Uptake and Oxidative Degradation of the Systemic Acaricide Aldicarb in Hops, Humulus lupulus L.

Abstract

Uptake of 14C-Iabeled aldicarb by potted hop plants, Humulus lupulus L., began within 6 h of application and continued for 18-48 h, depending on the application rate; higher rates took more time. Accumulation was greatest in the leaves, with relatively little in stems and roots. Leaf and cone residues were determined at 5-d intervals for 60 d following an application. In leaves, aldicarb residues peaked in 10 d (36.5 parts per million [ppm]), and peak accumulations of aldicarb sulfoxide and sulfone occurred at 25 d (89.9 ppm) and 45 d (14.9 ppm), respectively. Aldicarb residues were much lower in cones than in leaves. In cones, the peak (1.3 ppm) occurred 60 d after an application. Aldicarb sulfoxide and sulfone residues were low throughout the test period and reached peak levels (11.6 and 3.1 ppm, respectively) at 60 d. Residue levels were higher in dried hop leaves and cones. Drying increased the concentration of residues approximately three-fold in leaves and fourfold in cones.