The plant pictured appears to be a member of the mustard family (examples of mustard family plants: field mustard, yellow rocket).

Toxicity of Mustards - toxicity to horses may be considered a low to moderate risk because of unfavorable palatability. Mustard family members have a pungent, sulfurous odor and/or taste. Horses will typically avoid eating these plants if other desirable forage is available. All parts of the plant, especially the seeds could be considered problematic. In general, health concerns may arise when large quantities of seed are consumed.

Common signs – oral and gastrointestinal irritation leading to colic, abdominal pain, diarrhea, anorexia, excessive salivation.

Control of this weed can be accomplished through hand pulling, proper grazing management to allow forage to out compete the weed, timely mowing (right before seed set or flowering), and chemical control.

If choosing to utilize a chemical option, refer to the MSU Weed Control Guide. Table 4B – Weed Response to Herbicides in Established Forage Grasses. As always, read the label for harvest and grazing restrictions that may apply. Also keep in mind that when using a broadleaf herbicide sprayed on grass/legume pasture may result in significant injury to the legumes.