In addition to the suggestions already made (vinegar, bleach) -- there is another that gets berry stains out of clothes -- pour boiling water over the stain. I've read NOT to use any kind of detergent (dish, laundry), which will set the stain.

I used boiling water on an old berry juice stain on my son's stark white fencing jacket, and it took it right out. It took about four cups of boiling water to get rid of it, pouring slowly.

I did not have to get to the next suggestion, which was to use Oxyclean or another oxidizing cleaner.
Joie