diquat

Diquat is a non-selective contact herbicide belonging to the bipyridinium class. It is used broadly for rapid weed control and desiccation of certain crops, as well as for aquatic weed management in some applications. Diquat is commonly applied as a water-soluble salt, most often as diquat dibromide, to actively growing foliage.

Mechanism of action for diquat involves light-driven redox cycling that generates reactive oxygen species in treated plant tissue. This leads to lipid peroxidation and disruption of cell membranes, resulting in rapid necrosis of foliage. Because diquat acts mainly as a contact herbicide, its effectiveness depends on thorough coverage of the aboveground parts, and it does not widely translocate to other plant tissues, making unsprayed tissues a source for regrowth in some species.

Applications and use patterns vary by crop and region. Diquat is employed for postemergence weed control in crops like potatoes, beets, and certain fruits, as well as for pre-harvest desiccation of some crops. It is also marketed for aquatic weed control in water bodies. Due to its mode of action and limited systemic movement, timing and coverage are important for achieving desired control.

Environmental and safety considerations include notable toxicity to aquatic organisms and potential irritant effects on skin, eyes, and the respiratory tract. Diquat is not highly persistent in soil, and many formulations degrade relatively quickly when exposed to light and moisture. Regulatory status and label directions vary by country, with use restricted to approved applications and protective measures to minimize human and environmental exposure.