Yellow StarthistleCentaurea solstitialis
BACKGROUND: Yellow starthistle was introduced from Europe. It grows well on dry sites in rangeland, roadsides, and waste areas. It can cause “Chewing disease” in horses that consume it.
DESCRIPTION: Yellow starthistle is a two to three foot tall winter annual with blue-green coloration. Rosette leaves are deeply lobed and could be confused with dandelion. Stems are sparsely leaved and heavily ridged. Flowers are yellow. Cream-colored thorns, one-quarter to three-quarter inches long, protrude from the flowering heads. Bloom is in early summer.
CONTROL: Several biocontrol agents have been tested but availability is limited. Select herbicides offer fair to good control when applied between rosette and bloom stages. Tillage is effective. Contact your local state or county weed specialist for specific updated information.