The first step is to make sure what you have is “common pokeweed” ( Phytolacca americana L.). Contact your local Extension office and take advantage of a weed identification program.
If it is pokeweed and you are going to get rid of it, springtime is when poke needs to be sprayed with herbicide. Poke has a very large taproot and is difficult to control. Ready-to-use formulations of glyphosate are not strong enough to kill this plant. A strong 5-percent mix of glyphosate with water is recommended to get the job done. Avoid getting the glyphosate mixture on surrounding vegetation; as this non-selective herbicide will damage surrounding turf and ornamentals. It generally takes two to three applications a couple of weeks apart to get adequate control. Always read and follow herbicide label instructions.