Eutypa Dieback, also known as a part of the “dead arm” complex, is a destructive woody tissue disease. Symptoms typically become visible on vineyards that are 6 or more years old, even though the infection might have occurred several years prior to symptom expression. The first symptom to appear is a canker, usually on the main trunk, a flat, elongated discoloration found under the bark, surrounded by healthy tissue. Cross-section of canker reveals a “V” or wedge-shaped piece of necrotic wood; however, these symptoms are very similar to those of Botryosphaeria canker. However, with Eutypa, delayed shoot emergence and stunted shoot symptoms are most visible in the spring, and may recover as the season progresses. Leaves on stunted shoots are chlorotic (yellow), cupped upwards, and are often deformed. Uneven berry size is another common symptom in severe Eutypa infections.

(Photo credit: Renaud Travadon)

Causal Agent – Eutypa lata, E. leptoplaca, and other fungi in the Diatrypaceae family are the causal agents of Eutypa Dieback. Spores released by rain, spread by air and water, to open pruning wounds.

Management – The prevention at the time of winter pruning is the best approach for management.  Double pruning, protection of pruning wound using paint with boron (trade name: B-Lock), as well as chemical control, such as use of thiophanate-methyl (trade name: Topsin-M) and/or myclobutanil (trade name: Rally) to protect pruning wounds are known to reduce risk of infection to pruning wounds.  Also, it is advised to prune vines on a day followed by several days of sunny conditions.  (I.e., avoid pruning before the rain).  If you decide to use the aforementioned fungicides, make sure to obtain the label for the specific uses.  Although symptoms appear in the vineyard after 5-10 years of planting, young vines are as susceptible as the old vines; therefore, it is advised to implement a management plan from the early years of the vineyard.

For infected unproductive vines, remove the infected trunk or cordon arm 12 inches below the canker and move the infected wood out of the vineyard for burying or burning. Vine health is extremely important for the recovery after major cordon or trunk pruning. Provide sufficient water and nutrients to encourage healthy vegetative growth.

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