When the toxin, swainsonine, enters an animal's bloodstream, it interferes with protein metabolism. Animals were then tested for differences in protein patterns in their blood. Right now, calves in the feedlot that previously ate 20-percent locoweed diets are gaining about half the weight of calves that did not eat locoweed. Ranchers who spray locoweed while it's still young have a fighting chance of killing it, especially white locoweed, Graham says. Because woolly loco is more prevalent, it's tougher to control.
Ranchers can manage around it by moving cattle to loco-free areas.
But a tenacious insect may come to the rescue. Cleonidius trivittatus, a root-feeding weevil, has been found in higher numbers this year throughout the state. Some ranchers have known about the native bug for many years. The larvae feed on the inside and outside of locoweeds and cut off the roots. These beetle grubs can take out populations of woolly loco, but they don't attack white loco.