Explore the three types of pesticide degradation as part of earning a CEU toward the renewal of FDACS restricted-use pesticide license.
In our last blog, we shared the three fate processes for pesticides from an article in Citrus Industry that earns “one continuing education unit (CEU) in the Core category toward the renewal of a Florida Department of Agriculture and Consumer Services restricted-use pesticide license when the accompanying test is submitted and approved.” The continuation of our blog looks at three types of pesticide degradation. See them below.
The Degradation of Pesticides
According to the article, “three types of pesticide degradation are microbial, chemical, and photodegradation.”
“Microbial Degradation. The breakdown of pesticides by fungi, bacteria and other microorganisms that use pesticides as a food source is known as microbial degradation. Most microbial degradation of pesticides occurs in the soil. Soil conditions such as moisture, temperature, aeration, pH and the amount of organic matter affect the rate of microbial degradation because of their direct influence on microbial growth and activity.
The frequency of pesticide application is also a factor that can influence microbial degradation. Rapid microbial degradation is more likely when the same pesticide is used repeatedly in a field. Repeated applications can actually stimulate the buildup of organisms that are effective in degrading the chemical. The possibility of very rapid pesticide breakdown is reduced by using pesticides only when necessary and by avoiding repeated applications of the same chemical. Alternating between different classes, groups or formulations of pesticides can minimize the potential for microbial degradation problems as well as pest resistance.
Chemical Degradation. The breakdown of pesticides by processes that do not involve living organisms is referred to as chemical degradation. Temperature, moisture, pH and adsorption, in addition to the chemical and physical properties of the pesticide, determine which chemical reactions take place and how quickly they occur.
One of the most common pesticide degradation reactions is hydrolysis, a breakdown process in which the pesticide reacts with water. Many organophosphate and carbamate insecticides are particularly susceptible to hydrolysis under alkaline conditions. Some are actually broken down within a matter of hours when mixed with alkaline water.
Product labels may warn against mixing a pesticide with certain fertilizers, other pesticides or water with specific characteristics. Following these precautions can help prevent pesticide degradation and potential incompatibility problems. In some situations, buffers or other additives may be available to modify spray mix conditions and prevent or reduce degradation.
Photodegradation. The breakdown of pesticides by light, particularly sunlight, is called photodegradation. Photodegradation can destroy pesticides on foliage, on the surface of the soil and even in the air.
Factors that influence pesticide photodegradation include the intensity of the sunlight, properties of the application site, the application method and the properties of the pesticide. Pesticide losses from photodegradation can be reduced by adding the pesticide to the soil during or immediately after application.”
See considerations concerning water quality and pesticides in our last blog.
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