Mouton Noir

Index _{13. Canopy Management 14. Sustainable Viticulture}

13. Canopy Management

13.1 Introduction

Canopy management is the organisation of the grapevine plant's shoots, leaves and fruit to maximise the quality of the microclimate surrounding them, thus improving quality and yield.

It is particularly important in cool-climate areas.

Since the Second World War, technological advances (particularly in vine nutrition and pest control) and the planting of vines on fertile soils have increased problems of vine vigour leading to poor canopy management.

Canopy management in viticulture was first developed in grapevines by Nelson Shaulis (Cornell University), and further extended by Alain Carbonneau of the University of Montpellier and Richard Smart, formerly of the Ruakura Agricultural Centre in New Zealand.

See: Smart R & Robinson M Sunlight into wine. Winetitles

13.2 The Main Aims of Canopy Management

To maximise the effectiveness of light interception by vine canopies:

• Present a large canopy surface to the sun
• Encourage early development of that canopy in the spring
• Avoid inter-row shading by having a maximum ratio of canopy height to alley width of 1:1

To reduce canopy shading, particularly in the cluster/renewal zone:

• In highly shaded leaves, the rate of respiration outstrips that of photosynthesis, so the leaf consumes rather than produces energy
• Shade reduces the viability and success of floral initiation in dormant buds, thus causing an imbalance between leaf area and fruit weight leading to Smart’s vegetative cycle.
• Shaded flowers have lower rates of successful fertilisation and fruit set
• Shaded berries keep cooler and so do not ripen as well in cool climates
• Shaded fruit have lower-quality flavours and colours, as some of the
  biochemical reactions that produce these are stimulated by sunlight
• Shaded fruit and leaves have far greater risks of contracting fungal diseases, especially powdery mildew and grey rot

To produce a uniform microclimate for fruit:

• A uniform microclimate leads to more synchronised ripening, which leads to a greater chance of picking at the optimum period.

To achieve an appropriate distribution of the products of photosynthesis:

• Too much fruit and not enough leaves (over-cropping) will generate poor-quality fruit and reduce vine vigour
• Too many leaves and not enough fruit will cause over-vigorous growth, which will also produce poor-quality fruit.

To arrange the locations of individual organs in restricted zones in space:

• This facilitates mechanisation, particularly in pruning, pesticide application and harvesting

The first step in canopy management is diagnosis.

13.3 Assessing Canopy Quality

The Richard Smart Vineyard Scorecard (on the next page) can be used from veraison to harvest to assess the quality of canopies.

In order to obtain data for this scorecard, a point quadrat technique can be used:

• A sharpened metal rod is stabbed 50 times into the canopy at right angles in the fruit zone in random areas.
• Contacts with leaves (L), clusters © and canopy gaps (G) are noted.

% Canopy Gaps = (Number of Gs / 50) x 100

Optimum 40 % Canopy Gaps Mean leaf layer number = (Total number of Ls/ 50)

Optimum 1 – 1.5 leaves Fruit exposure = (Number of external Cs/ Total number of Cs ) x 100

Optimum 60% fruit exposure

13.4 Canopy Management Techniques

13.4.1 Site Assessment

This is done by:

• digging a soil profile
• assessing the water supply
• soil fertility tests
• Observing the performance of plants on a similar soil

Smart classes sites into three categories:

• High potential sites: Deep (> 1 m), fertile soils, good water supply, high nutrient levels.
  • These require low-density planting (< 3000 plants/ha) and complex trellis systems, such as RT2T & GDC
• Medium potential sites: Soils 0.5 – 1m deep, adequate water supply and average fertility
  • These require average plant densities (3000 – 5000 plants/ha) and systems such as Lyre, Scott-Henry and large VSP
• Low potential sites: soils less than 0.5 m deep, poor water availability during the growing season and low fertility.
  • High-density (> 5000 plants/ha) VSP systems can be used on these sites.

13.4.2 Trellis selection

Criteria for assessing trellis systems:

• Legislation
• Plant density, alley width and trunk length requirements
• Features of site, e.g. frost susceptibility, wind exposure.
• Effectiveness of light interception (total exposed canopy surface/ha)
• Quality of canopy microclimate
• Cost & time of establishment (posts, wire, plants)
• Cost and time of maintenance (pruning, shoot positioning)
• Mechanisability (harvest, pruning etc...)
• Popularity and attractiveness

13.4.3 Winter Pruning

Reasons for pruning vines:

• To organise the plant on the trellis
• To allow for the passage of machinery and manpower
• To produce a balance between the crop and leaf area

13.4.4 Vigour Control

Excessively low vigour is generally due to:

• Drought stress —> Irrigation
• Low soil fertility —> Increase fertilisation, drainage, soil organic matter, etc.
• Disease —> Diagnose & treat

Excessively high vigour can be more difficult to control.

Possible strategies include:

• Selection of low vigour rootstocks
• Water stress in irrigated vineyards
• Cover cropping in alleys
• High-density planting: this only works in low-potential sites
• Removing alternate vines along the row: this allows vines to spread along a greater length of trellis, thus reducing shoot vigour and canopy density
• Root pruning: a subsoiling tine is passed through the vineyard at 30 – 50 cm from the vine row after harvest or pre-budburst. Difficult to predict response as pruning will stimulate root growth.
• Retro-fitting a more complex trellis system: e.g., going from VSP to Scott Henryby increasing post length

13.4.5 Shoot Positioning

Shoot removal or bud-rubbing Vine shoots are removed if they are:

• Badly positioned and so will have to be removed at winter pruning anyway
• In contact or too close to the ground (Peronospora)
• Infertile (low-yielding plants)
• Rootstock shoots
• Causing too much canopy shade, particularly if growing in the centre of the plant, thus causing shade in the renewal zone for cane-pruned systems. Aim for 15 shoots/metre of trellis
• Supplementary to those left during winter pruning, the fruit/leaf surface ratio is affected.
• Laterals

This operation should be carried out after the risk of spring frosts but before flowering. It should not be done too severely on young plants.

Often done by hand (17 ~ 50 hours/ha), but shoots can be removed from the trunks by machines or herbicides (half-dose Paraquat)

Tucking in

• The aim is to organise the canopy and facilitate mechanisation.
• Important that upright canopies or shoots will bunch together and flop onto the ground, preventing the passage of machinery.
• Can be done by hand, using moveable wires, or with machines.
• Also important in downward-growing canopies, as shoots will resist growing downwards and form irregular canopies.

13.4.6 Summer Pruning

This is the least effective method of canopy management.

Pinching

• The selective removal of shoot tips around flowering. Usually done manually.
• The aims are to regularise shoot growth and improve the berry set.
• In vigorous vines, this leads to an increase in the development of lateral shoots, so these have to be removed.

Trimming The cutting off of shoot extremities, either by hand or by machine.

Objectives:

• Control excessive shoot growth to facilitate the passage of manpower and machinery and reduce inter-row shading and wind damage
• Reduce canopy thickness to improve the microclimate and increase spray penetration
• Encourage the onset of maturity by discouraging shoot growth, which stimulates berry development
• To look good

Trimming normally starts in July after the last tucking-in. It should not be done too early or too severely.

Leaf stripping Removing leaves around the fruit zone, usually between veraison & berry ripening. Usually done by hand, but can be done by machine.

Objectives:

• Improve canopy microclimate, thus improving fruit quality
• Improve fruit health
• Improve spray penetration
• Increases speed of manual harvesting

Aim for 60% bunch exposure, but it should not be too severe in one pass. It can take up to 70 hours/ha!

For northern hemisphere vineyards:

• In N —> S rows, start on the Eastern side and only do the Western side in cool climates
• In E —> W rows, start on the Northern side and only do the Southern in cool climates

Crop thinning or green harvesting The removal of flowers or berries to regulate the crop.

Essential in very young vines to help them get established.

The aim is to:

• Control leaf area: fruit ratio so as to get optimum ripeness
• Conform with legal control on yields

Usually, the bunches on laterals and those nearest the shoot tips are removed.

If done too early (pre-veraison), vines will react by increasing the rate of berry cell division, thus increasing berry size.

It will be less effective if done post-veraison, as sugars will already have moved into the berries. So best done around veraison.

Usually done by hand: a very laborious task that will take around 50 hours/ha.

It can be done by a chemical spray (Ethrel C), but not recommended, as the results are unpredictable.

13.5 Conclusions

Canopy management theory has influenced New World viticulture considerably, particularly in areas of high vine vigour. Many varied training systems have been developed and are used commercially.

14. Sustainable Viticulture

14.1 Organic Viticulture

14.1.1 Principles

Aims:

• To coexist with, rather than dominate natural systems:
  • Enhancement of biological cycles
  • Maintenance of ecological diversity within and around cropped land by managing habitats such as banks, hedges, ponds, etc.
• To sustain or build soil fertility (“feed the soil, not the plant”)
  • Use of crop rotations
  • Rational use of manure and vegetable wastes
  • Use of appropriate cultivation techniques
• To minimise damage to the environment
  • In particular, avoid mineral salt fertilisers and agrochemical pesticides
• To minimise the use of non-renewable resources

Regulation:

• Guidelines are laid down by IFOAM (the International Federation of Organic Agriculture Movements)
• Enshrined in EU regulation 2092/91 (July 22 1991)
• Regulations enforced by the UK Register of Organic Food Standards, a division of Food from Britain. This body receives notifications from operators, inspects Organic growers, and approves and supervises private inspection bodies (Approved Sector Bodies)
• The Soil Association is an Approved Sector Body (one of 5 in the UK), but the only one to approve vineyards. Founded in 1946 to research and promote Organic practices and guardian of the Soil Association symbol. Registration is currently about £300 plus an annual fee of 0.25% of sales (minimum £300, maximum £5000)

14.1.2 Production Standards

Record keepin Must keep physical and financial records of:

• Brought-in materials (e.g. fertilisers and sprays)
• Brought-in plants (noting things such as source, status and any treatments during propagation)
• Field cropping histories
• Details of manure, fertiliser and spray applications

Conversion from conventional production systems

• A 3-year plan designed to result in a viable and sustainable system operating to full organic standards must be drawn up by the grower.
• This must include a soil fertility-building stage with details of crop rotation, manure management and appropriate cultivations.
• Conversion must take place on a farm or part of a farm that is large enough to be viable and free from pollution from spray drift, traffic and factories
• Prohibited inputs may not be used at any stage during the conversion.
• This conversion plan must be submitted to a Certification Committee appointed by the Approved Sector Body, which reviews and monitors it at least once a year.
• In-conversion produce may be sold using the wording “Soil Association approved Organic conversion” or “IOFGA approved organic conversion.”

Soil Management Developing and protecting optimum soil structure and fertility is the main goal of Organic soil management.

Optimum soil structure is described as: “a water-stable, organically enriched, granular structure where all the water reserves within aggregates can be fully exploited by root hairs and the space between aggregates will be large enough to allow rapid drainage to admit air and to facilitate the deep penetration of roots” (Elm Farm Research Centre; The Soil 1984).

In order to attain this, the following recommendations are made:

• Regular input of organic residues
• The encouragement of a high level of activity in soil organisms, particularly micro-organisms
• A protective covering of vegetation, if applicable, and in particular, the use of green manure
• Appropriate cultivations, well timed, which achieve a deep loosening of the soil but avoid damage to the existing structure.

Crop rotations These are recommended to:

• Aid the maintenance of soil fertility, in particular, soil organic matter levels and soil structure
• Provide adequate nutrients and reduce nutrient losses
• Minimise weed, pest and disease problems

Manure management In Organic systems, there must be maximum recycling and minimum losses of materials.

All brought-in or conventionally produced manures must be approved by the Certification Committee and must be composted before use.

Compost heaps should be covered up and maintained for at least three months. High temperatures (optimum 60°C) are recommended to destroy weed seeds, pathogens, chemical residues and antibiotics.

Brought-in manures from un-organic farms are ‘restricted’ (permission from the Certification Committee must be sought), and manures from ethically unacceptable livestock systems are prohibited.

The maximum levels of heavy metals in manures and soils are controlled.

Care must be taken to avoid contamination of waterways or underground water in manure storage, handling or spreading.

Supplementary nutrients Mineral fertilisers should be regarded as a supplement to, and not a replacement for, nutrient recycling within the farm.

Only fertilisers that release nutrients through an intermediate process, such as weathering or the activity of soil organisms, are allowed, but ‘restricted’ use of highly soluble nutrients is allowed to treat severe mineral deficiencies.

Weed control The objective is to suppress rather than eliminate weed populations by:

• Crop rotation
• Manure management
• Fertilisation
• Utilisation of green manures

The short-term use of plastic mulching is permitted, but all synthetic herbicides are prohibited.

Pest control Emphasis is on prevention rather than cure.

Key control methods:

• Good husbandry or hygiene
• Balanced supply of plant nutrients
• Use of resistant varieties
• Creation of an ecosystem that encourages predators (e.g. use of hedgerows, plant breaks, companion planting)

The routine use of Bordeaux mixture and sulphur is restricted, but all other pesticides approved on vines are prohibited. ‘Pesticides’ based on plant extracts (e.g. horsetail, onion, garlic, tansy, wormwood, stinging nettle, rhubarb, regania, neem, quassia, pyrethrum, rotenone) are permitted.

Conservation Prohibited practices include:

• Drainage of wetlands
• Hedge trimming between the end of March & beginning of September

13.1.3 Conclusions

Still a very small part of the English Wine sector, but rapidly expanding in countries such as Italy (30,000 ha), Germany & France.

14.2. Biodynamic Viticulture

14.2.1 Introduction

Derived from the work of Rudolph Steiner (1861 – 1925), an Austrian social philosopher, founder of ‘anthroposophy’ and a Theosophist in later life.

Ms Maria Thun and her team in Germany & Holland developed a Biodynamic farming method. This method is not prescriptive but is, above all, a base for individual work inciting each person to develop personal relationships with his environment.

In 1998, there were 15,000 hectares of Biodynamic vines in France 200 hectares in the USA.

The approach is highly spiritual and rather intangible, but some of the basic principles include:

• A holistic (almost anthropomorphic) approach to the planet Earth
• Earth having a ‘cosmic’ relationship with the other planets in the Universe
• The plant is sensitive to these ‘life forces’, and so its cultivation must consider cosmic aspects. Different arrangements of the sun, moon, and planets will favour different parts of the plant, such as the roots, leaves, flowers or fruit.
• Cultural methods and products are employed that aim to channel cosmic forces in the plant and soil, making them vibrate in harmony with the universe

14.2.2 Biodynamic Practices

As Earth and the plants are sensitive to ‘cosmic’ forces, interventions must be governed by the positions of the planets (particularly the sun and the moon) in the zodiac.

For example:

• Root and fruit days are best for planting
• Fruit days are best for cultivating and any treatment that aims to produce quality fruit

Three preparations (or ‘medicines’ are used), which must be ‘dynamised’ by putting the product in water and mixing in a special way for a precise period of time:

1. Dung compost or Maria Thun (502 – 506)

• Made up mainly of cow dung, silica, limestone and various plant-based preparations (such as chamomile, nettle, oak-bark and dandelion)
• For soil applications: supports and reinforces the decomposition of organic matter

2. Horn dung (500)

• Made of dung placed in a cow’s horn that is buried over winter, where it fills up with vitalising energy.
• It activates the elements of the soil towards the plant, thus stimulating root development. This enables better absorption of nutrients and enhances drought resistance.

3. Horn silica (501)

• Made of finely ground silica placed in a cow’s horn and buried during the summer, where it becomes energised by the sun’s forces.
• It treats the atmosphere to allow light forces to reach the plant and helps assimilation by the leaves of micronutrients found in the atmosphere in homoeopathic quantities.
  

Biodynamic growers also use compost and manure for plant nutrition.

The aim is to produce plants with ‘harmony’ that defend themselves rather than attract pests.

However, growers are still permitted to use Bordeaux mixture (3 kg/ha) and sulphur (7 kg/ha), but are encouraged to use natural herb concoctions.

Dynamised ashes of target pests (e.g. insects or rabbits) sprayed onto the foliage are also used to control pests.

14.2.3 Conclusions

Some growers come to Biodynamics through the philosophy, but most begin by applying the practices.

Growers claim to have healthy vineyards, improved wines, improved health, and the ‘honour of participating in the regeneration of our planet’.

However, they have increased monitoring of the vineyard and are constrained by the Seedling Calendar, which over-rides public holidays, etc.

14.3 Integrated Viticulture

Developed by the International Organisation for Biological Control (IOBC) over 40 years. Has it roots in IPM.

Now firmly established in Switzerland (7000 hectares) and Southern Germany.

Definition: Integrated Production is a system that produces high-quality food and other products by using natural resources and regulating mechanisms to replace polluting inputs and to secure sustainable farming.

14.3.1 Aims

A holistic approach whose main aims are:

• Better management of resources
• Viewing the entire farm as the basic unit
• Balanced nutrient cycles
• Preservation and improvement of soil fertility
• Environmental protection
• The central role of agro-ecosystems
• Maintenance of a diversified environment
• Improved crop quality
• Economics

14.3.2 Guidelines

Guidelines for Integrated Production of Grapes (IOBC 1999):

• To promote viticulture that respects the environment, is economically viable, and sustains the multiple functions of agriculture, namely its social, cultural and recreational aspects
• To secure sustainable production of healthy grapes of high quality and with a minimum occurrence of pesticide residues
• To protect the farmers’ health while handling agro-chemicals
• To promote and maintain a high biological diversity in the ecosystem of the vineyard and in surrounding areas
• To give priority to the use of natural regulating systems
• To preserve and promote long-term soil fertility
• To minimise the pollution of water, soil and air

14.3.3 Recommended Practices

Practices that are promoted to meet these principles are:

• Reduction in chemical inputs, particularly broad-spectrum pesticides in order to protect and enhance natural regulating mechanisms
• The establishment of a permanent or temporary green cover in regions with precipitation above 700 mm/year, thus increasing the biodiversity and ecological stability of the system and encouraging insect predators and parasitoids and controlling pests. This also controls the nitrogen cycle, reduces erosion, improves soil structure and reduces nutrient loss
• The proper management of that cover (alternate mowing) to allow a constant supply of flowering plants
• The mowing of the cover crop to synchronize the nitrogen availability in the soil with the nitrogen demand of the grapevine
• For new vineyards, the selection and harmonisation of new sites, rootstocks, cultivars and planting systems to produce regular yields of quality grapes with minimum use of agro-chemicals and environmentally hazardous practices
• The training and pruning of grapevines to achieve a balance between growth and regular yields and to allow good penetration of light and sprays
• The proper ventilation of the grape zone in humid areas
• The conservation of soil quality and life by recycling nutrients and restricting the quantities of fertiliser used
• The avoidance of groundwater pollution with fertilisers, especially nitrates
• Irrigation only applied according to need, on close monitoring of soil water content
• Priority on plant protection given to indirect preventative measures (such as the use of resistant cultivars, appropriate training systems, and avoidance of excess nitrogen), followed by direct control measures, if necessary based on economic thresholds, risk assessment and forecasting services
• At least two key natural pest parasitoids or predators must be identified or introduced, then protected and augmented.
• Populations of pests and diseases must be regularly monitored and recorded using scientifically established assessment methods appropriate to the region.
• Any treatments must be based on scientifically established threshold levels and scientific forecasts of pest risk.

14.3.4 Implementation

To gain endorsement by the IOBC, viticulturists form IP-organisations that submit statutes, guidelines and protocols. These can vary regionally.

For certification, the grower submits complete records on fertilisers, pesticides and cultural practices and is subject to unannounced inspection at least once a year.

The performance of the grape growers is evaluated annually using a point system or Bonus-Malus system:

• No points are given to traditional practices that do not make use of ‘softer’ alternatives
• Bonus points are given to practices that are in line with IP guidelines
• Any practice that violates IP objectives is given a Malus point and causes the disqualification of the respective farmer as an IP grower.

Certain levels of Bonus points, say 50%, are required for a grower to be approved in a regional IP association, e.g. VINATURA in Switzerland.

Index _{10. Vine Nutrition 11. Vineyard Floor Management 12. Pest Management in Vineyards}

10. Vine Nutrition

10.1 Soil Fertility

Soil is the primary raw material from which all food is produced, and so is the basis of all agriculture.

Agriculture is blessed with a raw material that, with careful husbandry and supplementation of some ingredients, will regenerate itself to be used year after year.

The soil is not a simple inert medium. For plants to grow in it, it must have a characteristic called fertility.

Essential that a good farmer understands the basics of soil science so that he/she can assess & maintain the soil's fertility.

Fertility is a complex feature influenced by the following factors:

• Texture
• Structure
• Organic matter content
• Mineral content
• Availability of air and water
• Acidity

10.1.1 Soil Texture

The size of particles that make up soil and their proportions relative to each other.

The particles in soil are graded according to their diameters in the following way: 0 – clay – 0.002 – silt – 0.02 – fine sand – 0.2 – sand – 2 – gravel – 2+ (mm)
Heavy soils: high clay Light soils: high sand

Clay soils retain more moisture than others, as they comprise very small particles: a kilogram of clay will contain a much larger surface area for water adsorption than a kilogram of sand.

Clay soils will also hold more minerals, as the particles are negatively charged.

But clay soils have several disadvantages:

• Take longer to heat up in spring and tend to be colder all year round.
• Swell when they absorb water and shrink when they dry. This can cause severe cracking.
• As clay becomes wet, it becomes very sticky
• If clay soils are worked when wet, their structure can deteriorate severely.

The ideal soil texture is loam, which combines the nutrient-holding features of clay with the good drainage of sand.

Soil textures can be assessed by feel.

10.1.2 Soil Structure

Describes how the soil forms lumps or crumbs

Controls water and air availability to plants and fine-feeding roots' ability to divide within the soil and hence exploit the essential plant nutrient supply.

Influenced by agents such as:

• Organic matter
• Earthworms and other soil organisms
• Wetting and drying
• Freezing and thawing
• Presence of plant roots
• Cultivation
• Texture
• Drainage
• Compaction

Good soil structure is where the particles form firmly bonded, stable, crumb or granular rounded aggregates 1 – 5 mm in diameter. For this to occur, there must be high to moderate organic matter content (3 – 10%).

Poor soil structure leads to capping, puddling and sieving.

10.1.3 Soil Organic Matter

The raw material consists of plant and animal remains and animal excreta. Broken down in the soil by soil organisms: beetles, mites, earthworms, fungi and bacteria.

These are present in vast numbers in fertile soil; worms can number 2 million per hectare, and microorganisms can weigh 2.5 t/ha.

Organic matter is composed of:

• Sugars, starches, cellulose, nitrogenous compounds
• Lignins and mineral matter

The soil organisms rapidly break down the sugars, starches, nitrogenous compounds and some cellulose. This process is called mineralisation.

The remaining matter is decomposed much more slowly and forms a black or brown mixture called humus.

This humus has several beneficial effects on the soil:

• Maintenance of soil structure
• Retention of available nutrients
• High water-holding capacity
• Low plasticity and cohesion
• Gradual release of available nutrients
• Darkening of colour

Losses of organic matter from arable soils will be increased by any activity that increases microbial activity, such as cultivations and nitrogen fertiliser applications. Permanent pasture and minimally cultivated soils maintain their organic matter content better than cultivated soils.

10.1.4 Soil Depth

Very important, as it can compensate for low nutrient status and low water-holding capacity. When digging soil profile, look for:

• Drainage barrier
• Root barrier
• Pale & mottled colours (poor aeration)

10.1.5 Water and Air in the Soil

Water is essential in the soil as:

• It allows organisms to live in the soil and break down organic matter to release nutrients for the plant.
• Maintains structure (e.g. prevents erosion)
• The plant absorbs most of its nutrients from the soil in water and relies on this water for the transport of nutrients and sugars within its body
• It keeps plant cells turgid ('bloated') to provide support.

Vines need at least 500 mm of available water during the growing season.

Aeration is essential in the soil as:

• Provides oxygen to aerobic organisms and suppresses the growth of harmful anaerobic organisms.
• Removes carbon dioxide and other waste gasses formed by the breakdown of organic matter and by plant roots
• Provides the roots with essential oxygen, thus sustaining their respiration & growth.
• Prevent the reduction of iron and manganese to their reduced forms, particularly in acid conditions, which are toxic to plants.
• This air movement can be severely restricted in poorly structured clay soils and heavily compacted soils.
  

10.1.6 Soil Nutrients

Soil nutrients are divided into major or minor elements according to the relative quantities plants use.

Major elements:

Element	—	Description
Nitrogen	N	Major constituent of plant cell proteins, nucleic acids, chlorophyll, & hormones. Second only to water in controlling plant growth.
Phosphorus	P	Key element in energy fixation. Encourages root growth and the ripening process.
Potassium	K	Regulates flow of water and sugar in the plant, regulates internal acidity, enzyme activator. Encourages ripening.
Calcium	Ca	Regulates cell acidity, a component of cell walls.
Sulphur	S	Essential constituent of some amino acids and enzymes.
Magnesium	Mg	Essential component of chlorophyll, regulates internal acidity and sugar metabolism. Encourages ripening

Minor or trace elements include Boron, Manganese, Copper, Iron, Molybdenum, Zinc, Cobalt, Chlorine & Silicon.

A deficiency of any of these elements will lead to serious crop reduction and in some cases will lead to leaf or shoot symptoms.

Carbon ©, Hydrogen (H), and Oxygen (O) are also essential for plant growth, but these are taken from the air or as water, and so are not considered as soil nutrients.

10.1.7 Soil Acidity

Soil acidity is measured by the pH scale. This measures the concentration of hydrogen ions in the soil solution. A pH value of 4 ~ 7 is acid, pH 7 is neutral, and 7 ~ 8.5 is alkaline.

Acidity has a considerable influence on nutrient availability and soil organisms. Different crops have different pH tolerances.

Soils tend to become more acidic with cultivation due to the release of organic acids on the breakdown of organic material.

10.2 Vine Nutrition

Vineyard nutrition is not an exact science as:

• Soil fertility is a complex concept
• Low nutrient crop, as:
  • Little is exported from the field
  • Perennial plants explore a large area of soil
• Influence of rootstock
• Problem of quality vs. quantity

Grapevines can grow and crop satisfactorily in a wide range of soils, but many ignore vine nutrition at their peril!

Need to answer these questions: 1. What are the essential elements for the growth and performance of vines? (See above) 2. How can you measure the need for these? 3. What fertilisers can you use to fulfil this need? 4. How much and when should these be applied?

10.2.1 Determining the Vine’s Nutritional Requirements

Calculating the loss of nutrients from the field Could be simple, but in fact, complicated:

Losses	Gains
Uptake by vine Removal of crop Leaching Erosion	Return of leaves and prunings Fixation of Nitrogen from air Rain

Soil analysis Essential before planting and every 2 – 3 years The most crucial part is getting a representative sample:

• Divide the vineyard into blocks according to different types of soil
• Don’t sample areas that have had recent fertiliser applications or very wet soils
• At least 25 samples/block. Use a zigzag shape
• Depth 20 – 60 cm, but useful to take surface ones as well.
• The larger the sample, the better
• Mix samples in a bucket, then send about 500 g
  

Nitrogen is not usually measured in soil analysis, as its levels are particularly dependent on seasonal factors such as soil moisture, aeration, temperature and the activity of soil organisms.

Interpretation is not easy, but can use ADAS figures as a rough guide.

Leaf and petiole analysis Remove 100 leaves from the nodes opposite the lower bunches at veraison or full bloom (or both). In dry areas, samples should be taken early in the day (before stress) but not directly after overhead irrigation.

Wash leaves to remove pesticides, dry, and then send off leaves or petioles for analysis.

Useful for:

• Confirming visual symptoms
• Comparing good vine areas with bad
• Assessing the effectiveness of fertiliser applications or changes in practices such as irrigation and weed control

Unfortunately does not tell you how much to add.

Observing deficiency symptoms Must learn to recognise them, but:

• If symptoms are sporadic, they are probably due to something else, such as root or bark damage, girdling with ties, viral diseases
• Deficiencies might affect vine performance without showing symptoms (‘hidden hunger’) e.g. Magnesium & zinc
• Multiple deficiencies are difficult to diagnose

10.2.2 Fertilisers

Straights: containing only 1 plant nutrient Compound: two or more nutrients (more expensive, but more commonly used as easier) Organics: derived directly from fresh or composted plant or animal material.

Nitrogen

• Ammonium nitrate: (34% N): most popular, used in spring or early summer
• Ammonium nitrate lime: (21 – 26% N) same as before, but better on acid soils, as it does not raise acidity. Difficult to store, as it soaks up moisture & goes pasty
• Urea (46% N): the cheapest & most concentrated but needs to be washed or worked into the soil, or losses are high, particularly in alkaline soils.

Phosphorus (P) Can be: Water-soluble: readily available to plants Citrate soluble: slowly available to plants Acid soluble: unavailable, except in acid soils

• Triple superphosphate (47% water-soluble): treated with phosphoric acid
• Superphosphate (18 – 25 water-soluble): ground rock phosphate treated with sulphuric acid. Most commonly used, usually mixed with sulphate of ammonia and a potassium carrier.
• Ground rock phosphate or Hyperphosphate (29% P): acid-soluble P only, so use only in acid soils. Permitted by the Soil Association.

Potassium (potash)

• Muriate of potash (potassium chloride): Commonest form (cheapest) but does not store well or spread easily. High chlorine levels can be toxic to the vine.
• Sulphate of potash: more expensive. Restricted use is allowed by the Soil Association. Potassium nitrate – too expensive, but can be used in foliar sprays & fertigation.

Magnesium

• Epsom salts (10% MgO): magnesium sulphate. Soluble, quick acting, often used as a foliar spray. Restricted use allowed by the Soil Association
• Kieserite (16-17% MgO): slower acting, minimum 1 month, restricted use by SA
• Calcinated magnesite (48% MgO): the most concentrated form, but the slowest acting (3 months)
• Dolomitic limestone (9% MgO): can be used instead of lime in acid soils.

Calcium Used to correct soil acidity. Measure in CaO units.

Graded according to neutralising values (NV), which is the same as % CaO content. Limestone or chalk (NV50 –55) or dolomite (magnesian limestone NV50 – 55) is used. The finer the lime, the more rapid its reaction. Particles greater than 2 mm are ineffective.

The amount needed will depend on the following: * Actual soil pH & optimum required (6 ~ 7.5 depending on rootstock) * Soil texture (clay soils need more) * Soil organic matter (organic soils need more due to high buffering capacity)

Autumn is the best time to apply. Do not apply rates above 10 tons/ha in a single application

Organics Derived from plant and animal materials

Advantages:

• Cheap or even free
• High in humus, therefore good for soil structure & water retention
• Encourage soil organisms
• Improved soil aeration
• Slow-release
• Often approved by Soil Association

Disadvantages:

• Slow release, often nutrients are in insoluble forms that need to be broken down by micro-organisms, thus requiring incorporation into the soil
• Bulky and so expensive to transport and spread

Farmyard manure (FYM)

• Animal dung & urine, and litter are used as slurry
• Animals only use about half the nitrogen, most of the phosphates and nearly 40% of potassium found in their feed. The rest remains in the faeces.
• Varies in composition, according to the animal that produces it, whether it is breeding or fattening stock (better), the way the animals are kept and the amount of straw used, the time and manner of storage

Slurry

• Cheaper than using straw, easier to handle & store
• Again, very variable composition.
• Higher risks of polluting watercourses, particularly if applied in cold weather when microbial activity is insufficient to bind the nutrients.
  

Cereal straws

• One ton of straw supplies about 4 kg N, 1 kg phosphate & 9 kg potash but needs the addition of about 6 kg extra nitrogen.

Green manuring

• Growing and ploughing in green crops to increase the organic matter content of the soil.
• Planting is usually in the early autumn, ploughing-in in early summer.
• Most common is white mustard, sown at 9 ~ 17 kg/ha, which can produce a crop ready for ploughing within 6 ~ 8 weeks.
• Fodder radish also grown
• Leguminous crops such as vetch will increase soil nitrogen content due to their associations with Rhizobium bacteria in their root nodules.
• Cereal roots can also be beneficial, as their roots break up the soil.

A good crop can produce 20 t/ha, which will produce 300 – 600 kg of humus Improvement of OM of soil is short-lived as the crop consists mostly of cellulose, which is rapidly broken down.

Cover crops have other advantages, such as reducing water run-off, facilitating weed control, binding nutrients otherwise lost by leaching, and reducing dust problems.

Can be too much competition with the vine in dry summers.

Foliar fertilisers

Advantages:

• Less waste
• Useful for nutrients that may otherwise become immobilised in the soil
• Some can be applied at the same time as pesticides (not chelates with copper)
• Very rapid action
  

Disadvantages:

• Some nutrients, such as phosphate, are not easily taken up by the leaves
• Risk of leaf burn if the concentration is too high

Best to apply under conditions in which the droplets remain unevaporated on the leaf surface to allow for penetration.

Best to use high volume applications (over 1000 l/ha) Usually only used for temporary deficiencies as high doses and concentrations will cause scorching

10.2.3 Fertiliser Application

Pre-planting

• To correct soil deficiencies or high acidity (raise pH above 6)
• To give young plants a good start in life

Especially used for slow-migrating minerals like P, K, Ca & Mg, not usual for nitrogen due to the high level of mineralisation of organic matter & high mobility.

Common to add organic manure to improve soil structure and stimulate soil life.

Fertilising established vines Based on the assessments above Importance of balanced nutrition, in particular: Mg/K, N/K, Mn/Fe

Timing:

• N in spring. The greatest period when the vine’s demand outstrips the soil’s supply is at flowering
• P & K in autumn (or spring in light soils)

11. Vineyard Floor Management

11.1. Introduction

The aim of vineyard floor management (VFM) is not just to control the weeds in the vineyard but to provide an ideal environment for root development and the vineyard's management.

Ideal Soil Condition	Soil Management Technique
Loam texture	-
Stable crumb structure	Adding OM, lack of disturbance, VFM
Sufficient water	Irrigation, improve structure, VFM
Good drainage and aeration	Drainage, good structure, control soil compaction, VFM
High level of microbial and microbial activity	Correct pH, add OM, reduce chemical ferts & herbicides, VFM
pH 6.5 – 7.5	Lime applications
Sufficient nutrients	Fertiliser/FYM applications, VFM
Sufficient depth & volume	VFM, drainage

11.2 The need for weed control

A weed is any unwanted plant in a cultivated area.

Calling a plant a weed is very subjective, e.g. blackberry is generally regarded as a weed, but in the USA, they can be encouraged, as they are the overwintering host of the Anagrus wasp that parasitises the grape leafhopper.

Disadvantages of weeds:

• Compete with vines for soil water, space & nutrients. The dock can even block drainage pipes.
  • Note that wild plants are usually better adapted to the soil conditions than crop
• Smothering of aerial parts of the vine, especially young ones
• Hamper the passage of:
  • Machinery, e.g. harvesters & black nightshade
  • Manual labour – e.g. thistles, nettles, brambles
• Increase frost risk by forming an insulating layer on the soil surface
• An act as hosts for pests and diseases, e.g., broad-leaved species of ground cover will host eggs of light brown apple moth in Australia
• Look unattractive

Advantages of ‘weeds’:

• Prevent soil erosion
• Prevent nitrate leaching
• Encourage biodiversity
• Reduce excess vine vigour
• Improve soil structure
• Indicator weeds
• Can look attractive
• Possible crop

Important to understand wild plants:

• Identify, particularly when young
• Know whether ephemeral, annual, biennial, perennial, monocotyledon, dicotyledon
• How they reproduce, spread and perennate

The main weed control methods in vineyards are cultivation, ground cover, herbicides & mulching.

Need to know how to do it and the advantages and disadvantages.

11.3 Cultivation

Traditional method: ‘quatre façons’:

• Autumn (after harvest): the soil is ridged up under row with vineyard plough max 20 cm in depth, creating a middle furrow.
• Spring (when soil is dry enough): de-ridging with shares pointing inwards & inter-row shares (finished off manually)
• Can be repeated twice during summer or replaced by other tools such as harrows (spring tines, discs, duck’s feet) or powered implements (rotary cultivators, power harrows), inter-row weeders

To preserve its structure, the soil must be cultivated as little as possible and never when wet. It is best to cultivate when vine roots are active (6 leaves apparent) to take up released nitrates.

Advantages:

• Very effective weed control
• More efficient use of fertilisers
• Decreases disease risk due to burying of trash and reducing puddling
• Decreases soil compaction
• Increases rain penetration, thus reducing runoff and erosion
• Increases soil evaporation in damp climates, decreases it when dry
• Brings stones to the surface
• Encourages root vigour and deep root development
• Protection of trunks against the winter cold
• Aesthetic
• Ecologically sound

11.5 Natural Vegetation

Well-suited to conditions, cheap and leads to greater biodiversity, but it can be difficult to manage and harbour pests.

Important to manage cover crop properly:

• Mow very closely before budburst (frost)
• Mow again a couple of weeks before flowering to boost vigour
• Allow to grow at veraison
• Alternate row mowing will allow better biodiversity

Note that some cover crops will not survive close mowing.

As crops get more mature, their biomass increases, and they become woodier, thus taking longer to break down when mown or incorporated into the soil.

Advantages:

• Increased bearing capacity (trafficability) of the soil, particularly in wet weather
• Good soil structure: high organic matter levels and roots break up soil, reducing compaction.
• Leguminous plants (clovers, medics and vetches) can reduce fertiliser requirements.  Control of vine vigour due to competition with water
• Encourage deep rooting in vines
• Reduced erosion risk & increased water infiltration
• Suppression of undesirable weeds by competing for light
• No dust or mud problems
• Surface mulch is formed, which can trap moisture in the soil
• Reduced nitrate leaching.
• Possibility of secondary crop
• Aesthetic
• Environmentally acceptable, can increase biodiversity.
• Promotes soil life

Disadvantages:

• Reduction in vine vigour can be excessive, particularly with young vines, poor and shallow soils or dry climates (<650 mm annual rainfall)
• Humidification of microclimate, encouraging fungal diseases
• Cooling of microclimate, discouraging ripening
• Inefficient use of fertilisers
• Increased spring frost risk
• High maintenance costs compared with herbicide control, particularly as the under-row area usually has to be controlled separately
• Can be too slippery on slopes

Generally regarded as a quality method, and gaining in popularity for low density highly mechanised vineyards.

Good compromise could be to alternate rows of cover crop/cultivation, changing around every few years.

11.5 Chemical Weed Control

Also called minimal cultivation or no-till cultivation

Vines are one of the last crops to be grown with the aid of herbicides, as vines are very sensitive to weedkillers, and selective weedkillers are rare (often selectivity is only due to dose levels).

Herbicides are grouped according to their mode of action: – Pre-emergence (residual) – Contact – Systemic

11.5.1 Pre-emergence Herbicides

Poorly-soluble compounds become trapped in the upper layers of the soil. They are absorbed through the roots and inhibit photosynthesis in young seedlings. They are best applied before budburst on weed-free soils (weed-shadow effect). The higher the clay content of the soil, the less they are leached, and so the less risk there is to the vine.

They are slowly broken down by micro-organisms, but their effect can last several months. Prolonged use can cause problems in re-plantations.

Residuals approved in the UK include Isoxaben (FLEXIDOR) and propyzamide (KERB). Simazine used to be used, but there is now too much resistance to it, so its approval has been withdrawn.

11.5.2 Contact Herbicides

Also called ‘wilters’ or knockdown’. Absorbed through the green organs on which they land, stay localised, and destroy those parts.

The effect is only temporary in plants with well-established root systems, such as perennials. They are broken down in the soil almost immediately in some cases.

Contacts approved in the UK include:

• Diquat (REGLONE)
• Carfentrazone-ethyl (SHARK)

11.5.3 Systemic Herbicides

Absorbed by the leaves (sometimes roots) and translocates in the sap (upward and downward systemy). Destroy the whole plant, usually by destroying the chlorophyll, preventing root growth and distorting growth.

Generally very slow acting.

Approved in the UK:

• Glyphosate (ROUNDUP) – Dangerous to vines
• Fluazifop-P-butyl (FUSILADE MAX)

Do not use common hormonal herbicides such as MCPA & 2,4-D!

11.5.4 Herbicide Selection

Selecting the correct herbicide depends on: * The weeds you wish to control * The type of soil * The age of vines * Time of year

115.5 Herbicide Application

Usual programme: Get weeds well under control in the first few years by many applications, and then reduce numbers

• Systemic after leaf-fall if perennial weeds present
• Pre-emergence before budbreak
• Spot applications of contacts (or systemics) after budburst

Minimal cultivation is usually used over the whole vineyard surface in high-density plantations, but it is reserved for the under-row region in lower densities.

Advantages of using herbicides:

• Least expensive in terms of manpower and equipment
• Highly effective
• Hand-held applicators are particularly good for plots that are inaccessible to machinery
• Suited to stony soils
• Maintains good levels of organic matter  good soil structure  Reduced spring frost risk

Disadvantages:

• Herbicides can be expensive to buy
• Can be toxic to young vines (must be protected) and vines in light soils  Promote high vigour
• Some risk to the operator (esp. Paraquat)
• Some risk to the environment, especially waterways
• Decreased activity of some soil microorganisms and invertebrates
• Can get trapped in soil (Paraquat)
• Soil surface can become rutted & soil compacted
• Increased erosion
• Increased disease risk
• Manures and fertilisers are more difficult to incorporate into the soil
• High level of nitrate leaching in winter
• Weed resistance (e.g. Glyphosate & willowherb)
• Unaesthetic
• Unsustainable
• Lack of wild plants can increase pest problems, e.g. omnivorous leaf-roller

In conclusion:

• Still very popular due to low labour costs
• Less popular than it used to be due to environmental concerns.

11.6 Mulching

The spreading of matter onto the soil surface to suppress weeds (and ultimately provide a food source for the plant) by preventing light from reaching the young weeds.

Types of mulches: black polythene, straw, grass clippings, paper, tree bark, wood (not coniferous) chips, marc, timber milling, sugar refining & household waste.

‘Strategic’ mulching can be used to:

• Reduce variability in the establishment of young vines by applying mulches with a high C:N ratio (straw, paper, woodchip) on more vigorous plants
• Materials with higher nutrient components (manures, mushroom compost) can benefit sections of poor growth
• Deeper mulches reduce soil moisture in wetter months
• Organic materials that encourage earthworms can assist drainage in waterlogged areas (don’t use fresh manures).

Optimal depth depends on the properties of mulch material and site characteristics: most compost mulches are used between 50 & 100 mm. Organic mulches need to be topped up each year.

Can be used in the alley or under the row.

Advantages:

• Effective if spread thickly enough
• Conserves water- reduces soil water evaporation and increases water infiltration (good for dry climates)
• Increased earthworm activity and surface soil microbial activity  Improves soil structure
• Reduces erosion (except plastic)
• Reduces soil temperature variation: limits heat loss from soil at night & reduces maximum soil temperature
• Protects roots from cold
• Increased vigour & yield with little change in quality

Disadvantages:

• Expensive to spread
• Encourages superficial rooting
• Can promote high vigour
• Increases frost risk
• Risk of nitrogen deficit
• Possible increase in fire risk
• Possible pest infestation

11.7. Other Methods

11.7.1 Animals

Sheep, poultry, rabbits Trunks must be long enough & young plants protected Beware of pesticide poisoning

11.7.2 Flame Weeding

Either with a ‘flame-thrower’ (Atarus Ranger 3000) or a tractor-mounted heated stainless steel mesh with a blower unit.

Index _{4. Vine Rootstocks 5. Vine Training Systems 6. The Winter Pruning of Grapevines 7. Vine Propagation & Grafting 8. Planting Vines 9. Vineyard Design}

4. Vine Rootstocks

4.1 Reasons for using rootstocks

4.1.1 Phylloxera

Phylloxera vastatrix was first identified in Europe in 1863. Accidentally introduced from the US, this louse destroyed two-thirds of European vineyards in the late 19th century. In 1872, Laliman discovered that the roots of American vine species were not destroyed, and so recommended grafting V. vinifera on rootstocks of American vine species.

The only other effective remedies for Phylloxera are growing vines on sandy soils or flooding the vineyard for 40 days a year.

Symptoms of Phylloxera

• Vines die (with drought symptoms) in patches that increase in size year by year
• The roots of infected vines are covered with:
  • insects, which appear as oval yellow-brown dots surrounded by lemon-yellow eggs
  • Nodosities (whitish or yellowish growths) near the root tip
  • Tuberosities (swellings) on older roots
• Pale green leaf galls on the under-surface of the leaves

4.1.2 To influence the vigour of the vine

Different rootstocks have different vigour levels and take up nutrients at different rates, which influences the scion's vigour.

In general, high vigour plants will have:
– Greater yield – Longer vegetative cycles – Berries with lower sugar and higher acidity – More susceptibility to disease

4.1.3 To confer resistance to nematodes

Nematodes (also called round, thread or eelworms) are very common in soils but are usually too small to be seen by the naked eye.

Some (such as Pratylenchus and Meloidogyne species) cause damage by feeding off the roots, while others (such as Xiphinema index) transmit virus diseases.

Rootstocks have differing susceptibilities to nematodes.

4.2 How to select the correct rootstock

The majority of rootstocks used today originate from crosses of three American species: Vitis riparia, V. rupestris, V. berlandieri.

Vitis riparia rootstocks are low in vigour but suffer from iron deficiency (chlorosis) in chalky soils

Vitis rupestris rootstocks are very vigorous, with a deep rooting system, but are also very susceptible to chlorosis

Vitis berlandieri is very vigorous, deep rooting, and highly resistant to chlorosis. Its cuttings have a very poor ability to root, so it is rarely used as a pure species.

Many hybrids of these species have been developed, and the correct choice depends on many factors:

• The calcium content of the soil. This can be measured as a percentage, as a pH, or as the index of potential chlorosis (IPC). The latter considers the size of the chalk particles and the total iron content. If in doubt, go for a Vitis berlandieri hybrid.
• The vigour of the vine required. This will also be influenced by the fertility of the soil so that a vigorous rootstock may be used for poor soils and a weak one for fertile soils. The plant density and training system selected must relate to the vigour of the vines.
• The depth of soil: use vigorous, shallow rooting rootstocks in shallow soils
• The water-holding capacity of the soil. No rootstocks will permit the production of quality grapes on very humid soils, but Vitis riparia-based hybrids are generally more tolerant of damp conditions, whereas Vitis rupestris-based hybrids are more drought tolerant. Some rootstocks are more sensitive to soil compaction than others
• Soil acidity and salinity. Excess acidity can lead to aluminium toxicity problems in some rootstocks, and some rootstocks (e.g. Salt Creek) have been specially bred for saline soils.
• Vine cultivar. Some rootstock/scion matches are not advisable.
  • For instance, cultivars with problems at flowering or wood-ripening should not be grafted onto vigorous rootstocks
• Climate. Weak vigour rootstocks are usually used in cooler climates, as they shorten the vegetative cycle.
• Yield and quality required. Generally, only weak to moderate vigour rootstocks should be used in quality wine production.

The principal rootstocks used in the UK are SO4, 3309C, Fercal, 101-14, 5BB, 41B and 420A.

5. Vine Training Systems

A training system refers to the way a vine is positioned in space.

It incorporates the trellis and how the vine is manipulated to cover it. The aim is to maximise quality and yield and reduce costs (facilitating mechanisation).

In cool climates, the most appropriate way growers can improve yield & quality is to increase the interception of light.

When selecting a training system, the choices to be made include: Planting mode: – Plantation density – Distance between rows – Distance between plants – Row orientation

Plant shape: – Trunk length – Shape of canopy

Trellis systems

There is no one ideal training system for vines, and choice will depend on climate, soil, cultivar, rootstock, and economic constraints.

5.1 History

Before the Phylloxera epidemic, vines were planted very close together in a random arrangement, untrellised or trellised on individual stakes.

After Phylloxera, European vineyards were planted in straight lines to allow cultivation using animals. The higher-quality northern vineyards could afford to buy stakes & wire to erect standard trellises.

In the 1950s, over-planting + technological improvements + cultivar improvements —> massive overproduction —> drop in prices

So vine growers had to reduce costs, and the very severe winter of 1956 helped.

Many growers removed alternate rows, and culture systems such as the Lenz Moser and the Sylvoz were developed.

Often these systems cut costs but did not produce quality wine, so they have been replaced by systems such as the GDC, the Lyre and the Scott Henry.

5.2 Planting mode

5.2.1 Plantation density

This is calculated on a field of 1 hectare (100m x 100m)

Plantation density = number of rows x number of vines in a row = (100 / Alley width) x (100 / Distance between plants)

There is little direct correlation between high-density planting and quality, although high densities often increase the effective leaf surface in a vineyard.

There must be a balance between the vine’s root system and its canopy, and the vigour of the cultivar, the planting density, the fertility of the soil and the training system determines this.

The poorer the soil, the higher the root density to obtain the right balance. As vine vigour is low in poor soils, it is best to plant high densities.

The exception to this is in low-water situations, where plants need to exploit a large amount of soil.

On a high-potential site, low-density planting is preferable.

Minimum legal densities for quality wines: – Burgundy: 9,000 – Bordeaux: 4,500 – Muscadet: 6,500 Most high-quality European vineyards are in the 5 – 10000 range.

5.2.2 Distance between rows

This is a compromise between different factors. Factors that favour narrow alley widths:

• Need for high Effective Leaf Surface Area
• Reduced loss of light energy on alleys at mid-day in N->S planted vineyards
• High quality/yield requirement on low potential soils
• Improvement of canopy microclimates by windbreak action

Factors that favour wide alley widths:

• Adjacent rows can cast shade in each other’s fruiting zones: alleys should never be narrower than the heights of the row’s canopies.
• Narrow alleys require the use of specialised tractors
• Many operational costs, such as spraying & weed control, are strongly influenced by total row length

5.2.3 Distance between plants

The correct distance between plants will give a shoot density of 15 shoots/m. This is a function of the trellis system's ability to support the plant's vigour.

Generally, the wider the alleys, the greater the distance between plants, as the plants have more vigour (they have more soil space available) and so need more trellis space.

5.2.4 Row orientation

Can be dictated by the following: – Shape of the field – Direction of the slope – Prevailing wind

In N-S rows, maximum interception in the morning & afternoon, minimum at midday

In E-W rows, and vice-versa, the maximum light is intercepted at midday
Note that in midsummer, more light is intercepted by N-S rows, but in spring and autumn, E-W rows receive more light.

However, N-S has the advantage that both sides of the trellis receive the same amount of light.

5.3 Plant shape

5.3.1 Trunk length

Increasing trunk length has the following effects:

• Decreasing ground frost risk
• Decreasing the beneficial effects of convected heat from the soil. Chaptal (1943) found that the average difference between maximum temperatures at 20 cm and 2m above the soil was 1.6°C
• Easing of manual operations. The optimum height for workers is 1.1 – 1.4m
• Easing of weed control and mechanical harvesting
• Increased starch storage, leading to more regular yields and increase in sugar levels
• Decreased risk of downy mildew and grey rot
• Decreased vigour due to increased resistance to sap flow
• Increased drought sensitivity

5.3.2 Canopy shape

Features of an ideal canopy (for cool climates):

• Maximum exposed leaf area
• Homogenous canopy density at 15 shoots/metre
• Homogenous canopy thickness of 1 leaf or less
• 60% or more fruit exposed
• 10 – 20 node shoot length
• Renewal & fruiting zones well aerated and exposed to the sun
• Shoots droop after veraison
• Trellising is cheap to install and maintain
• Plants establish themselves quickly, and husbandry costs are low
• Machinery designed for its upkeep is available.

5.4 Criteria for selecting trellis systems

Note this is a permanent decision:

• Legislation
• Plant density/ Alley width/trunk length requirements
• Features of the site
• Effectiveness of light interception (total exposed canopy surface/ha)
• Quality of canopy
• Cost & time of establishment (posts, wire, plants)
• Cost and time of maintenance (pruning, shoot positioning)
• Mechanisability (harvest, pruning etc...)
• Popularity and attractiveness

6. The Winter Pruning of Grapevines

6.1 Background

Parts of the vine

The vine life-cycle The vine vegetative cycle: Budburst –> shoot growth –> bud formation –> shoot ripening –> dormancy

The vine reproductive cycle: Floral initiation –> bud dormancy –> budburst –> flowering –> fruit set –> veraison –> ripening

Floral initiation is essential to the reproductive cycle as it sets the maximum production potential for the following year.

It is promoted by adequate heat, light and plant photosynthesis.

6.2 Reasons for pruning vines

Winter pruning is the second most costly manual intervention in the vineyard.

6.2.1 To organise the plant on the trellis

Pruning enables the vine to be well-organised on the trellis so that:

• The plant can capture the maximum amount of light (particularly important in cooler climates)
• Leaf bunching is avoided, thus reducing disease risk and increasing yield and quality
• Bunch ripening is better synchronised

An ideal canopy is homogenous along the row (15 shoots/metre) and has an average leaf thickness of 1-1.5.

6.2.2 To allow for the passage of machinery and manpower

Winter pruning organises the plant along the trellis so that personnel and machines can pass along the alleys without causing damage, and mechanical operations such as spraying and harvesting are more efficient and effective.

6.2.3 To produce a balance between the crop and leaf area

Unpruned vines produce: – Many short shoots further and further away from the trunk – Many small bunches of high acid low sugar berries – Irregular yields

In order to get quality fruit, there must be an appropriate balance between the crop level and leaf area on each shoot.

The number of flowers on the vine shoot is determined in the previous year according to conditions at floral initiation.

The size of each shoot (and therefore its leaf area) is determined at pruning, as the more buds are left on, the weaker their individual vigour. This is because more shoots have to share the limited amount of winter reserves and the capacity of the plant’s root system.

A heavy crop on short shoots will lead to over-cropping, which produces high yields of low-quality fruit and weakens the vine the following year.

Shoots with a disproportionally low crop will be over-vigorous and may carry on growing past veraison, to the detriment of the quality of the fruit. Furthermore, they will have many large leaves and laterals, which will cause canopy shading.

6.3 Factors to be taken into account when pruning

6.3.1 Pruning depresses vigour

A vine’s vigour is measured by the weight of wood it produces in a year.

Heavily pruned vines will grow fewer shoots the following summer than lightly pruned vines and fewer leaves. This reduces the vine's total photosynthetic capacity, and so reduces its vigour.

This effect is particularly important in young vines, which should be pruned lightly to allow them to establish themselves. Flower removal is also a good idea.

In older vines, lightly pruned vines are devigourated by increasing fruit production.

6.3.2 The notion of ‘Charge’

One of the aims of winter pruning is to produce an ideal balance between fruit and leaf area. This balance depends upon the yield and quality desired, which is determined by the returns on the sale of the wine.

As a rough guide, the ideal balance between fruit and leaf occurs on a shoot with a moderate yield of about pencil thick, 12 – 15 nodes long, and an internodal length of 60 mm. These weigh about 30 – 40 g in winter.

To calculate how many buds to leave on a vine at winter pruning (the charge), the vinegrower can:

• Count how many ideal shoots were produced in the previous growing season. When counting, small shoots may count as ½ and larger shoots as 2 or even 3
• Remove most of the canes from the vine, weigh them, and divide the weight by 30 – 40.

The charge is increased significantly in young (< 8 years old) vines and by 5 – 15% in mature vines to compensate for buds that won’t break due to winter injury.

6.3.3 The choice of wood retained at pruning

The wood retained at pruning should be in a good state of health.

Look out for spotting due to Botrytis (grey rot), powdery mildew, Phomopsis, and poorly ripened wood.

Canes with deformities such as double buds and ‘twinning’ may be infected with viruses and so should be eliminated if possible.

6.3.4 Choice of buds

The buds on canes formed in the previous year are the most fruitful.

If a vine is pruned severely, old buds on the trunk will break, but the embryonic flowers within these will have degenerated, and so they will produce little fruit.

6.3.5 Large pruning wounds damage the vine

Wounds over 30 mm in diameter will never heal properly but will die back and may affect the sap flow in the trunk. They will also deepen due to frost cracking and may allow the entry of parasitic fungi such as Eutypa.

If large pruning cuts have to be made, leaving a short stump that can be cut back the following winter is a good idea.

On the other hand, canes must be cut back to the old wood, or the surviving basal buds will turn into watershoots.

6.3.6 The end-point principle

Vines will grow more vigorously at their extremities, so the buds at the ends of canes will tend to break first and produce the most vigorous shoots.

The longer the cane, the greater the difference in vigour between shoots at the end and those in the middle, leading to uneven canopies.

6.4 Pruning by the Guyot system

The Guyot system is a traditional practice popularised by Charles Guyot in the 1860s. It is a cane-pruned system with spurs.

The cane buds grow into shoots that produce the yield in the following season.

The spur buds produce shoots that can be used as canes the following year, thus preventing the vine from sprawling too far along the trellis. Often, spurs become part of the old wood.

In a single Guyot, only one spur and one cane are left at winter pruning. In double Guyot, two spurs and two canes are retained.

The choice between single and double Guyot is decided by the vigour of each individual plant.

6.4.1 The choice of spur and cane

The spur should always be selected first. It should be: – Not too low or under the crown – Pointing along the row and not into the alley – Not too high or centrally located on the crown – Nearer the roots than the cane

The cane should be selected so that it is further from the roots than the spur, and it should be able to be tied down (bowed) so that: – It does not protrude into the alley – It does not invade the neighbouring vine’s trellis space – The buds are evenly spread along the trellis

Canes are often tied down in the shape of an arch to regularise shoot vigour along their length.

6.4.2 Establishing young vines in the Guyot mode

Young vines must be pruned carefully to ensure that they have a straight trunk and that their crown is well positioned in relation to the fruiting wire.

It is important to remove badly positioned shoots as they grow and all flowers should be removed from the least vigorous young vines.

6.5 Pruning cordon systems

Cordon systems are those where the cane is left permanently attached to the fruiting wire so that it becomes a permanent cordon.

The canes coming off these cordons are often spur-pruned. The shoots arising from these spurs can be trained either upwards or downwards.

The most common cordon system used in UK vineyards is the Geneva Double Curtain (GDC), but there are many others, such as the Cordon de Royat, the Sylvoz and the Lenz-Moser.

The advantages of cordon systems are that:

• They are easier to prune and can be pre-pruned mechanically more easily
• They are lower-yielding and so may produce higher-quality fruit in fertile cultivars

The GDC has other advantages, such as increasing the exposure of basal buds and fruit to sunlight, which can produce higher yields of finer-quality grapes.

The systematic method for cordon pruning is to: 1. Count the charge 2. Count the number of growing points 3. Divide the charge by the number of growing points 4. Leave that number of buds per growing point

However, most pruners will prune each growing point according to its success in the previous season.

6.5.1 Problems encountered with cordon systems

The loss of growing points along the cordon This can be reduced by keeping cordons short and pruning according to charge. If this fails, the cordon will have to be replaced.

The lengthening of growing points This can be controlled by pruning using the alternate crenel system.

6.6 When to prune

Earlier pruning will encourage earlier budburst and so increase the risk of spring frost damage.

However, it should not be left too late, as when the buds start breaking, it takes longer to bow down the canes, and many young shoots may be damaged.

6.7 The use of pruning

These can be collected and used as fuel or mulched in the alleys.

Mulching is easier and increases the humus levels in the soil, but some diseases, such as Eutypia and Blackrot, can overwinter on the canes. Prunings should be immediately burnt if these diseases are present in the vineyard.

7. Vine propagation & grafting

7.1 Vine propagation

7.1.1 Seeds

Used to produce new cultivars, hybrids & rootstocks, but not in commercial viticulture nurseries, as:

• Need to use controlled pollination techniques
• The vine’s progeny have a wide variation of characteristics, often inferior to the parent
• Propagation from cuttings is quicker & easier

7.1.2 Layering

It occurs naturally, often used commercially for species like Vitis berlandieri & rotundifolia (which are difficult to root from cuttings) or for replacing missing plants in vineyards.

Carried out at winter pruning Cane is buried in the ground, leaving the last bud or two above Can twist a wire around the cane to constrict the sap flow.

During the growing season:

• Remove shoots growing on the cane except for the tip
• Remove flowers for the first year
• Roots grow on the cane’s nodes so that plants can be separated the following year

7.1.3 Cuttings

Cuttings are pieces of parent plants (stems, roots, leaves) that will develop into a new plant when placed in the right conditions.

In viticulture, use: – Hardwood cuttings (commercial) – Softwood cuttings (research) – Meristematic tissue (in vitro research)

Important to choose hardwood cuttings carefully:

• Autumn or early winter, so that reserves are highest
• Collect wood from healthy, virus-free and productive vines
• Wood grown in the previous year, well-ripened
• About pencil-thick, internodal length about 6 cm, no dodgy blotches. Avoid canes which are flat or angular in cross-section
• When cut, the inner bark is green and full of sap, wood is firm and free from dark specks

Length of cutting 30 – 45 cm, depending on how deep the roots need to be: the lighter the soil, the longer the cutting

Cuttings are bundled, labelled, and then stored.

Could heat-treat by placing at 50°C for 30 minutes. This will eliminate Phylloxera, nematodes, mycoplasmas (grapevine yellows & Pierce’s disease), Phytophthora & crown gall.

If they are to be grafted, they should leave in water overnight.

Otherwise, store in a cool (1 ~ 4°C), damp place, maybe buried in moist sand or sawdust.

If cuttings are not to be grafted, they can plant straight away into a nursery or pot in a greenhouse.

In order to encourage this:

• Make sure that they get plenty of water, as the leaves grow faster than the roots. Use mist propagation or a propagating frame
• Keep warm, a temperature of 15 – 25°C is best. Best to heat from below, as this encourages root development
• Use a loose, well-drained soil in a nursery or potting compost that has good aeration, a high water-holding capacity, good drainage and protection from vine weevils.

7.2 Grafting

Grapevines are grafted to:

• Confer resistance to Phylloxera or nematodes
• Match the plant roots to soil conditions
• Influence scion vigour
• Change varieties in an established vineyard (top-grafting)

7.2.1 Field grafting

Traditional practice where the rootstocks are planted in the vineyard first, then top grafted

7.2.2 Bench grafting

Carried out indoors during the late winter/early spring :

• Prior to grafting, the cuttings are stored in damp sawdust and then soaked for 24 ~ 48 hours before the operation to make them less brittle.
• Cut rootstocks to 24 ~ 36 cm lengths with the lower cut immediately below a node
• Remove all buds, and align them in order of the diameter of the top
• Scions cut to one-node lengths of 2 cm above the node and 5 ~ 6 cm below.
• Align them above the rootstocks according to the diameter of the base
• Graft, either by hand (whip technique) or by machine (omega technique)
• Dip top in molten paraffin wax up to just below the graft union
• Store in crates containing sand or sawdust.
• Maintain humidity at 90% (but with good drainage) and temperature between 21 ~ 29ºC for 3 ~ 5 weeks.
• Once callusing is complete, remove grafted cuttings and trim off any roots from the scion or shoots from the rootstock.
• Re-dip in molten paraffin wax
• Transfer to cold store (1 ~ 4ºC) or plant into pots and keep at 18 ~ 21ºC for 7 to 10 days, then move to temperate greenhouse.
  

Grafted rooted cuttings are either sold as:

• Bare cuttings that have spent one season in a vine nursery after grafting
• Potted plants that have been ‘forced’ in a greenhouse can be planted within 10 months of grafting.
  

7.2.3 Top-grafting

Used to change cultivars in an established vineyard.

7.2.3.1 Cleft grafting

Usually carried out on vines less than 15 years old with trunk diameters 2 ~ 6 cm:

• Just before budburst, saw a trunk 3 cm above the graft union
• Split the trunk to a depth of 3 – 5 cm across its widest point.
• Insert two wedge-shaped two-bud scions into the slit, ensuring that the cambium layers match
• Tie up tightly with raffia
• Cover the graft, either with soil, or with a rigid plastic sleeve filled with sand, and keep covered until callusing is complete (1 season)
• Keep graft well-watered, but allow excess water to drain away
• Tie shoots carefully to supporting stake
  

Good success rate (60 % minimum) 2/3 of a normal harvest is expected the following year.

7.2.3.2 Bud grafting

Now more common, as the success rate is better.

Both methods require scion cuttings to be collected in the winter and stored at 1 ~4ºC, 90% humidity.

The two methods most commonly used are chip-budding and T-budding. The two methods can be used in succession to ensure success.

Aftercare of plants is very important:

• Protect from drought stress and weed competition
• Remove all suckers
• Support rapidly growing (tender) new shoots effectively

Works well in warm climates, but difficult to succeed in the UK.

8. Planting vines

All in the planning and preparation.

The planting calendar:

8.1 Removing existing vegetation

• Remove vegetation, large stones, former vines, trees etc.
• Beware of preservation orders
• Trees should be uprooted rather than cut down, as roots may harbour Armillaria (honey fungus). Best to gather roots into piles and burn on the spot.
• Have trees checked for Armillaria, & leave fallow for 2 ~ 3 years.
• May wish to kill off troublesome weeds such as couch grass or bindweed with a total non-residual herbicide such as glyphosate (ROUNDUP)
• Some growers will leave the field fallow for 1 year to ‘rest’

8.2 Levelling

Dips in which water accumulates can cause root asphyxiation and problems with passing machinery, so best level them. Best to remove topsoil, level subsoil, and then replace topsoil. Don’t try it on wet soils.

Assess the risk of erosion at this point. Erosion is influenced by:

• Slope
• The type of soil & its structure: greater in sandy or silty soils and low in humus.
• Spoils with crusts or caps will increase erosion by increasing surface run-off
• The type and depth of subsoil: shallow clay subsoils increase erosion
• The rate of rainfall: 1 ~ 2 mm/hr is OK, but 40 ~ 100 mm/hr causes erosion on most soils
• The size of droplets (larger ones run off more)
• The amount of rain that falls
• The weed control method: herbicide –> cultivation –> pasture

If there is a risk of erosion:

• Plant trees or dig ditches above the field
• Establish paths with ditches across field
• Lay concrete surface guttering
• Plant along the contours
  

8.3 Terracing

• If the slope is over 10%, rows must go up & down. If the slope is over 20%, it must terrace
• Not appropriate for unstable clay soils
• Walls can be made of grass, dry stone, masonry, planks, basketwork, etc…

8.4. Subsoiling

Used to break up the subsoil at depths of 50 – 100 cm. Single tine, often with vibrating action. Requires 4-wheel drive & over 50 hp. Benefits:

• Improves drainage
• Improves deep rooting

Watch out for stones or bombs!

8.5 Corrective fertilising

Soil test is vital. Soil nutrient deficiencies must be corrected

Some people put in up to 10 years’ supply of slow-releasing fertilisers. Shouldn’t be a need to put nitrogen, as this will leach out before the plants can reach it and may lead to over-vigorous growth in the young plant.

However, common to raise organic matter levels above 2% by adding FYM, thus improving the structure.

pH should be increased above 6.5, if possible, by liming. Generally, use calcite (lime-CaCO3), magnesite (magnesian limestone – MgCO3) or dolomite, a mixture of both.

Gypsum (CaSO4) can be used to improve structure. It reduces the dispersion of surface soils & minimises swelling of sub-surface soils (improves permeability & aeration). Particularly good for sodic clay soils, which crust.

8.6 Deep ploughing

Depth of 20 – 50 cm Advantages:

• Incorporates fertilisers
• Increases aeration & drainage (can double vine root weight at the end of the first year)
• Exposes large roots which can be removed
• Destroys existing vegetation – beware of ploughing in long grass –> anaerobic layer.

In heavy soils, best done in autumn to benefit from freeze-thawing action during winter.

8.7 Deep cultivation

A power harrow, spader or rotary cultivator produces a medium-fine tilth to a depth of 200 ~ 300 mm.

Aims: * Makes planting easier by loosening and levelling the soil * Destroys weeds * Helps establishment of vine roots
This must be done on dry soils.

8.8 Tracing out the plantation

Must be done carefully to ensure vine rows are straight and evenly spaced.
Unless planting by machine or using plastic mulching, this can be done well before the day of planting.

8.9 Planting

Best to plant rooted cuttings as early as possible, but it is important to wait until the spring frost risks are over and to be able to prepare the ground effectively.

If the plants are delivered before being planted, they must be protected from drying out by keeping them in a dark, cool place, either in the plastic bags in which they were delivered or in buckets of water.

Potted plants can be planted as late as July.

8.9.1 Planting by hand

• After cultivation, plant the supporting stakes unless plastic mulching is used.
• Supporting stakes can be bamboo canes or chestnut/treated softwoo droppers if the young vines are to be cultivated.
• If the ground is well-prepared, the young plants can be pushed into a slit made by a spade, but usually best to dig a hole.
• This hole can be dug by a spade or a planter and should be deep enough to hold the graft union out of the soil.
• The plant’s roots may need trimming to fit the hole.
• The plant should be placed well against the stake (south or windward side), and fine earth should be placed around its roots. Watering is recommended, particularly for potted plants.

8.9.2 Machine planting

Planting machines are usually tractor-trailed and often laser-guided. Their success rate is even more dependent on the quality of the soil preparation than hand-planting.

8.10 Plastic mulching

The plants are planted without their supporting stakes.

A film of plastic (high in UV inhibitors) about 1 m in width is unrolled using a trailed implement that buries 200 mm on each side to a depth of 150 mm.

Holes are then cut in plastic to allow the vines to poke through. Canes or stakes are then planted next to the plants. Advantages:

• The young plants do not suffer from drought, even in dry summers
• There is no weed competition
• No under-row weed control is required
• Soil structure under row is maintained
• Soil temperature is increased, increasing microbial activity
• The young plants grow much faster and can gain one year

Disadvantages:

• Initial expense of plastic and hire of machine
• Increased frost risk, as plants grow earlier & faster
• Weeds develop at the base of the plant that is difficult to control  Plastic harbours slugs, mice and snakes
• Any perforations in the plastic cause weed problems
• Possibility of foliage scorch in very hot summers
• Available tractor space is reduced
• Increased erosion risks
• Eventual removal of plastic is arduous, and disposal difficult
• Promotes superficial rooting

8.11 Tree guards

These can be either rigid grow tubes or polythene sleeves.

They are placed on the plant after plantation and secured to the supporting stake.

Advantages:

• Increases growth rate dramatically –> earlier crop
• Reduced drought stress
• Protection from pests (disease?) and herbicides
• Suppression of lateral growth
• No need to tie up plants as they grow
  

Disadvantages:

• Cost of purchase, application and removal
• Risk of shoot burn in high temperatures (35 ~ 40°C)

8.12 Care for the young plantation

This is very important; twice as much time is often spent on young plantations as on established vines.

• Watering: Particularly important for potted vines
• Weed control: Essential, as weeds compete for water and soil space. Care must be taken in herbicide selection & application
• Protection from rabbits: Plastic blue netted sleeves often used  Protection from slugs & snails – Slug pellets in sleeves
• Wind protection: Temporary windbreaks?
• Disease protection: Beware of late-season attacks
• Tying up and summer pruning: Remove any flowers, shoots from rootstock and roots from scions.
• Replacing unsuccessful vines: Recommend ordering a few extra and potting them up to replace missing vines.

9. Vineyard Design

Topic	—
Macroclimatic Evaluation	Heat (summation, ripening month)
	Rainfall (total annual & distribution)
	Sunshine hours
Mesoclimatic Evaluation	Frost risk
	Aspect & Elevation
	Wind exposure
Site Survey	Map
	Soil survey (texture, structure, depth, drainage, pH, nutrients)
	Risk of erosion
Vine Variety	Legislation
	Market research
	Local vineyard survey
Rootstock Selection	Soil assessment (chalk)
	Vigour requirement
	Nematode risk
Culture System	Fertility of field (plant density, alley width)
	Cost of establishment & maintenance (mechanisability)
	Microclimatic advantages
Block Design	Windbreak requirements
	Row length & orientation
Mechanisation	Field accessibility (alleys, headlands, pylons)
	Storing, cleaning, loading areas
Pre-planting Operations	Clearing
	Soil preparation (levelling, sub-soiling, fertilisation, cultivation)
Planting Operations	Method (manual, mechanical)
	Plastic mulching, polythene sleeving
After-care of Plantation	Watering
	Pest control
	Wind protection
	Summer pruning

Index _{1. Site Evaluation 2. Site Improvement 3. The Selection of Vine Cultivars}

1. Site Evaluation

The climate of a vineyard should be evaluated on three different levels:
The macroclimate: that of the region or county. This is influenced by its: – Geographical location – Temperature summation – Dominant winds – Sunshine – Rainfall

The mesoclimate: that of the area, field or farm. This is influenced by its: – Aspect – Altitude – Wind exposure – Frost susceptibility – Proximity to seas, lakes, rivers, towns or forests.

The microclimate: that immediately around and within the plant's leaf canopy. This is influenced by its: – Row spacings – Row direction – Trellis system – Soil type and drainage – Plant management techniques

In turn, making a detailed assessment of a site's potential for growing vines will help the vine-grower to make decisions on: – The choice of cultivars grown – The pruning and training methods – Other cultural practices, such as soil management – The expected returns from the venture

1.1 The effects of vineyard macroclimate

1.1.1 Temperature

This is the major factor in determining the suitability of a region to viticulture. Sufficient heat for a sufficient length of time is required by the vine to complete its yearly growth cycle. However, most quality wines are produced in climates that are only just suitable for vine culture. This may be because slow berry ripening produces the finest tastes and aromas.

Climatic indices are useful for comparing potential and existing vineyard sites and determining which varieties are most suitable.

The most commonly used is Amerine & Winkler’s heat summation system. Amerine and Winkler (1974) found that the quality of wines produced in California reflected the heat summation of the sites on which they were produced.

The heat summation for vines is usually calculated by measuring the mean temperature for the month, subtracting 10°C (the minimum temperature for vine growth), and multiplying the result by the number of days in the month.

For example, if the average temperature for June is 15C, the heat summation for that month is: (15 – 10) x 30 days = 150 Growing Degree Days (GDD)

The heat summation for every month is then added together to obtain the heat summation for the year.

Average heat summations for major vine-growing regions are:

England has a very cool climate indeed, with heat summations averaging about 800 GDDs (Growing Degree Days), but the trend over the last 20 years has been for a significant increase.

• Category I vineyards (less than 1350 degree days) are said to produce the finest dry white wines.
• Category II & III (1351-1930 degree-days) are said to produce the finest red wines.

Vine varietals can also be classified by the same sort of categories, allowing them to be matched to their appropriate areas.

There are considerable inaccuracies in the Heat Summation system:

• Relationship between vine growth & temp is not linear
• Vines can be actively growing in months when the mean temp < 10ºC
• Soil temperatures are not taken into account
• Doesn’t take cold nights into account

There are other indices that can be used:

• Continentality: the difference between the average mean temperatures of the hottest and the coldest months.
• Latitude-temperature index – LTI = Mean temperature of the warmest month (60 – latitude)
• The average mean temperature for the ripening month.

Very low winter temperatures will injure vines: freeze injury to dormant vinifera buds and wood begins at -15°C, is very serious at -20°C, and -25°C is usually fatal unless the vine is insulated by snow.

It is reckoned that a site will not be successful for vine culture if its temperature falls below minus 20°C as often as every 20 years or if the mean temperature for the coldest month is less than -1°C.

1.1.2 Sunshine

Sunshine has several effects on vine growth: – Indirect effect due to heat accumulation – Direct effect (through phytochromes) on: — Bud viability — Floral initiation — Ripening — Cane maturation

Vitis vinifera is thought to require at least 1250 hours of sunshine to produce ripe fruit. Sunshine hours decrease as you get further away from the coast, particularly the south coast, and with increased height above sea level. The amount of sunshine will also be decreased if the vineyard is close to a large town or city (by up to 10 %!) or if it is shaded by buildings, trees, hills, etc.

Sunshine hours can be measured using a Campbell-Stokes recorder. It is important to note that high sunshine and temperatures can lead to berry scorching (even in England!), particularly after leaf stripping or spray application.

1.1.3 Rainfall

Sufficient rainfall (450 – 500 mm) is necessary for the vine primarily to keep its cells from collapsing (causing wilting), which prevents them from fulfilling their vital functions. Some water stress during berry maturation may improve the quality of the crop, but severe stress is detrimental as it halts vegetative growth and causes leaf loss.

In England, drought is a problem on very young vines and in exceptional years in very shallow or free-draining sites. In fact, the availability of rainfall to the plant depends very much on the soil type and the season and rate at which it falls.

The best areas for vine-growing in England are those with low rainfall, as excess rain will:

• Cool the climate
• Make it more difficult to pass machinery in the vineyard.
• Increase the risk of fungal disease, especially mildews, grey rot and Phomopsis.
• Reduce fruit set, especially if accompanied by low temperatures.
• Cause bunch compaction and eventually berry splitting before harvest
• Dilute the must if it rains just before harvest

High winter rainfall has little effect on vine growth, but some water is stored for later use. Moderate spring rain is beneficial, as it promotes shoot growth.

Some summer rain is useful, but this can encourage disease and reduce fruit set. Autumn rain is nearly always detrimental to the quality of the crop.

1.1.4 Hail

Hail can devastate a vineyard and is a serious problem in some vine-growing areas like Bordeaux. Unfortunately, hailstorms have a very localised action and are difficult to predict, so they are rarely considered when selecting a vineyard site.

1.2 The Mesoclimate

1.2.1 Aspect

Sunlight loses intensity if the angle with which it hits the ground is less than 90 degrees. This is partly because it has to travel through more air, and thus more energy is absorbed, but mostly since it spreads out over more land area. Example: A column of sunlight illuminating one hectare of land when falling perpendicularly will cover 1.5 ha if it falls at 45° and 2.5 ha if it falls at 22.5°.
A field that slopes in the direction of the sun will compensate for this to some extent, thus increasing the intensity of sunlight that it receives.

To compensate for the effect cited in the example above, the slopes should have a gradient of 45° (1:1) and 67.5° (1:2.4), respectively.

Some Rhine vineyards have a gradient of 1:2, but this is too steep for tractors to be used, so vine growing becomes very expensive.

The steeper the slope, the greater the effects of soil erosion, though other factors should be considered, such as rain intensity and the texture of the soil.

1.2.2 Altitude

The mean annual temperature decreases by 0.6°C with every 100-metre rise above sea level. This corresponds to a reduction of heat summation of around 105 degree-days a year, which makes for a later budburst and flowering and reduces the chances of the fruit achieving an acceptable level of maturity.

The generally accepted maximum limit for English vineyards is 150 metres. Altitude also increases the effects of wind exposure.

1.2.3 Topography

Slopes can be beneficial, as they:

• May allow the slope to face the sun
• Allow for cold air drainage, which provides protection from frost and causes mists to settle in valleys
• Soils tend to be poorer & more coarsely textured due to erosion
• Slopes have better rainfall drainage (lower specific heat capacity)

But they can be disadvantageous:

• Increased level of erosion, although other factors such as rain intensity and soil texture and structure play a major part
• Can increase costs. Wheeled tractors start to have problems with a 6° slope, whilst manual labour has problems with a 30° (1:3) slope.
• Isolated hills are beneficial as there is no cold air flowing from above

1.2.4 Wind exposure

The dominant winds in the UK are:

• Southwest: Tropical maritime – causes rain, but mild
• Easterly: Polar Continental – dry, sunny, warm in summer, cold & sunny in winter
• Southerly: Tropical Continental – hot, dry and sunny, thunderstorms
• North-westerly: Polar maritime – cold, sunny periods & showers. Snow in winter.

Light winds can be beneficial in vineyards as they help to dry the canopy, but excess wind can have the following effects:

• Leaf damage, particularly if the wind carries ice crystals, soil particles or salt.
• Microclimatic cooling; on a still day, the temperature in the canopy will be several degrees above the ambient temperature.
• Physiological disruption; the winds may induce water stress by increasing transpiration or reduce photosynthetic activity by causing stomatal closure.
• Damage to shoots, shoot tips, inflorescences and fruit, causing loss of vegetation and an increase in the incidence of Botrytis.
• Damage to trellising
• Canopy disruption: especially important for drooping canopy systems
• Root damage through rocking and water logging due to the formation of a hollow at the base of the stem.

1.2.5 Frost susceptibility

In winter, once vines are fully dormant, they are hardy and can tolerate temperatures as low as -15°C.

However, during the growing period: -1 to -2°C destroys young shoots and inflorescences -2 to -4°C destroys all green parts and partly opened buds.

The dangerous periods are in spring and autumn: – Late spring frosts destroy the young shoots. The secondary buds will sprout, but these are less fertile and will have less time to mature. – Early autumn frosts destroy foliage prematurely and so affect the maturity of the berries and canes. Frosted berries will also shrivel up and oxidise.

There are two causes of frost: Air frosts: North winds bring air of a lower temperature than freezing. This form of frost is rare in England during the growing season.

Ground frosts: During the night, the soil and the plants lose heat by infrared radiation. On cloudy nights, this is reflected downwards by the clouds, but on clear nights, this energy dissipates into the atmosphere. If the night is still, a layer of cold air develops on the surface of the ground.

If the ground is sloping, this cold air will flow downhill as it is heavier than the cool air above it. It will continue to flow downhill until it reaches an obstacle or the valley floor, where a frost pocket will be formed. Planting vines in frost pockets is not recommended!

1.2.6 The influence of forests, seas, lakes and rivers

The close proximity of forests can be an advantageous factor as they act as windbreaks, store heat in cold weather, and reduce the effects of erosion. They can also be a disadvantage as they cool the mesoclimate in warm weather an increase its humidity. They can also harbour large flocks of birds, the most serious pests in English vineyards.

Most quality vine-growing regions are situated near a body of water, whether a sea, lake, or river. These are beneficial as they reflect the sun's rays, store heat for the autumn, moderate summer temperatures and can provide morning mists to encourage the development of 'noble rot'. However, they do increase the humidity of a site, thus increasing the risk of fungal disease, particularly powdery mildew.

1.3. Soil type

It is difficult to rationalise soils, as: – Quality is more important than quantity – Quality in wine involves individuality or typicity & so there is no absolute

Growers in traditional wine-producing countries maintain that the soil on which the vine is grown is vital to the character of the wine produced, but very little hard evidence has been brought to light to support this view.

In fact, apart from possibly the pH of the soil, no other chemical constituent has been proven to confer any particular quality to particular wines.

Vines grow successfully on a wide range of soil types as long as the rootstock is appropriate and the vine's minimal nutritional requirements are met. Fertile soils, however, are not appropriate for vine growth as they encourage vigorous vegetation that can cause problems.

The soil's structure and texture are much more important than its chemical composition. These affect its water retention and drainage properties.

Vines do not grow well on poorly drained soils as these are cooler and take longer to heat up in spring and restrict root growth leading to reduced resistance to drought and an increased risk of mineral deficiency.

Poor drainage will also reduce the bearing capacity of the soil, causing problems when passing machinery through.

To assess poor drainage, look for: – Water lying in pools on the surface for several days after heavy rain – Rushes, sedges, horsetails, tussock grass and meadowsweet – Pale green or yellow and unthrifty young plants – Blue or yellow clay subsoils or panning.

There is also common agreement that vines grow best on poor soils, as: – These restrict canopy growth (canopy management?) – They are often stony & well-drained, leading to a high thermal conductivity

2. Site Improvement

2.1 Wind protection

The effects of gale force winds are well known, but the effect of even a moderate but regular prevailing wind is less obvious and yet can result in a serious loss of yield and quality.

2.1.1 The Benefits of Shelter

• Improved microclimate for better vine growth, fruit set and development
• More suitable days for spraying
• Possible savings on trelliswork.
  

2.1.2 The provision of shelter

Artificial windbreaks Advantages: – These provide instant protection – They require little maintenance – They can be mobile – No competition for nutrients and water – No harbouring of pests or diseases

Disadvantages: – Expensive – Do not last as long – Not aesthetically pleasing

Natural Windbreaks – Salix spp. (Willows) & Populus (Poplars): vigorous, best for perimeter planting – Ulnus spp. (Alders): better as internal breaks, particularly recommended are the grey or black alder. – Leylandii & Cedars: fast-growing evergreens that can become too thick

Natural windbreaks should be planted well before any vines to allow them to establish. These should be self-supporting, but if stakes are needed, they should only be one-third of the tree's height and be removed as early as possible. If allowed to sway, the resulting roots will be firmer.

Trees will need regular maintenance – weed control, fertiliser, trimming or topping and even root trimming. Care must be taken that they do not block drainage systems.

An effective windbreak slows the wind down by a filtering action. A solid block, such as a wall or hedge of Leylandii that has become too thick, will result in severe eddies and turbulence on the leeward side. This can be more damaging than the original wind. Artificial windbreaks are therefore made of small mesh netting, and trees should be of a twiggy nature without dense foliage.

A permeable windbreak can reduce the wind speed for a distance of up to 30 times the height of the windbreak. For maximum effect, the crop should be within 10 times the height. For instance, windbreaks of 8 m high should be planted every 80 m across the vineyard.

Living trees can, of course, hold pests and diseases, e.g. red spider mites & brown scale, but on the whole, they offer far more in terms of protection and beneficial predatory insects.

2.2 Frost protection

Once vines are fully dormant, they are hardy and can tolerate quite severe frost, but temperatures below – 0˚C will cause damage once the vine buds have burst.

2.2.1 Control

Site selection – This is the most effective method. Avoid frost hollows where cold air collects.

Cold air drainage – Do not create a frost pocket by planting a thick hedge or erecting a solid fence across a sloping site and thin existing hedges to allow cold air to drain away.

Height of pruning – The closer to the soil, the greater the frost risk. High wire training (e.g. Geneva Double Curtain) can raise the height of buds out of the risk of ground frost.

Delay pruning – By delaying pruning until the buds on the tips of the vines start to burst. The buds closer to the head of the vine will be slower to break, and the removal of the top growth with stimulate lower buds to develop, and these will be a week or so later.

Soil condition – Frost risk will be reduced if the soil condition is such that heat can easily be conducted from lower layers. Therefore compact, damp and weed-free soils perform best if there is a risk of frost.

Polymer coatings – Young vines can be sprayed with a polymer coating (ANTI-STRESS) that provides some insulation and protect the shoots from desiccation. The vine easily grows through the thin polymer coat.

Fans/windmills – These can mix the upper layer of warm air with the cold air layer closest to the vines (cold air sinks). Wind machines are available in two types: – Permanently installed tower mounted 1 per 15 – 20 acres
– Movable on a short tower 1 per 10 acres Generally speaking, a machine providing 10 hp/acre will effect a temperature rise of one-quarter the difference between the air temperature at 2m and that at 15m.

Heaters – Candles, burners, and braziers heat from direct radiation and convection. Effective, but can be expensive and can cause smoke nuisance.

Water sprinkling – As the water sprayed onto vine shoots freezes, it releases a little heat, ensuring that the temperature of the shoot will never fall below 0°C, even when the air temperature is as low as -9°C.

• However, this means that sprinkling must be continuous throughout a frost, starting as temperatures reach 1°C and continuing until the risk of frost has gone. Water sprinkling can be automated and can be used as an irrigation system during the summer.
• This is not a method to use on a site that has poor drainage for to use overhead sprinklers during a frost that could last for 8 hours, a very considerable amount of water will be used (30,000 litres per hectare per hour).
  

2.3 Drainage

Natural drainage ensures that water is distributed in several ways: – Runs off the surface – Taken up by plant roots – Absorbed into pores in the soil particles – Evaporates from the soil surface – Drains down through the soil

If natural drainage is insufficient for the rainfall falling on the field, then control methods are necessary.

2.3.1 Improving natural drainage

a. Improving the soil structure This can be improved by adding farmyard manure (FYM), organic matter, sand, grit and even lime to open up heavy clay soil. Therefore, it is necessary to understand the soil type of the site in question.

b. Ditches Ditches are the cheapest method of putting in artificial drainage

If the land slopes, dig a cut-off ditch across the top of the plot to intercept water from higher ground. Connect this with another ditch at the bottom of the slope.

It is important to maintain ditches and their outfalls every few years.

c. Drainage pipes Check to see if systems exist – farm records & aerial photography will show any previous drainage.

The problem may be isolated if the original system was well installed and in good condition, so try restoring: – Use divining rods to mark out. – Check ditches and outfalls – Look for patches of wetness or rust-coloured staining on the surface. – Expose pipe and rod from outlet up.

If a new system is needed: – Survey area – Draw up plans – Obtain quotes – Clean ditches

Ensure that all drainage installation is carried out when the vineyard soil is dry

Clay pipes are no longer used. Perforated plastic is now commonplace: 60 – 80 mm laterals 100, 125, 150, 250 mm for mains

Distance between drains depends on soil type. Positioning of drains depends upon the slope of the field and the occurrence of springs and wet patches.

If the slope is greater than 2% (1:50) the laterals should run across the slope. The minimum fall on laterals should be 1:250 The minimum fall on mains should be 1:400

The pipe must be surrounded by gravel (v. expensive). The depth of the fill is more important than the width. So narrow trenches are dug. For large operations, use a machine with laser depth control.

d. Mole drainage The cheap method is usually used on fields with clay subsoil (no stones). Mole ploughs have a torpedo or bullet-shaped “mole” attached to a steel coulter and form a cylindrical channel in the subsoil.

They can be mounted on the three-point linkage, on a wheeled frame or as a simple skid.

The best conditions are when the subsoil is damp enough to be plastic and form a good channel but sufficiently dry to form cracks. The field surface should be dry for a good grip and reasonably even. Dry weather after ploughing allows the surface of the bore to harden, so the effect lasts longer.

The channels should not be less than 75 mm in diameter, at least 300 mm below the soil surface, and spaced no more than 4 m apart. Some machines will fill the bore with gravel.

e. Subsoiling Subsoiling mechanically bursts the soil and artificially creates the passages which enable the free movement of water and air and allow root systems to develop fully. Subsoiling should be carried out when the subsoil is dry to obtain the maximum shattering effect.

Subsoiling in wet conditions is of little benefit and may cause further compaction. It should be carried out at right angles to any drains and should clear any drains by 75 mm to avoid damage.

3. The Selection of Vine Cultivars

Vine selection is as old as vine culture itself; for example, selecting vines with hermaphrodite flowers from the dioecious wild vines. As vine culture spread, vines were selected according to their level of adaptation to their particular environment and the types of wine required in that region.

This gave rise to the large range of varietals that we have today. Up to the nineteenth century, the selection was made by importing foreign varietals and by Mass Selection methods. Now these have been superseded by hybridisation, mutagenesis, and clonal selection.

The criteria used in vine selection are:

• Adaptation to the climate; cold, short growing season, drought etc.
• Resistance to disease; Phylloxera, nematodes, mildews, Oidium, Botrytis.
• Adaptation to soil conditions; lime, drought, acidity, salt. (Most important for rootstocks)
• Economic characteristics: high yield, high quality, good grafting possibilities, mechanisability (?)

3.1 Methods used in Selection

3.1.1 Importing foreign varietals

This method has been very successful in the last few decades, as is shown by the world spread of varietals such as Cabernet Sauvignon and Chardonnay. This has brought out some surprising results as a cultivar's characteristics change drastically under different climatic conditions.

3.1.2 Mass selection ('Selection Massale')

This method involves passing through the vineyard before harvest and marking out those plants from which to take cuttings from. This is best done in poor years and can be carried out by eliminating plants instead of selecting them.

This method was very common but is now virtually abandoned due to the necessity to graft plants and the successes of clonal selection.

3.1.3 Clonal selection

Clones are plants originating from a single parent, which are propagated vegetatively (usually by cuttings) and, therefore, genetically identical.

The clonal selection was first carried out by Froehlich in 1896 on Sylvaner. It was almost exclusively carried out in Germany up till the 1950s but is now also done in France by ENTAV (Etablissement National pour l'Amélioration de la Viticulture) and by INRA (Institut National de la Recherche Agricole).

The criteria for selection are: – Yield; bud fertility, size of berries, coulure etc. – Sugar concentration – Must acidity – Phenolic and aroma constituents – Sensitivity to disease, drought, cold etc. – Organoleptic quality – Freedom from viral infection, esp. fan-leaf, leaf-roll, fleck, vein necrosis, corky bark, stem pitting.

The following methodology was used by J Balthazar at INRA Colmar on Savagnin Blanc in 1976:

Visual symptoms are not enough for virus testing; use serological and immuno-enzymatic tests and grafting onto indicator varieties (e.g. 5BB).

To eliminate viruses, thermotherapy can be used.

The life of a clone is 30 – 40 years due to spontaneous mutation and infection, but it can be withdrawn earlier if better-performing clones are found.

There are some disadvantages in clonal selection:

• If all vines in the same area are closely related, the spread of disease is facilitated.
• Some clones are only suitable for certain regions.
• Clonal selection has led to an increase in yield leading to overproduction.
• It has also led to a reduction in vine genetic resources. To counter this, collections of old varietals have been established, both in the field and in vitro.

3.1.4 Selection by sexual reproduction

Very little hybridisation was carried out pre-Phylloxera, as it was unnecessary. The only exception to this was the work of Bouschet (1824-1845), who crossed Aramon X Teinturier and produced Alicante Bouschet, a good quality teinturier variety.

3.1.4.1 Hybridisation

Vine hybridisation between species (interspecific hybridisation) began in the United States. The early settlers found that conditions for the culture of V. vinifera were unsuitable and grew indigenous varieties such as V. riparia, V. labrusca and V. aestivalis. The wines produced were not very palatable as they were too harsh, foxy or herbaceous. Hybrids with V. vinifera were soon developed, such as Concord, Black Hamburg and Clinton.

Interspecific hybridisation started in Europe with the development of rootstocks for grafting in the late 19th century. The problem was that V. riparia and V. rupestris are very Phylloxera resistant and graft well but have a very poor calcium tolerance. V. berlandieri has a high calcium tolerance but doesn't graft or root well from cuttings. To resolve this problem, nurserymen developed many hybrid rootstocks to cope with a wide range of soils.

The introduction of downy mildew in 1878 spurred other nurserymen to hybridise vinifera species with American ones, and many thousands of hybrids were developed. The resulting hybrids produced good yields and had some mildew resistance, but the organoleptic quality of the wine was poor.

In the late1950s, hybrids occupied 30% of the French vineyard area (400,000 ha). This led to severe overproduction problems.

Due to the poor quality of the wine produced, most areas in Europe have forbidden the production of quality wines from interspecific hybrids and only approved a small number for the production of table wines.

Nevertheless, hybrids are still used widely in Eastern USA as they have a high winter cold resistance. Although the breeding of interspecific hybrids was abandoned in France and Italy in the 1950s, in Germany, the Institute for Grapevine Breeding Geilweilerhof, among others, has been carrying on the work up until the present day. Its present aim is to develop fungus-resistant cultivars that must be grafted onto Phylloxera-resistant rootstock rather than developing a direct producer.

The most successful vines that have been developed at this institute are Phoenix, Orion and Regent.

3.1.4.2 Intraspecific vinifera crosses

These are crosses of one vinifera varietal with another.

After Bouschet came Prof. Muller from Thurgau in Switzerland. He produced the Muller Thurgau varietal by crossing Riesling and Madeleine Royale. This was a great success and presently occupies 20% of the German vineyard.

The Germans developed many other vinifera crosses at their research centres at Geisenheim, Geilweilerhof and Friburg: Scheurebe, Kerner, Reichensteiner etc.

3.1.5 Genetic modification

Some virus-resistant rootstocks have been produced but are not used in commercial vineyards.

3.2. The Choice of Vine Varietals for the English Vineyard

The choice of vine cultivars can be very confusing for the English wine producer due to the large number of varietals available and the lack of reliable data on the performance of different varietals under English conditions.

Winkler suggests there are as many as 8,000 different vine cultivars, including wild and table grapes, while Jancis Robinson lists I000 as important to today's wine drinker. Also, since 1882 when Muller-Thurgau was developed, there has been constant research by continental viticultural stations (particularly in Germany) to produce better and more productive vines varietals. To complicate the picture further, it is common to find significant differences in performance in different clones of the same varietal!

Accurate and reliable information regarding the performance of varietals in the UK is difficult to find as there are no government research stations to assist growers. Choice of a vine from its performance on the continent is not a recommendation for UK growers since the performance of vines is found to be remarkably different over here. There are also further complications, such as the effects of rootstocks, soil, meso- and microclimate etc.

3.2.1 Criteria for selecting cultivars

• EU legislation (see 3.2.2)
• The rate at which the varietal completes its vegetative cycle: As the growing season for vines in England is short, only varietals with a short vegetative cycle can be grown successfully. However, some varietals, such as Scheurebe, ripen so early that they are difficult to grow commercially, as they are prone to wasp damage. It is also generally agreed that varietals produce their best product when grown in the coolest areas possible. It is, therefore, vital to have a good idea of the vineyard's mesoclimate when selecting varietals.
• The winemaking qualities of the varietal:
  • The genetic characteristics of wine grapes, more than any other factor, predetermine the style and quality of a wine. While climate influences the levels of sugar, acid, pigments, tannin and the intensity of fruit flavours, the relative winemaking quality of different varietals is constant from region to region.
  • Furthermore, the wine-buying public is greatly influenced by fashion, and so the varietal chosen must reflect a style for which there is a market.
• The yielding potential: The amount of harvest produced by a varietal is influenced by its capacity for floral initiation and fruit set in adverse English conditions.
• Resistance to disease: This can drastically reduce the number of spray applications and increase the health of the vintage. In some cases, as in resistance to Eutypa, this factor may become determining. Interspecific hybrids are the most resistant, but there is also a wide variation in sensitivity within pure vinifera varietals.

3.2.2 European Union legislation

The EU exercises certain controls over viticulture and viticultural techniques. There are rules concerning: – The classification of vine varieties – The classification of wine-growing areas – The prohibition on planting vines for the production of table wine – The certification of vines and propagating material – The declaration of areas for the production of propagating material.

There is a considerable effort to reduce wine legislation in the EU, and few of these controls are likely to be imposed on the UK in the foreseeable future, apart from the ban on the use of interspecific hybrids for the production of quality wine.

Sadly, vines can contract diseases. Here are the major must we need to watch out for and strategies to handle them.

Downy Mildew (Plasmopara viticola)

A fungus-like (oomycete) organism that causes yellowish patches on the leaves and can cause losses in yield and fruit quality.

• Conditions: Warm, wet, humid conditions.
• Susceptibility: Most susceptible in the spring and early summer, when new growth is abundant and weather conditions are often wet.
• Identification:
  • Leaves:
    • Roughly circular yellowish discolourations, called “oil spots”
    • White fluffy growth primarily on the lower leaf surface
    • As lesions age, they turn brown from the centre outward
    • Severely infected leaves may drop
  • Shoots:
    • Infected shoot tips curl (“shepherd’s crook”)
    • Covered with white fluffy sporulation
  • Rachis:
    • Severe infections will cause the rachis and cluster to twist like a corkscrew
    • Entire surface can be covered with sporulation
  • Berries:
    • White fluffy sporulation when shot-size
    • May shrivel and drop off
    • Berries of red cultivars infected between 3 and 5 mm in diameter size will turn colour prematurely
    • Those of white cultivars acquire a mottled appearance
    • Stay hard when healthy berries start to soften at veraison
• Conventional treatment: Application of fungicides.
• Organic treatment: Use of copper-based sprays, improving air circulation in the canopy and promoting biodiversity.

Note: Why copper? When applied correctly, a protective barrier of the copper compound coats the plant tissue. The copper compound releases copper ions in the presence of moisture which are passively taken up by the fungal spore of the downy mildew pathogen to the point that they stop germination and infection.

Powdery Mildew (Erysiphe necator)

A fungal disease that can cause stunted growth and reduce yield and fruit quality.

• Conditions: Warm and dry conditions, high humidity, poor air circulation.
• Susceptibility: Can strike at any time, but it's most prevalent in mid to late summer.
• Identification:
  • Leaves:
    • Frequently first found on the undersides of leaves
    • Lesions become apparent on the upper sides of leaves as well
    • Increase in size and number if the disease is left unchecked
    • On rapidly growing leaves, infections on the underside may cause the leaves to appear puckered on top
    • Severely infected leaves may become brittle and drop off
    • Starting as early as late July, very small orange then brown and eventually black spherical structures (cleistothecia) develop on the upper and lower surfaces of infected leaves
  • Shoots:
    • Initially greyish-white, develop into brown irregular blotches Up to a few cm
    • Indistinct margins and remain visible after shoot hardening
  • Rachis:
    • Severe infections make the rachis brittle
    • Can result in clusters being dropped, especially if mechanical harvesting is done
    • Symptoms on the rachis are similar to those on shoots
  • Berries:
    • Become covered in conidia
    • An initial floury appearance that later becomes dark and grey
    • Dry out and may drop off
    • Later infections (3-4 weeks post bloom) will have superficial greyish scarring but not a lot of mycelial growth or sporulation
    • On all tissues, powdery mildew looks like a greyish-white powder.
• Conventional treatment: Application of sulfur and synthetic fungicides.
• Organic treatment: Use of sulfur-based sprays and milk, increasing canopy air circulation, and selection of resistant varieties.

Note: Why milk? Scientists are not exactly sure how milk sprays work, but most think proteins in the milk interact with sun to create a brief antiseptic effect.

Botrytis Bunch Rot (Botrytis cinerea)

A fungal disease that can lead to significant loss of crop and reduction in fruit quality.

• Conditions: Cool, wet environments, especially during or after veraison.
• Susceptibility: Most susceptible from veraison to harvest, especially if the weather is persistently wet.
• Identification:
  • Leaves:
    • Infection begins as a dull green spot
    • Typically including the edge of the leaf blade, eventually becoming necrotic
    • When incubated under high humidity, produce greyish-tan spores
  • Rachis:
    • Infected areas dry out, causing berries below the affected area to shrivel
  • Berries:
    • White cultivars become brown and shriveled
    • Red cultivars become reddish-brown
    • Covered with greyish-tan conidia frequently first seen in tufts or along splits in the berries
    • Skin is easily removed from the flesh (“slip skin”)
    • If dry weather follows infection, infected berries will shrivel, and the infection will not progress (Noble rot)
• Conventional treatment: Use of synthetic fungicides and careful canopy management.
• Organic treatment: Canopy management, proper site selection, and the use of resistant grape varieties can help. Biological control agents and copper or sulfur sprays are also options.

The defense system of a vine

Vines, like other plants, use a sophisticated system of defences to ward off pests and diseases. Their “immune system” is based on recognising and responding to molecular signals from attacking organisms, combined with physical and chemical defences.

The defence system of a vine consists of two tiers of immunity: Pathogen-Associated Molecular Pattern-Triggered Immunity (PTI): The vine's initial response is to common pathogenic features, known as Pathogen-Associated Molecular Patterns (PAMPs). These are recognized by Pattern Recognition Receptors (PRRs) in the plant cells, triggering defense responses like strengthening of the cell wall, production of antimicrobial substances, and programmed cell death to inhibit pathogen growth.

Effector-triggered immunity (ETI): Some pathogens can evade the vine's initial defenses and infect the plant, releasing specific molecules called effectors into the plant cells to help the pathogen suppress the plant's immune response and colonize the plant. If the plant has resistance genes that recognize these effectors, it can initiate a more specific and strong defense response. This often includes localized cell death (hypersensitive response) to prevent the pathogen from spreading further.

Both these levels work together, and a vine's immune response will involve several physical, chemical, and cellular changes. It's also worth noting that the vine's ability to protect itself against diseases and pests is significantly influenced by environmental conditions and its overall health.

Systemic Acquired Resistance (SAR) is another aspect of a vine's defense mechanism, where an initial localized infection leads to an increased resistance throughout the plant. This is similar to immune memory in animals, where the immune system “remembers” previous infections and responds more effectively to subsequent encounters with the same pathogen.

To enhance a vine's natural defence system, it's crucial to maintain the overall health of the vine through adequate nutrition, water, and sunlight. Proper pruning practices and pest control also play a critical role. In some instances, the use of biological control agents (beneficial insects or microbes) or organic compounds that stimulate the plant's own defences can be helpful. Disease-resistant grape varieties are also a crucial strategy for managing diseases in vineyards.

However, our understanding of plant immunity is still growing, and future research will continue to shed light on how we can better protect our crops from pests and diseases.

Before we dive deep into Agricultural Course by Rudolf Steiner, let's understand the key differences between organic and biodynamic farming.

Both frameworks share a commitment to sustainable, chemical-free methods of agriculture. However, there are some significant differences between the two.

Holistic Approach: While organic farming tends to focus on the health of individual plants or fields, biodynamic farming views the entire farm as a single, self-sustaining organism. This includes the integration of crops and livestock, recycling of nutrients, maintenance of soil, and the health and well-being of the people involved.

Biodynamic Preparations: Biodynamic farming uses specific preparations, as outlined by Rudolf Steiner, made from fermented manure, herbs, and minerals. These are used to enrich the soil and stimulate plant growth. While organic farming also uses compost and natural fertilizers, it doesn't use this specific set of preparations.

Cosmic Rhythms: Biodynamic farmers use an astronomical sowing and planting calendar. They believe the moon, planets, and stars have an influence on the growth and development of plants and make farming decisions based on these celestial bodies. This is not a practice generally associated with organic farming.

Pest and Disease Control: Both methods use natural means for pest and disease control, but biodynamic farming emphasizes the use of the farm's inherent biodiversity and ecosystem balance for this purpose. While organic farming may often bring in external, natural means for pest and disease control, biodynamics primarily seeks to prevent pests and diseases by maintaining overall farm health.

Certification: Certification for both is rigorous, but biodynamic certification (Demeter Certification) requires a higher standard than most organic certifications. All biodynamic farms are organic by default, but not all organic farms meet the requirements to be biodynamic.

Spiritual/Philosophical Aspects: Biodynamic farming has a spiritual/philosophical component that organic farming doesn't necessarily have. Biodynamic farmers consider themselves to be mediators between the land and cosmic influences. This doesn't mean that organic farmers can't have a spiritual connection to their land, but it's not a prescribed part of organic farming like it is with biodynamic.

I don't know if Mr. Steiner would appreciate my comment but he definitely was a Daoist.

Back to the book.

“Agriculture Course” is the foundational text for biodynamic farming. Rudolf Steiner delivered it as a series of eight lectures to farmers in Koberwitz, Germany, in June 1924.

Here's the overview of the key points in each lecture:

Lecture One: Steiner begins by noting that agricultural methods have evolved away from nature and towards mechanization and artificial fertilizers. He proposes that a farm should be viewed as a self-contained organism, where the interrelationships between all elements are taken into account. In this lecture, Steiner starts to establish the foundation of biodynamic agriculture, emphasizing the need for an in-depth understanding of the life processes occurring on a farm.

Lecture Two: The focus here is on soil health. Steiner criticizes the reliance on purely mineral fertilizers and advises farmers to consider the living nature of the soil. He introduces the idea of cosmic and earthly substances, explaining that both play a vital role in plant growth and soil vitality. Steiner also emphasizes the importance of various animals and their manure in contributing to the vitality of the farm ecosystem.

Lecture Three: In this lecture, Steiner delves into the nature of plant growth and explores the roles of nitrogen, potassium, and calcium in the process. He also introduces biodynamic preparations and explains how they are made. For instance, he details preparation 500 (horn manure), which involves filling a cow's horn with manure and burying it over winter.

Lecture Four: Steiner discusses the influence of celestial bodies on plant growth. He suggests that the phases of the moon, movements of the planets, and positions of the zodiac constellations can impact plant development. He talks about different types of plants (root crops, leafy plants, etc.) being influenced by different celestial bodies. This lecture lays the foundation for the biodynamic planting calendar.

Lecture Five: Steiner focuses on the role of animals within the farm ecosystem. He discusses how animals' physical and spiritual characteristics relate to their surroundings. The link between an animal's diet and its manure is also explored, emphasizing how this relationship can affect soil fertility. Steiner talks about animal diseases and their connection to the overall health of the farm organism.

Lecture Six: Here, Steiner delves deeper into the nature of different types of plants. He discusses the unique forces at play within fruit-bearing, leafy, and root plants and how these forces are influenced by their environment. Steiner expands further on the use of biodynamic preparations, including how and when they should be used for maximum impact.

Lecture Seven: Steiner explores the correct approach to pest and disease control. Rather than simply reacting to diseases and pests when they appear, Steiner suggests maintaining the overall health of the farm organism to prevent their occurrence. If pests do appear, he recommends using natural methods, such as promoting the pests' natural enemies, to control them.

Lecture Eight: In the final lecture, Steiner emphasizes the importance of spiritual understanding in farming. He encourages farmers to see themselves not just as observers but as active participants in the life of the farm. Steiner believes that through this engagement, farmers can mediate between the cosmos and the earth, leading to a more balanced and productive farm ecosystem.

Without trying to sound like someone whose favourite book is Eat, Pray, Love, I definitely believe everything in this universe is vibration. For instance, mass is “created” through the interactions between electron or quark fields and the Higgs Field. (We are all interference patterns!) However, it's tough not to be sceptical of some of the more “esoteric” elements of biodynamic farming.

My current theory is that the placebo effect of adhering to the principles affects the vines through us. Again, I cannot help but think Steiner was a Daoist.

1. History, Uses and Production

Family, Genus, Species and Related Plants

Vitis includes many species, including V. vinifera, the most widely planted grape species in the world, which is used primarily for wine, table consumption, juice and raisin production.

Natural Growth Conditions

V. vinifera is much more tender, and generally cannot withstand temperatures below -15°C without suffering damage.

Unlike tree fruits, e.g. apple or pear, which set a terminal bud as winter approaches, grapevines will continue to grow as long as conditions are met.

Uses

The grape attains a high concentration of sugar when ripe, and also (depending on cultivar) pectin, as well as a wide range of aromatic compounds. These factors, in concentration with the presence of relatively high levels of acids (particularly tartaric acid), mean that the fruit is amendable to many different end uses.

Fermented Grape Products

Evidence that humans were fermenting grapes with the specific purpose of making an alcoholic beverage can be traced back to around 7000 BC in China, in the Near East around 6000 BC. There is an association between grapes and various types of yeasts (usually living on the surface of the berry), so it is likely, at least initially, that fruit which had been picked and stored may have started fermenting naturally.

Wine can be thought of as a naturally made storage form of the fruit as it retains characteristics of the grape and, protected from oxidation, can remain palatable for many years.

2. Cultivars, Anatomy and Improvement

Main Cultivars for Various Uses

The Organisation Internationale de la Vigne (OIV) list approximately 250 cultivars as being significant to the wine industry, and many more recent data state that 33 cultivars are responsible for 50% of the global vine area, and 13 cover more than 33%.

Clones

In practical terms, a clone is a selection of a cultivar that has some distinguishing characteristic that someone noticed and thought was significant enough to warrant separate propagation of the vine.

Examples of characteristics that may be used to select a clone are vine growth (vigour), disease resistance, leaf or shoot appearance, cluster shape, fruitfulness, fruit composition, etc.

In a practical sense, clones have value because they are all the same variety, but not quite.

In general, it is good practice to have a few different clones in a planting to spread some of the risk by having slightly greater genetic diversity, while still being able to produce a varietal product.

Anatomy and Physiology

The grapevine structure is very similar to that of many other woody perennials. It has a root system that serves to anchor the plant in the ground but also gathers and sends water and nutrients to support plant growth and acts as a carbohydrate reservoir for carrying over energy from season to season. There is also a trunk, which serves as structural, carbohydrate storage and conduit roles, and the branches (called canes or cordons) that support the shots, fruits, and leaves.

Roots

The root system is made up of the larger arms and branches, down to root tips and root hairs. The latter organ is the workhorse of the root system, where the vast majority of nutrient and water update occurs.

The root system, as does the shoot system, produces plant growth regulators that can modify the growth of the other parts of the vine.

Mycorrhizae

These are a group of fungi that form beneficial relationships with most species of plant, including grapevines. In trees, shrubs and woody perennial vines, vesicular-arbuscular mycorrhizae (VAM) are the most common. These are symbiotic relationships, as both the plant and the fungi benefit.

I highly recommend reading Entangled Life: How Fungi Make Our Worlds, Change Our Minds & Shape Our Futures by Merlin Sheldrake.

The exploration of soil is very important to the survival of the vine. Some nutrients, such as phosphorous, are immobile in the soil and thus, for the plant to obtain a supply of it, the roots must grow into areas of soil that have those nutrients available. This is unlike a nutrient like nitrogen, which is mobile in the soil solution and is brought to the roots by water percolating through the soil profile.

Roots grow in all directions and, if an area of higher nutrient or water availability is grown into, there is a more rapid proliferation of roots there.

Management decisions, such as the severity of pruning, also affect root life, with more severe pruning reducing the average lifespan of a root. Those parts of the root that continue to develop become more permanent branches and are a site for carbohydrate storage,

Above the Soil

The above-ground parts consist of the trunk, which is the portion of the vine from the ground to about the fruiting wire and provides support for canopy growth as well as being a carbohydrate storage site. Also shown are new canes, which were the previous year's shoots and a non-count cane, which are shoots arising from buds buried in the bark (formerly at the base of shoots).

It took me a while to understand why we distinguish shoots/branches by age. I only understood why after learning why and how to prune vines. In short, flowers (therefore, fruits) only grow out from a fresh shoot, and shoots grow from the buds located at nodes. Therefore, we need to choose a shoot to become the cane (almost 1 yr old shoot at the time of/after harvest) from which fresh shoots will grow with flowers.

Along the cane are nodes, separated by internodes. At this point in the season, the nodes are where the following season's shoots will arise. Positioned at alternate sides of the cane are compound buds, so called because they contain three (the primary, secondary and tertiary) pre-formed shoots. Each of these will have six to nine leaf primordial and, in some cases, flower cluster primordial already formed.

It is worth noting that grapevines do not form adventitious or spontaneously formed buds – all shoot growth originates from a previous node position.

Therefore, we must be thinking for at least two years (the current season and the next) at all times when we are taking care of the vines.

Photosynthesis

The workhorse of photosynthesis is the chloroplast, which collects light energy using primarily chlorophyll. Chlorophyll appears green because it absorbs most red and blue wavelengths of light. The light energy collected is used to split water molecules (H₂O), adding the hydrogen (H) to carbon dioxide (CO₂) to form carbohydrates (CHO) in the form of sugar (glucose). As a result of this process, oxygen (O₂) is released.

Ingredients that the photosynthetic process needs are light, moderate temperature, CO₂ and water. Temperature also influences respiration, where its rate increases the warmer it gets.

Specialized guard cells form the pore when the cells become turgid, and the pore closes when the cells lose water. In this way, there is an efficient method for the vine leaf to regulate the passage of gases, including water vapour, in and out of the leaf. When the vine has a good water supply, the guard cells are turgid and the stomatal pores are open; when the vine suffers water stress, the guard cells become flaccid and the pores close.

_{From Google.}

_{Masseto, June 2023}

Here's the tl;dr. I decided to become a winemaker a few months ago. After spending the first month visiting as many wineries as possible, primarily for sanity checks, it's time for studying.

I plan to organise my notes here for my brother and Jenny.