What does back-siphoning refer to in pesticide application?

Back-siphoning refers specifically to the reverse flow of liquids into a fill hose during pesticide application. This phenomenon can occur when there is a pressure drop in the water supply system, often if the water source is higher than the pesticide container or if there is a disruption in the supply line. When back-siphoning occurs, it can lead to contaminated water being drawn back into the clean water supply, posing significant environmental and health risks. Understanding this concept is crucial for pesticide applicators, as it highlights the importance of proper equipment use and installation of backflow prevention devices to mitigate such risks.

The other options describe different issues related to pesticide use or storage but do not accurately define the specific process of back-siphoning. For instance, the escape of gases from storage containers pertains to venting issues rather than liquid flow dynamics. Improper disposal of pesticide containers addresses environmental practices but is unrelated to the flow of liquids. Lastly, evaporation of pesticides refers to the physical change of pesticides from liquid to vapor form, not the movement of liquids within hoses or containers.