Basal streamline sprays for hardwood resprout control: herbicides, concentrations, and streaks per stem
Basal streamline sprays were tested to control sweetgum, water oak, and southern red oak that ranged from 0.5 to 2 inches groundline diameter. Primary test herbicides and mixtures were triclopyr (Garlon 4) at 20 and 40 percent mixed with 10 percent d-limonene (Cide-Kick) and the remainder diesel; and imazapyr (Chopper) at 5 and 10 percent mixed in only diesel. Primary herbicide mixtures were applied with three doses: (a) to one stem side using one streak; (b) to one side using two streaks; and (c) to two sides using two streaks per side. Secondary test herbicides were tested only using two streaks to one side. All applications were in April. Individual rootstocks were the experimental units and assessment was 18 months after application. Increasing doses of primary herbicides resulted in increasing control. Both triclopyr and imazapyr at the highest concentrations and doses yielded greater than 80 percent crown volume reduction for sweetgum and the oaks. Rootstock control was greatest for the highest concentration doses as well. Treatments to one stem side were most effective with imazapyr at the high concentration. Southern red oak was the most difficult species to control. In general, the secondary herbicides were less effective than the primary herbicides.