Effects of Thiazopyr and Trifluralin on Dodder (Cuscuta indecora) in Alfalfa (Medicago sativa)

Abstract

Trifluralin selectively controls dodder in alfalfa. However, its soil activity dissipates allowing some late season dodder germination. Thiazopyr applied PRE was also found to control dodder selectively in alfalfa. Thiazopyr was more effective when applied in February than in November. Thiazopyr did not control dodder longer into the season than trifluralin in field tests, however it was more effective in greenhouse experiments. The effect of thiazopyr on dodder shoot tips was similar to that of trifluralin, in that both herbicides produced bulbous cells with thickened, globular nuclei, typical of cells treated with herbicides affecting microtubules.