Anthracnose on Bunch Grapes

More rain is falling today and is expected for the next few days.  All this wet and cooler weather creates good conditions for anthracnose infections.  Anthracnose (Elsinoe ampelina) can be severe in years with heavy and consistent rainfall (like this year).  Optimal conditions for disease development are in the upper 70s F.  The spores are splashed from plant to plant by rain.  It is seen most commonly on young, succulent green shoots and leaves.  The lesions are sunken on shoots and on leaves the leaves can be distorted and have a shot-hole appearance.  A photo of the disease on a ‘Victoria Red’ cluster is below.

Severe anthracnose infection on Victoria Red grape cluster

Severe anthracnose infection on Victoria Red grape cluster

How can anthracnose be controlled?  If you are in the Deep South, not too easily, I’m afraid.  Sanitation can help (get rid of infected plant parts).  Canopy management that promotes sunlight penetration and good airflow can also help.  But likely the best way is a dormant fungicide spray or two of lime sulfur followed by subsequent fungicide applications until veraison. More in-depth information can be found here:

http://www.smallfruits.org/smallfruitsregguide/Guides/2015/BunchGrapeSprayGuide2015.pdf

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