2,4-D

Short for dichlorophenoxyacetic acid, among the oldest selective herbicides still in wide use. It mimics the plant hormone auxin, triggering uncontrolled, lethal growth in broadleaf weeds while leaving grasses such as wheat, barley and maize comparatively unharmed. Decades of use have made it one of the most studied agrochemicals on earth. Food safety attention focuses on residues in harvested grain and produce, spray drift onto neighbouring crops, and applicator exposure. Regulators in most jurisdictions maintain maximum residue limits and buffer-zone rules, and the compound remains a fixture of debates about herbicide reliance in modern agriculture.