Fungicides, Bactericides, Biocontrols, and Natural Products
fun·gi·cide (ˈfənjə-sīd). n. A chemical that inhibits, prevents, or stops fungal growth.
bac·te·ri·cide (bak-tîrə -sīd). n. A chemical that inhibits, prevents, or stops bacterial growth.
bi·o·con·trol (bī′ō-kən-trōl′). n. Short for biological control. The use of living organisms to control plant diseases and other pests.
nat·u·ral prod·uct (nat´u`ral prod´uct). n. A chemical substance produced by a living organism, often a plant or microorganism in a fermentation process.
Fungicides, bactericides, biocontrols, and natrual products prevent or mitigate damage caused by microorganisms, typically fungi and bacteria, to other living organisms such as people, animals, plants including agricultural crops, as well as physical structures such as buildings and plant products (e.g., wood). Biological controls are living organisms, whereas natural products are derived from natural sources. Fungicides and bactericides may be developed from natural products or they are chemically synthesized but most newer products are heterocyclic, carbon-based compounds that are degradable in the environment. In general, pesticides used in modern agriculture need to have high efficacy and have a critical role in the development of our society by improving crop yields and reducing labor needed to produce food. This enables society to diversify and endeavor into activities other than food production. Overall, the benefits of pesticides such as fungicides and bactericides far outweigh the risks associated with using them, especially when they have been thoroughly evaluated and characterized by regulatory agencies, universities, and private testing labs.
The Evolution of Fungicides
In the last 50 years, there has been a dramatic change in conventional fungicide properties to improve their overall safety, performance, and targeted activity. In general, acute and chronic toxicities to humans and other non-target organisms have been dramatically reduced, and much higher amounts per body weight are required to cause damage in mamalian test subjects. The amounts needed to be toxic are so high that they are generally considered unattainable over a lifetime. Environmental persistence has been reduced in favor of shorter half-lives by designing them without metal ions, and thus, fungicides have less opportunity to contaminate waterways or adjacent ecosystems through air, water, or soil movement beyond the intended treatment area. Fungal pathways have been selected as biochemical target sites of fungicides that are highly specific to these organisms, resulting in lower amounts of active ingredients needed to manage plant diseases. Furthermore, different modes of action (MOA) allow rotations that prevent overuse of any one MOA and the selection of resistant sub-populations. An illustration of major steps in the evolution of agricultural fungicides for disease management is shown below:
