Wine-Grower-News #5
June 7, 2007
Information included in this issue includes:
A Review of Cluster Thinning
Petiole Analysis vs Soil Analysis
The Midwest Grape & Wine Industry Institute is now Online
2008 Annual Conference Dates to Remember
Iowa Wineries Stuck at “65”
“Free” Online Grape Grower Guides
Google Identifies & Quantifies Search Trends in a Graphical Format
Neeto-Keeno WWW Stuff
A Review of Cluster Thinning
There are three primary times flower clusters or immature grape clusters are removed from vines.
Flower clusters removed before bloom reduces the number of flower clusters without removing the number of leaves. This early flower cluster removal will typically increase flower set and produce larger berries and longer more evenly filled out heavier clusters. This is a common practice in table grape production.
Early cluster thinning is normally done after the berry set and up to the time the berries are pea sized. This early cluster thinning is used to help balance the crop to canopy size. Undesirable sized and shaped clusters, those on renewal canes, basal buds, clusters on lateral shoots, and those located outside the fruiting zone can be removed to enhance the remaining cluster weights, quality and ripening. Cluster thinning at this time will enhance the growth of poor vigor vines and reduce the crop of overloaded vines.
Later cluster thinning around veraison is done to hold back the growth of highly vigorous vines. After the excess clusters are removed, the remaining grape quality and ripening will be enhanced.
Just because you used the proper balanced pruning method does not mean that everything will be just hunky dory the rest of the season. Pruning followed by early cluster thinning gives you another chance to balance the crop to the capacity of the vine. Keeping good records over time of average cluster weights will give you a better idea as to how many clusters you may want to retain.
The following average cluster weights have been taken from MANY sources from both inside and outside of Iowa. Cluster weights for each variety can vary greatly based on many growing season factors. Consider these as guestimates and not as gospel. Something to use until you have your own records to refer to.
Variety Ave. lbs/cluster Variety Ave. lbs/cluster
Bluebell 0.35 Leon Millot 0.15
Brianna 0.25 Louise Swenson 0.25
Chardonel 0.40 Marechal Foch 0.20
Catawba 0.35 Noiret 0.25
Cayuga White 0.60 Norton/Cynthiana 0.20
Chambourcin 0.4 – 0.8 Niagara 0.40
Chancellor 0.35 Prairie Star 0.40
Concord 0.25 Reliance 0.60
Corot noir 0.30 Sabrevois 0.30
DeChaunac 0.25 Seyval Blanc 0.4 – 0.8
Delaware 0.30 Steuben 0.50
Edelweiss 0.35 St. Croix 0.35
Elvira 0.15 St. Pepin 0.15
Esprit 0.55 St. Vincent 0.35
Frontenac 0.30 Swenson Red 0.30
Frontenac Gris 0.30 Swenson White 0.35
GR-7 0.30 Traminette 0.40
Kay Gray 0.15 Valvin Muscat 0.20
LaCrescent 0.30 Vidal Blanc 0.40
LaCrosse 0.20 Valiant 0.30
Vignoles 0.25
Petiole Analysis vs Soil Analysis
Soil tests are used prior to planting a vineyard to primarily determine the levels of organic matter, phosphorous, potassium, zinc, boron, magnesium and pH. ISU recommends taking 15-20 soil cores anywhere from 12-16” deep. The top half (6-8”) of these cores should be placed in one sample bag and the lower depth (6- 12” or 8-16”) of these cores be placed in another sample bag. Each sample bag should be identified before sending into a soil test lab for analysis. Optimum soil fertility ranges will vary slightly between states and regions primarily due to variations in soil, climate and varieties being grown. Example,.. French varieties (Vitis vinifera) and many of their resulting hybrids can often tolerate slighty higher soil pH’s than most of our American varieties. The following table compares the optimum soil test levels recommended in the Midwest Small Fruit Pest Management Handbook, (Bulletin 861) versus the ranges recommended by Iowa State University.
Analysis Bulletin 861 ISU
pH 5.5 – 6.5 6.0 – 6.5
Organic Matter OM 2 – 3% 2 – 4%
Phosphorous P 20 – 50 ppm > 30 ppm
Potassium K 125 – 150 ppm > 150 ppm
Magnesium Mg 100 – 125 ppm . -------
Boron B 0.75 – 1 ppm --------
Zinc Zn 4 – 5 ppm 4-5 ppm
______________________________________________________
Petiole tests are the primary tool used to determine fertility needs once the vineyard is established. Petioles (stem portion of the leaf) is the tissue recommended for determining the nutritional needs of grape vines. Obtaining a representative sample is critical. Optimum nutrient ranges are based on petioles sampled at specific times during the season. The following guidelines should be used for proper sampling and handling procedures:
1. Full bloom (now) and veraison (1st week of August) are the two times of the season to sample grapes. The full bloom sample is primarily used for nitrogen. The veraison sample is more reliable for all the other nutrients.
2. At least 25-50 vines should be selected for a sample collection. Vines not typical of the vineyard should be avoided.
3. Vines should be of the same age, variety, and rootstock growing on similar soil/site conditions.
4. For full bloom sampling, take the petioles from leaves opposite the bottom flower cluster. For samples taken at veraison, take the petioles from the most recently developed matured leaf.
5. Collect from 75 to 100 petioles. Short petioled varieties like Marechal Foch will need 150 to 200 petioles collected. Do not pick more than one petiole from any one shoot and do not sample any petioles connected to heavily diseased, insect or mechanical damaged leaves.
6. Dusty or dirty petioles should be rinsed with distilled water and patted dry with a paper towel. Place the collected samples in a “paper” bag and send into a testing laboratory. Make sure to record all the necessary information required by the testing laboratory.
7. Make sure to contact the testing laboratory prior to sending in the petiole test. You want to do it right the first time!
Many factors can affect the nutrient composition of plant tissue. Soil moisture, soil fertility, diseases, insects, crop load, weather, and cultural practices can directly affect petiole tests. But, when properly used, petiole testing will provide the most reliable method to determine fertilizer needs for established vineyards. Comparing petiole tests from year-to-year often will show more reliable trends over time.
Additional Resources:
1. Midwest Small Fruit Pest Mgt. Handbook: http://ohioline.osu.edu/b861/index.html
2 ISU Petiole Sampling Guidelines with a list of plant analysis labs:
http://viticulture.hort.iastate.edu/info/pdf/leafsampling.pdf
The Midwest Grape & Wine Industry Institute is now Online
http://www.extension.iastate.edu/Wine/
The Midwest Grape and Wine Industry Institute in now online. This is our initial debut. More information will coming on board quickly. Slowly but surely we are moving forward to provide staff, educational resources and services that can serve our grape and wine industry in both Iowa and our neighboring states. A wine analysis lab that will be oriented to serve our local wineries is scheduled to begin doing some initial testing in July. The lab will be located in the Food Science Building on the ISU campus. Sebastian Donner has been hired to be the lab manager. Sebastian is currently finishing up his doctorial studies in Analytical Chemistry at Iowa State University.
The Midwest Grape & Wine Industry Institute was approved by the Iowa Board of Regents on 9-27-06. The Institute resides within the College of Agriculture and Natural Resources at Iowa State University. Dr. Murli Dharmadikari is the director. The advisory board which is now being selected will consist of individuals from industry, education and government. Financial support for the institute comes several sources which now include, Iowa State University, ISU Ag Marketing Resource Center, The Iowa Grape & Wine Development Commission, Iowa Wine Growers Association, and various grants.
2008 Annual Conference Dates to Remember
Jan. 29-31, 2008 Unified Grape & Wine Symposium, Sacramento, CA
(Largest in U.S.): http://www.unifiedsymposium.org/
Feb. 2-4, 2008 Midwest Grape Growers Conference, Tan-Tar-A Resort in MO
Feb. 15 & 16, 2008 MN Cold Climate Conference (location not announced yet)
Feb. 21 – 24, 2008 IL Grape Growers & Vintners Assn Annual Conference
Springfield, IL
Feb. 29 – March 1st 2008 NE Grape Growers Annual Conference, Kearny, NE
March 4-7, 2008 Wineries Unlimited, King of Prussia, PA (2nd largest in U.S.)
http://www.vwm-online.com/dpage.asp?pid=185
Note: Details of the Iowa Wine Growers Conference will be announced soon. Several
alternative locations and times are being considered.
Iowa Wineries Stuck at “65”
There were 70 wineries in Iowa with a state license in February of 2007. This number dropped to 65 wineries by the end of March of 2007. According to the Iowa ABD we remain at the current 65 wineries today. What happened? Several wineries in the Amana Colonies have closed or consolidated to the now five existing Amana wineries. Two additional wineries consisting of one that had not opened yet failed to renew their Native Iowa license in 2007. The Iowa Wine and Beer WWW site currently shows 53 wineries open for business: http://www.iowawineandbeer.com
“Free” Online Grape Grower Guides
1. Growing Grapes in Missouri, 80 pp
http://mtngrv.missouristate.edu/Publications/grapeguide.pdf
2. Midwest Grape Production Guide, 155 pp,
http://ohioline.osu.edu/b919/index.html
3. Mid-Atlantic Wine Grape Growers Guide, 126 pp:
http://www.ces.ncsu.edu/resources/winegrape/
4. Growing grapes in Wisconsin, 28 pp:
http://learningstore.uwex.edu/pdf/A1656.PDF
5. Growing Grapes in Indiana, 8pp:
http://www.hort.purdue.edu/ext/HO-45.pdf
6. Growing Grapes for Wine & Table in the Puget Sound Region:
http://cru.cahe.wsu.edu/CEPublications/eb0775/eb0775.html
7. Colorado Grape Growers Guide, 86 pp:
http://www.colostate.edu/Programs/wcrc/Viticulture/GrapeGrowersGuide1998.pdf
Google Identifies & Quantifies Search Trends in a Graphical Format
Google has a new site that identifies and quantifies search trends by topic, location, and time. Trends are shown in graphical format. Type in “Wine, Wineries, Viticulture, Cabernet, etc… and see what happens. I am not sure what you can do with this information, but… it is interesting. Check it out here: http://www.google.com/trends
Neeto-Keeno WWW Stuff
1. Largest Global Directory of wineries, vineyards, vintners, books & wine links:
http://www.asiantimes.com/winelinx.htm.
2. “Free The Grapes” A national organizations to reduces consumer wine shipping
restrictions: http://www.freethegrapes.org/
3. “Super Gigantic Y2 Winegrape Glossary” – huge grape parentage database:
http://www.stratsplace.com/hawkins/wgg.html
Past issues archived here: http://www.extension.iastate.edu/ag/newsletters/winegrowers.html
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