What is the main activity difference between contact and translocated herbicides?

The primary distinction between contact and translocated herbicides lies in how they interact with the target plants. Translocated herbicides are designed to move throughout the plant system after application. This means they are absorbed through the leaves and can be transported to various tissues, including the roots and stems. This mobility allows translocated herbicides to effectively kill the entire plant, including parts that are not directly treated.

In contrast, contact herbicides act only on the surface of the plant where they are applied. They kill or damage the plant tissue directly exposed to the chemical, but they do not spread within the plant. As a result, contact herbicides are often less effective against perennial plants that can recover from damage to some of their parts.

The ability of translocated herbicides to penetrate deeper into the plant makes them suitable for controlling a broader range of weed species, especially those with extensive root systems. Understanding these differences is crucial for selecting the appropriate herbicide for specific control situations.