Which phenomenon refers to the optimal and most effective application point of pesticides where further application is unnecessary?

The optimal and most effective application point of pesticides, where further application is unnecessary, is best described as the application threshold. This concept refers to the specific level at which the application of a pesticide achieves the desired effect on pests while minimizing waste and environmental impact. Applying pesticides below this threshold may not effectively control the pest population, while exceeding it could lead to adverse effects, including potential harm to non-target species, groundwater contamination, or resistance development in pests.

The point of runoff refers to a situation where excess pesticide is washed away, typically due to rainfall or oversaturation of the soil. This scenario is not ideal for pesticide application, as it indicates that the product is not being utilized effectively.

Maximum efficacy point could imply the highest concentration at which a pesticide is effective, but it does not necessarily represent the threshold of optimal application.

The spray saturation point indicates the level of saturation of a surface with spray product, but it does not inherently define the optimal efficacy of the pesticide for pest control. Therefore, the application threshold is the term that encapsulates the idea of applying pesticides effectively and efficiently.