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

Stem

  • Up to 8 ft. tall; many tillers arise from crown; stems slightly flattened with prominent nodes
Photo of green johnsongrass stem
 

Leaves

  • Up to 2 ft. long, 0.25-0.75 in. wide, white midvein and mostly hairless except near collar; ligule is membranous and tipped with fine hairs; NO auricles
Photo of johnsongrass adult plant growing outside
 

Flower

  • Seedhead open and pyramid-shaped; purplish-brown at maturity 
  • Seed is narrow, less than 0.25 in. long and reddish-brown to black 
Photo of dark brown and tan colored johnsongrass seeds
Photo of Johnsongrass seeds

Root

  • Deep, fibrous root system; rhizomes are white and fleshy with brown to purple nodes; roots and new plants often form at nodes 
Photo of green johnsongrass plant

Other

  • Grows best in moist soils; often found in crop fields, pastures, fencerows, roadsides, and along waterways; known to occur in Clark, Lincoln, and Lyon counties
  • Perennial; reproduces by seed and rhizomes; seedlings resemble corn and can best be identified by pulling a plant and examining the roots for an attached seed
  • Plants can be toxic to livestock after frost or drought
 

Control

  • Frequent mowing or tillage is effective; burning is NOT
  • Apply fenoxaprop, fluazifop, or sethoxydim to actively growing plants before boot stage; glyphosate, imazapic, or imazapyr between boot and bloom stages

Learn more about the author(s)

Heidi Kratsch
Heidi Kratsch
 

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