Control effects of four pyridine herbicides on Eupatorium odoratum L. at different growth stages

Eupatorium odoratum L. is an important invasive weed in south China. In order to select effective and security herbicide to control E.odoratum at different growth stages, four pyridine herbicides including, 48% triclopyr EC (3 750~6 255 mL/hm2), 24% picloram AS (1 125~3 375 mL/hm2), 75% clopyralid SGX (134~240 g/hm2), and 20% fluroxypyr EC (750~1 050 mL/hm2) were tested for the effectiveness to control E.odoratum at seedling stage, middle growth stage, and adult stage with the control of 41% glyphosate AS (2 250~9 000 g/hm2). Results showed the control effect of triclopyr on E.odoratum were good was similar with that of glyphosate at seedling stage and was higher than that of glyphosate at middle growth stage and adult stage. The control effect of picloram on E.odoratum lower than that of glyphosate and was similar with that of glyphosate at middle growth stage and adult stage. The control effects of clopyralid and fluroxypyr on E.odoratum were relatively poor at three different growth stages except for high dose at seedling stage.