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

Stem

To 5 ft. tall; forms basil rosette, then rapid growth forms flower stems; lower parts of flowering stems are winged

Leaves

Fuzzy leaves with deep, rounded lobes; leaves decrease in size higher on the plant

Flower

White to pink to purple petals, 0.5 in. tall and 0.5 in. wide with fuzzy hairs at their base; flowers often appear to have no petals; bracts at the base of the flower have light brown, pointed spines; seeds are tiny, barrel-shaped and have a crown of fine hairs that aid in wind dispersal

Root

Stout, deep taproot and many fine, water-absorbing, surface roots

Other

Grows best on disturbed ground and seasonally flooded sites; no known occurrences in Nevada
Winter annual; each plant can produce several thousand seeds; seed remains viable in soil for several years
Can outcompete native vegetation by rapid growth which shades out other plants

Control

Mechanical removal by pulling, digging or hoeing is effective; if plant is flowering, bag up plant and dispose of properly
Apply aminocyclopyrachlor+chlorsulfuron, aminopyralid or clopyralid preemergence or post emergence in the seedling to rosette stage; apply 2,4-D or dicamba post emergence during rosette to early bolting stage

Learn more about the author(s)

Heidi Kratsch

Also of Interest:

Nevada Noxious Weed Field Guide – Mediterranean desert knapweed