Which of the following is considered a mechanical control technique?

Hand-pulling of weeds is classified as a mechanical control technique because it involves the physical removal of weeds by hand. This method directly eliminates unwanted plants without relying on chemical agents. Mechanical controls are typically methods that involve physical actions to manage pests or unwanted vegetation, such as cutting, mowing, or removing plants entirely from the soil.

Hand-pulling is particularly effective for small infestations or in gardens, where precision and care can be exercised to minimize the impact on desirable plants and the surrounding environment. By using this approach, it can also help prevent the spread of seeds and reduce the chances of herbicide resistance developing in weed populations.

In contrast, the other options you listed involve different control strategies. The application of herbicides is a chemical control method, while planting competitive species is a biological control approach. Flooding can alter the growing conditions but is not categorized purely as a mechanical control technique.