Round-up will not effect the berries, but it will translocate through the plant to your side. If any of those suckers are still attached to one of your plants you could lose them.

If your plants survive (let's hope) your berries will be fine and production will not be effected.

I know that in the past 3 years of spraying honcho(roundup) on sumac plant suckers we have inadvertently killed the mother plants along the field line. Not the worse thing to kill, but still food for thought.

It looks like all the suckers are dead on their side. From now on I will just use my shovel to sever the suckers on their side of the fence before they have another chance to arm themselves with a poison. These are nice people, though completely clueless about yard maintanance or gardening.
The berries still look good, and the plants are OK so far. Lets wait and see.
Thank you Josie23!