Which of the following is NOT a method for applying liquid aquatic herbicides?

Drip irrigation is not typically a method used for applying liquid aquatic herbicides. This method is primarily designed for delivering water and nutrients directly to the root zone of plants, especially in terrestrial agriculture. It involves a network of tubing and emitters, which is not suitable for dispersing herbicides in aquatic environments.

In contrast, methods such as direct metering into pump suction and using spray tanks are common practices for applying liquid herbicides to water bodies, allowing for precise control over the dosage and coverage. Hydrostatic spraying also applies herbicides effectively in aquatic environments by utilizing high pressure to ensure even distribution across the water surface. Thus, the selection of drip irrigation as the answer highlights a clear distinction between appropriate herbicide application methods and irrigation techniques.