Stem

Up to 2 ft. tall, highly branched and rough-textured; multiple stems can arise from woody crown; NO wings on upper stems

Leaves

Exist as a basal rosette prior to bolting; alternate; lower leaves pinnate-divided and 4-8 in. long; sometimes covered with short grayish hairs; upper leaves strap-like (linear) with smooth edges (margins)

Flower

Pink to purple, each located at the tip of a branch; base of flower is narrow vase-shaped, 0.3 in. long, 0.12 in. wide and covered with comb-like bracts; bracts tipped with a spine less than 0.12 in. long that curves outward

Root

Deep, stout taproot

Other

Often infests rangelands, waste areas and roadsides; known to occur in Elko and Humboldt counties
Perennial; reproduces by seed

Photo of squarrose knapweed plant with small pink flowers

Control

Mowing plants in bud to flower stage can reduce seed production; repeated hand removal can be effective; DO NOT burn
Several insect biological control agents are available
Apply 2,4-D, dicamba, or glyphosate in the rosette stage; aminocyclopyrachlor, aminopyralid, clopyralid, or picloram preemergence to mid-bolt stages

Blecker, L., Creech, E., Dick, J., Gephart, S., Hefner, M., Kratsch, H., Moe, A., Schultz, B. 2020, Nevada Noxious Weed Field Guide – Squarrose knapweed, Extension, University of Nevada, Reno, Field Guide

Extension Associated Contacts

Heidi Kratsch

Also of Interest:


Needs Assessment for Noxious Weeds in Churchill County: Part 4 of 5 - Criteria for Herbicide Use and Selection This fact sheet is the fourth in a series of five that reports the results of a needs assessment survey completed by faculty in University of Nevada Cooperative Extension (UNCE). The survey attempted to identify the major issues related to the management and control of weeds in N... Davison, J., Powell, P., Schultz, B., and Singletary, L. 2012, University of Nevada Cooperative Extension
Nevada’s Priority Agricultural Weeds: Hoary Cress Plants commonly referred to as hoary cress (Cardaria sp.), or short whitetop, are one of three different but closely related perennial forbs. The Cardaria species are widespread across all eleven Western states, including every county in Nevada. B. Schultz, S. Foster 2021, Extension, University of Nevada, Reno, SP-21-03
Nevada Noxious Weed Field Guide – African mustard African mustard 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., H. Kratsch, Moe, A., Schultz, B. 2020, Extension, University of Nevada, Reno, Field Guide
Nevada Noxious Weed Field Guide – Common crupina Common crupina 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
Nevada Noxious Weed Field Guide – Common St. Johnswort Common St. Johnswort 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

Garden plant and pest sprayers image by Olga Seifutdinova from Getty Images

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.

Master Gardeners of Nevada

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

Grow Your Own, Nevada!

Learn the secrets of high desert gardening

Nevada Noxious Weed Field Guide – Squarrose knapweed