How do herbicides control weeds in cereal farming?

In cereal farming, herbicides are used to manage weeds that compete with crops for essential resources like water, light, and mineral nutrients. These chemical agents control unwanted plants through several methods and classifications:1

Mechanisms of Control

Herbicides are categorized by how they interact with plants and when they are applied:
* Selectivity: Selective herbicides target specific plant species, allowing cereal crops to survive while eliminating weeds. Nonselective herbicides affect plants generally.23
* Application Timing: Chemicals may be applied preplanting, preemergence (after sowing but before seedlings emerge), or postemergence (after seedlings have emerged).23
* Mode of Action: Contact herbicides kill only the plant organs they touch, whereas translocated herbicides are absorbed and transported through the plant to affect roots or other areas.3

Application Methods

Modern cereal farming benefits from the ease of herbicide application, which can be performed via aerial spraying or specialized ground machinery. Equipment can often perform multiple tasks simultaneously, such as planting seeds and incorporating preemergence herbicides in a single operation. Additionally, some cereal crops are genetically engineered as herbicide-resistant crops, allowing farmers to apply specific chemicals that kill weeds without harming the crop.234

While effective, the use of these chemicals requires careful management to mitigate environmental impacts and prevent the development of resistant weed populations.34