Why are my blackberries inferior on some plants?

Question:I have two rows of blackberries 10 feet apart. One row is Brazos and the other Brison. The Brazos berries are plump and full. The Brison row has one plant of full plump berries and the others are tiny worthless berries. I used 13-13-13 on them this spring. What are they lacking? Brazos out by fence gone wild is also worthless for berries.

Answers:
If they normally perform well they could be having, very simply, an "off season".

I grow blackberries in my backyard and they were getting huge. This last fall though, all of the stems lost their life and it basically cut back itself. New growth came back strong this spring, but they won't have as much berries this season. I suppose the plants know what they needs more than we do.

Good luck!