Woolly cup grass (Eriochloa villosa) is a troublesome weed of the grass family (Poaceae). It competes strongly 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.
Report a woolly cup grass sighting
Where it's found
In Canada, woolly cup grass has been reported in southern Quebec since 2000 and in eastern Ontario since 2023. Woolly cup grass is native to Asia and was introduced into the United States in the 1950s. It mainly grows in cultivated fields and in disturbed areas along fences, ditches and roadsides.
How to spot it
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Plant -
Ligule -
Inflorescence -
Inflorescence branch -
Spikelet -
Base of spikelet with cup-like callus
Woolly cup grass is an annual grass that grows 30-200 cm tall. Roots are fibrous and may occasionally appear on the stem at lower nodes. Leaves are dark green, densely hairy and have a velvety feel. One edge of the leaf blade is often crinkled. The base of the leaf blade has a thin membrane with a hairy fringe. Inflorescences are one-sided, usually with two rows of partially overlapping spikelets. Flowering branches are densely hairy beneath the spikelets. The spikelets are egg-shaped, pointed at the tip and have a distinct cup-like callus at the base.
How it spreads
Woolly cup grass seeds are commonly spread by farm equipment. They are also found as contaminants in seed and grain of corn, soybean and other cereals such as millet and sorghum.
What can you do
- Use clean, high-quality seed that is certified if possible.
- Use clean grain, hay and straw.
- Ensure machinery, vehicles and tools are free of soil and plant parts before moving them from one area to another
- Brush off clothing and clean footwear to avoid spreading seeds and plant material
- If you think you've spotted woolly cup grass, report it to the Canadian Food Inspection Agency (CFIA). The CFIA will follow up and determine if further action is needed.
What we are doing
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.