Disease cycle of Eutypa Dieback. We wish to thank the New York State Agricultural Experiment Station for use of this figure. Figure taken form the Grape IPM Disease Identification Sheet No. 1. The fungus survives in infected trunks for long periods, whether as part of the in-place vine or as old, dead grape wood in the vineyard. Unfortunately, most spores are released at about the same time pruning is being conducted.
Air currents can carry the ascospores long distances to recent wounds on the trunk.
Pruning wounds are by far the most important points of infection. The ascospores germinate when they contact the newly cut wood, and a new infection is initiated. Stunted shoots and small, cupped leaves appear 2 to 4 years after infection. After approximately 5 years, the fungus produces perithecia and ascospores in the dead wood on cankers. The primary control method is removal of infected trunks from the vineyard.