Leaf Thinning for vineyarads and wineries

Leaf Thinning

Leaf thinning is a key step towards quality fruit at harvest. The June 2017 program discussed the practice of leaf thinning around the world, the benefits to growers and winemakers, as well as location, timing, and quantitative results.

Grower Benefits

  • Better air flow
  • Better spray penetration
  • Less disease pressure
  • Even ripening
  • Easier harvest

Winemaker Benefits

  • Consistent fruit quality
  • Less disease
  • Color stability
  • Enhanced phenolics
  • More fruit, less vegetative flavors

pdfDownload the presentation (minus videos) here

Video 1: Vit Minute Leaf Pulling
Video 2: Jordan Winery: Leaf pulling preparing our grapevines for ripening
Video 3: One Acre in Napa Valley – Episode # 5 Leaf removal
Bonus Video:  Sheep thinning leaves at Shannon Ridge

Other Primary Resources: Recent Advances in Grapevine Canopy Management – July 16, 2009 University of California, Davis

Oklahoma State Capitol

Legislation Impacting Oklahoma Wine

Oklahomans for Modern Laws is leading a grassroots effort to bring Oklahoma into the 21st century because our antiquated, prohibition-era beer and wine laws are holding us back.

See more information and follow the legislation here  – http://www.okmodernlaws.org


Free the Grapes is advocating reform of the liquor distribution laws, to result in the availability of a greater variety of wines to consumers.

See more here – http://freethegrapes.org/

Average Last Freeze Date for Oklahoma City

March often feels like spring. But the warm days can give way to a late killing freeze, ending a crop before it’s even begun.

The average last freeze date in the Oklahoma City area is March 30, and freezes can occur throughout April.

The National Weather Service has published freeze data from 1891-2015.   See the full article here.  

dormant vines

Spring Vineyard Checklist

  • Order replacement vines. If you are wanting to use cuttings from your own vines or from another grower, get permission and coordinate with them about their pruning schedule.
  • Be sure that you have the chemicals and supplies that you will need for the first month or so of spraying and vineyard maintenance
  • Check your spray equipment for damage due to freezing this winter or need for maintenance from last season.
  • Decide on the winter pruning method you are going to use this spring. Remember that pruning can stimulate bud break. So consider one of the multiple stage pruning methods that have been talked about over recent years.
  • Re acquaint yourself with the life cycles of the pests that have plagued you in the past and layout a theoretical spray program for their control. “The plan is worthless but the process of deriving the plan is priceless!” Ike Eisenhower talking about the Normandy Invasion planning.
  • If you have not had a soil test in the last 3 to 5 years, it is time to take another one. You know your soil better than anyone. If you have distinct differences, take separate samples from each area…very sandy and more clayey.
  • grape bud slicesWhen you are ready to begin your final pruning stage this spring, it would be good to examine your buds for damage first. You will want to look at several samples across the vineyard. I usually do this in the field with a multi-lens magnifying glass and a razor blade knife. Look at the buds that are closer to the end of the shoot, since you will be cutting this part of the shoot off in your final pruning. If you find considerable damage, it would be advisable to plan to leave more buds than you normally would.
  • All of those suckers are not your enemy. We use interstate 40 as a rule of thumb for varietal selection. Most think that you can be pretty safe over the long haul to plant Vitis vinifera vines south of I-40. However, the farther north of I-40 your vineyard is located, the more you should consider French-American hybrids. That does not mean that the Vitis vinifera vineyards south of I-40 are always safe. Freeze damage is cumulative. So we get a little each year. And that damage can be the entry point for insects and fungus. So it is beneficial to have a multi trunk vineyard with planned renewal. Plan to have two trunks. Each year as you prune through the vineyard, inspect the trunks for damage. As damage increases, use those suckers as renewal trunks. It is possible to not miss a crop by using those suckers as renewals.
  • Spray Schedule 1st spray when shoots are 3”; 2nd spray when shoots are 10”; 3rd spray pre bloom; 4th spray is post bloom; 5th through the 9th are cover sprays and every 14 days unless rain is frequent and then reduce the interval to 7 or 10 days. You need to be ready but remain flexible. You cannot cure black rot in a berry. All you can do is prevent it. So as rain becomes less frequent, watch the weather and be prepared to spray your grapes before the rain arrives. One of the most important spray applications is the “pre-closure spray”. This is particularly important for varietals that form tight clusters. The idea is to get that last spray into the center of the cluster before it closes up. If black rot is established inside the cluster and it is closed to your spray program, it will spread unabated no matter how many times you spray.The 1st and 2nd applications can come pretty close together depending on the moisture and temperature.

GLYPHOSATE that wonder chemical that keeps you from being the “best hoe-r on the block”

MANCOZEB has a 66-day harvest interval so it can only be used for the early sprays.

RALLY is the workhorse for black rot prevention

ABOUND is the rotational spray for black rot prevention to prevent developing immunity in the existing strain of fungus.

SEVIN is the workhorse insecticide for chewing insects.

PROVADO is good with sucking insects.

MICRO NUTRIENT FERTILIZER an insurance policy for nutrient imbalances can be applied in a tank mix with other sprays.

SURFLAN is a pre-emergent chemical that can be tank mixed with glyphosate and sprayed in the row and other areas where weeds are a problem.

Pre-bloom is after the flowers are evident but before they have opened.

Post-bloom is well you know…

All of the above applications can use Mancozeb, so you need to plan on at least 4 applications. If insects become evident, it is best to spray before or after bloom to avoid harming the beneficial insects in the vineyard.

ABOUND is a good chemical to alternate with RALLY. RALLY is less expensive so will probably be the chemical of choice. But to prevent a strain of Rally resistant fungi from developing in your vineyard it is good to intersperse a couple rounds of ABOUND to be safe.

Contributed by Tom Knots, January 2016 meeting.

healthy vines

Oklahoma Vineyard Quality Report – Final

In 2014 Dr. Eric Stafne was tasked to analyze the vineyards throughout the state.  The Oklahoma Vineyard Quality study was funded through the Oklahoma Department of Agriculture, Food, and Forestry.

The purpose of the study had four primary goals;

  1. Identify quality improvements needed in Oklahoma Vineyards and pathways to implement them through educational programs.
  2. Identify geographically the grape cultivars grown throughout Oklahoma’s eco-regions.
  3. Grow high quality grapes which can be made into high quality juices and/or wines.
  4. Provide additional subject matter for incorporation into educational and extension programming.

Dr Stafne had the following recommendations and conclusions.

Recommendations for GENTOPYE (cultivar) selection:

  • Limit vinifera production north of I-40, except on very good sites/soils and choose cold hardy cultivars. Use
    a rootstock.
  • South of I-40 only plant vinifera on very good sites/soils. This region has more options in terms of cultivars to choose from, but quality and quantity of fruit is still a concern.
  • Use rootstocks on vinifera and some high-percentage vinifera hybrids
  • Look to incorporate high quality hybrids as a hedge against disastrous years
  • Wineries must further integrate hybrids into their plans if vineyards are to survive. Prices paid for the fruit must be competitive and reflect the value and quality of the fruit.
  • Three to four tons/per acre should be the minimum for production of vinifera. Hybrids should range from 4-8 tons per acre.

Recommendations for MANAGEMENT to improve fruit quality:

  • Soils in Oklahoma may limit productivity due to low organic matter, high Boron, heavy clay textures, salinity, and other factors. Amend prior to planting and monitor thereafter to improve soil quality.
  • Water is a critical element in the vineyard. Increase irrigation to reduce stress during the summer and improve cold hardiness.
  • Strive for a well-balanced canopy. Canopy management not only helps to produce higher quality fruit in- year, but also in the future. Balancing vegetative growth and crop load is important for overall vine health.
  • Pest control is critical, especially control of fungal diseases, grape berry moth, and weeds in young vineyards. These pests rob vines of critical nutrients, water, sunlight, and other elements, thus weakening the vine.
  • Determine if mechanized harvest and pruning is something that can be done in the future. A well-trained and competent labor force is lacking now and will continue into the future.
  • Keep detailed records and adjust management strategies from year-to-year as necessary.

Recommendations for SITE selection to improve fruit quality:

  • Perform a soil test prior to planting and then every 2-3 years after planting.
  • Modify and amend the soil if needed, especially pH and macronutrients
  • Avoid planting in low spots
  • Maximize air flow and sunlight as much as possible
  • Recognize that all sites are not good locations for grape production

Recommendations for future EDUCATION programming:

  • Encourage growers to incorporate the Oklahoma Vineyard Workbook into practice. Workshops that explain the book and allocate time for completing the ratings are necessary for better participation
  • More educational programs on plant and soil nutrition, irrigation and water allocation, and pest management (including disease, insects, weeds, and animal) are needed
  • Refreshers on proper pruning practices, including balanced pruning methods
  • Specific Workshops on pest management, pruning, plant and soil nutrition, canopy management (including crop load management, shoot and leaf thinning, and crop load estimation), and irrigation are needed to get current growers up-to-speed on the latest strategies for improving overall vineyard and fruit quality.Pest management – During the course of this project the evaluators saw too much disease, insect damage, and poor weed control. Some vineyards were good, but most were poor. It seems there is a lack of understanding about the prevalent pests, timing of control, and products used for control. This is an area that, with a little diligence, can really help vine health and fruit quality.
    Pruning – One outstanding problem among so many vineyards was poor pruning practices. Some obviously had no idea how to prune. It is a skill that takes practice and a keen eye, but it is not a difficult thing. Some untrained vineyard managers are scared to make a cut because they don’t want to remove too much. This is a common mistake. Along with proper pruning is estimation of bud and cane winter injury. Of course it may not be necessary every year, but in years where temps drop very low it is important to do this in order to ensure vine balance.
    Plant and soil nutrition – Nutritional status of the plant and soil may be the area that is least understood in Oklahoma vineyards. It is important do deal with the health of the vine and the soil. Petiole and soil tests cost money and are often considered “optional”. They should not be. They are a mandatory part of any good management program; however, the manager must be educated in methods to improve nutritional problems.
    Canopy Management – Canopy management is a labor intensive endeavor if leaf-pulling, shoot removal, and crop load dropping is done. This is a definite area that needs improvement in Oklahoma. However, this topic is secondary to the three above because those have so much bearing on vine longevity. Canopy management also affects that, but not as critically as the others.
    Irrigation — Irrigation is not being used to its full potential in Oklahoma viticulture. The vines can survive without irrigation, but they will be better off with a good irrigation management program. Tools exist within the Mesonet that along with good soil moisture monitoring would reduce vine stress and improve overall vine longevity.

Since much of Oklahoma viticulture is predicated on winegrape production, the end product must be considered. What makes Oklahoma wine different from its competitors? What makes Oklahoma wine special? Is it, or can it be, integrated into the social fabric of Oklahoma’s citizenry? If the products and industry as a whole are embraced by the public as a critical component of the state’s heritage, then long-term sustainability will be achieved. This requires an understanding of the state’s history as well as an acute perception of its future. All wineries and vineyard owners must work together as a team. It is essential to recognize that one in-state winery is not in competition with another. The competition is out-of-state wine. This leads back to the point of making Oklahoma wine special. How can it be made an essential point of pride for Oklahomans?

  1. Please continue to support OSU’s viticulture and enology efforts.
  2. Contribute your voice to an industry organization and keep abreast of what is happening in the industry now.
  3. Growers and wineries need to stick together and display a unified front to legislators. Find a way past the differences and work together. To be honest, other states have really gotten their acts together and formed cohesive state organizations that get a lot done. It might be a good idea to talk with leaders from other states that are on a similar scale to Oklahoma (like Kansas, Minnesota, Iowa, Nebraska, etc. to find out what they are doing that is successful).
  4. Stay positive. Oklahoma is a difficult place to grow grapes, but it can be done (with proper variety selection, site selection, management, and education). Setbacks will happen, but Oklahoma has a terroir different from anywhere else, so it is exciting to be able to taste that through the grapes. “Taste Native Oklahoma” is something to strive for. Will it be possible to have an industry built entirely on Oklahoma grapes? I don’t know, but with a positive attitude anything is possible.
  5. Continue a life-long education in viticulture.

The complete report from Dr. Eric Stafne can found here.


nutrient deficiency

Nutrient Requirements for Grapevines

Heavy rains early in April, May, and June contributed to several problems for vineyards in Oklahoma.    Although we spent most of our days fighting black rot, it may be time to turn our attention to replacing nutrients leached out of the soil.

UC Davis provided a presentation by Andrew Teubes, a viticultural consultant from South Africa, on the nutrient requirements for grapevines.    The presentation specifies the most important nutrients, the recommended levels, and timing of foliar and granule applications.   See the Powerpoint presentation here (PPT).

Soil tests and petiole are the best ways to determine if you have deficiencies in the soil or grapevines.  Samples of can be submitted through the Cleveland County Extension office on Robinson.