I am looking for a growth regulator for Rhus Aromatica (Fragrant Sumac). The best option I can find is Atrimmec by PBI Gordon, although Rhus is not listed on the label. Was wondering if anyone has experience using a chemical control on Rhus Aromatica to reduce the amount of trimming required. This is growing in islands on a parking lot and creeps out over the curbs into the lot and must be trimmed a couple times a year. Thanks for your input.