Vineyard Management Series: Grafting a Vine

Vineyard Management Series

This is the first in my Vineyard Management Series, after spending some short time working in wineries, I have come to appreciate that the hard work that goes into winemaking truly begins in the Vineyard.

Arte Della Vigna

Grafting a vine involves joining two parts of the grapevine together to create a single, more resilient plant. This technique allows grape vines to express the desirable varietal characteristics of the scion (upper part of the joined plant) in the fruits, while developing or keeping the root system of the rootstock (lower part of the joined plant).

In the past grafting has been used since the Ancient Roman times, although this became a widespread practice in Europe after the phylloxera louse devastated the European vineyards in the late 19^th century (see my previous blog post for more in-depth information on the outbreak). The winemakers grafted the European vines (called the scion) onto American root systems (called rootstocks), which allowed them to keep the European fruit quality, flavour and varietal characteristics whilst also having the phylloxera resistant American rootstocks.

Scientists have now developed a range of rootstocks that are not only resistant to various pests in the soil but also have a better tolerance to different environmental conditions, including lime content, pH and moisture levels. Nowadays, the rootstocks used in most vineyards are hybrids of three species; Vitis rupestris, Vitis riparia and Vitis berlandieri – which together provide rootstocks which have lime resistance, drought resistance and good vigour.

Therefore, grafting is not just used in vineyards which are vulnerable to disease but also allows winemakers to convert existing vines into different, more desirable varieties. It is also a method which can help to reinvigorate old or damaged vines by replacing unproductive wood and potentially improving yields.

Grafting two vines together can be thought of as like a surgical procedure, where the winemaker is connecting injured tissues together to promote healing in the vine (also known as callus formation). Therefore, it is also very important that the tools used for this process are clean to minimise the risk of any infection of the open wound and encourage healing. The timing of the graft is also important as the winemaker wants to give the vine as high a chance of a successful graft as possible. Therefore, the procedure of grafting is often performed during the vines dormant season or in the early spring when the sap is flowing through the vine, this will allow for better callus formation.

However, it is important to note that Grafting is not a way of healing sick rootstocks. If the vineyard is unhealthy, attaching new scions to your unhealthy rootstocks will most likely not heal them. Likewise, grafting does not make old vines young. If your rootstock and trunk is very old, grafting young healthy new wood will not make the vine young again – it is only as young as the root.

There are a few different types of Grafting, and the general gist of it is that the injured tissue of one vine heals to the injured tissue of another. However, the crucial element for a successful graft is ensuring that there is proper alignment and permanent contact between the cambium layers of the scion and rootstock. The cambium layer is the layer of green living tissue that lies between the bark and the wood. Therefore, the incision made on the trunk of the rootstock and the incision made on the scion must be done in a way that will allow as much of the cambium tissue on both pieces to contact each other. Increased cambial contact (the more are that touches) between scion and rootstock increases the chances of success.

Whip Grafting is a common bench grafting method, especially for younger vines (or smaller diameter trunks), which involves cutting both the scion and rootstock at complementary angles, matching the cambium layers and then wrapping the graft to secure and protect it. This is usually performed in a nursery so that the young, grafted vines can be kept in a warm and moist environment for weeks so that the callus can join the two cuttings together.

University of Florida

Field grafting allows winemakers to alter the expression of the existing vines which already have a developed root system (rootstock), without uprooting and replanting the vines. This can be an economical way of changing a whole vineyard rather than replanting.

Cleft Grafting is often used on older vines (or thicker trunked vines) and involves splitting the rootstock from the top of the trunk about 5cm down and inserting the scions into the split, taking care to align the cambium layers and then wrapping the graft to secure and protect it.

Nature & Garden

Bark Grafting is a technique used when the rootstock is larger than the scion and involves making an incision in the bark of the rootstock and inserting the cut scion underneath and then wrapping the graft to secure and protect it.

Nature & Garden

Chip and T-Budding are slightly different methods used for grafting as only one bud is used (in the previous methods usually 2 buds are used). The scions’ buds onto the rootstock by making a chip or “T” shaped cut into the rootstock and slotting the bud of the scion into it.

Nature & Garden

Graft unions are fragile, take time to heal, and unfortunately not every graft is successful. It is a time-consuming process requiring patience and practice. Nonetheless, by understanding the principles and techniques of grafting, vineyard managers can make informed decisions to ensure healthy, productive vine with high-quality grapes.

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Sources

Australian Wine Research Institute

Decanter

Wine Maker Mag

Grapes

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