Canopy Management Flashcards
What are the key aims of canopy management?
Maximise the effectiveness of light interception by the vine canopy.
Reduce the shade within the canopy.
Ensure that the microclimate for the grapes is as uniform as possible so that grapes ripen evenly.
Promote balance between the vegetative and reproductive functions of the vine.
Arrange the vine canopy to ease mechanisation and/or manual labour.
Promote air circulation through the canopy to reduce incidence of disease.
Explain head training and what pruning options you have.
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. They can either be spur-pruned or replacement cane-pruned.
Explain cordon training and its common pruning option
These vines typically have a trunk and one or more permanent horizontal arms of permanent wood, typically called ‘cordons’. They are usually spur-pruned. Cordon training takes longer to establish than head training due to the amount of permanent wood.
Explain spur pruning
Spurs are short sections of one-year-old wood (the shoots 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.
Explain 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 tying to a trellis for support and positioning. Replacement cane pruning is more complex than spur pruning and requires a skilled labour force to pick suitable canes and train them.
Explain trellising and advantages and disadvantages.
Trellises are permanent structures of posts and wires that help to support and position the vine’s shoots. 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.
The advantages of trellising are that the shoots can be spread out to maximise light interception, increase air flow through the canopy (reducing risk of fungal disease) and, by positioning the fruit in one area, aid mechanisation. The disadvantage compared to untrellised vineyards is that they are expensive to establish, particularly for more complex systems, and need maintaining.
What is an untrellised vineyard and advantages and disadvantages of it.
In some regions, the vines may not have a trellis. In most cases these vines are head-trained and spur-pruned, and are called bush vines. The benefit of this system is that it is simple and therefore easy and inexpensive to develop. The shoots may also droop down, providing shade for the grapes. These vines are usually planted in hot and sunny regions, such as La Mancha in Spain, so some shade can be beneficial to avoid the grapes becoming sunburnt.
A potential disadvantage is that it is not suitable for mechanisation. It is best suited to vineyards that have dry conditions, which restrict the vine’s vigour. If the vine is too vigorous, the canopy can become too dense and shade the fruit too much. Wet conditions would also promote the development of disease in this dense canopy.
Explain VSP
VSP is the most common type of trellising system and one of the most simple. It can be used on both head-trained, replacement cane-pruned vines and cordon-trained, spur-pruned vines. When used on replacement cane-pruned vines, it is typically called Guyot training: one cane is retained in Single Guyot; two in Double Guyot. The vine’s shoots are trained vertically and are held in place onto the trellis forming a single narrow canopy. It is best suited to vines with low or moderate vigour.
What are examples of complex training systems and when would you use them?
Vines that are vigorous can produce a lot of shoots and ripen high yields of fruit. If these vines are trellised using VSP the canopy can be too dense, resulting in too much shading of leaves and fruit. Therefore complex training systems have been invented to split the canopy to reduce shade and maximise light interception.
The canopy can either be split horizontally, in the case of Geneva Double Curtain (GDC) or Lyre, or vertically, as in the case of Smart-Dyson or Scott-Henry. Using these systems, it is possible to make best use of vineyard space and resources to produce large yields or high-quality fruit, but they are more difficult to manage and mechanise.
What is disbudding and why is it used?
This activity (also called debudding) is 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 in case buds are damaged early in the growing season, for example, by spring frost. Disbudding in the late spring can be used to adjust the number of buds to bring the vine into balance and, where necessary, to comply with grape growing regulations. It is also a chance to remove buds that are poorly positioned, for example, those facing downwards or too close together. Disbudding is also used to remove buds of non-fruit-bearing shoots, which may compete with the grapes for sugar and other resources.
What is shoot removal?
The removal of shoots, often laterals, that are infertile or poorly positioned (e.g. too close together or low down on the trunk) will help to maintain a well-organised, open canopy.
What is shoot positioning?
The shoots are tucked into the trellis wires to better organise the canopy and facilitate mechanisation.
What is pinching?
This removes the shoot tips at flowering to improve fruit set.
What is 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, and lowers disease pressure through better air circulation and improved spray penetration.
What is leaf removal?
Removing leaves to reduce shading of fruit and hence enhance 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.
