Which physical factor contributes to the susceptibility of selective herbicides?

The placement of herbicides is crucial in determining their effectiveness and selectivity. When herbicides are applied appropriately in relation to the target plants, it maximizes their absorption and interaction with the specific plant physiology. This factor includes considerations of the depth of application, the stage of growth of the plant, and the environmental conditions at the time of application.

Proper herbicide placement helps to ensure that the chemical reaches the target plant while minimizing drift or runoff into non-target areas, which can lead to unintended effects on non-target species. Effective placement contributes to the overall efficacy of a selective herbicide, as it allows the herbicide to act more specifically and efficiently against the intended pests or weeds.

Other factors like soil type, time of day, and humidity do influence herbicide behavior and efficacy, but they are secondary to the direct impact that proper placement has on the overall success of herbicide application.