Chemical
Chemical control tends to be the first control option most people utilize. There are many chemicals available that selectively control Yellow Starthistle. The table to the right is taken from Yellow Starthistle Management Guide.
A landowner should check with their local agricultural commissioner’s office on which application is approved for the target weed. In some cases, permits are required to use chemical control.
Chemical control can be an important component of an integrated approach. Research demonstrated a controlled burn in year one and a chemical treatment in year two was very successful at controlling YST. For more information you can read Integrating prescribed burning and clopyralid for the management of yellow starthistle.
Common name |
Trade name |
Registered in California |
Mode of action |
Weed Spectrum |
Soil residual |
Effective timing |
2,4-D |
Weedar®, Weedone® and many others |
Yes |
Growth regulator |
Broadleaf species |
Less than 2 weeks |
Postemergence only, from seedling to bolting |
Aminopyralid |
MilestoneTM |
Yes, in 2006 |
Growth regulator |
Certain broadleaf families (between clopyralid and picloram) |
Full season |
Effective both pre- and postemergence; applied fall, winter or spring |
Chlorsulfuron |
Telar® |
Yes |
Amino acid synthesis inhibitor |
Mainly broadleaf species |
At least 2 months |
Preemergence only |
Clopyralid |
Transline® |
Yes |
Growth regulator |
Certain broadleaf families (e.g., Apiaceae, Asteraceae, Fabaceae, Polygonaceae, Solanaceae) |
Most of the season |
Effective both pre- and postemergence; applied fall, winter or spring |
Dicamba |
Banvel®, Vanquish® |
Yes |
Growth regulator |
Broadleaf species |
Less than 1 month |
Postemergence only, from seedling to bolting |
Glyphosate |
Roundup®, and others |
Yes |
Amino acid synthesis inhibitor |
Non-selective |
None |
Postemergence only, from seedling to early flowering |
Imazapyr |
Stalker®, Chopper®, Arsenal®, Habitat® (for aquatic use only) |
Yes; not in rangelands |
Amino acid synthesis inhibitor |
Non-selective |
Full season |
Mainly as a preemergence treatment, postemergence control with seedlings or rosettes |
Metsulfuron |
Escort® |
No |
Amino acid synthesis inhibitor |
Broadleaf species |
At least 2 months |
Fairly effective; preemergence only |
Picloram |
TordonTM |
No |
Growth regulator |
Broadleaf species, weak on mustards |
Up to 3 years |
Effective both pre- and postemergence; applied fall, winter or spring |
Triclopyr |
Garlon®, Remedy® |
Yes |
Growth regulator |
Broadleaf species |
Less than 1 month |
Postemergence only, good on seedlings, fair on mature plants |
Control of YST on the left, untreated on the right.