Effect of Temperature and Photoperiod on Triclopyr, Picloram, and 2,4,5-T Translocation

The effects of photoperiod and temperature on the translocation of triclopyr {[1(3,5,6-trichloro-2-pyridinyl)oxy] acetic acid}, picloram (4-amino-3,5,6-trichloropicolinic acid) and 2,4,5-T [(2,4,5-trichlorophenoxy)acetic acid] were studied on tanoak [Lithocarpus densiflorus(Hook. & Arn.) Rehd.], snowbush ceanothus (Ceanothus velutinusDougl.), bigleaf maple (Acer macrophyllumPursh), bean (Phaseolus vulgarisL. var. ‘Red Kidney’) and barley (Hordeum vulgareL. var. CM-67). Isolation of14C and analysis for the radioactive herbicides revealed little metabolism of the herbicides. Regardless of herbicide or plant species herbicide movement was greatest under warm temperature and long day conditions. Among the herbicides tested,14C associated with triclopyr was the most mobile in each species. Each herbicide moved readily in the symplast but root applications of each herbicide revealed limited apoplastic mobility.