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:


*Nevada Noxious Weed Field Guide – Diffuse knapweed* Diffuse knapweed 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
*Paradise Valley Weed Control Demonstration Plot: Russian Knapweed* Russian knapweed is a long-lived perennial broadleaf forb. New populations typically establish from seedlings. Long-term, its spread is largely from the lateral expansion of an extensive creeping root system. Individual plants reproduce vegetatively (i.e., are clonal) and become ... Schultz, B. 2005, University of Nevada Cooperative Extension
*Managing Spotted Knapweed* Spotted knapweed is an invasive, noxious weed that should be prevented from invading lands in Nevada. It can be successfully managed over time using a variety of integrated measures if addressed in an aggressive, consistent manner using the best knowledge about control methods av... Graham, J. and Johnson, W. 2004, University of Nevada Cooperative Extension
*Nevada Noxious Weed Field Guide – Russian knapweed* Russian knapweed 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’s Priority Agricultural Weeds: Russian Knapweed* Russian knapweed (Acroptilon repens) is a non-native perennial forb (wild flower) that arrived in the United States in the late 1890s. This weed is well adapted, growing in damp to poorly drained soils with high salinity and/or alkalinity. B. Schultz, S. Foster 2021, Extension, University of Nevada, Reno, SP-21-02

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Nevada Noxious Weed Field Guide – Squarrose knapweed