Berry Splitting in Grape Clusters

Some of the vineyards I visited recently are beginning to see the emerging grape berries (or fruits) cracked open. Berry splitting or cracking is a physiological disorder that leads to fruit loss. The exact cause of grape cracks is still debatable; however, most researchers think it could be due to abundant irrigation/rainfall or lack of it thereof. Berry cracking typically occurs in the stage of growth of the fruits when they are rapidly enlarging, accumulating sugars and reduced organic acids.  Regardless of the cause, when grape cracks open, it opens the doors for pest attacks such as grape berry moth or diseases such as powdery mildew or may serve as reservoirs for other diseases that may eventually contribute to bunch rot or next season’s infections. Since most Oklahoma vineyards are of small acreage, one practical thing that could be done is to remove the split berries as soon as they occur. Netting is another practical option as the grapes mature. Be consistent with your irrigation and avoid stressing the grapevine (no over irrigation or inadequate irrigation). Monitor your vineyard frequently, especially after heavy rainfall or severe storm to access any damage to the grapes.

 

Figure 1. Severe berry split as seen recently in an Oklahoma vineyard.

 

 

Figure 2. Severe berry split as seen recently in an Oklahoma vineyard.