What is the purpose of shank or spray blade application methods?

The purpose of shank or spray blade application methods is indeed primarily for the broad treatment of pests that are living deeper in the soil. This technique is particularly effective for delivering pesticides directly into the soil where many pests may reside, such as root-feeding insects or nematodes. The shank or spray blades can penetrate the soil, allowing the pesticide to reach areas that might not be accessible with surface applications. This method ensures that the treatment is applied at the correct depth and provides better control over pests that are not just on the surface.

In contrast, other application methods serve different purposes: controlling surface pests typically relies on different mechanisms, such as broadcast or contact applications designed to affect pests that are actively feeding on or on top of the soil. Quick applications of granular formulations would require a different approach that is suitable for solid materials rather than the specific capabilities of shank or spray blade methods. Aerial treatment is mostly used for large areas where ground access may be limited, and not necessarily focused on addressing specific soil-dwelling pests. Thus, shank or spray blade methods are uniquely suited for targeting deeper soil pests effectively.