Which method is used to effectively apply treatment in the bottom 1 to 3 feet of water?

The method that effectively applies treatment in the bottom 1 to 3 feet of water is the use of flexible hoses with nozzles and a rigid weighted boom. This approach allows for precise targeting of aquatic pests in deeper water layers where they often reside. The flexible hoses enable the operator to maneuver and position the nozzles at the desired depth, ensuring that the treatment solution is distributed accurately where it is needed most. The weighted boom helps submerge the treatment apparatus, allowing it to remain stable and effective at applying the pesticide evenly across the targeted area in the water column.

In contrast, other methods such as surface spraying techniques are designed for applications on the water's surface and are not suitable for reaching deeper areas. Dragging nets along the bottom may capture organisms but would not effectively apply chemical treatments. Lastly, handheld sprayers from the shore are impractical for addressing aquatic pest issues in deeper water because they cannot reach the targeted depth effectively.