Which of the following applications requires a spray permit?

The correct answer focuses on the requirement of a spray permit, which is typically necessary for activities that may pose a higher risk of environmental contamination or public health concerns. Spraying with standard ground application equipment is a method that often involves the use of chemicals in significant volumes and under conditions that could lead to drift or runoff, potentially impacting non-target species or areas.

Regulatory authorities generally mandate permits for aerial and ground spraying to ensure that the applicator is trained, follows safety protocols, and applies pesticides in a manner that complies with local environmental regulations. Such permits are designed to prevent misuse and to monitor the application of pesticides effectively.

In contrast, methods such as using a mop for herbicide application or injecting herbicides are generally considered to have lower risk profiles and do not typically require the same level of oversight or permits. Spraying in a residential area might seem like it requires a permit due to potential safety concerns, but this often depends on the specific regulations of the locality. However, the broad category of spraying with standard ground application equipment stands out as typically requiring a permit.