It could be a nutrient deficiencies (phosphorous, magnesium, or iron) and not a disease. Add some phosphorous and magnesium to the soil to see if it will help. You can also google the internet for images of purple spots on blackberriy leaves to see if you can find an image similar to your leaf problem.
It could be a nutrient deficiencies (phosphorous, magnesium, or iron) and not a disease. Add some phosphorous and magnesium to the soil to see if it will help. You can also google the internet for images of purple spots on blackberriy leaves to see if you can find an image similar to your leaf problem.