Feed your nice trees root killer? Hmmmm
Spaugh, already mentioned your way would be longer lasting results but suggested a cost time benefit analysis be considered.
No nitrogen or other plant feeding ingredients in it.... Only herbicide that according to google search says "Dichlobenil is an herbicide commonly used to control weeds in gardens, lawns, near ornamental trees, and various other settings. It also controls aquatic (water) weeds such as cattail and purple loosestrife. Dichlobenil stops seed germination, cellulose (cell wall) formation, and growth in plant roots and shoots.Jul 1, 2017"
I see no listing of it ever killing a tree from use in septic systems but am open for your findings?
https://www.roebic.com/faq.shtmlWill Foaming Root Killer harm my trees?
No, Foaming Root Killer is a contact root killer and will only kill the roots it comes in direct contact with