Fate Characterization of Benzene Kresoxim‐Methyl (a Strobilurin Fungicide) in Different Aerobic Soils

Abstract

Benzene kresoxim-methyl (BKM) is a promising broad-spectrum strobilurin fungicide widely used to control fungal pathogens in crops. However, information on its environmental fate is limited. To broaden our understanding of this fungicide's kinetic fate in aerobic soils, we labeled BKM with C on its benzoate ring and used ultralow-level liquid scintillation counting coupled with high-performance liquid chromatography analysis. Results show that degradation, mineralization, and bound residue (BR) formation of BKM was controlled by soil type and microbial community composition. Degradation of BKM followed first-order dynamics, and the half-lives () were 51.7, 30.8, and 26.8 d for clay, loamy, and saline soils, respectively. After 100 d, about 0.13, 4.35, and 5.94% of the initial C-BKM was mineralized, and 14.43, 19.90, and 28.81% was formed as BRs in the clay, loamy, and saline soils, respectively. About 60 to 85% of the C-BKM residue in soil was extractable; of this fraction, 30 to 50% was composed of incomplete degradation intermediates. Up to 40% of extractable C-BKM in soil was readily available. Our results suggest that BKM and its incomplete intermediates had a relatively long persistence in soil, which may lead to exposure for nontarget organisms. Soil microbes may play a dominant role in controlling the fate of BKM in soil as sterilization sharply decreased its mineralization rate from 4.35 to 0.03%, increased from 30.8 to 85.6 d, and decreased the BR fraction from 19.90 to 3.25%.

An Overview of Strobilurin Fungicide Degradation:Current Status and Future Perspective

“…According to Liu et al (2014), the degradation and mineralization process of a newly developed strobilurin fungicide (SYP-3343) was affected and accelerated by soil microbes. Zhao et al (2017) explored the kinetic fate of BKM in aerobic soils and suggested that the soil type and microbial community composition controlled the process of BKM degradation and mineralization. Soil microbes can sharply decrease the residues of BKM as well.…”

Preservative Effects of Strobilurin Fungicides on Citrus Storage Diseases and Residue Safety Assessment

“…So, strobilurin fungicides have been intensively adopted by many countries such as America and Brazil to control the diseases of citrus or other diseases (OChoa-Acuna et al, 2009;Mahoney & Gillard, 2014;Benelli et al, 2016;Debona et al, 2016aDebona et al, , 2016bWoodward et al, 2016). The residue levels and degradation pattern of strobilurin fungicide on various horticultural crops were widely investigated (Marin et al, 2003;Wang et al, 2014;Xue et al, 2014;You et al, 2015;Campillo et al, 2015;Raina-Fulton, 2015;Wu et al, 2016;Li et al, 2016;Guo et al, 2017;Kolosova et al, 2017;Zhao et al, 2017). However, the levels, dose and effectiveness of strobilurin fungicide used in postharvest treatments for citrus fruit were seldom explored in terms of controlling decay.…”