Absorption and translocation of triclopyr ester in Populus tremuloides

The effect of three spray variables (droplet number, active ingredient conc entration, and droplet size) on uptake and translocation of formulated C-14 -triclopyr ester was studied in greenhouse-grown Populus tremuloides seedli ngs. The dose per plant in all treatments was held constant. In all experim ents, absorption las a percentage of dose applied) was much greater than tr anslocation las percentage of dose absorbed). Absorption and translocation decreased as concentration (ai) was increased and droplet number decreased. Absorption and translocation also decreased as droplet number decreased an d droplet size increased. When concentration (ai) was increased and droplet size decreased, absorption again decreased but to a much lesser extent tha n in the other two experiments; there was no significant effect on transloc ation. A time-course experiment indicated that uptake rate began to decreas e within 1.5 h of application. The rate of decrease was greater at the high er concentration (ai), suggesting that the decrease was associated with con tact injury. A model to integrate the application parameters and translocat ion gave a high correlation between dose per unit droplet stain circumferen ce and translocation.