How did 2,4-D change chemical weed control after 1945?

The introduction of 2,4-D (2,4-dichlorophenoxyacetic acid) in 1945 revolutionized chemical weed control by initiating an era of "miracle" herbicides. Before this development, weed control often relied on substances like arsenic trioxide or sodium chlorate, which required application rates as high as one ton or 100 pounds per acre, respectively.12

In contrast, 2,4-D was highly effective at dosage rates as low as one to two pounds per acre. As a selective, translocated foliar spray, it allowed for the targeted elimination of broad-leaved weeds without harming cereal crops. This shift toward high-potency, selective chemicals fundamentally changed agricultural practices, making weed management more efficient and economically impactful than previous methods of plant-disease or insect-pest control. The success of 2,4-D spurred the synthesis and development of over 100 new herbicides within two decades, permanently altering the landscape of modern herbicide application.12