What is a key feature of using mechanical methods for controlling established plants?

The correct choice highlights that mechanical methods for controlling established plants often involve using translocated herbicides. Mechanical control strategies sometimes employ herbicides that can move within the plant system after application, effectively targeting the entire plant, including its root system. This technique is particularly useful for perennial plants, where the goal is to destroy the root system as well as the foliage to prevent regrowth.

Translocated herbicides work by being absorbed and moved throughout the plant, which allows for thorough control, especially in cases where the physical removal of the plant may not be feasible. Thus, this method can complement mechanical practices by ensuring that any remaining plant parts may be effectively managed.

The other choices do not accurately represent the nature of mechanical control methods. For instance, mechanical methods do not inherently require less labor; they may be labor-intensive depending on the scale and type of plants being managed. Additionally, they are not the only method of control; there are various strategies available, including chemical, cultural, and biological controls. Lastly, mechanical methods do not inherently promote the growth of weeds; rather, they aim to reduce or manage unwanted plant species.