Threadleaf and riddel groundsel
I have about 5 acres on which I keep 2 horses. Last winter both became ill from toxcicity due to threadleaf and riddel groundsel. Now that is is spring, how do I get rid of this weed without killing what grass there is?
Groundsel's often become a problem when a pasture is over grazed. Evaluate your pasture and determine if this is the case. If so, then while treating the pasture you will want to give it a rest by keeping the horses off. You can keep the horses in a corral or other pasture while the grass and other grazing plants are recovering. Below is the URL to a fact sheet on Groundsel. It has control recommendations included. Be sure to follow all grazing restrictions so your horses don't get ill from the pasture treatment.
After looking at the fact sheet if you still have questions, get in touch with your El Paso County Extension Office or eXtension.