For scientific application of chlorothalonil, deeply understand the deposition, distribution and dissipation of chlorothalonil on pakchoi, and reduce its application dosage. The effects of application dosage, application season, planting environment and planting area initial deposition, field dissipation and metabolism of pakchoi were studied. The deposition amount of chlorothalonil gradually increased with the increasing dosages, which followed an order of leaf &gt; edible parts&gt; petiole&gt; planting soil. The half-lives of chlorothalonil on pakchoi in May, October and December were 2.86 - 5.79 d, 3.08 - 5.87 d and 6.41 - 11.32 d, respectively. The deposition concentration and the dissipation half-life of chlorothalonil in different parts of the pakchoi plant and the planting soil in the greenhouse environment were higher than those in the open field environment and increased with increasing application frequencies. The initial deposition concentration and half-life of chlorothalonil on pakchoi gradually decrease from north to south: Beijing＞Hefei＞Changsha in April, Hefei＞Sanya in December. Chlorothalonil can be converted to metabolite I (C8HCl3N2O) on pakchoi plants, and can gradually dechlorinate to produce metabolite II (C8HCl3N2) and metabolite III (C8H2Cl2N2), metabolite IV (C8H3ClN2). Long-term intake of the leaves and edible parts of pakchoi will cause unacceptable dietary risks, when the application interval was 7 days. This study was helpful to improve the utilization rate of chlorothalonil and provides technical guidance for the scientific application of chlorothalonil in the pakchoi planting ecosystem.

Application method and environment on deposition, dissipation and metabolism of chlorothalonil on pakchoi

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