Degradation dynamics of azadirachtin in cabbage and soil

Objective  To identify the residual and degradation dynamics of azadirachtin in cabbage and soil after spraying 0.3%azadirachtin emulsifiable concentrate during the growth period of cabbage (Brassica oleracea).

Method Azadirachtin was added with three concentrations of 0.1, 0.5 and 1.0 mg·kg^-1 within the range from 0.05 to 5.00 mg·kg^-1. Azadirachtin was extracted from cabbage and soil using acetonitrile assisted with ultrasonic, purificated using a florisil solid phase extraction column, detected by HPLC and quantified by external standard method.

Result The average recovery rates of azadirachtin in cabbage ranged from 88.52% to 93.21% with relative standard deviations ranging from 2.75% to 3.55%, and the average recovery rates in soil were ranged from 90.69% to 93.32% with relative standard deviations ranging from 2.09% to 3.46%.The half-lives of azadirachtin in cabbage and soil were 0.89 and 2.40 d respectively.

Conclusion Azadirachtin is an easily degradable pesticide. Application of 0.3% azadirachtine mulsifiable concentrate is safe and recommended.