Wikipedia
Aminocyclopyrachlor is a selective, low- toxicity herbicide that provides pre- and post-emergent control of broadleaf weeds, woody species, vines and grasses on several non-food use sites, such as rights of way, wildlife management areas, recreational areas, turf/ lawns, golf courses and sod farms. It was conditionally registered as Imprelis bu DuPont in August 2010, and first used in Fall 2010. The chemical is a systemic herbicide and acts by disrupting gene expression. This causes undifferentiated cell division and elongation.
Due to the possibility of damage to specific evergreen species, the United States Environmental Protection Agency and DuPont advised professional applicators and residential consumers to not use Imprelis where Norway spruce or white pine trees are present on or near the property being treated.