Dicamba (3,6-dichloro-2-methoxybenzoic acid) is a selective systemic herbicide first registered in 1967. Brand names for formulations of this herbicide include Dianat , Banvel , Diablo , Oracle and Vanquish. This chemical compound is a chlorinated derivative of o -anisic acid. It has been described as a "widely used, low-cost, environmentally friendly herbicide that does not persist in soils and shows little or no toxicity to wildlife and humans."

Despite its success in improving crop yields, dicamba has attracted controversy. According to the United States Environmental Protection Agency (EPA), dicamba's primary ecological risk is for non-target terrestrial plants from exposure through spray drift, whereby dicamba inadvertently migrates to non-targeted neighboring areas, damaging those plants.

In 2016, dicamba was approved for use in the United States over GMO dicamba- resistant crops created by Monsanto. Dicamba came under significant scrutiny due to its tendency to spread from treated fields into neighboring fields, causing severe damage. The controversy led to litigation, state bans and additional restrictions over dicamba use.