I have 3 year old black raspberry plants. They are loaded with berries but some of the berries have light tan spots. I'm not sure what the cause of this is and how to fix the problem.
Light Tan Spots on Black Raspberries
Certified GKH Gardening Expert
It may be orange rust, which is dangerous for black raspberries. Typically, this disease appears on the leaves, but it can occasionally show in the fruit. Here is more information on that:
It could be another form of fungus as well. You can treat the plant with fungicide, which will kill most fungus, but will not kill the range rust mentioned above.