The effect of three spray variables (droplet number, active ingredient concentration, and droplet size) on uptake and translocation of formulated ¹⁴C-triclopyr ester was studied in greenhouse-grown Populus tremuloides seedlings. The dose per plant in all treatments was held constant. In all experiments, absorption (as a percentage of dose applied) was much greater than translocation (as 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 and droplet size increased. When concentration (ai) was increased and droplet size decreased, absorption again decreased but to a much lesser extent than in the other two experiments; there was no significant effect on translocation. A time-course experiment indicated that uptake rate began to decrease within 1.5 h of application. The rate of decrease was greater at the higher concentration (ai), suggesting that the decrease was associated with contact injury. A model to integrate the application parameters and translocation gave a high correlation between dose per unit droplet stain circumference and translocation.

Nomenclature: Triclopyr; Populus tremuloides Michx. POPTM; trembling aspen.