It sounds like Black Rot, a fungal infection. Organic controls involve pruning to increase air circulation and cleanup of any debris where spores can overwinter. This never worked for me. You can start a spraying program next year that begins when the buds break and continues until shortly before harvest. Check with the experts on the fruit forum.

I never got ahead of the problem as I hate to spray. This was one of my greatest gardening failures.

Thanks for the tip, I'll give it a try next year.