Which substance is added to herbicides to help them spread uniformly on plant leaves?

Surfactants are substances that have the ability to reduce the surface tension of liquids, which enhances the spreading and wetting properties of a solution. When added to herbicides, surfactants facilitate even distribution on plant leaves, allowing the active ingredients to contact more surface area. This increases the efficacy of the herbicide by improving absorption and ensuring that it adheres to the target plants more effectively.

Using surfactants can also help prevent the formation of droplets that might roll off the leaf surfaces, which is particularly important for achieving optimal herbicide performance. This is a critical aspect when managing vegetation, as uniform coverage is essential for successful weed control. Other choices may serve different purposes but do not specifically assist in the uniform spreading of herbicides on plant surfaces.