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Woolly Cup Grass - Eriochloa villosa

Weed Seed - Woolly Cupgrass (Eriochloa villosa)

Woolly cup grass is an invasive plant that competes with crops, especially corn and soybeans, reducing their yield. It has become well established in the mid-western United States, where it is an economic concern to corn and soybean farmers. It is more challenging to control than other annual grasses. Targeted herbicide applications may be required.

Where it's found

To date in Canada, it has been reported in a number of sites in Quebec. Woolly cup grass is native to Asia and was introduced into the United States around the 1950s. It grows in cultivated fields, pastures and disturbed areas along fences, ditches and roadsides.

What it looks like

To the untrained eye, this invasive plant looks a lot like other common grasses native to Canada.

Woolly cup grass gets its name from the hairs covering many parts of the plant. It is a 30-200 cm annual grass with dark green and densely hairy leaves that have a velvety feel. Only one edge of the leaf blade is typically crinkled, and the flowering branches are also one-sided.

How it spreads

Woolly cup grass seeds are commonly spread by farm equipment. It is also found in seeds and grains of corn, soybean and other cereals such as millet and sorghum.


Woolly cup grass is regulated as a pest in Canada under the Plant Protection Act. It is also listed as a prohibited noxious weed in the Weed Seeds Order, 2016 under the Seeds Act. Importation and domestic movement of regulated plants and their propagative parts is prohibited.

What you can do about it

  • Use clean grain, hay and straw.
  • Use clean, high-quality seed that is certified if possible.
  • Ensure machinery vehicles and tools are free of soil and plant parts before moving them from one area to another.
  • Contact your local Canadian Food Inspection Agency (CFIA) office if you suspect you have found this invasive plant. The CFIA will follow up and determine if further action is needed.

Learn more about invasive species.

Woolly cup grass inflorescence
Woolly cup grass inflorescence
Anna Gardner, Iowa University, 2000
Woolly cup grass infesting the edge of a corn field
Woolly cup grass infesting the edge of a corn field
Woolly cup grass inflorescence branch
Woolly cup grass inflorescence branch
Romain Néron, Le ministère de l'Agriculture, des Pêcheries et de l'Alimentation du Québec