Woolly cupgrass (Eriochloa villosa), also known as hairy cupgrass, is an annual grass that was recently identified in New York for the first time. It has been found as a problem in NYS in field crop systems. Although germination can continue well into the summer season, most woolly cupgrass seeds germinate in the spring. Other species that are commonly confused with woolly cupgrass include prairie cupgrass and foxtail.
Mature woolly cupgrass plant
Photo by Bruce Ackley of The Ohio State University via Bugwood.org
Identification
Seedlings: Leaves of the seedling are wide and pointed with the first true leaves being short and parallel to the soil. Lower stem of the young plant is purplish.
Leaves: Leaves of the mature plant are densely covered with short hairs and dark green. The leaf blades are flat, typically crinkled on one side (particularly near the base of the leaf), and approximately 2-12 mm (0.1-0.5’’) wide. The leaves are shorter than those of foxtail, another weed that woolly cupgrass is easily confused with, and they also fall from the stem at a more obtuse angle.
Mature woolly cupgrass plant leaves
photo by Bruce Ackley of The Ohio State University via Bugwood.org
Mature woolly cupgrass leaves
photo by Bruce Ackley of The Ohio State University via Bugwood.org
Mature plant: The mature plant has a sheath densely covered with short hairs, as is the same with the plant’s main shaft (rachis). Alongside the leaf blades are also ligules which are covered with hairs and are 1-1.5 mm (0.04-0.06’’) long. The mature plants can grow as tall as 0.9-1.2 m (3-4 ft).
Mature woolly cupgrass plant
Photo by Bruce Ackley of The Ohio State University via Bugwood.org
Height indication of a mature woolly cupgrass plant
Photo by Bruce Ackley of The Ohio State University via Bugwood.org
Flowers/Fruits: Woolly cupgrass flowers consist of flower clusters (racemes) arranged in panicles. The group of florets (spikelets) are arranged in compressed groups of 1-2.
Woolly cupgrass spikelets
Photo by Bruce Ackley of The Ohio State University via Bugwood.org
Management
Chemical control
Woolly cupgrass is may be difficult to manage due to its relatively higher tolerance of herbicides compared to other grass species and its long emergence window of approximately 8-10 weeks. Because this weed has only recently been found in New York it is not covered by our normal management sources. Ohio State University Extension’s ‘Weed Control Guide‘ has chemical management information for woolly cupgrass.
Non-chemical control
Woolly cupgrass is may be difficult to manage due to its long emergence window of approximately 8-10 weeks and its prolific seed production. False seedbed practices, rotary hoeing, and planting early crops all help manage this weed, but late-germinating plants may escape cultivation.
Herbicide resistance
Currently reported:
None
Visit the International Herbicide-Resistant Weed Database homepage for more information: http://www.weedscience.org/Home.aspx
References
Weed Control Guide provided by the Ohio State University Extension. A document of background information on weed control and details on chemical management of various weeds, including woolly cupgrass.
Weed Management document provided by the University of Minnesota with comprehensive information regarding cultural and mechanical with details for specific weeds, including woolly cupgrass.
Sweet Corn Pest Identification and Management guide provided by the Purdue Extension offering information on the weeds of sweet corn. Includes short descriptions of identification and management of each mentioned weed, including woolly cupgrass.
University of Missouri’s Division of Plant Sciences’ webpage on woolly cupgrass. Profile on woolly cupgrass including short descriptions of identification and management of the weeds, as well as a variety of woolly cupgrass images.
Iowa State University’s Extension and Outreaches webpage on woolly cupgrass. Profile on woolly cupgrass including key ID traits and miscellaneous information of the weed, as well as a variety of woolly cupgrass images.
University of Missouri’s foxtail identification webpage.
University of California IPM’s prairie cupgrass identification and management webpage.