What should be done after foaming occurs during mixing?

When foaming occurs during mixing, adding a defoamer is the best choice because it directly addresses the issue of excess foam that can interfere with the application process. Foaming can result in difficulties with measuring and mixing pesticides accurately, as well as hinder the even application of the product. Defoamers work by reducing the surface tension of the foam, allowing it to collapse and preventing it from causing issues.

The other options do not effectively remediate the foaming issue. Stopping the application immediately might prevent further complications, but it does not solve the existing problem of foam. Changing the water source may not address the root cause of the foam, which could be related to the mixing process or the products being used rather than the water itself. Adding more surfactant could exacerbate the foaming because surfactants are designed to reduce surface tension and can actually contribute to increased foam formation. Therefore, using a defoamer is the most practical and effective solution to control foam and ensure successful mixing and application.