Del Voight Penn State Extension
If it indeed is Perilla mint it can be very difficult to control. Many herbicides are not that effective on it and those that are active only suppress it (70-75% or so). I agree most of the literature comes out of the South since they deal with it more than we do up here. We do have some populations here in PA but whenever people have submitted samples of suspected Perilla it turned out to be something else (e.g., white vervain, etc.). Not to be a Doubting Thomas but It would be good to get another sample to look at it.
In the meantime, here are some resources to consider:
Since it's an annual, mowing or chopping it if possible will help. Just try not to let it go to seed. Here are some fact sheets to consider:
Hope this helps,
Dwight Lingenfelter PSU Weed Team