Attempting to Diagnose Raspberry Bush Fungus-es and Viruses.

 
 
Question
Can you tell me what is wrong with my black raspberry bush?  I have attached a picture.

Answer
From the picture, you have one of two problems on your black raspberry plant. From the picture, I can't be sure of which problem it is. Either you have a fungal problem or a viral problem. I lean to the fungal side of the problem. All members or the cane berry plants sold in Idaho has to come from an inspected nursery that has been tested to be 100% sure that the plant is virus free. If you bought the plant from a nursery store you are protected from the virus. If you dug the plant from someone's back yard there is a chance of a virus. I think that the problem is a fungus attacking the leaves because it is starting from the bottom of the plant and working up to the higher leaves.

My recommendation is to apply a fungicide. Because the plant being a cane berry your choice is limited to using a copper based spray. Follow label instructions when using the product. You can help avoid the spread of the fungus by avoiding applying a high nitrogen fertilizer and using a dormant spray in the early spring.