Eutypa dieback

The fungus survives on dead wood in fruiting bodies (perithecia) which have a darkened, charcoal appearance. These structures release spores throughout the pruning season and following hydration are spread by wind and rain splash. Infection occurs when spores land on fresh pruning wounds, or invade reworking or other wounds. Toxins are thought to be produced by the fungus in the wood and these are translocated to the foliage, producing the unique foliar symptoms of Eutypa dieback. Cankers form around initial infection points and damage vascular tissue, causing wood necrosis and dieback.