We’ve all done it: We’ve sprayed herbicides to get rid of the weeds at some point.
Herbicides are designed to be toxic to their target organism, be it a weed, insect, or fungus. The impact of pesticides extends beyond their target organisms, however, and may include effects on farm workers, consumers, and the environment.
As has been suggested above, some substantial benefits can be gained through the use of herbicides to manage unwanted vegetation. Compared with alternative means of weed control, such as mechanically weeding by hand or machine, herbicides are less expensive, often safer (especially in forestry), faster, and sometimes more selective, isn’t that what we have been told. But I say where does the seepage go? The environment of course. Therefore, what is the benefit?
In addition, some important environmental effects are associated with the use of herbicides. These include unintended damage occurring both on the sprayed site, and offsite. For example, by changing the vegetation of treated sites, herbicide use also changes the habitat of animals such as mammals and birds. This is especially true of herbicides used in forestry, because biodiverse, semi-natural habitats are involved. This is an indirect effect of herbicide use, because it does not involve toxicity caused to the animal by the herbicide. Nevertheless, the effects can be severe for some species.
Furthermore, not all of the herbicide sprayed by a tractor or aircraft deposits onto the intended spray area. Often there is drift of herbicide beyond the intended spray site, and unintended, offsite damages may be caused to vegetation. There are also concerns about the toxicity of some herbicides, which may affect people using these chemicals during the course of their occupation (i.e., when spraying pesticides), people indirectly exposed through drift or residues on food, and wildlife. For these and other reasons, there are many negative opinions about the broadcast spraying of herbicides and other pesticides, and this practice is highly controversial.
The intention of any herbicide treatment is to reduce the abundance of weeds to below some economically acceptable threshold, judged on the basis of the amount of damage that can be tolerated to crops.
Sometimes, this objective can be attained without causing significant damage to non-target plants. For example, some herbicides can be applied using spot applicators or injectors, which minimize the exposure to non-pest plants and animals. Usually, however, the typical method of herbicide application is some sort of broadcast application, in which a large area is treated all at once, generally by an aircraft or a tractor-drawn apparatus. This is the normal method and again I want to know where does all the seepage go? I don’t believe that chemicals seeping into the earth is a good practice to continue with. I don’t want the environment left to the next generation to deal with because we polluted it.
An important problem with broadcast applications is that they are non-selective—they affect many plants and animals that are not weeds—the intended target of the treatment. This is especially true of herbicides, because they are toxic to a wide variety of plant species, and not just the weeds. Therefore, the broadcast spraying of herbicides results in broad exposures of non-pest species, which can cause an unintended but substantial mortality of non-target plants. For example, only a few species of plants in any agricultural field or forestry plantation are abundant enough to significantly interfere with the productivity of crop plants.
I can see it… your eyes have glazed over by now.
You’ve said to yourself. Mary, what does this have to do with me? What can I do right now to help stop the affects of herbicides on the environment. Read on.
This common non-target effect of broadcast sprays of herbicides and other pesticides is an unfortunate consequence of the use of this non-selective technology to deal with pest problems. So far, effective alternatives to the broadcast use of herbicides have not been discovered they say, for the great majority of weed management problems. However, there are a few examples that demonstrate how research could discover pest-specific methods of controlling weeds that cause little non-target damage. I say bring in the goats!
Unfortunately…Not everyone sees the goats as a viable means to weed management problems. Until people see that better methods of control are available, herbicides will continue to be used in agriculture, forestry, and for other reasons. When will we take responsibility for what we are doing to the environment? We are the stewards or caretakers of the environment. I say now is the time.