Q. I have pignut on my property and I want to know how to get rid of it.
A. If this is in fact pignut then it will require either killing or exhausting the “nuts” or tubers that will cause the plant to regrow if the top is killed. It is a perennial weed that grows from these tubers once it is established. Of course it spreads by seed at first or comes in with contaminated, transported soil if any was brought in. A three to four inch surface mulch will help to keep this plant from getting established from seed.
Once the plant grows from seed it produces tubers which will regenerate the top of the plant year after year. So if you try to hoe the top out or “grub it out” the tuber will use its food reserves and grow back. However if the tops are grubbed out religiously as soon as they appears this practice will eventually exhaust the tuber and the plant will die. In wetter climates these tubers can be about a foot deep so digging up the tubers is another possibility if you do not have a lot of this weed around and want some exercise.
Because the nuts are so deep, soil solarization or tilling the soil and covering it in plastic and “cooking” the soil is not practical. I would not use the chemicals recommended for its control (Tordon/picloram). These are primarily soil sterilants and can make the soil unusable for years.