The persistence, transport and metabolism of fenitrothion in conifers.

Abstract

An investigation was carried out to determine the fate and persistence of fenitrothion (0,0-dimethyl-0-(3-methyl-4-nitrophenyl)-phosphorothioate), applied to four year old seedlings of balsam fir, white spruce, and Jack pine under greenhouse conditions. The insecticide disappeared rapidly from the surface of conifer tissue while the absorbed residues were more persistent. Greater absorption of the pesticide was coupled with increasing persistence in pine, spruce and fir. An in vitro study carried out on glass surfaces demonstrated that rapid disappearance of the pesticide was primarily due to volatilization. TLC analysis of the conifer extracts was consistent with this dissipation mechanism since 14C-ring degradation products were present for the most part only in trace amounts. Autoradiographic tracing studies demonstrated the ability of 14C-fenitrothion to be transported acropetally into the young foliage of fir, and to a lesser extent in spruce. That this took place via the xylem (apoplastic transport) was confirmed by histoautoradiography. These results were taken as evidence for the systemic potential of fenitrothion for budworm control.