What ever you do, be very careful.
Snakes love blackberry patches.
Some of my fondest memories are of a very large BB patch near our home. I would stop by, eat my fill, and then visit the nearby waterwell.
BTW, BB packed in water with spoon of sugar then frozen. Damn good eating.
Just beat me to it (about the snakes)...LOL
That's a good reason to hire a service to do the job.