A weed killer turns out to be a compound formulation that has an impact of removing weeds whenever sprayed (or otherwise implemented, according to directions) on a particular field. A weed, by the way, is any plant growing where it isn't supposed to be growing. Lawyers working against Monsanto weed killer are working for the welfare of the people to know more about weed killer.
Weeds tend to emerge out prominently whenever they attempt to grow alongside other (deliberately implanted, useful) plants. When they do so, it usually means that they are in direct competition with those desired plants for life care sources: water, soil nutrients, air and so forth. It doesn't help things that, as an evolutionary adaptation, the weeds seem to have become more competitive than most of the domesticated plants within their competition for life support tools.
This means that unchecked, they have the capability to eventually decimate the desirable plants in a bid to keep all of the life support tools to themselves. That would, of course, be the plant-care giver's worst nightmare; hence the necessity to keep the weeds in check.
Several methods are utilized in keeping weeds in check. Ultimately, however, they fall into two big classes: mechanical weed control procedures and chemical weed control methods. And it is the agents used in the latter (chemical weed control) that are referred to as weed destroyers in this circumstance.
There are many types of weed killers, created to satisfy unique kinds of marijuana challenges. Selecting a weed destroyer is not always a very easy job. Indeed a frequently asked question by individuals involved in plant maintenance is concerning the way to go about selecting good weed killers.