Photodegradation of fungicides: An appraisal

Fungicides are commonly used to manage disease problems in a wide range of crops grown in different environments throughout the world. however, their fate after application is relatively less known. Most of the fungicides and other pesticides are broken down to secondary products in soil, water or on plant surface under the influence of sunlight. This photolytic breakdown of fungicides, commonly known as photodegradation, is accomplished through photolytic reaction under the influence of sunlight. Their photo-degraded products may be more toxic than the fungicides themselves. However, limited studies have been conducted to understand this whole process and the relevant information is available for selected fungicides only. Photolysis on soil is still only partially understood because of the limited number of investigations, whereas on plants it is mostly speculation derived from plant metabolism studies. Under these circumstances, photodegradation on soil and plant surfaces requires more examination, not only experimentally but also theoretically, to reveal the mechanisms controlling photophysical and photochemical processes in fungicides and other pesticides on solid phases and to apply such knowledge to better understand their dissipation profiles in the field.