Welcome , Figment2 and CindyKansas.
I don't know how accurate this information is, but it might be of some help to you.
It sure sounds like an awful nuisance, good luck!!
" I'm afraid mint doesn't blow in, it ain't a dandelion. the underground runners from a neighbor perhaps, made a beeline for your tree. it is hard, if not impossible to eradicate. best thing todo is wait til after a really soaking rain, very, i mean very gently try and pull the main plant out of the ground. you don't want to break off the underground runners, because they will then be stimulated into putting out leaves , and more runners. follow the runners from the main plant and try to ease them out of the soil, they are normally quite close to the surface. it's a big task, every piece you leave brhind is a potential plant. face it, mint is eternal. you can keep cutting back the plants that do pop up, and eventually(?) you'll starve them, perhaps your children or grandchildren will take over ,afteryou've gone. if you do succeed, do as the previous writer suggested and plant it in a pot, WAY above ground."
Kim
