Few scientific innovations in this century have had as much impact on society as the discovery of plant growth regulator substances (phytohormones) by plant physiologists and their development in the 1940s into agricultural herbicides. By the 1950s a once-esoteric line of academic research had left the botany laboratories and entered the fields, transforming farming practices worldwide and shaping agribusiness throughout the last half of the 20th century. This study uses archival sources and the scientific literature to investigate the trajectory of U.S. research on plant hormones in the 1920s through the 1940s. Particular attention will be given to connections between academic plant biologists, the chemical industry, and government agricultural agencies in the development and dissemination of this innovation after the war. While a history of plant physiology will have intrinsic interest and utility, the study aims to examine broader issues, such as emerging links between science, industry and the state forged during the war and patterns of agricultural research and development that have persisted from that era through the recent recombinant DNA revolution and thus inform biotechnology today.
