Background Information
Pesticide literally means "pest killer". The specific type of pesticide is revealed in its name; i.e. herbicides kill plants (herbs), insecticides kill insects, fungicides kill fungi, rodenticides kill rodents and so forth. Pesticides work on pests in a variety of ways and each has a specific route of entry for the pest and certain possible routes of exposure for the applicator. The advantages of using pesticides in the landscape are that they are usually quick acting, easy to use, and relatively cheap. Disadvantages include their possible toxicity to humans and non-target species, potential negative environmental effects, pesticide resistance due to overuse, and the unknown cumulative effects of their use over time.
There is a shift in the way pesticides are being made and used. Pesticide use in the U.S. has dropped significantly from a high of 1.46 billion pounds in the 1970s, compared to approximately 1.23 billion pounds today.[6] This is due to the advances in pesticides. Pesticides are now more selective and are applied at lower rates, while having lower inherent toxicity and a lower impact on human health and the environment. For example, tree farm herbicides use was approximately 2.1 pounds of active ingredient per acre before 2001, today it takes only about 0.25 fluid oz of active pesticide ingredient to fight the same weeds in that acre.
When the major water pollution control laws were enacted around 1970, a great concern was DDT and other very persistent insecticides that polluted water and sediments. In rural areas, the greater problem is from herbicides that, because they are applied directly to the land, have an inherent tendency to get into runoff and into water sources. These older more potentially toxic pesticides are being phased out under numerous changes to pesticide regulated legislation. The Food Quality Protection Act has allowed the EPA to fast track reduced risk synthetic pesticides and biopesticides helping these products get to market much sooner. This act has helped transition pesticide use in the U.S. to safer pesticide use. These new pesticides reduce risks to non-target organisms and reduce the contamination of valuable environmental resources.
Integrated pest management (IPM) has also become common practice in agriculture as well as landscape management. This relies on the life cycles of pests and controls pests economically by withholding use of pesticides until their damage reaches a certain threshold. Pesticides are really the last line of defense in a green chemistry approach to managing pests of the landscape. You should teach your students the practice of IPM. There are many great websites about IPM; you should do more research on this if you are not familiar with this idea. I have a limited amount of space for this unit, so I will not be elaborating much more on this topic. One place to get you started is an online book on IPM at the University of Minnesota website.[7] IPM is a way to control pests that uses both chemical and non-chemical methods. The steps taken through this approach really are designed to minimize the risk to humans and non-target organisms. The first step is preventing an outbreak which is accomplished by keeping the plants in the landscape as healthy as possible through the proper selection of plants for site conditions and proper nutrition, and by using good cultural practices to reduce the conditions that cause disease. Secondly, you must monitor the landscape for pests, noting areas that have any sort of disease or pest that is affecting them and then assessing the extent of infestation. Identification of the pest is critical to the effectiveness of treatment; you have to go over the common pests with the students and the signs of infestation to allow them to make good decisions for the last step. The last step is to plan the control strategy for the pest in question. There are many biological control methods you can use such as the use of predator insects, parasites, pathogens, and they are developing more and more biopesticides to control a myriad of pests and diseases. Chemical intervention is the last line of defense once the pests have reached the tolerable threshold. Many times at this point you can treat the smaller affected areas with a very selective or narrow spectrum pesticide. Using a broad spectrum pesticide, which kills lots of different organisms, is not an ideal situation. This will harm many non-target organisms such as pollinators, fish and other aquatic organisms.
All pesticides contain active ingredients that control pests by interfering with their natural body functions. The chemical structure of the active ingredient determines what chemical class it belongs to. This information can be found on the Material Safety Data Sheet (MSDS) for the product you are applying. I believe this is knowledge that the applicator should be aware of, and it is important in protecting not only the environment but also the pesticide applicator. Understanding the properties and modes of actions of the common chemicals used in the landscape will help my students use the pesticides most effectively and minimize adverse environmental and health effects.
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