Eutypa dieback

Eutypa dieback is a chronic fungal disease caused by the ascomycete Eutypa lata. It primarily affects grapevines and several other woody plants, attacking the perennial wood and causing wood necrosis, which eventually leads to the dieback of entire branches, cordons, or the total collapse of the vine.

The fungus acts as a wound pathogen. Its spores are spread primarily by wind and rain, infecting the vine through pruning wounds, large cuts, or mechanical damage. Once inside the wood, the fungus colonizes the xylem, producing toxins that translocate upwards and induce the characteristic foliar symptoms seen in the spring.

Symptoms become apparent during the growing season: affected shoots appear stunted with shortened internodes, and leaves show interveinal chlorosis with necrotic, cupped margins. Fruit clusters on infected shoots are typically undersized and may wither or fail to develop, signaling the disruption of the vine's vascular system caused by internal wood decay.

Environmental conditions play a crucial role, as spore release is triggered by rainfall during the dormant season. Because the disease progresses slowly from the initial infection site into the older wood, symptoms might not be visible for several years after the pathogen has established itself, making early identification difficult and long-term control challenging.

Management strategies focus on sanitation and preventive measures. Pruning should be performed during dry periods to minimize spore infection potential. It is essential to protect pruning wounds with fungicidal paints or pruning sealants and to sanitize pruning tools frequently. Infected branches must be pruned back well beyond the discolored wood and removed from the vineyard to prevent further inoculum spread.