I have a weed that believes "what doesn't kill makes you stronger". I don't know what it is and I'm not sure how to deal with it. The grow 2 to 3 several feet tall, have hollow reddish stems (that snap easlily), DEEP roots (I can't pull them). Eventually they get these berry things that are currently green, the size of a pea and a pumpkin shaped and will turn a dark blue / purple over time. I've got a picture of them, but can't post it. I put down vegetation killer in April (season long... there's no grass there) but there's back. They're growing under pine trees & I don't want to kill the trees by using too many chemicals. Help? Thanks. -Robin