Herbicides 101

Flowing along Illinois’ borders and through its interior are more than 87,000 miles of rivers and streams. Many, if not most, of these waterways exist within or adjacent to agricultural land. This is not surprising, as agricultural land covers approximately 76 percent of Illinois’ surface area, with slightly more than 60 percent of this land planted in soybeans and corn.

With so much land utilized for industrial agriculture, it’s not a surprise that in our recent “Building Capacity in Illinois Watershed’s” survey, over 64% of the survey respondents reported pesticides/herbicides as a known water quality impairment in their watershed.

But pesticide and herbicide use is not limited to the agriculture community. If you have ever been in a hardware store or superstore you’ve surely walked past the aisle full of lawn, garden, and home care chemicals that will help rid you of unwanted plants and animals. Unfortunately, these chemicals not only effect targeted species, but also harm or kill unintended plants or animals.

Many pesticides and herbicides can become pervasive in the environment. When applied to the large scale farm, to your lawn, or to a backyard rosebush, pesticides and herbicides inevitably make it to water bodies via runoff from rain, sprinklers, or irrigation systems, then through storm drains or agricultural drainage tiles into the nearest stream.

Limiting or avoiding the use of lawn and garden chemical pesticides and herbicides can help us all have cleaner and healthier rivers and communities. There are numerous organic methods of pest control available and they are as near as your local lawn and garden center.

In order to fully understand what it is that you are using on your property it is important to read and follow the application instructions carefully. Be sure you purchase products from licensed and informed sales persons that can offer tips on application rates and times that may also save you money.

Also very important is gathering your own information, researching chemicals and understanding the broader scope of their potential impacts. After all, each of our actions, even the most simple and habitual, impacts our neighbors. We are all part of a greater system and the chemicals we use in our homes, on our gardens, and on our farms effect the fish, birds, insects, and humans around us.

What are Herbicides?

Herbicides are chemicals used to kill or otherwise manage certain species of plants that are considered to be “pests” that compete with more desirable plants for water, light, & nutrients.

Types of herbicides

Chlorophenoxy acid herbicides (e.g. 2, 4-D)

Chlorophenoxy acid herbicides cause toxicity to plants by mimicking their natural hormone-like auxins, and thereby causing lethal growth abnormalities. These chemicals are moderately persistent in the environment, meaning half-life (time required for half the substance to degrade and become inert) in solid form is typically measured in weeks, and may remain in the environment for a year or so.

Triazine herbicides (e.g. Atrazine, Cynazine, Hexazinone, Metribuzin, and Simazine)

Triazine herbicides are mostly used in corn agriculture, and sometimes as soil sterilants. These chemicals are not very persistent in surface soils, but they are mobile and can contaminate groundwater.

Organic phosphorus herbicides (e.g. Glyphosate)

Organic phosphorus herbicides are few, but they include the commonly used chemical, glyphosate. Glyphosate has a wide range of agricultural uses, and it is also an important herbicide in forestry. To kill plants, glyphosate must be taken up and transported to tissues, such as roots and rhizomes, where it interferes with the synthesis of certain amino acids. Because glyphosate can potentially damage many crop species, its effective use requires an understanding of seasonal changes in the vulnerability of both weeds and crop species to the herbicide. Glyphosate is not mobile in soils, has a moderate persistence, and is not very toxic to animals. Recently, varieties of certain crops, notably the oilseed canola, have been modified through genetic engineering to be tolerant of glyphosate herbicide. Previously, there were no effective herbicides that could be applied to canola crops to reduce weed populations, but now glyphosate can be used for this purpose. However, this has become controversial because many consumers do not want to eat foods made from transgenic crops.

Although glyphosate is not mobile in soils, has a moderate persistence, and does not appear to be very toxic to animals, many of the surfactants – chemicals mixed with the glyphosate to help it spread and adhere to plants – can be harmful to animals. Some surfactants have been reported to remain in the environment for much longer than the glyphosate itself. These surfactants have also been shown to disrupt the reproductive and growth hormones of animals exposed to them.

The above information is from http://science.jrank.org/pages/3303/Herbicides-Types-herbicides.html

 
Additional Resources on the use of Pesticides and Herbicides in Illinois

The Illinois Department of Agriculture and the Illinois Environmental Protection Agency are both responsible for testing the waters of Illinois for pesticides and herbicides. To learn more about their procedures, testing locations, and findings visit the sites below:

 

  • For information on the herbicide Metolachlor click here.
  • For information on the herbicide Acetochlor click here.
  • For a printable version of Best Management Practices (BMPs) for agricultural herbicides click here.