imazapyr

Imazapyr is a systemic herbicide in the imidazolinone family used to control a broad range of annual and perennial weeds, including many woody species. It is widely applied in forestry site preparation, rights-of-way maintenance, and other noncrop settings to suppress competing vegetation. Because it is absorbed by leaves and roots and then translocated throughout the plant, treated vegetation dies over days to weeks rather than immediately.

Mechanism of action: Imazapyr inhibits the enzyme 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) in the shikimate pathway, blocking the production of essential aromatic amino acids and thereby disrupting protein synthesis and plant growth.

Application and properties: Imazapyr is relatively persistent in soils and can provide residual activity for months, especially in well-drained media. It can be applied as a foliar spray or, in some formulations, to the soil. It has low volatility and can move in the soil profile, which raises potential for groundwater involvement in coarse-textured soils. The herbicide is active on a wide spectrum of weeds, including many woody species, making it useful for vegetation control in noncrop areas.

Environmental and safety considerations: Regulatory agencies classify imazapyr as moderately toxic to aquatic life. Label precautions emphasize avoiding entry into surface water, preventing drift, and minimizing contamination of water bodies. In humans, it has low acute toxicity, though exposure can cause skin or eye irritation. Non-target vegetation and aquatic ecosystems can be affected, so applications should follow all label directions and safety practices.

Regulatory status: Imazapyr is registered for use in many countries under various brand names, alone or in formulations, for forestry, industrial, and noncrop vegetation management.