Possibly root rot--how old is the berry patch?

Borers usually go after my first-year canes, but you might look near the base of yours for the tell-tale tunneling just under the cane surface and spiraling around the cane.

If it is root rot try using a solution of water and hydrogen peroxide at a rate of 1/2 cup per gallon. I use h2o2 all the time in my garden and with my seedlings. For what its worth, it has cleared up many plants with root problems for me.

Here is a link that might be useful: h2o2 uses

Thanks guys. Ill take a look at the bases today. The plants are new. They were put in last year. There are wild raspberries on our property but not near these plants.

How's your weather been?

...then it's a little soon for root rot unless there was very soggy soil the past winter. Borers can happen overnight.