Persistence, mobility and degradation of hexazinone in forest silt loam soils

Abstract

Abstract This study reports the persistence, degradation, vertical leaching and lateral movement of hexazinone, 3‐cyclohexyl‐6‐(di‐methylamino)‐1‐methyl‐1,3,5‐triazine‐2,4(1H,3H)‐dione, in a white spruce plantation treated at 4.3 kg active ingredient (ai)/ha by a helicopter equipped with a MICROFOIL boom. Soils were monitored for 104 days after treatment for residues of hexazinone and its metabolites A, 3‐(4‐hydroxycyclohexyl)‐6‐(dimethylamino)‐1‐methyl‐1,3,5‐triazine‐2,4(1H,3H)‐dione and B, 3‐cyclohexyl‐6‐(methylamino) ‐1‐methyl‐1,3,5‐triazine‐2,4(1H,3H)‐dione. Soil at 3 depths, including a surface organic, and 0–15 cm and 15–30 cm mineral layers, were collected and analysed before and at 9, 23, 55, 104 days after application. Sixty six percent (66?) of hexazinone was degraded and dissipated at the end of 104‐day monitoring, decreasing from 7.12 ug/g (9 days) to 2.09 ug/g (104 days). The higher amount of metabolite‐? (30–50? of hexazinone detected) compared to metabolite‐B (0–12?) indicated higher hydrox...