vine improvement, a group of practices designed to improve vine planting material for the benefit of vineyard yield and the quality of the fruit and wine produced. This is currently focused on eliminating harmful virus diseases and also on genetic improvement. Some virus diseases such as leafroll cause delayed ripening and can therefore have dramatic effects on wine quality. clonal selection is a technique which, by selecting high-performance vines, can achieve both ends. Other techniques of virus elimination include thermotherapy and tissue culture. Genetic improvement can also be achieved through beneficial mutation and selection, by genetic modification, and by vine breeding.
