Published online by Cambridge University Press: 12 June 2017
Temperature changes prior to picloram application affects its activity in leafy spurge. Absorption of 14C picloram was directly correlated with temperature changes; each 1 C increase in air temperature 24 h before treatment resulted in a 1% increase of 14C-picloram absorption in leafy spurge and vice versa. The greatest 14C-picloram absorption averaged 47% of applied 14C when the temperature increased from 18 C to 24 or 30 C 24 h before treatment compared to 33% when temperatures were constant. Translocation of 14C picloram was more sensitive than absorption to temperature changes with 4.3 and 1% of applied 14C-picloram translocated to the roots when the plants were maintained at 12 and 30 C, respectively. Even though absorption increased directly with temperature, 14C-picloram translocation to the root system declined as temperature increased.