a few questions

You should have got new growth (long canes) on your blackberry late last year and trained it along wires ready to fruit this year. Old growth that fruited last year will be brown and can be cut back to the roots. Leave any new shoots coming up now to be trained in Autumn/Winter.
Very unlikely your blueberry is sprouting from the base unless you buried a stem so it's probably some other plant. I discovered a raspberry cane coming up next to one of mine. Whipped it out quickly!
Try a gentle tug.....likely a weed.....