Quack grass, Agropyron repens

Life Cycle



Rhizomes and seed.


Stems erect, 30-120 cm tall, either not flowering during the whole growing season or producing a slender, unbranched inflorescence called a spike; stem nodes (joints) distinct and often purplish.


Leaves flat, nearly smooth; lower leaf sheaths hairy, upper ones often smooth, sheaths split with margins overlapping; auricles present and clasping the stem like little hooks.

Flowers and Fruit

"Spike (seed head) with 1 (rarely 2) unstalked spikelet at each node or joint. Spikelets alternating from one side of the rachis (central stalk of the spike) to the other, and with their flat or broad side towards the rachis; each spikelet made up of 3 to 7 florets (""seeds"") side by side between 2 outer glumes (empty chaff), and either with short awns (bristles) or awnless. Flowers from June to September."

Roots and Underground Structures

Rhizomes have nodes or joints and internodes, and hard, white, very sharp-pointed tips. They produce roots and branches from the nodes. Some branches turn upwards to emerge as leafy stems. Others continue growing and branching horizontally and expand the patch. Each internode is partly covered by a short, light brown, dry, scaly sheath.


Quack grass occurs in cultivated fields, pastureland, waste places, rights-of-way, lawns and gardens in almost any soil texture throughout Ontario. This is considered the most troublesome perennial weedy grass in Ontario and throughout Canada.


Corn yield loss (%)*: 4 % at 1 plant/m2 15 % at 5 plant/m2 Soybean yield loss (%)*: 4 % at 1 plant/m2 18 % at 5 plant/m2 *assumes that the weed has emerged with the crop and has been left uncontrolled all season.

Distinguishing Features

It is distinguished from Smooth brome by its slender, unbranched seed head (spike), the presence of auricles its split sheath, and its sharp-pointed light-coloured rhizomes with short scaly sheaths.


Quackgrass is not known to be toxic.

Human Health Issues

Quackgrass may cause allergies (hayfever).

Forage Quality

No information exists at this time.

Often Mistaken For

Wire-stemmed muhly.

Power Ranking Corn

Power Ranking

↑ 10


Power Ranking Soybeans

Power Ranking

↑ 14


Biological Control

Currently none available for this weed. For the latest research on biological weed control: http://res2.agr.ca/Lethbridge/weedbio/index_e.htm#toc

Biopesticide Control

Currently none available for this weed.

Herbicide Resistance

No documented cases of herbicide resistance to date. For more information on weed resistance: http://www.plant.uoguelph.ca/resistant-weeds/

Figure #1.

Quackgrass: A. Non-flowering plant. B. Leaf-base. C. Spike. D. 1 Spikelet.

Figure #2.

Ligule: membranous, but very short and hard to see.

Figure #3.

Auricle: present at the base of the leaf blade.

Figure #4.

Rhizomes: Sharp-pointed and far-reaching in the soil.

Figure #5.

Seed head.