Sunday, May 1, 2022

Black spots on rasberry fruit grown in tunnels

Black spots on ripe raspberry fruit

An agent recently sent me this image of raspberry fruit with black spots on them. The fruit was growing in a high tunnel. 

We have seen this type of thing in the past and this is what we have gleaned from discussions with other tunnel scientists and lab reports:

  • Past pathology reports from labs in NC and SC have identified botrytis and cladosoprium on fruit with similar symptoms.
  • One current theory is that tunnels have high relative humidity and lower air circulation. When the flowers begin to turn to fruit, the petals land on the developing fruit and create an ideal tiny spot for diseases to start. 
  • Suggestions for control would be to make sure there is good air circulation especially during petal fall.
  • Apply a fungicide during bloom/petal fall. Consult your state recommendations. 


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