how do you kill overgrown Cast Iron Plant

Question

I have Cast Iron plants outside in Louisiana and they need to be killed off in some areas.

Answer 1

You can cut the plants off to the soil surface and apply a herbicide directly to the open wounds of the plant. You may need more then one application.
The rhizomes can be dug up, but this can be difficult.

https://www.gardeningknowhow.com/houseplants/cast-iron-plant/cast-iron-plants-information.htm