What type of soil do you have? Are they planted in a location with bad drainage (e.g. an area that stay wet)?

I think the soil is fine and with good drainage, Because they were growing fine for several months, This just happen in the last week.

Can you post a picture?

Where are you? That could help us figure it out. Are these primocanes or floricanes? Any sign of borer entry at the base of the canes?
Some of my floricanes canes just died, and it was delayed winter injury. Also some that are producing look terrible, they really had a bad go of it! Some are barely hanging on, hoping to get berries before they go, it's the worst floricanes I ever seen. I guess depeding where the nursery was that could have happened too? Whatever it is ask for 12 replacements!

Did you pull a couple of them up and look at their roots? Compare what you see to the picture of Phytophthora Root Rot online.

Just getting back from a long ride so I will try to get some pictures up tomorrow, I'm in zone 6 PA, I'm not sure nif their primocanes or floricanes, Wife bought them and I planted them without even looking at the labels but I will try to find out tomorrow, I didn't pull any up to look at the roots as I'm new to these berries.