"The highly skilled technique of grafting vines on to a resistant rootstock saved the European vineyards from the destructive phylloxera"

All the vines at La Rosa are grafted onto a resistant rootstock in order to protect them against the aphid, phylloxera. The technique involves inserting tissues from one plant into another so that they join together. The top part of the plant is normally referred to as the scion, the grape cultivar, and the lower part, the rootstock. In order for the grafting to be successful, the cambium tissues of the rootstock and scion must have good contact. Both tissues must be kept alive until the 'graft' has taken which is usually a period of a few weeks. There are a number of different types of graft such as the cleft and omega graft.

There are two different methods of grafting, field or bench grafting, both of which are used at La Rosa.  

Field Grafting

Field grafting is the traditional method of planting young vines in the Douro. First the rootstock is planted in early spring and allowed to grow for a year or two to form a strong, healthy plant. As hand grafting is a specialised skill, an experienced grafting crew is employed to graft the scion, the grape cultivar, on to the rootstock in situ. Grafting normally takes place in the early spring when the sap  begins to rise in the vines  helping the new graft fuse and heal quickly. 

We rarely use this method now as we prefer to use bench grafts when re-planting or establishing a new vineyard as the vines enter production a year or two earlier making it a more economical method. The benchgrafts also tend to have a better success rate than the field grafts.  

However, when replacing a few vines which have died or have been removed we still use the traditional method of field grafting. The American rootstock is quite hardy and easy to establish while planting benchgrafts need attention and regular watering which for just a few vines is difficult.

We also use field grafting to change the grape variety in a vineyard which means we don't  incur the expense of replanting or loose several years of crop production. This procedure involves cutting off the top of the grapevine and inserting into the trunk two-bud canes of the chosen new grape variety. The conversion usually takes a season and the quick resumption of fruit production is a major advantage of this technique. We have used this technique successfully in some vineyards, such as Val Grande, where Tinta Roriz has been converted to Touriga Nacional. 

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