Pesticides, particularly insecticides and herbicides, are an integral part of modern agricultural production. In the States, agricultural pesticides are regulated under the Federal Insecticide,Fungicide,and Rodenticide Act (FIFRA), first passed in 1947, revised in a major way in 1972, and subjected to several amendments since then. Pesticide are responsible for much of the high productivity of modern agriculture as well as some of the major pollution problems associated with agriculture.
An interesting development regarding the use of herbicides in the late 1990s was the production of transgenic crops resistant to specific herbicides. The Monsanto company pioneered this approach with the development of "Roundup Ready " crops that resist the herbicidal effects of Monsanto's flagship Roundup herbicide(glyphosate). The seedling of crops resistant to the herbicide are not harmed on exposure to it, whereas competing weeds are killed. Although sales of glyphosate have been greatly increased by Roundup Ready crops, especially soybeans,increased plantings of these crops has reduced the use of herbicides overall with a net overall benefit to the environment.
The use on transgenic crops of glyphosate,for which the structural formula is show in Chapter 7,Figure 7.14, has made it a uniquely important product, the most widely produced pesticide in the world. Glyphosate binds strongly to soil colloid and is readily degraded by soil microorganisms. The properties of glyphosate make it difficult to measure in soil and water samples. The molecule is very polar and soluble in water, but not soluble in organic solvents commonly used to extract pollutants for analysis. It binds strongly to metal ions as well as orgenic, mineral, and clay solids making its isolation difficult. Because of glyphosate's structural similarity to naturally occuring amino acids and other plant biomolcules, there are numerous interferences in its determination.