What is the main criterion for the timing of herbicide applications to woody plants?

The main criterion for the timing of herbicide applications to woody plants revolves around the plant's growth phase. This is because herbicides are most effective when applied during specific stages of the plant's development, such as during active growth or when the plant is transitioning into dormancy. Understanding the growth phase allows for optimal absorption and translocation of the herbicide within the plant.

For instance, applying a herbicide during the spring or early summer when the plant is actively growing can enhance its efficacy, as the plant's physiological processes are at their peak, ensuring that the herbicide is taken up and distributed effectively throughout the plant system. Conversely, applying herbicides at the wrong growth phase can lead to decreased effectiveness, as the plant may not be able to absorb or utilize the chemical efficiently.

Other factors such as leaf color, the specific season of the year, or the type of soil may influence how the herbicide interacts with the environment or the plant, but they are not as critical in determining the timing of the application as understanding the plant's growth phase. This knowledge is vital for ensuring that herbicides work as intended and minimize the potential for harm to non-target plants and the environment.