Which of these is not typically an effective control method for broadleaf weeds?

Excessive watering is not typically an effective control method for broadleaf weeds because it can create a favorable environment for their growth rather than suppressing it. Over-watering can lead to saturated soil conditions, which may promote the health and proliferation of weeds since they thrive in moist conditions.

In contrast, cultural practices, such as proper lawn maintenance and promoting healthy grass growth, can significantly reduce the ability of broadleaf weeds to establish and spread. Mechanical removal involves physically pulling or cutting weeds, which can be effective, particularly for small infestations. Selective herbicides are designed to target specific types of weeds, including broadleaf varieties, while sparing desirable grass species. These methods can all effectively manage and control broadleaf weeds, making excessive watering an inappropriate method in this context.