How do herbicides control weeds?

Herbicides control weeds by inhibiting their growth or causing plant mortality through chemical intervention. These agents are categorized based on their selectivity and method of application:1

• Selectivity: Selective herbicides target specific plant species, while nonselective herbicides affect plants generally.12
• Application Method: Herbicides are applied either to the foliage or the soil.12
  • Contact herbicides kill only the specific plant organs they touch.1
  • Translocated herbicides are absorbed by the plant and transported to other organs, such as the roots, to kill the entire system.1

The mechanism of action varies by chemical. For example, glyphosate works by inhibiting the enzyme EPSP synthase, which is essential for synthesizing aromatic amino acids required for protein production and plant growth.3

To manage weeds effectively, farmers may use herbicide-resistant crops, which are genetically engineered to survive specific treatments that eliminate surrounding weeds. Because chemical control can impact nontarget species and the environment, it is essential to employ diverse management strategies to prevent the development of herbicide-resistant weeds and minimize ecological harm.123