Perilla... I wonder if that's the same herb which is used in Vietnamese cooking?

Yes - perilla=shiso. I've been trying to get my parents to find a local farmers' market vendor type to come pull the stuff and save them the trouble for years, and they refuse to believe me that it's perfectly safe for human consumption and reasonably tasty. So I send them pictures every time I see it on a plate. :)

Pulling/hoeing it up works better than spraying, depending on how much of it there is.

if you are wanting/needing to borrow a liquid herbicide sprayer, I've got a 25 gal unit, for a 3-point hitch I can loan.

My instinct pulled me to 2,4d, and then did some reading.

From the specimen label.
Do not graze lactating dairy animals on treated areas within 7 days after application. There are no grazing restrictions for non-lactating dairy animals, horses, sheep, goats and other types of livestock. Do not harvest grass cut for hay from treated areas for 30 days.

Seems it would be OK for all but moms.

2,4D is specifically listed for the control of Perilla Mint in pastures.

When/if you goto buy, the amine formulation is a bit different than the ester, if you want more info, drop me a note.

some reading material. http://24d.org/background/24D-Backgrounder-Benefits.pdf

Thanks for the food for thought (cough). My vet says to just pull it up when I get around to it. That vet practice hasn't ever had any reported deaths, so chemical warfare might not be necessary.