What differentiates contact herbicides from systemic herbicides?

Contact herbicides work by directly affecting only the plant parts that they come into contact with. When applied, they disrupt the cellular function of the areas they've touched, leading to tissue necrosis and ultimately the death of those parts of the plant. This means that if a contact herbicide is sprayed on the leaves, stems, or flowers of a plant, only those specific areas will be impacted, leaving untreated parts of the plant or nearby plants unharmed.

In contrast, systemic herbicides are absorbed by the plant and translocated through its systems, affecting not only the area where they were applied but also other parts of the plant, including roots and other foliage. This ability allows systemic herbicides to provide more thorough control over certain types of weeds and unwanted vegetation.

Understanding this differentiation is crucial for determining the appropriate herbicide to use depending on the desired control method and the types of plants involved in treatment.