That is so sad, @melinda010100. I was in St. Paul, MN last May and saw it all over the place. It's just one assault after another from invasive species. It's not a problem in my area -- yet. I know people see it every now and again, but so far, it hasn't taken over. Around here, it's Scotch Broom (Cytisus scoparius) and False Brome (Brachypodium sylvaticum) that are causing massive problems in the forests. And I've got fights in my own yard, but most everything is so altered anyway, that it's more about convenience than the loss of other plants. But the stress on the natural systems just keeps stacking up. Maybe that's why I try to get people to eat the weeds so much, lol. Good luck with your Garlic Mustard problem. I hope your Mayapples can hang on!
RE: Garlic Mustard