I took my grandson fishing last year and we saw 40 or 50 giant hogweed plants along the footpath. I called the local government the next day and the following weekend, when we went fishing again, the plants looked like someone had taken a flamethrower to them.
What area?
Some 2,4D mixed with laundry detergent would likely make it look that way. I use that stuff on my pasture every year, and it looks like someone selectively torched my lawn until I get to dethatching.