Cultivar, Rootstocks, and Trellis Blocks of the W-MEA Viticultural Model

I began the "fleshing out" of the Wine -- Mise en abyme (W-MES) Viticultural Model with an elaboration of the Site Complex and a comparison of the best practices elements to the Masseto site conditions. In this post I continue this "fleshing out" by detailing the elements of the Vineyard Establishment Complex (identified below within the red oval). As before, I will attempt to identify best practices and compare them against the Masseto conditions where data are available.

Variety
A number of factors are considered in selecting the variety (or varieties) to be planted: (i) experience of other vineyards in the area; (ii) the quality of the variety; (iii) the speed at which it completes its annual reproductive and vegetative cycles and how do those cycles match to the climate of the region; (iv) the yield potential; (v) adaptation to climate; (vi) adaptation to soil conditions; (vii) its resistance to disease; and (viii) the varieties that are allowed by existing legislation (in an area where that is a concern).

The climate of a grape-growing region will determine, to a large extent -- and all things being equal -- both the grape varieties that can be grown and the styles of wine that can be produced. The climatic requirements for successful viticulture include: a growing season long enough to mature both the fruit and vegetative aspects of the plant; production of sufficient carbohydrates to ripen the fruit as well as to maintain future productive potential; and an adequate supply of water.

The common wisdom holds that varieties produce at their best when grown at the coolest margins of viable ripening. Grapevines are selected either through mass or clonal selection and cuttings are grafted onto rootstocks based on the attributes required.

Rootstock
Most of the world's quality wines are based on vitis vinifera, a species which, when grown on its own roots, will succumb to attacks from phylloxera and parasitic nematodes. This problem has been solved by grafting the vitis scion onto phylloxera- and nematode-resistant rootstock.

Vine vigor and soil capacity are additional important inputs into the rootstock-choice decision. Varieties with large canopies (high-vigor varieties) can become less fruitful over time (thus reducing the capacity of the vine) due to reduced cluster number and size. Dr. Andy Walker of UC Davis defines vine capacity as "the ability to grow and produce foliage, roots, and fruit and to establish a trunk." According to Dokoozlian and Kliewer (AJEV 46, 1995, pp. 209-218), vigor is used to describe the growth capacity of grapevines, with those having "large dense canopies and low sunlight exposure ..." being referred to as high-vigor vines. Dense canopies can be detrimental to vine yield in that (i) the plant is deploying its resources in "unproductive" areas and (ii) they reduce the amount of light getting to internal leaves. And human activity (with the related costs) is required to reduce this physical manifestation of vine vigor and re-direct the vine's resources to more productive use.

Soil capacity is a function of the water-holding capacity and mineral wealth of the soil. Vine capacity, on the other hand, is the soil capacity plus the levels of carbohydrates stored in the vine trunk and cordons. Growers seek to blunt the upside of vine capacity by employing low-vigor rootstocks but, in most cases, capacity will trump vigor.

Rootstock(s) utilized in the vineyard environment should be (http://iv.ucdavis.edu/files/24347.pdf):

• Resistant to present and potential soil pests
• Suitable for the soil’s texture, depth, and fertility
• Compatible with soil chemistry (pH, salinity, lime content)
• Favored for the anticipated soil water availability, drainage, and irrigation practice
• Appropriate for the vineyard design
• Appropriate for the fruiting variety’s growth and fruiting characteristics.

Trellis
The rationale behind vine training systems is (i) an understanding that increasing the exposed leaf area improves fruit quality, (ii) that exposure of leaf area can be manipulated by training, and (iii) training alters the microclimate of the canopy. The amount of leaf area that can be exposed to the sun is a major consideration in the choice of a training system. It is affected by (Reynolds, Andrew G., and Justine E. Vanden Heuvel, Influence of Grapevine Training Systems on Vine Growth and Fruit Composition: A Review, Am. J. Enol. Vitic. 60(3), 2009, p251):

• The disposition of the bearing units
• the Trellis height
• The associated type of training.

Growth, yield, and quality are directly proportional to the ratio of exposed leaf area to fruit weight with a range of 7 - 14 cm² total leaf area/gram of fruit required to achieve full fruit maturity. The higher end of the range should be pursued in colder climates in order to ensure that the vine can complete its important physiological functions (Reynolds and Vanden Heuvel).

The trellis serves as the framework within which the vines are trained and supported and must (Paul Domoto, Constructing a Vineyard Trellis, Presentation, Iowa Grape Growers Conference, 2002):

• Be strong enough to support large crops and withstand high winds
• Last for 20 or more years with routine maintenance.

One of the most important considerations in trellis selection is the size of the canopy that it will be supporting. The vines growth potential has to be taken into consideration in order to ensure that it will bear the weight of the vine at maximum vegetative growth. The factors which drive vine growth potential are as follows (http://www.ucanr.org/sites/intvit/files/24348.pdf):

• Temperature
• Annual rainfall
• Sunlight exposure
• Winds
• Soil texture
• Vine rooting depth
• Pre-Plant soil preparation
• Cultivar
• Rootstock
• Cultural practices

Other elements that factor into the trellis decision are (Reynolds and Vanden Heuven):

• Plant and row spacing
• Row orientation
• Establishment costs
• Equipment requirements
• Desire for mechanization.

The details of the model elements for the W-MEA Model Vineyard Complex are provided in the table below. Red-colored text indicates a best-estimate.

      Masseto Vineyard Versus the W-MEA Viticultural Model -- Vineyard Complex

Block	Component	Element	Optimal Value	Masseto Position
Variety	Nomenclature		Depends	Merlot
	Climate Adaptation		High	High
	Soil Adaptation		High	High
	Local Custom		N/A	Compliant
	Variety Quality		High	High
	Yield Potential		Balanced	High
	Disease Resistance		High
	Allowed by Regulation		Compliance	Compliant
Rootstock	Nomenclature		Depends	N/A
	Soil Pest Resistance	Phylloxera	Med-High	Med-High
		Nematodes	Med-High	Med-High
	Soil Qualities Suitability	Texture	Loam, sandy loam	Clays
		Depth	Ø  3 feet	N/A
		Fertility	Low-Med	High
	Soil Chemistry Compatibility	pH	6.0-6.8	N/A; assumed high
		Salinity	Threshold 1500 μmho/cm	N/A
		Lime Content		N/A
	Water Availability	Drought Conditions	Adaptable	N/A
		Wet Soils	Adaptable	Inhibits performance
Trellis		System	Depends	Spurred Cordon
		Strength	Wind resistant; supportive of vine growth potential	Compliant
		Longevity	Ø  20 years	N/A
		Plant and Row Spacing	2.5 m between vines in Bolgheri	3 m x 0.85 m
		Row Orientation	Depends	Perpendicular to the fall line of the slope
		Set-Up Costs		N/A
		Equipment Requirements		N/A
		Mechanization Plans		N/A

©Wine -- Mise en abyme

Deconstructing the Masseto (Bolgheri, Tuscany) vineyard: Irrigation management

This post is the final in a series that sought to characterize Ornellaia's  Masseto vineyard using both publicly available data as well as reasoned supposition. Previous posts in the series covered soils, scion and rootstock, disease and virus management, training systems and pruning practices, and nutrient monitoring.   This post examines irrigation management.

Water is extremely important to the functioning of the vine plant but too much, or too little, can have adverse effects on the plant, with run-on effects on fruit quality.

One of the important viticultural philosophies in many new world grape-growing environments is that controlled water deficits, and the resultant vine stress, can improve wine quality while “full-potential water use” will most likely result in “heady canopies” and insufficient light getting through to the fruit as a consequence. Research carried out by UCDavis' Dr Terry Prichard on berry size and vine balance shows that:

• For a given berry size, vines grown with low irrigation have a higher anthocyanin concentration (between 15% and 33%) than those grown under higher irrigation conditions
• There is a higher concentration of skin tannins in low- versus high-irrigation environments
• Water deficits result in lower yields which, in turn, results in lower veggie characteristics and fruitier wines.

Water sources for the vine include stored soilwater, effective in-season rainfall, and any water that is added by the viticulturist. Vine water stress is created when this available water supply is reduced beyond the vines climatic needs.  In areas where irrigation is allowed, viticulturists use controlled irrigation to induce vine water stress. In this scenario, the soil water resources are utilized for the plants needs up through bud break and then amounts less than required are provided to the plant (This would include effective rainfall plus irrigation). This limited water access creates a stress situation for the vine, which, in turn, results in the quality enhancements that the viticulturist seeks. This controlled-irrigation option is not available to the Masseto vineyard because irrigation is not allowed in Bolgheri except under emergency conditions. That is, the soil will provide for the vine's needs with stored soil water and the vines will dive deeper -- a stressed situation -- in search of additional water when the near-in sources have been depleted. In the remainder of this document we will explore the implications of this situation for the Masseto vineyard.

According to Orlandini et al. (Water Use in Italian Agriculture: Analysis of rainfall patterns, water storage capacity, and irrigation systems), Tuscany gets about 22 billion cubic centimeters of precipitation annually with yearly values ranging from 2000 mm in the northwest to 500 mm in Maremma to the south. Overall, regional water requirements are 760 million cubic meters with agriculture demanding a paltry 150 million cubic meters. During April 2004, 92 mm of rain fell in Florence and effective rainfall (rainfall during the growing season) ranged between 53.6 and 78.5, depending on the conversion schema chosen. Precipitation is not the problem then. According to Orlandini et al., there is enough precipitation to supply the region’s water needs but the “temporal and spatial distribution can be responsible for severe water deficits” (see table below).

                           Effects of Severe Water Stress on the Grape Vine

Stage	Effects
Bud Break	Water stress infrequent at this stage Moderate levels -- uneven bud break and stunted shoot growth Severe levels -- poor flower cluster development; reduced pistil and pollen viability; nutrient deficiencies
Post-Berry Set	Severe levels -- flower abortion and cluster abscission; reduced canopy development; impact on following season’s crop potential
Post-Fruit Set	Restrict berry cell division and enlargement resulting in smaller fruit and lower yields Reduced shoot development Reduced yield potential Reduced fruit soluble-solids accumulation Higher pH fruit Decreased acidity Reduced color development in red varieties
Post-Harvest	Reduced root growth with resulting decreased nutrient uptake and micronutrient deficiencies the following spring

Source: Wample and Smithyman, Regulated deficit irrigation as a water management strategy in vitis vinifera production in Deficit Irrigation Practices, ftp://ftp.fao.org/agl/aglw/docs/wr22e.pdf%20.

Orlandini et al., recommend two solutions to addressing these emergency water deficit situations: (i) landforms and (ii) water repositories. The clayey soils of Bolgheri have an infiltration rate of .5 mm/hr and, coupled with the fact that terraced vineyards show runoffs of .72 g/l, while sloped vineyards experience runoffs of 4.18 g/l, point to terraced vineyards as a mechanism for slowing the runoff and keeping the water around to allow the max possible infiltration into the clayey soils.

A practice in the Italian farming community is the development of farm ponds to capture precipitation to hold for emergency situations. There are a total of 2462 farm ponds in Tuscany, up from 1707 in 1980 (Orlandini, et al.). A 1985 study has shown that the average farm pond can hold about 30,000 cubic meters of water, an optimal dimension for cost and maintenance. Allowed emergency irrigation is 60 mm/ha  which amounts to 780 cubic meters including losses and efficiency (Orlandini, et al.). A pond of 30,000 cubic meters can irrigate 30 ha, making it more than adequate to meet the emergency irrigation needs of the Masseto vineyard.

Masseto does support terraced vineyards and my guess is that they would have at least a 30,000 cubic meter farm pond to allow increased precipitation retention and to meet any emergency irrigation needs that may present.

©Wine -- Mise en abyme

Deconstructing the Masseto (Bolgheri, Tuscany) vineyard: Nutrient monitoring

Masseto is one of the the world's leading Merlot wines and its 6.63 ha vineyard is ensconced within the confines of the larger Ornellaia vineyard in Bolgheri, Tuscany. It has been difficult obtaining information on the details of the vineyard so I have undertaken the task of deconstructing it using data from publicly available sources as well as reasoned assumptions. In this post I cover nutrient monitoring practices.

Adequate amounts of the appropriate nutrients are required to support proper growth of the grape vine, fruit development, and fruit maturity and those nutrients are obtained from the soil.  The table below shows the mineral requirements of the vine plant, the role of each mineral, acceptable ranges of each mineral in the soil, and the impact of mineral deficiency on the vine. 

Toxicity is just as important to the vine as is deficiency as a surfeit of a particular mineral in the environment can also have adverse effects on the vine plant and/or fruit. For example, high levels of magnesium in the soil can inhibit the plant’s uptake of potassium, potentially leading to a potassium deficiency. The viticulturist must have a program in place to monitor the levels of nutrients available to the plant and a plan of action to address deficiencies or toxicity.

Prior to vineyard planting, the only recourse for assessing the availability of nutrients to the grapevine is an analysis of soil samples to determine soil texture, cation exchange capacity, soil organic matter, and pH (Skinkis and Schreiner). Staben et al., (Monitoring Soil Nutrients Using a Management Unit Approach, PNW 570E, October 2003, ie.library.oregonstate.edu) describe three methods of soil sampling and those are summarized in the table below. 

                                                    Soil-Sampling Methods

Whole-Field Sampling	Grid Sampling	Management-Unit Sampling
Soil cores collected from entire field, mixed together, and single compoite sample sent to lab	Field systematically divided into areas of uniform size and shape (cells) Samples taken from each cell and analyzed (composites of 10 or more cores) Patterns of estimated nutrient availability can be determined and a nutrient application map developed	Divide field into management units based on soil features and grower’s needs and priorities Collect soil samples throughout each management unit or for a smaller reference area within a management unit Select one of the two above approaches and use it consistently
Issues: Treats the entire field the same regardless of landscape or cropping history Conclusions drawn from the test may not be appropriate for all parts of the field Basing fertilizer application on these findings will have some areas over-fertilized and others under-fertilized	Advantages: - More accurate data than provided by whole-field sampling Issue: - Expensive given the labor, equipment, and lab fee costs	Advantages: Save time and money compared to grid sampling Obtain more accurate data than provided by whole-field sampling Provide many of the benefits of grid sampling while overcoming the costs

Once the soil analysis is complete, decisions regarding needed additions can be made. The suggested frequency of soil testing is shown in the table below.

Nutrient-Driven Soil Testing Frequency 

Nutrient/Characteristic	Frequency
Soil texture	Initial soil assessment
Cation exchange capacity	do.
Organic matter	do.
pH	Periodic
Bray or Olsen P	do.
K, Ca, Mg, Na, Zn, Mn, Cu, Fe	do.
Boron	Annually
Sulfur	do.
Electrical Conductivity	do.
Nitrate-N, NO(3)-N	As needed

Source: M. L. Staben, et al.

Once the vineyard is up and running, soil samples alone will not suffice. Soil samples may show adequate amounts of nutrients available in the soil, but nutrient presence in the soil does not translate on a one-to-one basis to nutrients in the plant. Issues such as  mycorrhizae population, rootstock type, presence of manganese, etc., may inhibit the takeup of nutrients into the vine. A much more fitting approach is the sampling and testing of plant tissue. Tissue for this type of analysis is generally taken from the (basal) petiole or blade at bloom (US) or veraison (Europe). According to Skinkis and Schreiner, tissue analysis gives an “idea of sufficiency, deficiency, and toxicity of mineral nutrients" in the vine. According to the authors, petiole samples provide information on chlorine, potassium, and sodium levels while leaf blade samples provide better nitrogen indicators than does petiole analysis and also indicates levels of magnesium, boron, calcium, copper, and manganese.

An effective nutrient management program for vineyards must contain the following elements (Schreiner and Kinkis):

• Good records of fertilizer and irrigation inputs
• Vigor assessment
• Yield
• Interpretation of soil and plant tissue results.

I am assuming that Masseto conducted an initial soil analysis using the management unit sampling approach and conducts concurrent soil and tissue analysis at veraison on an ongoing basis. I am assuming that the vibrancy of the clay soils obviates the need for nutrient additions. The Bolgheri zonation study failed to identify any toxicities in the soil so my assumption is that no additives to address this issue are required.

©Wine -- Mise en abyme

Training systems and pruning practices at the Masseto (Bolgheri, Tuscany) vineyard

Masseto is one of the the world's leading Merlot wines and its 6.63 ha vineyard is ensconced within the confines of the larger Ornellaia vineyard in Bolgheri, Tuscany.

It has been difficult to obtain information on the details of this vineyard so I have undertaken the task of deconstructing it using data from publicly available sources as well as reasoned assumptions. In this post I cover training systems and pruning practices.

According to the Article 4 rules of the Bolgheri DOC (Bolgheridoc.com):

• Vineyard layouts, training systems, and pruning practices must be those in general use in the area and in any case such as will not change the characteristics of either grapes or wine. Expansive training systems are not allowed.
• All vineyards planted after 21 March 2011 shall have a density of at least 4500 vines per ha calculated according to a vineyard with a maximum of 2.5 meters between vine rows.

Clay soils have an infiltration rate of .5 mm/hour, the slowest of all soil types. Vines planted in linked terraces have a runoff rate of .72 g/l while vines planted with the slope allow runoffs of 4.18 g/l. Given these variables, Masseto has opted for a vineyard layout that is perpendicular to the slope in order to allow the summer rains to percolate slowly into the soil rather than to run off vertically.

According to Paul Domoto (Constructing a vineyard trellis, Presentation at the Iowa Grape Growers Conference, 1/26/02), a vineyard trellis serves as a framework for training and supporting the vines and should be:

• Strong enough to support large crops and withstand high winds
• Able to last 20 or more years with routine maintenance.

Based on images from the Masseto vineyard, as well as other vineyards in the area, my perception is that the trellis construct of choice is an anchored end-post system with earth anchor. The longevity of this construct will be enhanced by pressure treating the posts with chromated copper arsenate.

Anchored end-post system (Source: Bernd Meyer, Trellis End
Post Assembly Designs for Vineyards, aces.nmsu.edu)

According to masseto.com, the Masseto vine planting density is 3.0 x 0.85.

The predominant cordon system in Bolgheri is cordon spur but there are also examples of guyot and gobelet.  Some viticulturists avoid the guyot system because of its increased growth on the outer edges of the plant and the additional work required to keep the vine in balance. In addition, Guyot is designed for low-to-moderate-vigor vineyards (Patty Skinkers, Guyot vine training system, Oregon State University, extension.org). Vigorous vines - a la Masseto -- are not suited to the guyot system because of “high shoot density and inner canopy shading” which reduces leaf surface area exposure. Masseto trains according to the unilateral cordon spur system.

The goal of canopy management is to provide a properly balanced vine with the right ratio of shoots to leaves and the “right” fruit exposure to light (Cliff Ohmart, The science behind canopy management, winesandvines.com, November 2009). Vine balance is affected by the trellis, spacing, pruning, irrigation, nutrition program, rootstock, and scion as well as the vineyard site and the regional climate (Ohmart). The canopy management strategy of choice is two leaf layers in the vine to (i) allow “good exposure to the leaves so that they are fully active and (ii) to provide light through the canopy to the fruit.” The canopy will be managed through pruning during the vegetative cycle and leaf removal during the summer period. Other practices such as hedging and the use of cover crops to provide competition could be utilized. Masseto prunes 5% - 10% of the production "to help the vines reach their optimum equilibrium" (masseto.com).

©Wine -- Mise en abyme