#178 - August 5, 2011

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Estimating Grape Yields - Good Idea!

Harvest will soon be here and our wineries and vineyards are making last minute deals to buy/sell their grapes. One key factor that often remains unclear in these negotiations are the amount of grapes that are being negotiated for. It is VERY, VERY common for a winery to find out that they have bought much less or much more than they expected. One way to keep these surprises to a minimum is to do a yield estimate prior to delivery. One can use estimated cultivar cluster weights taken from a table, but it is much better to take an actual representative sample of clusters and weight them to get an average. Recommendations vary, but counting all the clusters on 10 to 15 vines and weighing 100 clusters total

from these same vines should get you within (+ or -) 15% of the actual yield of a cultivar in a representative area. The larger the sample, the better the answer.

Some will even go so far as to get an average berry weight by counting the berries per cluster when weighing the clusters. Berry weights each season will vary much less than cluster weights and can be used to make a more accurate yield estimate in future years. Randall Vos at the Des Moines Area Community College (DMACC) has put together a good online yield estimation tool that can be used based on clusters and/or berries here: http://www.dmacc.edu/programs/viticulture/cropcalc/cropcalculator.aspx

An electronic fishing scale works very well for measuring cluster weights in the field. Many will weight up to 50 lbs. total in 1 oz. increments and are very accurate. The better ones typically run in the $30 to $50 range.

What about the weight of the rachis (the stem the grapes are attached to)? The rachis will run approximately 5% of the total cluster weight (varies slightly by variety).(3) The rachis weight should be of no matter if you are selling whole clusters to the winery. Mechanical harvesters tend to leave the rachis hanging on the vine so the rachis weight could be deducted from the estimated yield.

I have posted a simple yield estimate form you can use to guestimate your yields here: http://www.extension.iastate.edu/NR/rdonlyres/BBF8E01E-A0F3-4949-80D7-3D8F343BE2DA/129020/71210EstimatingGrapeYield.pdf

Other grape yield estimation resources:

  1. Methods of Crop Estimation in Grapes, Ohio State Univ. Extension:
  2. Crop Estimation, Des Moines Area Community College: https://go.dmacc.edu/programs/viticulture/blog/Lists/Posts/Post.aspx?List=815d7362-ea51-4f6e-8f6e-d971bcc45b9d&ID=36
  3. Yield Forecasting, University of Melbourne, AU:
  4. Crop Management in Vineyard, 6-2011, Penn State University Extension:
  5. Yield Estimation, Washington State University Extension:


Assessing Vineyard Hail Damage is Not Easy

Grapes are somewhat hail tolerant early in the season when the berries are hard and the canopy is not fully developed. Damaged early season grapes often end up drying up. The remaining grapes can also compensate their growth to cover small early season berry losses. Early season shoot and leaf damage can often be replaced by new growth from laterals, basal shoots and secondary

(Left) Hail damaged grapes in SD. 8-1-11

Hail damage is never good, but the closer we get to harvest the potential for hail damage increases. Midseason or later leaf and shoot damage may not be replaced soon enough to fill and ripen the hanging crop that remains. Some or all of the crop may need to be removed based on the severity of the damage and age of the vine. Older vines would have more stored carbohydrates in their roots, trunk and cordon to bounce back from hail damage.

It does not take much hail damage to soft berries to destroy an entire crop. The potential of bunch rots and insect damage can increase dramatically and there is little time for the plant to compensate with new leaf growth to aid the ripening process. Hail often occurs with high winds that damage only one side of the vine. Dropping the damaged clusters on this type of one-side damage may be the answer to save what crop is left. Delayed and/or uneven ripening may occur. Late fungicide applications and insecticide applications may be needed to prevent bunch rots and insect damage.

Purchasing hail insurance for grapes may be an option to consider. Unfortunately there is very little historical hail damage/yield information from our young Midwest cool season winegrape industry to build good actuarial tables. Most hail insurance companies here in the Midwest are not interested in insuring grapes. I do know that Rain and Hail Agricultural Insurance located in Des Moines, Iowa and Tricor Insurance located in Dubuque actively offers crop hail insurance for grapes. I think both would admit that this is a learning experience for them too! There may be other companies out there offering hail insurance for grapes here in the Midwest that I am not aware of.

I must admit. I have never been able to get a good handle on what is available for vineyard crop/hail insurance. Any comments from you readers on this subject would be welcome. mlw

Further hail resources:

  1. USDA – RMA - Grape Loss Adjustment Standards Handbook, 47 pp:
  2. Hail Damage, Michigan State University: http://www.grapes.msu.edu/hail.htm
  3. Evaluation of Hail Damage on Chardonnay Grape Production, 1999 to 2002, Colorado State
    University: http://www.colostate.edu/programs/wcrc/pubs/viticulture/Caspari_HailDamage.html
  4. Gintec Proguard (Bird-Wind-Netting), Windham Centre, Ontario:
  5. Hail & Wind Netting, U.S. Global Resources, Seattle, WA:


Number of Iowa Wineries UP –Number of Vineyards DOWN

I spent time last month going through by database and the respective state and federal databases to come up with the number of operating wineries and commercial vineyards in the state. My first call is always to the Iowa Alcohol Beverage Division to get the latest list of state licensed wineries. The Tax & Trade Bureau will normally post their list of federal licensed wine producers and blenders about twice a year. They posted their last list on July 11th. There were 97 state licensed wineries and 97 federally licensed wineries. No all were on both lists. There were several on each list who were no longer operating or had not opened their doors yet. After taking this into account, I came up with 92 wineries operating in Iowa today compared to 85 wineries in June of 2010. One must remember that an operating winery must have both a state and a federal license before they open for business.

Though, the number of wineries were up, the number of vineyards were down dramatically from last year. There is no “Official” government data for the number of commercial vineyards or acres in
Iowa. I end up using my database to come up with this figure. Eventually almost everyone with a commercial vineyard seems to contact me at some time in the establishment phase or later.

This year with the aid of the newer and faster Google Maps I was able to view the locations of many of these people who had not contacted me in several years. Many of these views showed me what I expected. Many of these vineyards had not grown to commercial size as their owners had envisioned, have been torn out or just weren’t there.

Our industry is maturing. Many of the acreage owners who wanted a commercial vineyard found out what we already knew – growing grapes is expensive and is VERY labor and management intensive. So, … the bad news is that we are down to around 301 commercial vineyards in Iowa compared to approximately 413 commercial vineyard I estimated we had one year ago. The good news is that I think we still have the 1,200+ acres I reported last year. Why? Because many of the remaining vineyards have increased their number of vines.

In my opinion, the number of commercial vineyards may still continue to decrease as people continue to get fed up with all the labor and expense of growing winegrapes on small acreages. The survivors will end up being those people who have invested in time saving equipment and infrastructure that can handle larger acreages of grapes. This is an old story that has been repeated many times for many crops over many years.

Below is my latest map of wineries and commercial vineyards in Iowa. Both the low and high resolution 2011 Iowa map can be found on the WWW here: http://www.extension.iastate.edu/Wine/


Veraison is Here

Véraison is a French term that has been adopted into English. The official definition of véraison is "change of color of the grape berries." Véraison signifies the change from berry growth to berry ripening. The berries become soft and take on the colors characteristic of their specific cultivars.
From the beginning of veraison to harvest, the berries will increase in volume, weight, and sugar content (brix). It is also identified as the 35th stage of 47 of the Eichorn-Lorenz Stages in Shoot Development

The beginning of veraison is a good time to walk through your vineyard to reinforce why plant to plant uniformity is so important in the ripening process. You will quickly begin to see how the following factors affect the ripening process:

a. High Vigor - will prolong ripening.
b. Heavy Crop Loads - will prolong ripening.
c. Open canopies - will hasten ripening.
d. Fruit Sun Exposure will - hasten ripening.

Veraison is also a good time to shut down any further fungicide applications, except for emergency sprays identified through scouting or specific sprays to fend off bunch rots for tight clustered cultivars like Seyval, Leon Millot or Vignoles.

(Left) Beginning veraison for Marechal Foch grapes.

Hedging of the canopy past this point in time is not recommended. It can have detrimental effects on the fruit filling and ripening process. Ideally, shoot growth will slow down dramatically or cease in a well balanced vineyard.

Second crop grapes that developed after the normal bloom period on secondary buds, on old wood and laterals are easily identified at veraison and much less so as they ripen further. Pickers will not see the difference and will mix the second crop unripe fruit with the ripe fruit at harvest. This is not good for the wine. It would probably be best to drop these green clusters to the ground now, aka “green harvest”. (3)

Additional information:

  1. What is Veraison, Legourmet.TV, 3:10 min.
  2. Grape Growth Stages, Michigan State Univ.: http://www.grapes.msu.edu/pdf/Growthstages.pdf
  3. Fruit Ripening Unevenly – Consider a Green Harvest, Randall Vos, 8-21-09 Wine Grower News
    #98: http://www.extension.iastate.edu/Wine/Resources/winegrowernews98.htm


WGGA Summer Vineyard Walk – Kewaunee, WI

What: Wisconsin Grape Growers Association (WGGA) Summer Vineyard Walk

When: 4 p.m., Saturday, August 13, 2011

Where: Parallel 44 Vineyard & Winery, N2185 Sleepy Hollow Road, Kewaunee, WI 54216
Ph: 888-932-0044

4:00 p.m. Registration
4:30 p.m. Welcome & Parallel 44 Wine Tasting
5:30 p.m. Vineyard Walk with Dr. Rebecca Harbut, UW-Extension Fruit Specialist
6:30 p.m. Dinner & Social Hour

Cost: $45 each for WGGA members and $55 each for non-members. Includes wine tasting, dinner
and two tickets for glasses of wine.

Register by contacting: Becky Rochester, Grape Marketing Coordinator at becky@wigrapes.org or 503-428-6331 by Friday, August 5th, 2011. You can pay at the door.

Lodging: Kewaunee Inn: 866-264-5744 or Harbor Lights Lodge: 866-267-9053

Full Details and Flyer here:


ISU - NE2010 Research Vineyard Field Day –Baldwin, IA

When: 2 p.m., Sunday August 21, 2011

Where: Tabor Home Winery, 3570 67th St. Baldwin, IA 52207 ph:877-673-3131

Who: Dr. Paul Domoto, ISU Fruit Specialist will review the 30 new cultivars planted.

Questions: Contact Paul Tabor at : iowawine@netins.net

Note: Music in the Vineyards series will occur after the field day.


Central Iowa Wine Tasting Tour

When: Saturday & Sunday, August 27 & 28, 2011

Tassel Ridge Winery
– Leighton, IA
Grape Escape Winery
– Pleasantville, IA
Summerset Winery
– Indianola, IA
Two Saints Winery
– St Charles, IA
Prairie Moon Winery
– Ames, IA
John Ernest Vineyard
– Tama, IA

Package includes:
- Round trip transportation from Cedar Rapids, IA
- Wine Tasting & Tours at 6 select Central Iowa Wineries
- Cheese Farm Tour and Tasting – Frisian Farms
- Lunch, snack, and dinner Saturday
- Breakfast on Sunday
- Opportunity to grape stomp
- Commemorative t-shirt
- Road-side picnic at Madison County Covered Bridge
- One night hotel accommodation

Cost: $175 each.

Hosted by:
Penny Fitzgerald – wine consultant
Jeff Fitzgerald – winemaker

Co-sponsored by: the Eastern Iowa Wine Club and Travel & Transport Vacations

Contact: Bobbie Van Hoeck, ph: 319-373-4232 or bvanhoeck@tandt.com

Note: Need not be a member of the Eastern Iowa Wine Club to attend.


Notable Quotables

  1. ”South Dakota wineries produced more than 78,000 gallons of wine last year alone.”
    From: Growing Wine Industry in SD, 8-3-11 – Keloland Television
  2. “having concluded that imbibing and getting buzzed are key to the development of humanity.”
    From: Beer and wine archeologist studies ancient stains, 8-3-11 – Digital Journal


Marketing Tidbits

  1. Top 5 Reasons People Hate Wine, 8-3-11 – Mr. Eds Wine Blog:
  2. 8 Reasons small businesses should be using facebook ads, 8-4-11 – Memburn:
  3. “A new study by Casale Media, based on their analysis of nearly two billion ad impressions
    generated during the 1Q 2011, shows that online ads appearing "above the fold" are nearly seven
    times more effective at generating a click through than those appearing "below the fold,"

    From: Seeing Ad First Increases Action Odds Sevenfold, 8-4-11 – Center for Media Research


Articles of Interest

  1. Pesticide Drift May Constitute a Trespass: - MN, 7-28-11 – ISU Center for Agricultural Law:
  2. Brut or sweet? Spain gets electronic 'tongue' to taste cava, 8-3-11- CNN Living
  3. Vineyard survey gauged to measure the impact of herbicide-resistant Weeds, 8-4-11 – Western
    Farm Press: http://westernfarmpress.com/grapes/vineyard-survey-gauge-impact-herbicide-resistant-weeds
  4. Southern Indiana-based Oliver Winery sees early success with sales of new hard cider, 8-4-11 –
    The Republic:


Videos of Interest

  1. Alternative Weed Control for Iowa Vineyards, 11-12-09, ISU Leopold Center & ISU Horticulture
    Dept, 3:30 min.: http://www.youtube.com/watch?v=CliO_KEJA4Y
  2. Heat is Good for Grapes and Wine – Belaire Estates Winery, St. Ansgar, IA: 7-26-11, Kimt-TV,
    2:23 min.


Neeto-Keeno WWW Stuff

  1. Brock's Cool Climate Oenology and Viticulture Institute (CCOVI), St. Catharines, Ontario, CA:
  2. Box Wine in a Microwave, 1-19-10 – College Humor, 1.28 min:


Calendar of Events

8-13, WGGA Summer Vineyard Walk – Parrallel 44 Vineyard & Winery, Kewaunee, WI. Details and Flyer: http://wigrapes.org/wp-content/uploads/2011/07/WGGA-Summer-Vineyard-Walk-2011.pdf

8-21, ISU - NE2010 Research Vineyard Field Day – Tabor Home Winery, Baldwin, IA 52207

8-24, Seedless Table Grape & Winegrape Field Day, Univ. of WI – Madison, West Madison Ag Research Station, Questions: Please check blog at: www.universitydisplaygardens.com for more information e-mail Judy at jreithrozell@wisc.edu or Rebecca at harbut@wisc.edu

8-27, University of Nebraska Mechanical Harvester Field Day, Ida’s Vitas Vineyard, Ogallala, NE
The western NE growers associated with the 5 Trails Winery have taken delivery of a machine harvester and will be discussing and demonstrating its merits at this field day. Details will be announced here: http://agronomy.unl.edu/viticulture/

8-(27-28), Central Iowa Wine Tasting Tour. Starts and end in Cedar Rapids, IA. Visit 6 wineries.
Contact: Bobbie Van Hoeck, ph: 319-373-4232 or bvanhoeck@tandt.com

10-(21+22), Small Scale Commercial Winemaking Course, Kimmel Education & Research Center, Nebraska City, NE. Details & Registration: http://www.nercd.com/r/p/119/

11-(16 & 17), 1st North American Wine Tourism Conference – Napa Valley. Details HERE.

4-(17-19)-12, License to Steal at the Lodge at Geneva, Ohio. Details soon here: http://nationalwinemarketing.com/


Total Circulation of 1,350+ recipients in AZ, CA, CO, FL, OH, IA, IN, IL, KS, KY, MI, MN, MO, MS, MT, NC, ND, NE, NH, NV, NY, OK, OR, PA, SD, VA, VT, WA, WA DC, WI, Australia, Canada, Israel, Nepal, Norway & Turkey

Michael L. White
ISU Extension Viticulture Specialist
909 East 2nd Ave. Suite E, Indianola, IA 50125-2892
ph: 515-961-6237, fax: 6017, cell: 515-681-7286

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