When performing a trench and treat, do you need to top with untreated soil after refilling the trench?

In the context of a trench and treat application, topping the trench with untreated soil after refilling is necessary to ensure that any pesticides effectively reach the intended areas of the soil and do not pose a risk to non-target organisms or the surrounding environment. By covering the treated area with untreated soil, the remaining pesticide concentration is minimized at the surface layer, which helps in preventing potential contamination and exposure to beneficial soil organisms and the environment above the treated surface.

This practice also aids in creating a buffer zone where the pesticide residues can bind to the soil particles beneath the surface layer, further reducing the likelihood of unintended movement or dispersal. It is crucial for proper pest management and environmental safety, aligning with best practices in pest control.