Standardization of Herbicide Injection Methods for the Effective Eradication of Robinia pseudoacacia in Winter Conditions

The black locust (Robinia pseudoacacia), native to North America, is known for its rapid growth and invasive nature, posing a threat to local ecosystems. This study aimed to standardize a method for inducing mortality in black locust trees through herbicide injection. Ten naturally grown trees with diameters greater than 30 cm on private land were selected. The herbicide used was "Geunsami," produced by FarmHannong Co., Ltd., with glyphosate-isopropylammonium as the active ingredient. Between December 26 and February 20, 50–150 ml of the herbicide was injected into each tree using a 50 ml syringe and a 15G needle, divided into 1 to 3 applications. The effects of treatment were evaluated in May and June by monitoring sprouting on stems and around the tree bases. None of the trees developed leaves on their stems. Among the eight trees injected with ≥100 ml of herbicide, no root suckers were observed. In contrast, the two trees injected with only 50 ml exhibited new shoots emerging from roots near the base. These findings suggest that injecting at least 100 ml of glyphosate herbicide during the winter is effective in killing black locust trees with a diameter of 30 cm or more. This study provides practical guidelines for herbicide-based control of black locusts, contributing to ecological restoration efforts.