Giant Ragweed

Cutting it down before it sets seed will take care of it, after couple years the seed bank should be depleted, then you will only have the occasional plant. They do not compete well, so planting something in it's place will help keep it out.

That you for that bit of commentary, Chester. Any advice on how to it clear out?

Main source of hayfever this time of year, the amount of pollen these plants produce is ridiculous, I have cleared areas of this stuff before, while in flower, and come out coated from head to toe.