Hoes to Herbicides: Economics of Evolving Weed Management in the United States

Over the past century, U.S. field crop farmers have controlled weeds with progressively less costly technologies, moving from hoeing and draft cultivation to motorized cultivation to selective herbicides to broad-spectrum herbicides associated with herbicide-tolerant (HT) crops. The advent of herbicides had the effect of reducing both capital and labor costs by reducing the number of field passes required for effective motorized weed control. The advent of HT crops again reduced both labor and capital costs. These innovations have attracted widespread adoption by farmers. Today, HT crops and broad-spectrum weed control are used by virtually all field crop farmers except those producing for markets that will not accept genetically modified crops. The accelerating spread of herbicide-resistant weeds (an adaptive evolutionary response to extensive reliance on a few herbicides) is triggering U.S. farmers to increase and diversify their herbicide use, increasing both financial costs and selected health and environmental risks.