What are the factors affecting herbicide selectivity?

Herbicide selectivity is primarily influenced by factors that relate to the plant characteristics and herbicide interaction at a biological level. These include morphological factors such as the structure and size of the plant, which can affect how a herbicide is absorbed and translocated within the plant. For example, differences in leaf shape or surface area can influence how much herbicide penetrates the plant tissues.

Additionally, physiological factors play a crucial role. Some plants have natural biochemical pathways or defenses that allow them to tolerate or metabolize certain herbicides more effectively than others. Understanding these factors is key to predicting which plants a specific herbicide will affect and which it will not, thereby guiding proper herbicide application for controlling unwanted vegetation without harming desirable plants.

While other options mention environmental and ecological factors, they do not directly address how plants' morphological traits and physiological responses specifically contribute to the selectivity of herbicides. These aspects are fundamentally important for accurately applying herbicides in forestry practice, ensuring efficacy while minimizing unintended damage to non-target species.