Abstract

Chemical treatment of sugarcane seed with fungicides and insecticides prior to planting increases yields of cane and sugar for the perennial, annually harvested crop. However, the fate of the applied chemicals is unknown. Therefore, the purpose of this study was to measure the aerobic dissipation of selected billet seed treatment chemicals in a mineral sugarcane soil from Louisiana. Soil samples from the surface 15 cm were treated with either thiamethoxam, azoxystrobin, fluxapyroxad, propiconazole, or pyraclostrobin and monitored over 100 days under laboratory conditions. Insecticide and fungicide levels were determined by high performance liquid chromatography. Dissipation data were fitted to four kinetic models: simple first-order (SFO), first order multi-compartment (FOMC), double-first order in parallel (DFOP), and hockey-stick (HS). The dissipation half-life (DT₅₀) of thiamethoxam, azoxystrobin, fluxapyroxad, propiconazole, or pyraclostrobin were 275, 100, 144, 74, and 39 d, respectively. Overall, the DT₅₀ for the pesticides in the study indicated medium to long persistence in soil under the conditions of the experiment. This is the first report for several of these pesticides related to the aerobic dissipation in soils used to grow sugarcane.

摘要

种植前用杀菌剂和杀虫剂对甘蔗种子进行化学处理，可以提高常年收成的常年作物的甘蔗和糖的产量。但是，所用化学品的命运尚不得而知。因此，本研究的目的是测量路易斯安那州矿物甘蔗土壤中选定的方坯种子处理化学品的有氧耗散。用噻虫嗪，嘧菌酯，fluxapyroxad，丙环唑或吡菌胺酯处理15 cm表面的土壤样品，并在实验室条件下进行100天的监测。通过高效液相色谱法测定杀虫剂和杀真菌剂的水平。耗散数据被拟合到四个动力学模型：简单的一阶（SFO），一阶的多隔间（FOMC），并行的双一阶（DFOP）和曲棍球棒（HS）。噻虫嗪，嘧菌酯，fluxapyroxad，丙环唑或吡咯菌酯的₅₀）分别为275、100、144、74和39 d。总体而言，研究中农药的DT ₅₀表明，在实验条件下，土壤中存在中等至长期的持久性。这是其中几种与用于种植甘蔗的土壤中有氧耗散有关的农药的首次报道。