metribuzin

Metribuzin is a selective systemic herbicide in the triazinone class used to control a broad range of annual weeds in crop systems such as soybeans, potatoes, sugar beets, and certain vegetables. It is marketed under brand names including Sencor and Lexone.

Mode of action: It inhibits photosystem II by binding to the D1 protein in the chloroplast. This blocks electron transport, leading to reduced photosynthesis, bleaching, and necrosis in susceptible weeds. Crop tolerance is provided by selectivity and appropriate application timing.

Chemical properties and application: Metribuzin can be applied pre-emergence or early post-emergence, depending on crop and formulation. It is absorbed by roots and foliage and translocated within the plant. It is commonly used in mixtures with other herbicides to broaden control and manage resistance, following label instructions.

Environmental fate and safety: In soils, metribuzin exhibits moderate persistence, with degradation influenced by soil organic matter, moisture, and light. It can leach in sandy soils and near water bodies, and may persist longer in tropical climates; therefore buffer zones near water sources and label restrictions are observed. Toxicity to humans is generally low for acute exposure, but it can irritate skin and eyes; workers should use protective equipment as directed.

Regulatory status: Metribuzin has been registered in many countries since the 1970s for use on a range of crops; regulations and approved uses vary by jurisdiction.