Uptake, translocation, and degradation of spirotetramat in tomato ( Lycopersicon esculentum Miller): Impact of the mixed-application with pymetrozine

In this study, we investigated the impact of the mixed-application with pymetrozine on the behavior (i.e., uptake, translocation, and degradation) of spirotetramat in tomatoes under laboratory conditions. Results showed that pymetrozine promoted the uptake of spirotetramat from the nutrition solution after root application. The root concentration factor was 0.290 and 1.566 after spirotetramat single application and mixed-application with pymetrozine, respectively. It had little effect on the degradation of spirotetramat, with the metabolites of M-keto, M-enol, and M-glu in tomato issue (root, stems, and leaves). After foliar treatments, pymetrozine accelerated the translocation of spirotetramat from leaves to stems, with the translocation factor of 0.145 and 0.402 after spirotetramat single application and mixtures with pymetrozine, respectively. Pymetrozine also promoted the degradation of spirotetramat to M-kto and M-enol in leaves. Besides, a partition-limited model was used to describe the distribution processes of spirotetramat in the tomato-water system after root application. It showed that pymetrozine accelerated the distribution balance of spirotetramat in the whole system. Our result indicates that the interaction among pesticides should be considered when studied for the uptake, translocation, and degradation of pesticides in crops.