Stem

  • 1-3 ft. tall, stiff, wiry and usually branched; wings less than 0.1 in. wide created by leaf bases that extend down the stem 
Photo of malta starthistle plant with pink and white flowers
 

Leaves

  • Gray-green, 0.75-6 in. long and densely covered with fine hairs; rosette leaves are oval to strap-like (linear) with smooth to deeply lobed edges (margins); stem leaves are alternate, strap-like to oblong with smooth, toothed or wavy edges
Photo of green leaf plant
 

Flower

  • Yellow, located at branch tips or axils in groups of 1-3; base of flower is vase-shaped, 0.3-0.6 in. diameter and covered with cotton-like hairs and stout, purple-to-brown colored spines 0.2-0.6 in. long
Photo of malta starthistle plant with yellow flower and red and pink thorns.
 

Root

  • Shallow taproot
Photo of green malta star thistle plant

Other

  • Grazing, mowing, burning and cultivation can be effective if done prior to seed production
  • Apply 2,4-D, dicamba or triclopyr to actively growing plants; aminocyclopyrachlor, aminopyralid, clopyralid or picloram pre- or post emergence 
 

Control

  • Repeated hand-removal can be effective; disturbances such as fire, tillage and grazing often promote mustard growth.
  • Apply 2,4-D, glyphosate or triclopyr post-emergence; chlorsulfuron or imazapic pre- or post emergence.
Blecker, L., Creech, E., Dick, J., Gephart, S., Hefner, M., Kratsch, H., Moe, A., Schultz, B. 2020, Nevada Noxious Weed Field Guide – Malta starthistle, Extension, University of Nevada, Reno, Field Guide

Learn more about the author(s)

Heidi Kratsch
Heidi Kratsch
 

Also of Interest:

 
Photo of iberian starthistle plant with pink flower on top
Nevada Noxious Weed Field Guide – Iberian starthistle
Iberian starthistle is a noxious weed that has been identified by the state of Nevada to be harmful to agriculture, the general public, or the environment. Learn more about this weed.
 Blecker, L., Creech, E., Dick, J., Gephart, S., Hefner, M., Kratsch, H., Moe, A., Schultz, B. 2020, Extension, University of Nevada, Reno, Field Guide
 

Associated Programs

Master Gardeners at tabling event

Master Gardeners of Nevada

Program trains local gardeners to provide research-based horticulture information to Nevadans

ladybug larva eating aphids on a pepper plant

Integrated Pest Management

Integrated Pest Management program is a long-term management strategy that uses a combination of tactics to reduce pests to tolerable levels with potentially lower costs for the pest manager and minimal effect on the environment.

Weed Warriors Invasive Weed Training cb

Weed Warriors Invasive Weed Training

The Weed Warriors program tackles the growing problem of weeds on public and private land.