Which of the following is NOT a factor that affects herbicide activity?

The brand of herbicide does not inherently affect its activity, as the effectiveness of a herbicide relies more on its formulation, chemistry, and the specific active ingredients rather than the brand name under which it is marketed. Different brands may offer products with varying levels of effectiveness, but the brand itself does not play a direct role in the herbicide's interaction with the target plants or its overall performance in the field.

In contrast, the type of crop is a significant factor because certain herbicides are selective and will work differently depending on the species of crop being treated. Soil moisture also plays a critical role in how well a herbicide can be absorbed by the target plant and how effectively it can control weeds. Similarly, application equipment is important because the method of application can influence coverage, distribution, and ultimately the effectiveness of the herbicide. Each of these factors contributes to how well a herbicide will perform in controlling unwanted vegetation, while the brand itself does not influence these key aspects.