Which of the following best describes pest runoff?

The term 'pest runoff' specifically refers to the movement of pesticides from their original application site into nearby water bodies, such as streams, rivers, or lakes. This process can occur due to precipitation or irrigation, which can wash the chemicals away from treated areas. Pesticide runoff is a significant environmental concern as it can lead to water contamination, affecting aquatic life and potentially entering the human water supply.

In contrast, the other choices describe different phenomena related to pesticide usage. The absorption of pesticides by plants pertains to how plants take up chemicals from the soil or through their leaves, which doesn't convey the concept of runoff. The natural decay of pesticides in soil relates to the breakdown process that occurs when pesticides degrade over time due to various environmental factors, not their movement. Lastly, the direct application of pesticides in water describes a method of application rather than the unintentional movement of pesticides away from the intended area, which is central to the concept of runoff. Therefore, the correct characterization of pest runoff is its movement into streams.