Pacific Northwest 1998 An Online Guide to Plant Disease Control

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OSU Extension Office
 
Grape -- Eutypa Dieback
 
Cause: Eutypa lata, a fungus. The disease is quite prevalent on 'Concord' vines in eastern Washington. Incidence is especially high in older vineyards where large pruning wounds were made to alter the training system. Infection occurs when airborne fungal spores contact fresh pruning wounds during or immediately following rain. Pruning wounds become resistant to infection about 2 to 4 weeks after pruning. Moderately infected vineyards can lose 19 to 50% of yield, severely affected vineyards 62 to 94%.

The disease has been observed more frequently on wine grapes in the Willamette Valley of Oregon. It is expected to increase as vineyards age and more acreage is planted. Also, the fungus can infect cherry trees, which are heavily planted within many of the same areas and can act as a reservoir of inoculum. The fungus can attack many other hosts including many Prunus sp., apples, pears and walnuts.

Symptoms: Stunted spring shoot growth, yellowed and cupped newly emerged leaves, shed blossom clusters, vascular discoloration, and cankers in stems associated with old pruning wounds. In advanced stages, part or all of a vine dies.

Symptoms are best seen in spring when healthy grapevine shoots are 10 to 15 inches long. Later in the season, affected shoots are stunted, and leaves become tattered and scorched. Clusters on infected shoots are poorly developed and often wither and drop. Infected vine foliage may be covered and masked by the foliage of healthy grapevines. It is also common to find one side of a vine dead or with disease symptoms and the other side apparently healthy. Symptoms may not appear on diseased vines for more than 3 years after infection. Cankers expand lengthwise in both directions from the wound and girdle and kill arms or trunks of infected vines in 5 to 10 years.

Notice the poor shoot growth and chlorotic, cupped leaves on right side of this trunk.

This is the springtime symptom of stunted shoot growth, sometimes occuring only on one side of the vine.

A large canker is revealed when the bark is peeled away near a large, old pruning wound.

A wedge-shaped (double-wedge in this case) area of dead trunk is seen when a cross-sectional cut is made through a canker on the trunk or cordon.

 
Cultural control:

  1. In spring, when symptoms are evident, mark diseased vines for future removal.
  2. Remove diseased wood 4 to 6 inches below the canker, and train a new, healthy shoot into position.
  3. If the canker is below ground, remove and replace the vine.
  4. Avoid large pruning cuts when possible, and avoid pruning during and before wet weather.
  5. When making large cuts during wet weather, leave a stub several inches long to be pruned off later during dry weather. Sometimes referred to as double pruning.
Chemical control: Useful when retraining vines and making large trunk or cordon cuts. Currently there are no chemicals labeled for control of this disease.

  1. A product called Prev-Am contains borax, is labeled for use on grapes and, based on limited preliminary research, may have some benefit when used against this disease. 12-hr reentry.
References:
Munkvold, G.P. and J.J. Marois. 1993. The effects of fungicides on Eutypa lata germination, growth, and infection of grapevines. Plant Disease 77:50-55.

Rolshausen, P.E. and Gubler, W. D. 2005. Use of boron for the control of Eutypa dieback of grapevines. Plant Disease 89:734-738.
Content edited by: Jay W. Pscheidt on January 1, 2009
 
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