Lots of info if you use your fav search engine w/ the search phrase "Garlic Mustard Seed Dispersal" (but no quote marks).

I'm pretty sure it disperses both through wind and by transport by humans and animals. Its a lightweight "stick" pod that has hundreds of seeds in it, so I'd assume small animals like squirrels or birds could also transport it.

I pull this stuff out of my garden beds but I have given up trying to control the forest and roads. It would just stress me out too much. Same goes for dandelion and some other weeds. I've made peace with them.

You just sometimes can't control Mother Nature. I learned to enjoy the flowers out there and soon they are gone for the summer. Bye Bye...see you next year! Some years are better (or worse) than others. The only thing I actually go out and kill is poison ivy, but only where I walk or on my property.

I have enough stress with what goes on in my garden! lol.