How do contact herbicides work?

Contact herbicides function by directly affecting the parts of the plant that they come into contact with. When a contact herbicide is applied, it does not move through the plant systemically; rather, it only harms the tissues it touches. This mechanism is particularly effective for managing specific target weeds, as only the plant areas exposed to the herbicide will be damaged or killed.

The reliability of this method relies on proper application techniques to ensure that the herbicide thoroughly coats the plant surfaces, particularly the leaves and stems. For instance, if a herbicide is applied without sufficient coverage, the unaffected portions of the plant can survive and potentially continue growth.

In contrast, other types of herbicides, such as systemic herbicides, are absorbed by the plant and can move throughout its system, affecting tissues that were not directly contacted by the application. This principle underlines the unique role that contact herbicides play in weed management strategies.