Chapter 3

3. Vine vigour control

The terraces built using Mas Martinet techniques are environmentally sustainable, although they may have two disadvantages from a vine grower’s point of view: 

• They keep the soil more fertile and retain more water than conventional terraces. This does not sit well with predominant viticulture criteria, according to which excessive fertility and production is incompatible with grape quality.

• The construction cost is higher than that of conventional terraces. According to the latest experiments carried out in the Priorat region, the terraces built using Mas Martinet techniques cost between 30,000 Euros/ha and 36,000 Euros/ha.

The grape quality and financial feasibility of the vineyard are obtained through vine vigour control, the second group of techniques presented in this Manual:

• Plant architecture (including pinching).
• Precise irrigation.
• Plantation framework.
• Clearing.

In fact, the vigour control techniques described in this chapter overcome the two disadvantages of building sustainable terraces for the vine grower. The conventional plantation develops between 4,500 and 5,500 linear metres of production branch per hectare, with an ELA close to 7,000 m2. As indicated later on in this Manual (Section 4.1), the application of vigour control techniques to sustainable terraces provides around 12,000 linear metres of production branch and an ELA easily in excess of 20,000 m2, maintaining and even increasing the grape quality, preserving the soil and retaining rainwater. The greater productivity of the vineyard using vigour control techniques provides the same grape production as with a smaller piece of land. Therefore, as well as the environmental benefits described in Chapter 2, reforestation is reduced for the vineyard plantation.

Two additional techniques are also described that are not strictly necessary for vine control but that do improve its effectiveness and eco-efficiency:

• Plant cover.
• Disease control using a specific model.

3.1. Technique basics

In the Priorat region in the early 90s, old vines produced the base grape for preparing good wines. As a result of Mas Martinet’s experience in old vineyard operations, it was seen that grapes with small, loose berries were suitable raw material for top quality wines: 

• Loose berries have more space to grow, are more aerated and exposed to the sun, making them less vulnerable to blight and rotting and, above all, ripen much more evenly.

This basic observation was proven by ripening tests that compared large, compact-berry grapes with small, loose-berry grapes. The curves indicated in Figure 3.1. show the likely alcohol content for each grape berry in graph form. In the case of the compact grape, a high percentage of berries either do not reach or exceed the required alcohol content. This percentage is much lower for loose grapes. In other words, with regards to the average values required, the compact grape is much more disperse (standard deviation on the Gauss curve) than the loose grape, thus explaining the difference in quality.

Figure 3.1 Comparison of the likely alcohol content of two types of grape berry
Compact grape	Loose grape berry

Grape ripening and wine quality During ripening, the sugar to have accumulated in the plant through photosynthesis passes through the sap to reach the grape. Through the action of sunlight, the hypodermic cells of the berry (in the skin) perform the enzymatic synthesis of the polyphenols and the aromas using the sugar. The polyphenols form an extremely wide and diverse group of compounds (tannins, flavonoids, etc.) that give the wine colour, bouquet and flavour. It can be said hat all the characteristics subsequently reflected in the wine are from the sugar of the reserves that synthesise the polyphenols during ripening. Ripening forms part of the vine’s reproductive strategy:  When the fruit ripens, it gives of smells that attract animals. Animals eat the ripe fruit. In the ripe fruit, the seeds are already covered with lignin that animals cannot digest. They therefore expel them without spoiling them and allow the plant to reproduce. The quality of a wine is determined by three main characteristics: Balance.  Concentration. Character. Balance. A wine is balanced when its aromas and flavours are faultless and reduce gradually until they disappear, with no sudden changes or peaks. Balance depends primarily on the ripeness of the grape. If the grape is not sufficiently ripe, green tannins are extracted during maceration that are responsible for different problems in the wine: astringency, dry mouth, acidity, etc. Excess ripeness causes sweetness with excessive tastes of dried fruits or figs. It is therefore extremely important for all grape berries to reach the required level of ripeness at the same time, i.e. evenly, with no excessively ripe berries next to others that are still green. Concentration: as well as the quality of the polyphenols and aromas, their quantity is also important so that the wine can mature correctly and produce evolving aromas during ageing. If the grape contains a small quantity of polyphenols, the biological activity of the wine during ageing will alter all the compounds and the wine will loose its required characteristics. Character: this characteristic enables wines with a good basic quality (balance and concentration) to stand out. The character of a wine depends on the “terroir”, the climate, the grape variety and the author. Whereas the balance and concentration can be assessed quite objectively by an expert, character is much more subjective. As with any work of art, the character of a wine can adapt to a greater or less extent to the specific tastes of each individual.

• If wines are to be produced for ageing (vintage), small berries have a larger specific skin area containing polyphenols, tannins, aromas and all the substances that, in sufficient concentrations, enable the wine to evolve.

It is clear that, if grape berries are separate and have a larger specific surface (surface per unit of volume), they receive more solar radiation and ripen more evenly, expressing all the aspects of the variety and the land harmoniously in the wine, making it different to other wines. And this is the basic aim.

Vigour, plantation framework and root soil volume of a stock The vigour of a plant is the strength of its vegetative activity. Technically, Mas Martinet defines the vigour of a stock as “the weight of the word in the form of shoots that adult stock is capable of producing during one vegetative cycle”. Vigour is expressed in grams. For example, stock may have a vigour of 300 g or 1,400 g. The vigour of dependent stock depends primarily on the variety of the vine, the fertility of the soil and the climate. The plantation framework (PF) is the area defined by the space between rows of stock forming the service passageway or middle width and the distance between stock on the same row. The root soil volume (RSV) is that available for the growth of stock roots without touching neighbouring stock. The RSV is determined by the plantation framework and the depth at which the roots are active, which may be 1 m.

It was also observed that the autochthonous varieties of Cariñena and Grenache on young vines planted in fertile land produced extremely compact bunches with very large berries that, once collected, had a deficient level of even ripeness (berries still green with others over-ripe).

Moreover, old vines are known to produce a quality grape for two reasons:

• The traumatic damage to the stock caused by yearly pruning prevents sap from passing and reduces its vigour, thus leading to grapes with small, loose berries.
• Plantations on steep slopes without terracing (“costers”) also reduce the vigour of the plant, given that any fertile soil is dragged away by the rain. In this case, erosion is the case of lower, yet higher quality production.

The problem is as follows: in new terraced plantations with fertile soil with no erosion and water retention for penetration, the stock expresses all its vigour and tends to produce very large, compact grapes. Its berries no longer ripen at the same time and, as a result, the vine loses quality.

To date, the conventional solution given to this problem of quality consisted of “making the plant suffer” to reduce its vigour: no irrigation, no tilling, less fertilisation, etc. In other words, vigour is dealt with like a defect that must be corrected to obtain lower products of a higher quality, similar to that of old vines.

However, the basis of the Mas Martinet technique is to consider vigour as a virtue of the plant - showing its good condition - not as a defect and trying to redirect it towards quality fertility. A large part of the experiments carried out by Mas Martinet since 1997 have focused on optimising vigour management of the autochthonous varieties in the new terraced plantations.

3.2. Plant architecture

3.2.1 Shoot diameter

Mas Martinet therefore knew what the grapes should be like, although it was unaware how to obtain these on young vines planted on terraces. Initial experiments based on leaving fewer bunches on the stock or on reducing the distance between stock did not give the expected results: the grapes remained large and compact.

Finally, the hypothesis that experiments have proven to be true was posed: the morphology of the grape is related to the diameter of its shoot. It was seen that shoots exceeding 10 mm in diameter produce compact grapes, but if the diameter is between 6 and 8 mm, the grape berries are small and loose (Figure 3.2).

Figure 3.2 The morphology of the grape is related to the diameter of its shoot

To ensure that the shoots were thin enough, a larger number of shoots were left on the stock so that competition between them would lead to the required reduction in size. Where the vigour of the plant, which is inherent to its characteristics and growing conditions, is distributed among few shoots, these would be thick and long. However, where the same vigour or amount of wood is to be distributed among a larger number of shoots, these will be thinner and shorter (Figure 3.3).

Figure 3.3 Competition among shoots for the same vigour

Compact grenache grape	Loose grenache grape

Experiments at Mas Martinet estimated that the optimum shoot was between 6 and 8 mm in diameter, around 1.2 m long and between 45 and 55 g. in weight.

3.2.2. Vine training

In “T” or “cordón royat” vine training with a distance between stock of 1.2 m, between 10 and 14 shoots are normally left with an average distance of 8-10 cm between them. It is also necessary to leave a larger number of shoots for the same plant vigour and, therefore, the production branch must be lengthened without varying the plantation framework. To do so, Mas Martinet has developed two new forms of vine training:

• Vine training with double production branch or “double training”
  Whereas the length of the production branch in cordon royat vine training is equal to the distance between stock, in double vine training the length is doubled without modifying the distance between stock. This vine training consists of tightened wires between two metal frames located every 5 or 6 vines, which means that it can only be used when the terrace area is basically straight.
• Individual ring training (circle)
  Given that terraces follow the level of the natural slope and do not adopt polygonal shapes, the straight sections of vine training are not generally a good solution. Where vine training cannot grow lengthways along the terrace, then the solution involves circular vine training. The length of the production branch allowing for this type of vine training is over 3 times greater than the linear distance
  available between stock (diameter): π x Ø, i.e. 3.14 x Ø.

Conventional 'cordon royat' vine training

Vine training and production branch Vine training is formed by fixed supported upon which the plant architecture is developed so that the shoots can grow sufficiently ordered and separated to provide aeration and sun exposure of the grape, pruning, the application of pesticides, collection and, in general, all viticulture work. The production branch is the length of woody stock from which the shoots grow.

Vine formed by double production line
Ring vine training

In new vine training, the technique consists of leaving an average distance between shoots of 7 cm. In double vine training, with a distance between stock of 0.5 m, up to 14 shoots per stock may be left, i.e. 14 shoots per linear metre of production branch. Where vine training in rings of 0.6 m in diameter is used, stock may house up to 27 shoots, as the production branch measures 1.88 m (once again, 14 shoots per linear metre of branch).

Therefore, there is more space for a larger number of shoots depending on the vigour of each stock. For example, in a plantation with a distance between stock of 0.5 m, if the stock has a vigour of 500 g then 10 shoots would be left. If the stock has a vigour of 600 g then 12 shoots would be left.

Compared with conventional vine training, for a certain plantation framework, new vine training no only allows for a longer production branch on stock but also increases the effective leaf area (ELA). This provides a higher ratio between the ELA and the root soil volume (ELA/\RSV), a parameter that, as seen later on, is essential for controlling the ripeness of the grape in adverse weather conditions. Furthermore, stock with a higher ELS may increase its production without reducing the concentration of polyphenols in the grape, as its larger “solar panel” enables it to synthesise larger amounts of sugars (Figure 3.4).

Effective leaf area (ELA) The effective leaf area (also known as exposed or active) is formed by the leaves of the plant directly exposed to solar radiation. The greater the ELA, the more solar energy the plant can attract for synthesis, through the chlorophyll function, of the sugars required for growth and fruit ripening. There is no single universally-accepted way of measuring ELA. A simple method consists of “scanning” the leaves on the shoot and measuring their area using computer software. However, not all the leaf area can be considered effective, i.e. directly exposed to solar light, given that in practice some leaves cover (shade) others, particularly if the shoots tend to intertwine.

	New vine training offers an orderly layout of shoots so that the ELA is spread continuous and effectively, thus reducing the shading effect and the overlapping of leaves. Mas Martinet is assessing the ELA of each of the grape varieties and its relationship to quality production at its Priorat plantations. As a conservative measure, this Manual adopts an average ELA value of varieties planted of 0.14 m2 for each shoot developed.
Leaf area in double vine training	Figure 3.4 The effective leaf area may be doubled without increasing the plantation framework and, as a result, the root soil volume

3.3. Precise irrigation

3.3.1 Basic functions of water

Thanks to the chlorophyll function of the vine leaves (ELA), the plant photosynthesises sugars, accumulates them in the reserve tissue and uses them as required to carry out its functions. Throughout its vegetative cycle, the plant must produce the necessary amount of sugar for three purposes:

• To grow until all the foreseen shoots are developed and to form the effective leaf area.
• To reach optimum ripeness of the grape berries.
• After harvesting, to keep enough reserves to restart growth the following year.

The availability of water plays a predominant role during these processes of the vegetative cycle. Water has two basic functions:

• Intracellular water takes up the space inside the cells and acts as a universal solvent. All the biochemical reactions that the plant needs for its metabolism (synthesise hormones and proteins, transform sugar, etc.) are produced in the aqueous medium of the cell. This water is not used up in its supply and its volume does not vary, in order to maintain a constant osmotic pressure.
• Extracellular water takes up the interstitial spaces between the cells and is basically taken in through the roots and released through the leaves after circulating around the wood and bast vessels. The capacity of the plant to adapt to its surroundings depends on this. When the environmental temperature increases, the plant evaporates its extracellular water trough leaf transpiration to cool the plant. Bear in mind that the chlorophyll function stops if the leaves reach a temperature of over 36-37ºC. The leaves must be cooled to be able to continue photosynthesising the sugars.

If, during the hot months, there is less external water (that collected by the roots and that contained in air humidity) than that required by transpiration (more demand than supply), the plant uses its intracellular water. This causes a change in its osmotic pressure and, as a result, the plant’s metabolism is modified:

• To transpire less and lose less water, it reduces the leaf area by eliminating the leaves around the base of the shoot, constricting the sap conducting vessels. These leaves turn yellow and fall off.
• It partially or totally dries the grape berries, which wrinkle and turn into raisins before dying off. These grapes will not longer ripen correctly and will affect the quality of the wine (strong acidity, green tannins, etc.).

Therefore, a shortage of transpiration water (hydric stress) has two harmful effects: plant dehydration, with the loss of leaf area and grape berries and a reduction in photosynthesis activity with, as a result, less available sugar production for ripening.

However, when there is excess extracellular water in relation to that required for transpiration (more supply than demand), the plant synthesises growth hormones and uses the sugar from the reserves to grow. This must take place during the spring months when the plant must develop all its growth and form ELA, although it must be avoided from early July until the grape is harvested, as described in the following section.

3.3.2 Need for irrigation water throughout the vegetative cycle

For the plant to correctly develop its vegetative cycle and for all the grape berries to reach the appropriate ripeness, the amount of water available to the plant is essential and must be controlled at all times:

• During the spring months, the plant needs water to grow. If it does not rain, water must be provided through irrigation. Too much water during this period has no significant negative repercussions, except for the wasting of a scarce resource. A lack of water would prevent the plant from expressing all its vigour and reaching the required architecture. If some shoots do not grow enough, the ELA will not be entirely formed and, as a result, will not attract the necessary solar energy to ripen all the target grape production correctly. Furthermore, it will be more vulnerable to an episode of heavy rain during ripening (late August and September).
• During the month of June, the plant must reduce its growth rate to stop completely early July. Growth is no longer necessary because the required architecture has already been formed and because it is not foreseen in the means of controlling the plant. Were it to continue growing, the shoots would double in size and the ELA would not increase. The sugars synthesised by the chlorophyll function must be accumulated in the reserves to await mobilisation for grape ripening during August and September. Irrigation must be reduced until the soil moisture is sufficiently distant from the field capacity, so that he plant can transpire to cool itself and continue with the chlorophyll function to accumulate sugar reserves, although without synthesising growth hormones that would lead to the sugar being used.
• This humidity must be maintained during the hotter months (July and August) and, therefore, the amount of irrigation required becomes more important: The plant needs the right amount of water - no more (growth in detriment to sugar reserves for ripening), no less (hydric stress and plant dehydration, with the loss of ELA when the humidity of the root soil drops to levels close to wilting point). However, excessive specific rainfall in July or early August does not necessary affect the grape quality, as the plant still has time to redirect its metabolism and accumulate enough sugar.

Soil moisture, field capacity and wilting point Soil moisture is defined as the weight of water present in the soil per unit weight of dry soil. Where: Msw: moist soil weight Dsw: dry soil weight (dried in oven to 110ºC) Therefore, moisture M (in %) = (Msw- Dsw) /Dsw * 100 After heavy rain, soil may be saturated with water (all its pores are full of water) to a certain depth. When the rain stops, part of this water (that contained in the larger pores) drains by gravity to lower layers at a speed that depends on the permeability of the soil. Once this infiltration has occurred, the moisture level remaining is known as the field capacity. Therefore, the field capacity is the maximum moisture the soil can retain once all the gravitational water has migrated to the lower layer, which is why it is also known as the water retention capacity. Where no new water is soaked up, the soil continues to lose water by evaporation and by plant transpiration (in this case, vines). Water absorption by plants becomes more and more difficult as the soil moisture decreases, until the plant can no longer absorb any more water because the force of the particles and soil salts is greater than that the roots can apply. The soil moisture at this time is known as wilting point, i.e. the level of moisture when the plants can no longer absorb any more water. In the Priorat “Licorella” slate soil, the field capacity and wilting point are around 17% and 7%, respectively.

• The situation becomes critical when the plant is concentrating on ripening (late August and September), given that there is no enough time to redirect a change in metabolism. The plant must direct the sugar towards berry ripening. Too much water would be counterproductive, although not because the accumulation of sugar would be stopped or because of a grape compacting effect (morphology is determined with the distribution of vigour and there is no longer cellular multiplication in the grape), but because the change in plant metabolism towards growth would leave ripening unattended (the activity of the hypodermic cells of the grape berry responsible for using solar radiation to transform the sugar in polyphenols, tannins, aromas and colour, etc.) would be reduced, with negative effects on the quality of the wine. It is then that control of the situation becomes more
  important. This is achieved using two basic mechanisms:
  • The soil moisture, which remains sufficiently distant from the field capacity, must be concentrated as much as possible within a section of 15 cm around the roots of the stock (which is achieved by using underground irrigation, as described in Section 3.3.4). Hence, the soil can absorb any heavy rain at its lower layers and the soil moisture prior to the episode of rain is re-established in a few days. Irrigation during this period must be as precise as possible.
  • The high ratio between the effective leaf area and the root soil volume of the stock (ELA/RSV) in Mas Martinet architecture is of the utmost importance here (Figure 3.5). In fact, the need for transpiration water (demand) per unit of supply in the roots is large enough to absorb a specific increase in soil moisture following heavy rainfall. Under these conditions, the risk that excess water be generated and the plant’s metabolism change towards growth is much lower than in a plantation with a comparatively weaker demand. In general, greater demand per unit of supply provides greater control over the plant at all times, i.e. with greater dependence on the fate of the weather.

In synthesis, the plant must have the water it needs: If it has too little water, then it must be supplied (irrigation) and if it has too much them it must be possible to effectively dissipate it. Managing the water available to the plant means that its vital functions can be controlled:

• Growth control (the plant expresses all its vigour and forms the foreseen architecture).
• Hydric stress control: the necessary sugars are accumulated for ripening and the plant remains hydrated to keep its ELA in good condition and ensure the grape berries continue to develop.
• Ripeness control: Changes in metabolism due to too much water are avoided and the grapes obtain the appropriate quality and quantity of polyphenols, aromas and likely alcohol content.

It can be said that the time of irrigation is just as important or even more so than the amount of water provided.

3.3.3. Control of the hydrous state of the plant

The plant behaves like a water deposit that absorbs it from the soil and loses it through its leaves.

When the vine uses its extracellular water to transpire with greater or less intensity, its volume reduces. During times of low demand (night time, cloudy days), the plant collects water through its roots from the moisture in the soil and recovers its initial volume. This activity is constant and the contractions it causes (of several tenths of a micron) can be measured in the trunk using movement sensors known as dendrometers, made using alloys that do not dilate with temperature.

Dendrometers (to measure stock trunk diameter variations)	Figure 3.6 Daily dendrometer oscillations

The extent of daily trunk contraction reflects the intensity of the demand on the hydrous reserves of the plant.

Between the minimum value of one particular day and the maximum value of the following day, the increase corresponds to the hydric recovery plus the vegetative growth.

Trunk diameter variations (TDV) give two indicators of great value for the hydric control of the plant (Figure 3.7): the maximum daily contraction (MDC) and daily growth (DG). If this latter parameter is accumulated over time, this gives the accumulated daily growth (ADG).

Figure 3.7 Indicators for the hydrous control of the plant based on dendrometer readings. On the Y-axis: dendrometer reading in microns Source: Moisés Cohen et al. Nutri-fitos 2003.

The daily growth (DG) is a good indicator of the plant’s hydrous state. Under severe hydric stress, the trunk diameter decreases continuously that is only recovered when the plant has enough water available again to transpire.

Depending on the water needs of the vine during its vegetative cycle described in the previous section, the dendrometer graph must appear as indicated in Figure 3.8:

• During the spring months, the dendrometer graph must be ascending. The daily growth (DG) indicator must be regularly positive, i.e. the ADG must increase.
• During hot months and until the harvest, the dendrometer graph must be primarily flat. The DG is nil or of a small value.

The only exception may arise during veraison (two or three weeks during which the grape changes colour, early July in Figure 3.8): The sugar concentration increases considerably and, with this, the osmotic potential, which creates strong demand on the plant’s hydrous reserves leading to the consequent decrease in the trunk.

After veraison, where the dendrometer shows a continued drop, the plant is suffering from hydric stress that puts ripening at risk: Irrigation is necessary for the plant to be able to cool itself and so that the leaves do not close its stomata and photosynthesis^[1] detained. Where the graph is ascending, this indicates excess supply and irrigation must be reduced or stopped.

• After the harvest, the day is shorter and cooler and natural humidity is normally high. As such, irrigation loses relevance. During this part of the cycle, maintaining the leaves in good phytosanitary condition (fungus free) is considered most important so that the residual chlorophyll function can remain active. The synthesised sugars will be used to start growth the following spring.

Figure 3.8 Balanced dendrometer graph

In red: dendrometer graph In blue: graph of the soil moisture sensor at a depth of 50 cm.

The dendrometer data is extremely useful because it provides information on the hydrous state of the plant a long time before the effects of a possible imbalance are visible (excessive growth, grape dehydration, leaf wilting, etc.). Bear in mind that it may be several weeks before the visible consequences of hydrous imbalances can be seen.

3.3.4 Irrigation application and control

The need for precise irrigation that maintains the appropriate soil moisture at all times without wasting water led Mas Martinet to experiment with the installation of an underground drip irrigation system. Thus, the water reaches the roots more directly without getting lost on the soil surface where it is not required. To do so, a specially-prepared piping system was used so that the roots did not put pressure on or obstruct it. It contains water outlet emitters every 40 cm and is 40 cm underground.

In conventional drip irrigation, the water piping system is placed above ground level. For the water to reach the roots, it is first necessary to saturate the top part of the soil, which leads to an unnecessary waste of water, made even worse by surface evaporation that may become quite severe.

With underground irrigation, a moist area is created around the roots.

However, the first year of irrigation must be above the surface because the roots have not yet fully developed. From the second year, irrigation can be placed 40 cm underground.

Precise irrigation requires sufficiently precise knowledge of the amount of water to be given to the soil during each session, i.e. when irrigation must be stopped, without waiting for the response from the plant through the dendrometer readings.

To do so, moisture sensors were fitted in the soil at three depths: 30 cm, 50 cm and 70 cm, providing the necessary information, e.g.

• When the soil moisture on the roots is low and the plant begins to have problems to extract the necessary water.
• When the field capacity is being reached and irrigation must be stopped so as not to saturate lower levels.

The data from the moisture sensors are radio transmitted to the control office where it is processed and the appropriate decisions made at all times. Irrigation can be started from that same office and can even be automatically programmed.

Figure 3.9 gives a guideline as to how the soil moisture levels must be kept during the vegetative cycle.

	To do so, moisture sensors were fitted in the soil at three depths: 30 cm, 50 cm and 70 cm, providing the necessary information, e.g. When the soil moisture on the roots is low and the plant begins to have problems to extract the necessary water. When the field capacity is being reached and irrigation must be stopped so as not to saturate lower levels. The data from the moisture sensors are radio transmitted to the control office where it is processed and the appropriate decisions made at all times. Irrigation can be started from that same office and can even be automatically programmed. Figure 3.9 gives a guideline as to how the soil moisture levels must be kept during the vegetative cycle.
Sensors for measuring soil moisture at three depths: 35 cm, 50 cm and 70 cm	Figure 3.9 Relative soil moisture levels that must be kept during the vegetative cycle (illustrative in Priorat “Licorella” slate soil)

The drip irrigation installation must also be precise, i.e. when irrigation is stopped then dripping onto the roots must quickly stop. It must be taken into account that irrigation is installed on a terraced estate with steep slopes and that the water in the upper pipes tends to accumulate on lower levels due to gravity. Hence, the emitter system must ensure irrigation can be controlled at every height of the vineyard. The stock at lower altitudes must not receive more irrigation than those situations at higher levels. This strict control is not as necessary during the growth period of the plant because excess water will not cause significant problems, although it is essential as of June.

The experiments carried out by Mas Martinet within regards to applying precise irrigation and its control using dendrometers and moisture sensors were carried out in collaboration with two supplier companies: 

• Netafim, Irriwise system (supplied in Spain by Regaber): drip irrigation including the applications for automatic irrigation, dendrometers and soil moisture sensors.
• Adcon (represented in Spain by Verdtech): dendrometers and soil moisture sensors.

The episodes of rain keep the soil moist and the dendrometer graph remains balanced	The dendrometer indicates a risk of hydric stress during August. Irrigation and rainfall balance the situation

Irrigation: comparison between quality drip emitters and irregularly working emitters

3.4. Plantation framework

As indicated in Section 3.3.2, a shorter distance between rows of stock reduces the plantation framework (PF) without altering the effective leaf area (ELA) of the stock, thus increasing the ELA/RSV ratio. A high ELA/RSV ratio makes all vine growing control processes easier, although particularly that of ripening.

The distance between stock on the same row completes the definition of the plantation framework. This distance has no impact on the ELA/RSV ratio, although it does play a decisive role in the speed with which the plant’s architecture is formed:

• All foreseen shoots with their optimal dimensions (1.2 m in length, 45-55 g in weight and 6 to 8 mm in thickness).
• The effective leaf area (an average of 0.14 m2 on each shoot) so that the plant synthesises the amount of sugar it needs during its vegetative cycle.

The sooner the foreseen architecture is formed, the sooner target production with the required quality will be obtained. The Mas Martinet experiments showed that if the stock on the same row are placed closer together, the production branch is formed more quickly (Chart 3.1). It was also seen that stock closer together leads to a more uniform distribution of the shoots. The vine is a liana plant (climber, creeper) and tends to develop larger and denser shoots on the production branch (furthest away from the trunk). If the stock is close together, this effect has a smaller impact.

Chart 3.1 Impact of the distance between stock on the formation of the plant’s architecture. Double vine training
Distance between stock on the same row	Stock production arm	Production arm formed over 3 year
m	m	%
1,5	3	45
1	2	75
0,5	1	100

With stock 0.5 m apart and applying the form of control developed by Mas Martinet and irrigation, the vineyard can complete development of the entire production line during the third year. In general, it was concluded that the increase in production obtained by bringing forwards architecture formation easily offsets the greater investment in the plantation.

In double vine training with stock at a distance of 0.5 m, the length of the production branch is 1 m. If shoots are left every 7 cm, 14 shoots would be possible and, therefore, the stock should reach a vigour of around 700 g (45-55 g/shoot). This would be achieved by irrigation (and fertilisation) to offset any bad weather and soil problems that might exist. Hence, the required vigour would be distributed optimally among the shoots. Bearing in mind that the ELA of a shoot is 0.14 m2 and with production for an initial vintage wine of 0.6 kg/m2 ELA (see Section 3.5), theoretic production of a stock would be:

14 shoots/stock x 0.14 m2 ELA/shoot x 0.6 kg/m2 ELA = 1.18 kg/stock

If the rows of stock are 2.5 m apart, there would be 8,000 stock per ha (10,000/2.5/0.5) and production would be 9,440 kg/ha (8,000*1.18). If the distance between rows is reduced to 2 m, as work with smaller tractors is then possible, the theoretic production capacity would reach 11,800 kg/ha.

On an estate with thousands of vines, not all will reach the required vigour at the same time and cultivation practices must be adapted until this is achieved. In other words, 100% of the production branch will have been developed by the third year, although longer will be needed to reach the theoretic production of the vineyard.

In practice, some vines are not feasible or do not reach the vigour required by the maximum plant architecture. In other cases, the distribution of heads and buds does not allow a shoot to be left an average of every 7 cm and vigour must be limited. Furthermore, to make cultivation work easier, the vigour of all stock is normally equalled in each of the areas into which the vineyard can be divided. In view of this, real production is normally between 60% and 80% theoretic production, theoretic being considered as that corresponding to the ELA resulting from leaving a shoot every 7 cm.

To conclude, when vigour control techniques are applied, the plantation framework is determined using three criteria:

• High ELA/RSV ratio.
• Speed in obtaining the target production (in quantity and quality).
• Passing of machinery.

In general, the Mas Martinet techniques require high plantation density (first two criteria) compatible with the passing of machinery that should specifically be small (1 m wide tractor).

3.5. Stock clearing

Grape production with a sufficient concentration for a wine to keep depends on the effective leaf area, which determines the stock’s capacity to synthesise sugars for ripening.

Mas Martinet experiments show that target production with vigour distribution is placed between 0.5 and 0.9 kg of grape per m2 of ELA. For a first wine, production must be close to the lower limit and, in the case of a second wine, the top limit will be used. Young wines would accept a higher limit.

However, these values are a reference based on experimental trials and do not yet respond to sufficient scientific evidence. Some important questions still stand in relation to the quality of the polyphenols and the aromas and to the likely alcohol content.

Experiments and studies on these matters will have to continue over forthcoming years.

What is considered sufficiently verified is that the group of vigour control techniques is effective in sugar synthesis and, therefore, production per m2 of ELA may be somewhat higher than in a conventional plantation.

It must be underlined that this production of between 0.5 and 0.9 kg/m2 ELA may be obtained in the shape of large, compact grapes or small, loose grapes. The morphology does not depend on stock production but on the diameter of the shoot, which adapts by distributing the vigour between a larger or smaller number of productive shoots. Other architectures, such as the Lyra vine, are designed to increase ELA and with it production, although without influencing grape morphology.

With Mas Martinet architecture, each stock has a larger number of shoots and, therefore, produces a greater amount of grapes. To adapt production of between 0.5 and 0.9 kg/m2 ELA, stock clearing is of greater significance here than in other architectures (Figure 3.10). The following depends on clearing:

• To reach the required ripeness of the grape berries (concentration, likely alcohol content).
• After harvesting, to keep enough reserves to restart growth the following year.

Figure 3.10 Clearing is essential with vigour control techniques

The weight range of one grape produced using vigour control techniques is known for each different variety. Using this weight, the number of grapes to be left on each vine^[2] in order to respect production per unit of ELA can be calculated.

3.6. Synthesis of the basic control parameters

When Mas Martinet techniques are applied, the vigour of the vineyard stock, its production and the quality of the grape are not left in the hands of the weather or soil conditions of each vineyard but can be controlled using four forms of intervention by the vine grower (Figure 3.10):

• Vine training and pinching (plant architecture).
• Irrigation (or fertilisation).
• Plantation framework.
• Clearing.

Grape quality depends to a great extent on its morphology, which in turn depends on the plant architecture achieved through vine training. However, production depends on the intensity of clearing in relation to the ELA of the stock, according to the type of wine to be produced.

Within the plantation framework, the speed with which the target production is reached with the required quality can be controlled by the distance between stock on the same row. The distance between rows, together with the plant architecture, determine the ELA/RSV ratio, i.e. the ratio between stock demand and supply. The higher the demand in relation to supply, the greater the capacity to control the weather and soil conditions to intensify or accelerate the processes or to slow down or stop them.

The difference with more common cultivation methods lies in the way of balancing stock vigour with plant architecture:

• In general, conventional methods are based (with no precise justification) on balancing down: irrigation is limited, fertilisation is limited, low fertility soils are sought, etc. until the stock vigour is low enough to be distributed among the few shoots left on each vine.
• The vigour control method is based on balancing up: using vine training and precise irrigation techniques to ensure the stock expresses all its varietal vigour for distribution among a much higher number of shots. The method also has an added benefit the higher ELA/RSV ratio helps make ripening independent to the weather conditions.

3.7. Additional techniques

3.7.1 Pant cover 

Vines have traditionally been worked for two main reasons:

• To close off the evaporation channels formed in the soil in order to retain more water.
•  To remove weeds that compete with the stock for rainwater during growth periods and increase the risk of blight.

Working the land also has certain disadvantages:

• It breaks up lumps of soil that protect the organic matter from aerobic degradation (Figure 3.12)
• It creates surface mud that prevents water penetration and increases runoff and, with it, the risk of erosion.

Figure 3.12 Lack of physical protection for organic matter through working the land

An alternative to working the land used by some conventional plantations involves the application of herbicides.

Under no circumstances do vigour control techniques consider working the vineyard, as they are perfectly compatible with the development of plant cover on terraces and on slopes. Plant cover does not respond to an apparent need to reduce stock vigour, increasing the competition for water, but to the notable benefits it provides^[3]:

• Grass must be regularly cut (clearing) to work the land and improve the health conditions of the crop. Cut grass is left on the terrace and a biotype is created that turns organic matter into humus, thus increasing soil fertility and its resistance to degradation (erosion, compacting).
• Grass avoids direct impact of rainwater on the soil, which decreases the formation of crusts that favour surface run-off. Hence, water infiltration to the roots is increased and erosion prevented.

The growth of plant cover using quick grass may be developed in two ways:

• Plant the appropriate quick grass (reproduction using tufts and shallow roots so that it only competes for the surface moisture of the soil, which is extremely ephemeral and has less impact on the vine).
• Cut other spontaneous grass before flowering so that it cannot reproduce and allow the quick grass to colonise the soil.

Quick grass

Moreover, it has been seen that working on terraces with a single outside row of stock ends up lowering the inside of the upper slope. The ploughed land is accumulated on the inside of the terrace and may even change the direction of the sideways slope of the terraces, which would lead to the lengthways draining system breaking up and a serious risk to the stability of the entire terracing.

3.7.2 Control of disease and blight

The risk to the vine is primarily concentrated into three diseases caused by fungus: 

• Oidium (Cendrosa): The most important damage is located on the roots, as strong attacks cause the skin to stop growing, making the fruit crack and tear. Shoots also wither and the penetration of grey mould (Botrytis cinerea) is favoured.
• Mildew: This is one of the most famous and most serious diseases, as if the weather conditions are favourable, it can attack all the green organs of the vine to cause losses of up to 50% or more of the harvest.
• Botrytis (grey mould): This is seen on herbaceous organs (leaves, shoots and flower fruits), on cuttings-grafts in warm stratification chamber and primarily on bunches.

In general, three strategies can be applied for controlling these diseases:

• Systematic application of phytosanitary productions at several times during the vegetative cycle of the vine, independent to the external risk. The same applications are repeated every year.
• Collective model: The application of phytosanitary products follows the instructions of a wine producing district body created by local governments or by farming associations. These bodies base their recommendations on general risk assessment models that are fed on data from the weather stations located in the district.
• Specific model: Each vineyard provides a set of specific data from its own estate for an interactive risk assessment model that provides results that are more closely adapted to the situation of  the estate.

This latter strategy has been experimented, applying a specific model from Holland. The following information must be added frequently to the model:

- Plant growth speed.
- Vegetative state (current time of the cycle).
- Grape variety (more or less sensitive).
- Level of plant densification or compacting.
- Weather data regarding the estate. It is therefore wise to install a weather station on the vineyard.
- Historic weather data from the closest or most representative station.
- Specific conditions of the estate (presence of a disease or blight on a neighbouring vineyard, stock affected on the vineyard itself, etc.).

Fungicides for the control of vine disease The main diseases attacking vines are caused by phytopathogenic fungi. Fungicides used to control these diseases can be classified in three groups, according to the way they act with regards to the plant: - Contact: these act on the green organs entering in contact with the product. They are used in a preventative manner, i.e. to prevent the disease from taking hold of the plant. Once the disease has taken hold, they are no longer of use to eliminate it (they are not curative). Rainfall of over 10 l/m2 washes the product away and the plant becomes unprotected. Another disadvantage is that their action is limited to the treated organs (those with which they come into contact) and those forming after the treatment are unprotected. - Penetrating: as their name indicates, they penetrate the treated organs and are, therefore, not washed away by rain. Their effects are preventative and curative (once the disease has affected the plant). They do not protect untreated parts. - Systemic: these penetrate the inside of the tissue and are transported by the sap, thus also protecting shoots formed after application. They are essentially curative and are not washed away by the rain. Preventative contact fungicides based on copper and sulphur compounds are the most commonly used. They are also the most environment-friendly, as the main ingredients exist in nature. Penetrating and systemic fungicides are synthetic and, therefore, are foreign to the environment. If used, they must be alternated so that fungi do not become resistant.

Experience must be accumulated and a learning curve followed on the use of the model in order to enter the appropriate data at all times and to interpret the results. If this is achieved, however, the model is extremely effective and avoids many different unnecessary applications in relation to the other two strategies, with the consequent financial and environmental savings. It can be said that the specific model and experience may become true risk management. For example, the results from Mas Martinet in the Priorat region for 2006 were as follows:

• Systematic treatment of oidium: 6 applications (preventative and curative); Mas Martinet: 2 preventative applications.
• Systematic treatment of Mildew: 5 applications; Mas Martinet: none.
• Systematic treatment of Botrytis: 3 applications; Mas Martinet: none.

The collective model for the district gave intermediate results.

Minimisation of the use of fungicides by using the specific model can be considered sufficiently experimented, with good results.

In the Priorat region, wineries often follow the collective model whereas farmers selling the grapes prefer systematic treatments to avoid any risks, except where their customers indicate another form of procedure.

Among other controlled diseases and blight that are not included within the model, the following are of note:

• Grape moths: This is blight, the damage of which is caused by the first-generation larva that destroys the floral buds, flowers and even recently-appearing fruit. The second and third-generation larva produce more severe damage and even loss of the entire crop. The trap system is used to count moths and to decide when an insecticide is necessary.
• Root rot: This disease is caused by the fungus Armillaria mellea that takes hold of the stock roots and causes them to rot. It affects specific stock and only spreads through contact among roots. It has no treatment. The affected stock must be pulled up, the hole cleaned and covered and irrigation removed. Before planting the vine, all roots must be removed and the land turned over so that it is aired and dried, thus causing fungus inactivation.

¹Some grape varieties have response behaviours to weather and soil parameters that are somewhat different to the general rule. A very notable case is that of the Merlot variety, as was seen on the Mas Martinet estates in the Priorat region. In situations of high temperatures and low relative humidity, the plant is incapable of absorbing irrigation water through its root system to overcome stress, even with the soil at field capacity. This affects photosynthesis and, as a result, the quality of the grape and the wine. Relative humidity is a decisive factor in the plant restarting its hydrous functions. Experiments show that the Merlot variety does not find its best potential in semi-arid areas such as the Priorat region (Merlot is from the Bordeaux region, with high relative humidity as it is where two large rivers join).
² Using vigour control techniques, the average is estimated at between 0.7 and 0.9 bunches per shoot.
³ The use of plant cover is in line with European Union recommendations through the Common Agricultural Policy (CAP). More specifically, the fight against erosion in fragile mediums promoted by the CAP encourages the following measure for the growth of woody crops on terraces: “On plots with average slopes of over 10 % and soils with insufficient permeability, in order to avoid run-off problems, plant cover must be established in the centre between rows, covering a minimum of 50% of the surface using
wild flora or planting cultivated species. The specific effects of run-off produced by torrential rain must be immediately corrected.” (See Annexe II of Royal Decree 708/2002).