stored and away from any “wet areas” on the production floor.  If possible, bottled wines should have a separated storage area with an ideal storage environment that is physically separated from production.  From there, stored wines can be moved into retail space when needed.

Get wines bottled prior to harvest. Photo by: Denise M. Gardner

Get wines bottled prior to harvest. Photo by: Denise M. Gardner

3. Check and prepare equipment

Many wineries experience equipment failures during harvest as most of the equipment has been left in storage throughout the winter, spring and summer months and was not routinely used.  This lack of use can be wearing on equipment and may lead to equipment failures during production.

Therefore, we recommend pulling out your crusher/destemmer and press to get it up and running before the first grapes arrive.  As the equipment is probably dirty, give it a good physical cleaning and sanitation regime to ensure that it is in its best condition before grapes come anywhere near it.  I have seen many presses with left over rice hulls inside of them, and cellar staff should be reminded that left over debris are potential contamination sources for microbial spoilage.  Additionally, old debris may alter the flavor for this year’s wines, which would minimize the efforts that were taken in the vineyard to mature fruit.  To make fresh, clean wines, cleaning and sanitation is quite important.

It is imperative to pull out all of your pumps and ensure that they are actually working before those first grapes arrive.  Pull down hoses and ensure they are all properly cleaned.  Give the hoses an inspection, clean and re-dry before their first use.

While it is busy work, and it may be tedious, having clean and working equipment is a life saver during the actual harvest period.

4. Double check you have plenty of analytical supplies to get you through harvest

For those that have analytical labs, make sure that your labs are properly stocked with hydrometers, Clinitests, refractometers, pipettes, glassware, pH probes, and all of the associated chemicals that you will need during harvest season.  This way, everything is ready to go when you need it.

Ensure that you have all of the appropriate lab equipment and supplies that you will need during the harvest season. Photo by: Denise M. Gardner

Ensure that you have all of the appropriate lab equipment and supplies that you will need during the harvest season. Photo by: Denise M. Gardner

Get your spreadsheets or data collecting systems prepared prior to when the grapes arrive so that you can easily input data throughout harvest season when you are crunched for time.

5. Timing is everything

If you are like many winemakers in Pennsylvania, you may be making several Pennsylvania-grown fruit wines.  Remember that several other fruits can be cold-stored (e.g., apples) or frozen (e.g., strawberries, blueberries, raspberries) until after the grape harvest is completed.  When the grape fermentations start to slow down, you can remove the stored fruit for processing and fermentation.  This allows you to focus on your grape wines first and then alter your focus to the fruit wines after the busy season associated with the grape harvest has passed.

On a positive side, freezing the other fruits helps to concentrate their flavors and will provide a fruitier base for fermentation.

6. Consider your resources

Remember that Penn State Extension is available to answer questions you may encounter during the harvest season.  It is always easier to prevent problems as opposed to fixing them in the wine, so please do not hesitate to use this resource.

Additionally, we have a full 2-page fact sheet and check list for considerations prior to harvest that may be helpful to many winemakers: http://extension.psu.edu/food/enology/wine-production/wine-made-easy-fact-sheets/preparation-for-harvest

When in a pinch, remember that there are calculators online to help you make product additions or alterations:

Looking Back at the 2015 Season

By: Michela Centinari and Bryan Hed

As harvest ends it is a good practice to review the season carefully, before getting busy with winter pruning and preparation for the next growing season. In the fall issue of Grape Press, the quarterly newsletter of the Virginia Vineyards Association edited by Bob and Chris Garsson, you can find some good examples of regional reports of the growing season written by wine grape growers across Virginia. It is interesting and informative to read growers stories and learn what they experienced in the vineyard and their perception of the current vintage. In addition, Drs. Tony Wolf and Mizuho Nita (Viticulture and Grape Pathology Extension Specialists, respectively, at Virginia Tech University) contributed to the quarterly publication. The final seasonal issue of Veraison to Harvest, electronic newsletter of the Cornell viticulture and enology Extension personnel, also provided a comprehensive overview of the grape and wine season in New York state, which was written by Chris Gerling [1].

With this short article we will provide a succinct overview of the season in Pennsylvania (PA) and we will share some of the data collected during the season for the research project NE-1020 “multi-state evaluation of wine grape cultivars and clones.”  Our observations are based on the data we collected and on feedback we received from some of the PA wine grape growers throughout the state. We welcome more PA wine grape growers to share their stories with us by adding a “comment” on this blog post.

Let’s start once again with the winter:

It was a cold winter in many regions of Pennsylvania, but in the Lake Erie region, it was extremely cold. 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 more cold events (-13, -14 and -15°F) were recorded over the following ten days.  As expected, extensive freeze injury was observed in the Erie region not only on Vitis vinifera cultivars, but also on inter-specific hybrids and native wine grape cultivars. Among the inter-specific hybrids Traminette, Cayuga White, Vidal and Valvin Muscat were some of cultivars that experienced extensive damage as reported by growers. Even Concord and Niagara sustained bud and trunk injuries [2]. Luke Haggerty and Kevin Martin reported that many Concord growers retained more buds than they typically do to compensate for observed winter bud injury. Large berries and more buds helped Concord growers to maintain crop levels near average [2].

After budbreak bud mortality data were collected on 10 hybrid cultivars established in the cultivar evaluation vineyard at the LERGREC (Figure 1). The vines were planted in 2008 as part of the NE-1020 project. Bud mortality was not evaluated in the V. vinifera cultivars due to the extensive level of winter injury (e.g., 100% bud mortality, and trunk injury in some of the cultivars). On a positive note, only 20% or lower bud mortality was recorded in Marquette, La Crescent, and MN1235, cold-hardy cultivars developed by the breeding program of the University of Minnesota (Figure 1). However, other hybrid cultivars, such as Vidal, Chambourcin, and NY 81.0315.17 (Cayuga White X Riesling) sustained 60% or higher bud mortality. Trunk injury was observed mostly in Noiret, NY81.0315.17 and Traminette.  Fifty, 17, and 8% of the Noiret, NY81.0315.17 and Traminette vines, respectively, collapsed during the summer.

The last two winters are a reminder of the importance of cultivar and site selection, and how crop diversification can help growers to maintain sustainable yields in cold climate regions.

Figure 1. Bud mortality assessed as percentage of dead buds over the total number of buds left with pruning. Data were collected at the Penn State Lake Erie Regional Grape Research and Extension Center.

Figure 1. Bud mortality assessed as percentage of dead buds over the total number of buds left with pruning. Data were collected at the Penn State Lake Erie Regional Grape Research and Extension Center.

The yield data collected at harvest from the cultivar evaluation trial established at LERGREC are shown in Figure 2. For the second consecutive year no crop was harvested from the V. vinifera cultivars. Within the hybrid cultivars, crop level varied from 1.8 tons/acre in Norton to 5.3 tons/acre in Chambourcin. The only cultivar that needed crop adjustment was Chancellor. The lower than average yield recorded in Marquette was attributed mostly to high levels of bird damage to the fruit. Due to its early fruit ripening, earlier than the nearby Concord that seems to work greatly as bird repellent, Marquette seems to be the preferred bird target.

Figure 2. Yield data (tons/acre) of the 15 winegrape cultivars in the NE-1020 cultivar evaluation trial established at the Penn State Lake Erie Regional Grape Research and Extension Center. Vines spacing is 6’ between vines and 9’ between rows.

Figure 2. Yield data (tons/acre) of the 15 winegrape cultivars in the NE-1020 cultivar evaluation trial established at the Penn State Lake Erie Regional Grape Research and Extension Center. Vines spacing is 6’ between vines and 9’ between rows.

Overall, we did not receive many inquiries from growers in the other regions of the state concerning cold injury as we did last season.  Although it was a cold winter, fewer temperature fluctuations were recorded in 2014-2015 as compared to the previous winter (2013-2014). The long stretch of cold temperatures may have provided a positive, reinforcing maintenance of the vines’ mid-winter cold hardiness.  Freeze damage was observed in Northeastern Pennsylvania in some of the V. vinifera cultivars, such as Pinot Grigio and Dornfelder. Growers attributed part of the damage (i.e., crown gall) to the previous winter (2013-2014) low temperatures. No above-average winter damage was observed in the southern part of the state.

Please note that these are general observations. The level of winter injury varies greatly with genotype, along with other factors. So these observations may not match what you experienced if, for instance, you grow tender V. vinifera cultivars (i.e., Tannat, Malbec, Syrah,  etc.) in a cool/cold climate region. For example, we harvested only 0.4 tons/ acre of Tannat and Malbec grapes at the Penn State Fruit Research and Extension Center in Biglerville (South Central PA). Those extremely low crop levels were due to bud and trunk injuries sustained by those cultivars in the last two winters.

The vast range of varietal winter hardiness expressed in the NE-1020 vineyards over the past two brutal winters has left us with many good lessons for grape growing in the Northeastern U.S., and will serve as a rich source of science based information toward more sustainable grape production in PA.

Weather during the growing season:

In Figures 3 and 4 we reported the cumulative precipitation and growing degree days (GDDs) recorded at the two Penn State research stations located in the South Central (Biglerville) and Northwest (North East) part of the state. We also included the 2013 and 2014 data, so you can compare this season’s heat accumulation (GDD) and precipitation’s pattern and amount with those of the two previous seasons.

Precipitation: June will be definitely remembered as the wettest month of the season in 2015 (Figure 3). For instance, in Biglerville (South Central, PA) around 10 inches of rain were recorded in June. High precipitation level during bloom may negatively affect the rate of fruit set (Fruit Set in Grapevines 101). Although some clusters with reduced fruit set level were observed, growers did not report reduced crop level. In the Northwest region of PA, 6 and 5 inches of rain were recorded in June and July, respectively.

Figure 3.  Monthly precipitation recorded in Biglerville (South central, PA) and North East (Northwest PA).

Figure 3. Monthly precipitation recorded in Biglerville (South central, PA) and North East (Northwest PA).

The best note of the summer was the warm and dry weather conditions observed in August and September in a majority of the state. In Biglerville the cumulative precipitation recorded from April to October was lower than that of the two previous seasons (Figure 3). However, in late September heavy rainstorms came through several areas of PA, raising concerns about bunch rot infections. Indeed some of the white cultivars and most of the reds were still hanging in Central and North PA. Despite the heavy rain, wine grape growers were mostly happy about the health of their grapes. Tony Wolf (Professor of Viticulture and Extension specialist at Virginia Tech University) offered some thoughtful advice on the dilemma: “Should I pick or wait out the rain?” which you can find on Grape Press, page 7 “How to Assess When Rain Threatens” [3].

Temperatures: High (or above-average) heat accumulation was recorded in many areas of PA in 2015. In Biglerville (South Central PA) GDD accumulation from April 1 to October 30 was 3500 in 2015, compared to 3089 in 2014 and 3270 in 2013 (Figure 4C). Specifically May, August and September 2015 were warmer than in 2013 and 2014 (Figure 4A). In the Northwest GDD accumulation in 2015 (2800) was similar to that of 2013 (2760), but higher than in 2014 (2590) (Figure 4 B). The greatest difference in heat accumulation among the three seasons was recorded in September (Figure 4D). Indeed both white and red wine grapes harvested at the LERGREC in 2015 reached a good level of ripeness.

Figure 4. Monthly growing degree-days (GDD) (A; B), and cumulative seasonal GDD (C; D) in Bigerville (South Central, PA) and North East (Northwest, PA).

Figure 4. Monthly growing degree-days (GDD) (A; B), and cumulative seasonal GDD (C; D) in Bigerville (South Central, PA) and North East (Northwest, PA).


Insects: Several growers reported problems with Japanese Beetles. Damage was worse than average, and in many cases required extra sprays (for more information please check: What’s Bugging your Vines?). In the Lake Erie region, the severe cold of the past two winters appears to have had no negative impact on populations of the grape berry moth, according to entomologist Jody Timer.  Her research has indicated that this insect continues to cause heavy damage in vineyards, particularly in rows bordering wooded areas, and has in some cases made inroads deeper into vineyards over the past two years. It’s imperative to remember that brutal winter temperatures do NOT necessarily reduce the threat of this grape insect pest; grape berry moth is well adapted to life in Pennsylvania and growers will need to continue to be vigilant with regard to timely insecticide applications, regardless of the winter cold.

Fungal disease:  Frequent and sometimes heavy rainfall in June and July was very conducive to the development of downy mildew and black rot on fruit (Figure 5). For example, at the Penn State lab at North East (LERGREC), we recorded 10.7 inches of rainfall from June 7 (immediately before bloom) to July 14 (about 3-4 weeks after bloom), that fell on 22 of those 38 days!!! This time period marks the peak period for fruit susceptibility to downy mildew and black rot for all wine grape varieties, and symptoms of these diseases could be found in many (most?) Lake Erie vineyards. In unsprayed research plots of Concord grape where black rot mummies were hung in the trellis (at LERGREC), almost two thirds of the crop was lost to black rot! So, conditions were nearly ideal for the development of this disease in the growing season of 2015.

However, very few serious problems were reported from commercial growers in the Lake Erie region and growers appeared to have, generally speaking, kept these diseases well under control during this challenging fruit loss period. After fruit became resistant, rainfall thinned out during August and September (even though the rainfall total for September was well above average, rainfall frequency was about half that recorded for the fruit susceptibility period). ‘Seasoned’ growers were watching their vineyards closely, and the potential threat of downy mildew leaf infections during ripening did not materialize to any great extent in most vineyards.

Figure 5. Concord clusters with black rot (A) and Chancellor clusters with downy mildew (B) symptoms.

Figure 5. Concord clusters with black rot (A) and Chancellor clusters with downy mildew (B) symptoms.

Everything we experience in one season is related, to some extent, to what happened in the previous season. For example, when planning your disease control strategy for 2016, keep in mind that inoculum levels for black rot and downy mildew are likely to be starting at higher levels next year, especially if you saw more disease in your vineyard (or your neighbor’s vineyard) than usual in 2015. This means that those first infection periods in spring could be more potent than usual, and if weather is consistently wet, fungicide application timing and frequency, and choice of material, will be more critical. For downy mildew control, be prepared to rotate chemistries to delay the onset of fungicide resistance, especially if you’re using the newer materials (Revus, Revus Top, Presidio, Zampro, any of the strobies, Ranman, Ridomil, and even the phosphorous acid formulations). Be aware that in southern PA there is downy mildew resistance to the strobies in some vineyards already, and that a wet year (and the resulting increased use of strobies to control downy) only serves to exacerbate the problem. On the up-side, we have lots of fungicide options for downy mildew control (as you can see), including the old standards like Captan, copper, Ziram, and any of the mancozeb products that carry a very low risk of resistance development. As for black rot, I know of no resistance problems associated (yet) with our long time ‘heavy hitter’ black rot materials like the sterol inhibitor containing fungicides (Rally, Elite, Mettle, Revus Top, Inspire Super, etc), the strobies, and Captan/Ziram/mancozeb formulations.

So, record your observations of your vineyards from the 2015 season: These are important questions growers should be asking themselves and recording now in order to understand what worked and what didn’t and prepare for the 2016 growing season:

  • How well did your weed and canopy management strategies work this season?
  • How was the overall vine balance?
  • Were there any obvious vine nutrition issues?
  • How well did your disease and pest control program work? How much disease did you observe on your fruit, on your leaves?
  • Any other important observations or notes.

Final notes on the 2015 harvest: Harvest weather was, for the most part, pleasant. Overall, growers are very happy with the quality of the fruit although in some cases crop level was lower than average due to winter injury. The warm and mostly dry conditions recorded in August and September helped the grapes to reach full ripeness within their specific region with good development of flavor and aromas.

As a general reminder, we will taste a series of the 2015 wines produced from various research trials conducted at Penn State University at the 2016 PA Wine Marketing and Research Board Symposium.  We may also feature a few of these wines at various Extension events across the state.  You can review some of the winemaking experiments on Denise’s previous blog post: Reflections: Winemaking at Penn State, and we look forward to sharing these wines with many of you in the months ahead.



[1] Gerling C. (2015) The 2015 Grape & Wine Season: Redefining Normal. Veraison to Harvest issue # 8, pp1-4. Cornell University

[2] Haggerty L., Martin K. (2015) Concord Crop Average Despite Winter Injury; Niagara Crop Reduced. Veraison to Harvest issue # 8, pp5-6. Cornell University.

[3] Wolf T. (2015) How to Assess When Rain Threatens  Grape Press, The quarterly Newsletter of the Virginia Vineyards Association. Vol. 31 No. 3.

It’s Never Too Early to Start Thinking about Harvest

By: Denise M. Gardner

While most of us are in the thick of the grape growing season, the start of harvest will be knocking on our doors all too soon.  Preparing for harvest can never start early enough!  Below is a list of recommendations for growers and winemakers to consider during prior to the harvest season.

Winemaking Supplies

July is just around the corner, which means that many wine supply companies are about to offer “Free Shipping in July” specials.  Not only is this a cost savings opportunity for many wineries, but it also provides a chance for winemakers to adequately plan for their fermentation needs.

Check with your current supplier to evaluate options for shipping and potential new products to incorporate into your winemaking portfolio.

Berry Sensory Analysis

Ironically, I found 2 articles in the July 2015 edition of Wine Business Monthly (WBM) related to why berry sensory analysis is important to both growers and winemakers.  The method first introduced to the wine industry by the Institut Francais de la Vigne et du Vin (IFV), has been integrated into wine regions throughout the world.  If you are lucky enough to obtain a copy of Monitoring the Winemaking Process from Grapes to Wine: Techniques and Concepts, you’ll find detailed instructions on vineyard sampling, matching grape ripening characteristics to the future wine, and an explanation on berry sensory analysis (pg. 27).

Seed evaluation - visual and taste

Seed evaluation – visual and taste

Berry sensory analysis involves analyzing the component parts of the berry (skin, pulp, and seeds) separately – both visually and through a sensory evaluation – to monitor ripeness of berries beyond the capabilities of many other analytical techniques.  It is not a method which involves selecting a berry or two from a cluster, popping them into one’s mouth, and giving a “thumbs up” or “thumbs down” evaluation to ripeness.  There is a strategic approach, including proper vineyard sampling, to evaluate ripeness.

In fact, berry sensory analysis goes beyond measuring the typical analyses (Brix, pH, TA) to indicate ripeness.   While the sensory technique may appear complicated at first, it can easily be mastered – quickly – with a little practice and good use of record keeping.

As noted by Mark Greenspan in his recent July 2015 WBM article, “Harvest: The Final Vineyard Decision,” many winemakers find it daunting to go out into a vineyard and regularly monitor the sensory changes affiliated with grape berry ripening.  Therefore, this offers an unique opportunity for growers and winemakers to work together.  Either both parties can learn the proper techniques affiliated with berry sensory analysis and switch regular responsibilities affiliated with recording ripeness development, or growers can adequately sample vineyards and routinely deliver berries to the winemaker.  Evaluating berries together allows for open communication between growers and winemakers in terms of sensory expectations for a given variety.

Need more information on berry sensory analysis before diving into a more formal training process?  Look no further!

2006 WBM article by Mark Greenspan titled, “Assessing Ripeness Through Sensory Evaluation”

2006 Wines & Vines article by Thomas Pellechia titled, “A Better Berry Evaluation?”

Curious about the berry sensory analysis technique?  Check out these explanations and protocols:

“Method for Sensory Analysis of Grapes” on the University of Minnesota Enology Blog

“Berry Sensory Analysis” by Bruce Zoecklein from the Enology Grape Chemistry Group at Virginia Tech

Finalize Grower and Juice Broker Contracts

The issue of grape negotiations comes up every harvest season.  While many individuals in the industry still use a common handshake or acknowledgement of a deal through a phone call to confirm grape sales or purchases, I annually hear stories from both parties indicating a lack of satisfaction regarding harvest deals.

It is important to recognize that growers and winemakers have two different end goals in mind by the end of a growing season.  Obviously, this can create points of tension in any negotiation if one party’s goals are not met to their liking.

In order to mediate many of these negotiations, the use of contracts between growers and wineries is often recommended.

eXtension has a document, written by Chris Lake, regarding the definition of grape and winery contracts, the end goals pertaining to both parties, and the essential topics of coverage related to a contract, which can be found here: http://www.extension.org/pages/62146/contracts-between-wineries-and-growers#.VYrlK_lVhBc.  Additionally, Chris has listed several resources for more information for those that are interested in developing future contracts.

Bruce Zoecklein from Virginia Tech’s Enology Grape Chemistry Group has also developed a sample contract available for grower and winery use.

Preparing the Cellar and Lab

The summer months are perfect opportunities for wineries to engage in harvest preparation.  These prep steps include:

  • Finishing up bottling to allocate space for the incoming new material
  • Finalizing grower contracts (see above)
  • Check cellar equipment to ensure it is working properly
  • Clean and sanitize any equipment or environmental surfaces
  • Train incoming, new staff members proper standard operating procedures (SOP’s) and safety operations
  • Make sure that there are enough analytical supplies to sustain your operation through harvest
  • Check and calibrate all lab equipment
  • Train all harvest interns and cellar/lab personnel how to handle harvest equipment and/or lab equipment
  • Review any SOP’s or safety protocols – for the cellar and lab – to evaluate if they should be updated before harvest

For further information on general harvest preparation steps, please see the Penn State Wine Made Easy Harvest Preparation fact sheet, or Dr. Muli Dharmadhikari’s detailed explanation on harvest preparation steps.

Make sure cellar equipment is properly cleaned and in good working order before harvest. [Opus One cellar, 2004.]

Make sure cellar equipment is properly cleaned and in good working order before harvest. [Opus One cellar, 2004.]

Safety First

There are many opportunities during the “off-season” for wineries to adequately enhance safety operations in the winery.  In general, all employees should be adequately trained on safety procedures, the use of safety equipment (e.g., how to wear safety equipment and when to wear it), and know the proper steps in handling an emergency (i.e., where the phones are located on the production floor, where the First Aid Kit is located, etc.).

As fermentation offers one well- known hazard to a winery – the rapid development of carbon dioxide – the summer months may be a good time for wineries to install carbon dioxide meters.

Ensure that proper equipment and instructions for making sanitizers is available to (and known by) all cellar employees.

Additionally, wineries should double check ventilation systems to ensure proper ventilation in the cellar area during the chaotic harvest season.

For more information on OSHA related safety techniques or developing a safety training program for your winery, please visit: www.osha.gov.

Late Season Insect Management

By: Michael Saunders

Well, the grapevines are primed for harvest and the main summer pests are hopefully a distant memory. However, there are still a few insect pests that can bedevil vineyards right up until harvest. Some of the more problematic insects in vineyards at this time of year are wasps and hornets. Typically, they will not feed on grapes until late in the season when these sugar seeking foragers find that the grape crop has become palatably sweetened. Unlike honey bees, which rely on pollen as their protein source, wasps acquire their protein by hunting other insects, many of which are agricultural pests. So, for the majority of the growing season, yellow jackets, paper wasps, bald faced hornets and other Hymenopterans (collectively called wasps) have been quietly and beneficially reducing the populations of other pest insects.

Oct 2014_Pic 1

As we approach harvest, wasps are particularly drawn to easily acquired sources of carbohydrates, and the juice of a ripe grape is exactly what they are looking for. There was an excellent presentation on wasp and bee management in grapes by Jody Gangloff-Kauffman at a grape grower meeting in Lancaster in 2013. This presentation is available online at:


Dr. Kauffman’s presentation emphasizes vineyard sanitation as a key factor in minimizing damage due to wasps and bees. She describes a number of procedures for destroying the nests of wasps that are in the vicinity of vineyards as well as traps that can be deployed during the season to reduce their numbers. It is important to bear in mind that these insects in general are beneficial and important regulators of pest insect populations. The best defense is to protect your crop from berry damaging pests, especially birds, as these damaged berries are the main attractant for wasps and bees. Often a grower will blame wasps for berry damage when, in fact, the wasp is merely taking advantage of berries that have been damaged by birds. There is no viable chemical control for wasps in the vineyard.

Perhaps we should not be focused so much on controlling populations of wasps in vineyards given the ecology of the ambient yeasts. It appears that some species of wasps carry Saccharomyces cerevisiae (brewers yeast) in their stomachs and can pass it along to their offspring. Some researchers believe this yeast is ubiquitous in some vineyards because of the wasps, although the connection between the wasp, its associated yeast, and yeasts in the vineyard will need further study. For more on this phenomenon visit: http://www.winespectator.com/webfeature/show/id/47188

Other insects that may be found in late season vineyards include a collection of relatively new invasive species. These include the brown marmorated stink bug, the spotted wing drosophila, and the multicolored Asian Lady Beetle. The brown marmorated stink bug (BMSB) was initially found in Allentown, PA after it was introduced from Asia. This insect has spread across several states and currently is a very serious pest in tree fruits and vegetables, and can be a household nuisance in that BMSB often enter homes in order to overwinter as adults.   There is a very large consortium of institutions researching BMSB life history traits, population dynamics, and assessment of damage thresholds in multiple cropping systems. Although the damage potential of BMSB in vineyards appears to be significantly less than what is found in other types of crops, there was serious initial concern that the odor (taint) of this insect would adversely affect wine quality. Work done by Joe Fiola has indicated that BMSB taint is unlikely to persist in finished wine.

The spotted wing drosophila (SWD) is an invasive fruit fly (native to Asia) that differs from most of our native fruit flies in that the female SWD has a serrated ovipositor that allows her to directly pierce the skin of fruit in order to lay eggs. Native fruit flies lay eggs only into previously damaged fruit. SWD can have many generations per year leading to great concern for fruit crops as this insect becomes widely established. Although raspberries, blackberries, and blueberries are the fruit crops most seriously affected by SWD, careful monitoring of any soft skinned fruits (including grapes) is warranted. There is excellent information on identification, monitoring, trapping, and damage detection by SWD at: http://extension.psu.edu/pests/ipm/agriculture/fruits/spotted-wing-drosophila

Oct 2014_Mike_Pic2

The multicolored Asian Lady Beetle (MALB) has been somewhat of an enigma in recent years. Like all lady beetles, MALB are voracious predators of other insects, and are considered a valuable biological control agent in many agroecosystems. This insect (again a recent invasive from Asia) protects itself via a process known as reflex bleeding in which it extrudes bodily fluids out of its joints. These bodily fluids contain alkaloids that can taint the flavor of wines should the insect be processed with the harvested grapes. Since MALB tend to seek sources of carbohydrates before overwintering, it is possible that this insect will be present in grapes during harvest. As recently as 6 years ago, it appeared as if MALB was going to be a major problem with massive populations developing in the late summer. Since that time, MALB populations have not been as numerous and the concerns over this insect and its impact on wine production have lessened.

Oct 2014_Mike_Pic3

As you approach harvest, be sure to take the time to check your vineyard for the presence of these pests. If you plan to use any insecticides, be very mindful of the preharvest restrictions and be sure to use all appropriate safety equipment.