Eutypa dieback is a disease caused by a fungus (Eutypa lata) which grows slowly through the wood of infected grapevines and other woody host plants. Vines become infected through fresh wounds such as those made during pruning. Toxins produced by the actively growing fungus cause stunting of the shoot, though the severity of stunting varies between years and varieties. Two or more years might pass between infection and the appearance of symptoms. It is unlikely that the disease can be spread through cuttings as it appears the fungus itself is isolated to woody parts of the vine. This page provides links to resources about this trunk disease.
Fact sheets and website links