Canopy management Flashcards
What is canopy management
Canopy management involves the organisation of the shoots, leaves and fruit of the vine in order to maximise grape yield and quality.
It can have important implications on both the production and ripening of grapes, including grape yield, health and ripening.
key aims of canopy management
1.maximise the effectiveness of light interception by the vine canopy
2.Reduce the shade within the canopy
3.Ensure that the microclimate for the grapes is as uniform as possible so that the grapes ripen evenly
4.Promote balance between the vegetative and reproductive functions of the vine
5.Arrange the vine canopy to ease mechanisation and/or manual labour
6. promote air circulation through the canopy to reduce incidence of disease
Impact of Sunshine and shade in the vine
Vine organs (buds, leaves, fruit) develop in different ways when they are in shade or exposed to sunlight. Exposure to sunlight is associated with greater bud fruitfulness, which describes the number of inflorescences developing inside a latent bud. Shady conditions are associated with reduced bud fruitfulness, with the bud producing more vegetative structures such a tendrils, rather than reproductive structures such as inflorescences.
Effects of promoting sunlight exposure within the canopy
- Increased sugar levels in grapes through greater overall photosynthesis in the vine
- Increased tannin levels and greater polymerisation of those tannins, leadin to less bitterness,
- Enhanced anthocyannin development in black grapes
- decreased malic acid - warmer temperatures lead to more malid acid being broken down in celllular respiration.
- Increased levels of some favourable aroma precursors and aroma compounds
- Decreased methoxypyrazines which give herbaceous characters in grape varieties such as Cabernet Sauvignon.
Define Yield
Yield is a measure of the amount of fruit produced. It can either be measured per vine or over a set area (kg per hectarea). There is a link between the yield of a vine and the quality of fruit in that vine that is either overcropped or under-crooped, and hence out of balance, is likely to produce fruit of lesser quality than a balanced wine.
Balance yield/Quality
It will depend on the natural resources of the vineyard, the planting material and the wine style. Therefore, some vines will be balanced at higher yields than others.
the yield over a set area will depend on the yield per vine and the planting density. The higher the yield within a set area, the more wine can be made and sold. Therefore, even if yield per vine is low, the vines may be planted very densely to gain as much yield from the vineyard as possible.
Vine density
Vine density is the number of vines that are planted per hectare of vineyard. Vine densities range from as low as few hundred vines per hectare to over 10,000 per hectare.
Vine density will influence within within row spacing and the between-row spacing of the vines, and therefore need to be considered during the vineyard establishment.
What influences the optimum vine density
the vigour of the vine, the type of trellising system used and what access is needed between the vines. Vines that are low in vigour and VSP trellised can be planted closed together within the row as the individual vines are relatively small. Planting the vines with greater within-row spacing would not maximise the vineyard land, particularly important on expensive land such as Grand Cru, Burgundy vineyards. By comparison vines that are high in vigour will need greater within row spacing to grow and be in balance. Planting this vines too close together could lead to overlapping canopies and increased shading, reducing rpeness and quality.
Vine training
It refers to the shape of the permanent wood of the vine and can be split broadly into two categories: Head training and Cordon training. Either system can be low-trained (the vine trunk is short) to benefit from heat retained by the soil or provide greater protection from wind, or high trained (the vine trunk is long) to better avoid frosts or make manual interventions, such as harvesting easier. Some trellising systems are only possible with relatively high training.
Head training
These vines have relatively little permanent wood. The permanent wood usually consists of the trunk, sometimes with a few short stubs growing from the top of the trunk. These vines can either be spur-pruned or replacement cane-pruned.
Cordon training
These vines typically have a trunk and one or more permanent horizontal arms of permanent wood, typically called “cordons”. They usually spur-pruned. Cordon training takes longer to establish than head traning due to the amount of permanent wood.
Vine pruning
Pruning is the removal of unwanted parts of the vine. It takes place in the winter and summer. Winter pruning is particularly important as it determines the number and location of buds that will form shoots in the coming growing season, and hence impacts on the potential yield there are two types of winter pruning.
Summer pruning includes a variety of techniques to keep the canopy of the vine maintained.
Summer pruning
To keep the canopy of the vine maintained. They are usually aimed at enhancing grape ripening, reducing chance of fungal disease or making the vineyard easier to manage. Except for pinching and disbudding, these techniques can all be mechanised if the vineyard is appropriately set up (straight, well maintained trellised rows) and this becoming increasingly common in areas where skilled labour is difficult to find.
Disbudding, shoot removal, Shoot positioning, Pinching, Shoot trimming, Leaf removal, Crop thinning or green harvesting
Disbudding
The removal of buds and is conducted both to manage vine balance and yields, and to remove buds that are poorly positioned. Growers will often leave a high number of buds on the vine at winter pruning
Shoot removal
The removal of shoots, often laterals, that are infertile or poorly positioned will help to maintain a well-organised, open canopy
Shoot positioning
The shoots are tucked into the trellis wires to better organise the canopy and facilitate mechanisation
Pinching
This removed the shoot tips at flowering to improve fruit set
Shoot trimming
Cutting shoots to limit growth and reduce canopy thickness enhances fruit ripening by reducing competition for carbohydrates between the shoot tips and fruit. It also lowers disease pressure through better air circulation and improved spray penetration
Leaf removal
Removing leaves to reduce shading of fruit and hence enhancing ripening, will also lower disease pressure through better air circulation and improved spray penetration. However, in warm and hot climates, excessive removal of leaves can expose the grapes to too much sunshine and heat and lead to sunburn
Crop thinning or green harvesting
This is the removal of bunches of grapes to increase ripeness of those grapes left on the vine. If this process is timed near veraison, it can enhance ripening. In cases where fruit ripening is uneven, the least ripe bunches of grapes may be removed to improve uniformity of ripening and hence enhance quality
VSP
Vertical shoot positioning - is the most common type of trellising system and one of the most simple. The vine’s shoots are trained vertically and are held in place onto the trellis forming a single narrow canopy. It can be used on both head-trained, replacement cane-pruned vines and cordon trained and spur pruned vines. When used on replacement cane pruned vines, it is typically called Guyot training(single or double).
It is suited to vines with low or moderate vigour
Complex training system
Vines that are vigorous can produce a lot of shoots and ripen high yields of fruit. If these vines are threllised using VSP, the canopy can be too dense, resulting in too much shading of leaves and fruit. Complex traning systems have therefore been invented to split the canopy to reduce shade and maximise light interception. Using these systems, it is possible to make best use of the vineyard space and resources to produce large yields of high quality fruit
Geneva Double Courtain (GDC) or Lyre
Is a complex traning system. The canopy can be split horizontally
Smart-Dyson or Scott-Henry
when the canopy is split vertically, as a complex training system in vines that have a vigourous growth
Effect of maximise the leaf surface to sunlight
This increases the vine’s photosynthetic capacity (compared to a vine with a dense shaded canopy) and means it can ripen larger yields.
How canopy management reduce fungal disease pressure
Due to poor air circulation, dense, shaded canopies dry out more slowly after rainfall or morning dew and provide suitable conditions for fungal diseases to develop. Dense canopies are also problematic when spraying fungicides, as it is more difficult to ensure the spray reaches all of the canopy
When a vine enters a vegetative cycle
If the yield of fruit is too low for the vigour of the vine, shoots and leaves growth continues through the vine cycle because there is not much to ripen. The growing shoots and leaves compete with the grapes for sugars and other compounds needed for growth and can negatively affect grape formation and ripening. This may also result I low yields the next year due to reduced bud fruitfulness. Low yields in the next season may lead to under-cropping in that year and hence the vine enters what is known as vegetative cycle.
Winter pruning vs summer pruning
Winter pruning is key time when decisions are made that will influence number of shoots and potential yield in the coming growing season.
Summer pruning techniques may be applied during the growing season to amend the vine balance and enhance ripeness as needed.
Row orientation
Row orientation will depend on both climatic and logistical factors. It is generally considered that a north- south orientation provides the most even sunlight exposure through the canopy. However, because conditions in the afternoon are usually warmer than those in the morning, grape bunches on the west side of the canopy may require more shading from leaves to protect them from suunburnt.
Prevailing winds may also be a factor in decisions on row orientation, with grape growers choosing to orient the rows at a 90 angle to the direction of the wind to provide most protection.
From a logistical standpoint, orienting rows parallel to the longest side of the vineyard is often the most efficient option. Vineyards on slopes at an angle of greater than 10% need to be planted up and down the slope rather than across or machinery may slip.
What’s important when choosing an appropriate training and trellising method
- The vigour of the vine: Vigour depends on the natural resources available to the vine (Particularly temperature, water and nutrients), the planting material ( Grape variety, clone, rootstock) and the presence of any disease. Humans can have an influence on the natural resources available reduced by purposely limiting water availability in regulated deficit irrigation or by using low-vigour rootstocks)
- The topography of the site - Many trellising systems cannot be used on steep slopes or wind sites. For instance, in the Northern Rhone, France and Mosel in Germany, must be trained on individual stakes, rather than a wired trellis.
- The need for mechanisation - Certain training and trellising systems are more suited to mechanisation than others. e.g VSP-trellised vines are generally suited to mechanisation as all the fruit tends to be in the same area for each vine. Bush vines or individually staked vines are less uniform and therefore much more difficult.
What’s important when choosing an appropriate training and trellising method
- The vigour of the vine: Vigour depends on the natural resources available to the vine (Particularly temperature, water and nutrients), the planting material ( Grape variety, clone, rootstock) and the presence of any disease. Humans can have an influence on the natural resources available reduced by purposely limiting water availability in regulated deficit irrigation or by using low-vigour rootstocks)
- The topography of the site - Many trellising systems cannot be used on steep slopes or wind sites. For instance, in the Northern Rhone, France and Mosel in Germany, must be trained on individual stakes, rather than a wired trellis.
- The need for mechanisation - Certain training and trellising systems are more suited to mechanisation than others. e.g VSP-trellised vines are generally suited to mechanisation as all the fruit tends to be in the same area for each vine. Bush vines or individually staked vines are less uniform and therefore much more difficult.
Types of winter pruning
Winter pruning is important as it determines the number and location of buds that will form shoots in the coming growing season and hence impacts on the potential yield. There are 2 types
- Spur pruning
- Replacement cane pruning
Types of winter pruning
Winter pruning is important as it determines the number and location of buds that will form shoots in the coming growing season and hence impacts on the potential yield. There are 2 types
- Spur pruning
- Replacement cane pruning
Spur pruning
Spurs are short sections of one year old wood (the shoot from the last growing season that have lignified) that have been cut back to only two or three buds. Spurs can either be distributed along a cordon (cordon training) or around the top of the trunk (head training). Spur pruning is easier to carry out than replacement cane pruning and can often be mechanised.
Replacement cane pruning
Canes are longer sections of one-year-old wood and can have anything between 8 and 20 buds. They are typically laid down horizontally and need trying to a trellis for support and positioning. Replacement cane pruning is more complex than spur pruning and requires a skilled labour force to select suitable canes and train them.
Trellising
Trellising are permanent structures of posts and wires that help to support and position the vine’s shoot. The vine’s tendrils will naturally curl around the trellis wires and help keep the canopy in place. The grape grower will also tie in branches and shoots to the trellis as necessary.
