For years been using Remedy, diesel. Not 100% guarantee on hickory kills and poor results on black locust. Been reading how great Harpers mix works. With generic herbicides prices though would try this winter. Have herbicides sitting here ready to go and had a O crap thought. Will this mix spray at below freezing temps being 40% water. Thinking could add small quantity of green antifreeze. Temps could range between 5 and 32 degrees.