GrazonNext, Grazon P+D, Cimarron Max and Weedmaster satisfactorily controlled horsenettle in pastures and hayfields. Yet it’s likely that additional herbicide applications would be needed in subsequent years to effectively manage the broadleaf weed, says Louisiana State University Extension forage specialist Ed Twidwell.

Horsenettle, one of the most invasive toxic weeds in Louisiana pastures, reproduces readily from seeds, root cuttings and creeping rootstocks. Because of its extensive root system, selective control can be difficult in pastures. Scientists evaluated post-emergence control by applying single applications of six broadleaf herbicides. In a perennial grass hayfield of mostly bermudagrass, horsenettle plants were generally in early flowering stage and actively growing during herbicide treatment.

GrazonNext provided the highest level of control (90%), followed by Weedmaster (74%), Grazon P+D (69%) and Cimarron Max (66%). The herbicides 2,4-D and PastureGard provided 46% control of horsenettle. Results were inconsistent, however, because of dry weather during the study.