I have a flail mower. Those obstacles would look lke I fed them into a wood chipper.i would mow but the terrain and multitude of obstacles i have set up for hawk protections make it pretty much impossible to mow back here
That said, there's good reason to have "obstacles" in a chicken run, and your birds will be hapier for it.
That's why they make gas trimmers with metal X blades where the string should go.
Wear jeans. Trust me.