The rise of weeds that are resistant to the herbicide glyphosate has led many US farmers to seek permission from the Environmental Protection Agency to use more-dangerous herbicides, such as propazine (see Nature 510, 187; 2014). To deal with this crisis, US agriculture must implement a multi-pronged strategy.
Tactics should include: annual switching between herbicides that have different chemical modes of action; using a variety of methods to remove weed seeds from the soil, including hoeing by hand; and moving to new tillage practices that require a shift from no-till to rotary hoeing and between-row cultivation of the soil to uproot weeds.
US policy-makers need to encourage crop rotation through new subsidies and to impose restrictions on herbicide use. It seems that Europe has dodged a bullet by resisting pressure to sow glyphosate-tolerant crops.