What precaution should be taken with the symbol W in relation to water?

The symbol W indicates that the associated pesticide is water-insoluble or that it poses a risk when it comes into contact with water. Therefore, taking precautions to avoid the use of water is essential when handling or applying this type of pesticide. This is especially important in preventing unintended contamination of water sources, which could harm aquatic life or lead to groundwater pollution.

The potential risks of using water with pesticides marked with a W symbol may include reduced efficacy or unforeseen chemical reactions. It is crucial for applicators to be aware of these implications to properly follow safety protocols and ensure they do not negatively impact the environment while administering pesticides.