Division of Agricultural Chemicals, Indian Agricultural Research Institute, New Delhi, India.
Pest Manag Sci. 2012 Jun;68(6):828-33. doi: 10.1002/ps.2331. Epub 2012 Mar 6.
Pyrazosulfuron ethyl, a new rice herbicide belonging to the sulfonylurea group, has recently been registered in India for weed control in rice crops. Many field experiments revealed the bioefficacy of this herbicide; however, no information is available on the persistence of this herbicide in paddy soil under Indian tropical conditions. Therefore, a field experiment was undertaken to investigate the fate of pyrazosulfuron ethyl in soil and water of rice fields. Persistence studies were also carried out under laboratory conditions in sterile and non-sterile soil to evaluate the microbial contribution to degradation.
High-performance liquid chromatography (HPLC) of pyrazosulfuron ethyl gave a single sharp peak at 3.41 min. The instrument detection limit (IDL) for pyrazosulfuron ethyl by HPLC was 0.1 µg mL(-1) , with a sensitivity of 2 ng. The estimated method detection limit (EMDL) was 0.001 µg mL(-1) and 0.002 µg g(-1) for water and soil respectively. Two applications at an interval of 10 days gave good weed control. The herbicide residues dissipated faster in water than in soil. In the present study, with a field-soil pH of 8.2 and an organic matter content of 0.5%, the pyrazosulfuron ethyl residues dissipated with a half-life of 5.4 and 0.9 days in soil and water respectively. Dissipation followed first-order kinetics. Under laboratory conditions, degradation of pyrazosulfuron ethyl was faster in non-sterile soil (t(1/2) = 9.7 days) than in sterile soil (t(1/2) = 16.9 days).
Pyrazosulfuron ethyl is a short-lived molecule, and it dissipated rapidly in field soil and water. The faster degradation of pyrazosulfuron in non-sterile soil than in sterile soil indicated microbial degradation of this herbicide.
吡唑磺隆乙酯是一种新型磺酰脲类水稻除草剂，最近在印度获得登记，用于稻田杂草防治。许多田间试验表明了该除草剂的生物功效；然而，在印度热带条件下，尚无关于该除草剂在稻田土壤中持久性的信息。因此，进行了田间试验以研究吡唑磺隆乙酯在稻田土壤和水中的归宿。还在无菌和非无菌土壤中进行了实验室条件下的持久性研究，以评估微生物对降解的贡献。
高效液相色谱（HPLC）分析吡唑磺隆乙酯在 3.41 分钟时给出单一尖锐峰。HPLC 法测定吡唑磺隆乙酯的仪器检测限（IDL）为 0.1 µg mL(-1)，灵敏度为 2 ng。估计方法检测限（EMDL）分别为水和土壤中的 0.001 µg mL(-1)和 0.002 µg g(-1)。间隔 10 天施药两次可获得良好的杂草防治效果。在本研究中，田间土壤 pH 值为 8.2，有机质含量为 0.5%，吡唑磺隆乙酯在土壤和水中的残留分别以 5.4 和 0.9 天的半衰期消散。降解遵循一级动力学。在实验室条件下，非无菌土壤中吡唑磺隆乙酯的降解速度（t(1/2) = 9.7 天）快于无菌土壤（t(1/2) = 16.9 天）。
吡唑磺隆乙酯是一种短寿命分子，在田间土壤和水中迅速消散。非无菌土壤中吡唑磺隆的降解速度快于无菌土壤，表明该除草剂可被微生物降解。
