What type of herbicide is usually employed to control broadleaf weeds?

The most suitable type of herbicide for controlling broadleaf weeds is selective herbicides. Selective herbicides are designed to target specific types of plants, which makes them effective against broadleaf weeds while minimizing harm to desired grasses and other plants. This selectivity arises from the herbicide's chemistry, allowing it to affect particular physiological processes that are unique to broadleaf species.

Pre-emergent herbicides, on the other hand, work by preventing the germination of weed seeds, which can impact a range of weed types rather than specifically focusing on existing broadleaf weeds. Non-selective herbicides kill all plants they come into contact with, making them less desirable for situations where you want to preserve certain desirable grasses or plants. Lastly, contact herbicides require direct contact with the foliage of the target plants to be effective, which makes them less efficient for controlling broadleaf weeds where systemic action is often more beneficial.

Thus, selective herbicides are tailored to effectively take out broadleaf weeds while safeguarding desirable vegetation, which is why this type is preferred for such applications.