PROBLEM TO BE SOLVED: To efficiently and safely kill water-extracted plants such as Scots chinensis that grow in lakes and the like. SOLUTION: A herbicide-impregnated wooden needle 1 is made by impregnating a wooden needle such as a toothpick with a glufosinate or glyphosate herbicide. A part of the stem 11 of the extracted plant 10 growing in a lake or the like is above the water surface 12. The herbicide is released from the herbicide-impregnated wooden needle 1 by piercing the exposed stem portion 11a of the extracted plant 10 with the herbicide-impregnated wooden needle 1. The herbicide comes into direct contact with the inside of the exposed stem portion 11a, and the extracted plant 10 is killed. [Selection diagram] Figure 2【課題】湖沼等に生えているオオバナミズキンバイ等の抽水植物を効率よく安全に枯殺する。【解決手段】除草剤含浸木針１は爪楊枝等の木針にグルホシネート系又はグリホサート系の除草剤を含浸させたものからなる。湖沼等に生えている抽水植物１０における茎１１の一部が水面１２より上に出ている。抽水植物１０の露出茎部１１ａに除草剤含浸木針１を突き刺すことにより、除草剤含浸木針１から除草剤が放出される。露出茎部１１ａの内部に除草剤が直接接触し、抽水植物１０が枯殺される。【選択図】図２
