Imazapyr, a systemic herbicide, was used to control cattail (Typha subulata Crespo & Peres-Moreau f.) in irrigation project drains as an alternative for mechanical control. Residue of this herbicide was analysed in water by high performance liquid chromatography (HPLC). Imazapyr dissipation curve with applied doses ranging from 500 to 1500 g ha-1 showed that it could be used to control cattail without injuring neighbor crops, as long as water drain be used at least 1.6 to 3.7 days after application.
Herbicide; residue; environmental monitoring; environmental impact; weeds