Multiple things can be true at once:
**Aerial spraying on a crop field didn't likely apply "brushkiller" (which terminology also does NOT define a chemical).
**Aerial spraying on a crop field applied a
broadleaf weed killer (which includes herbaceous broadleaves like clover, thistle, etc.) that does not affect turf nor the GMO crop to which it is applied - but sure will play havoc with off-target woody broadleaf plants.
Illinois is having a very bad time with non-selective and broadleaf herbicides applied aerially to crop fields growing GMO crops that resist/are unaffected by the herbicide. Many heritage trees individually and in woodlands do not "cotton" well to drift from these applications.
Take a gander at this,
ScotTi and all. This kind of carelessness bordering on criminality cost a Kentucky nurseryman his entire livelihood, when his entire inventory was affected by drift from applications next door.