DEGRADATION OF PESTICIDES ON PLANT-SURFACES AND ITS PREDICTION - A CASE-STUDY ON TEA PLANT

The degradative kinetics of pesticides on plant surface are characteri zed by an initial rapid degradation which follows a first-order kineti cs, then transferred to a more slower degradative rate. The degradativ e process mainly consists of photodegradation, evaporation, rainfall e lution and growth dilution. The influencing parameters of these proces ses were investigated by using the tea plant as a case study. The pred ictive model of the initial concentration, photodegradation rate const ant, evaporation rate constant, rainfall elution rate, growth dilution rate and the total degradation rate was discussed and verified in fou r locations situated in the range of 25 degrees-30 degrees N latitude, and acceptable results were obtained.