Plumpton Notes: Part 4

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:

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

To produce a uniform microclimate for fruit:

To achieve an appropriate distribution of the products of photosynthesis:

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

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:

% 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:

Smart classes sites into three categories:

13.4.2 Trellis selection

Criteria for assessing trellis systems:

13.4.3 Winter Pruning

Reasons for pruning vines:

13.4.4 Vigour Control

Excessively low vigour is generally due to:

Excessively high vigour can be more difficult to control.

Possible strategies include:

13.4.5 Shoot Positioning

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

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

13.4.6 Summer Pruning

This is the least effective method of canopy management.

Pinching

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

Objectives:

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:

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:

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:

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:

Regulation:

14.1.2 Production Standards

Record keepin Must keep physical and financial records of:

Conversion from conventional production systems

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:

Crop rotations These are recommended to:

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:

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:

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:

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:

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:

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)

2. Horn dung (500)

3. Horn silica (501)

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:

14.3.2 Guidelines

Guidelines for Integrated Production of Grapes (IOBC 1999):

Practices that are promoted to meet these principles are:

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:

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.