By Mark Loux
Cressleaf groundsel, which is poisonous to livestock, has caught some hay and livestock producers by surprise when they discover it in late spring in hay or pasture. Some hay producers have had to discard hay from first cuttings due to an abundance of this yellow-flowered weed. Cressleaf groundsel is a winter annual weed that is easily controlled in the fall, when in the rosette stage, in most crop situations. Take time to scout fields this fall to determine whether cressleaf groundsel is present, especially in new summer seedings or fields with a history of this weed problem.
Source: osu.edu