| [College of ACES] | [University of Illinois] | [Illinois CES] |
After identifying the herbicide there are a lot more questions, ie. was the herbicide sprayed directly onto the tree foliage, over the root zone, drifted onto the foliage (spray or vapour), moved into the root zone?
Then we need to know the species of trees you're concerned about.
Without this type of detail it is impossible to answer your question or even do any semi-intelligent speculation.