Have had a problem with brown druplets on my raspberrys for several years now.
It seems to be more prevalent on the red raspberrys (don't know variety, is what we used to call red-caps). It shows up on about 50% of the new berries. As the season progresses, it may go down to only 10-20% of the berries.
On the black raspberries, it starts at about 10% of the berries and goes down to about 5%.
Doesn't seem to be any consistent condition leading to the problem. Happens on canes with good sunlight and bad.
Have couple of pics.
Would appreciate any help in identifying the problem and possible solutions.
Note that someone in other forum thought it was a UV problem.