Rangeland Ecologist Matt Rinella at the Agricultural Research Service Lab in Miles City, Montana has conducted a 16-year study that shows it may not always help for ranchers to use herbicides to kill invasive weeds like leafy spurge. In fact - it may actually cause the weeds to increase. Even though the herbicide would have dissipated within a few years - it seemed to have long-term effects and caused a plant community shift.

The plots in the study were either grazed and sprayed, grazed but not sprayed, not grazed but sprayed or not grazed and not sprayed. Cattle grazing helped maintain native plant numbers when herbicide was sprayed. Since cattle grazing can help native forbs thrive - most native forbs did well with or without cattle grazing when herbicide wasn’t used. This study suggests that applying herbicides over large areas of land with herbicide-sensitive plants isn’t always the best thing to do.