I have tried everything to eradicate this from our 150 acre farm. The sap contains furanocoumarins which when they come.into contact with the skin and then exposed to sunlight can cause painful blisters and a discolored rash. I feel like it's demonized due to this but have recently discovered that the roots are edible, and actually consumed some last night and enjoyed them. Identification is key and use of the Latin name is helpful when looking for information as literally everyone confuses these plants. These plants are biennial unless they drop their seeds so from what I've learned the best way to eradicate is to either dig them up from the root or to carefully collect the flowers before they seed which is more dangerous as they are larger and there is a higher likelihood of sap exposure. Wearing gloves should go without saying but Please do and if you get sap on you ( I have multiple times) it isn't an immediate effect like nettles or poison ivy it takes 24-48 hours for it to develop. Rinse the effected area with water, and keep it covered from the sun. I also have used a jewel weed poultice to relieve the burn, it doesn't get rid of the blisters or discoloration though.
