Absorption and Translocation of Foliar-Applied Sulfometuron in Leafy Spurge (Euphorbia esula)

Abstract

Optimum conditions for leafy spurge control with sulfometuron were determined. Absorption and translocation of14C-sulfometuron to roots in leafy spurge averaged 11 and 0.1% of applied herbicide, respectively, and were not affected by growth stage. Absorption and translocation increased to 40 and 4%, respectively, of applied14C-sulfometuron when the relative humidity remained at 90 and 95% for at least 72 h after treatment Absorption and translocation of14C-sulfometuron to the roots were similar at 18/14 and 24/20 C and when14C-sulfometuron was applied with picloram or 2,4-D. Absorption of14C-picloram was greater but14C-2,4-D absorption was less when applied with sulfometuron compared to picloram or 2,4-D applied alone. Sulfometuron plus picloram applied during the fall regrowth stage provided better leafy spurge control than either herbicide applied alone. The combination treatment would be useful especially in areas where grass injury was acceptable in order to extend the fall treatment season by 2 to 3 wk compared to present practices.