During the cold winter months, deciduous fruit growers and nurseries are focused on propagation and renewal. During the period of winter dormancy, the fruit tree and grape vine nurseries prepare the new trees and vines for growers, ensure that each of these is grafted.
Grafting is done by combining two pieces (the scion for the canopy and the rootstock for the roots) of different species of a plant to grow as one plant unit. It is vital that both parts of the plant material are dormant when the process is done. The survival of the scion is dependent on successful fusion with the rootstock as it cannot feed itself without this. During springtime, the rootstock sugars will move up to and into the scion in support of active growing, and to the graft site where healing and union occurs.
Grafting is necessary as the fruit varieties that are produced commercially are not resistant to certain diseases that are endemic in the soil and cuttings from these plants need to be grafted onto disease resistant rootstocks.
Grafting is a standard practice for vine and fruit tree nurseries to ensure disease resistance. It is also practiced in situ in established orchards and vineyards. When improved varieties become available, rather than destroying the established root system, growers will sometimes replace only the scion or top section of the plant while retaining the existing established root systems.
Within the table grape and wine industry, grafting became a standard practice in the wake of the phylloxera epidemic in the 1880’s. Phylloxera is an American aphid and its global decimated vineyards throughout the world, including the traditional wine production regions in Europe as well as vineyards in the Western Cape. This was a massive crisis and for a while it seemed that the production of wine would not be able to continue. Through extensive research over time, the world’s vineyards were restored through the practice of grafting vines onto phylloxera resistant rootstocks. Due to the continued presence of phelloxera and other diseases in soils throughout the world, both table grape and wine grapes are routinely grafted onto rootstocks before any vineyards are established.
In addition to strengthening the plant’s resistance to certain diseases, grafting thus also makes it possible to preserve and extend the life of valuable established orchards or vineyards and can also be used to repair injured trees and produce dwarf trees and shrubs. In fact, much of the fruit and wine we enjoy owes its existence to this nifty ability of nature to make two plants fuse and grow together.
Article by Louise Brodie and Jacques Burger (co-author)