Overview:

Japanese brome is a cool-season annual grass that is native to Pakistan, central Europe, and east to Japan.¹ It reproduces by seed only and can germinate over a wide range of temperatures, but it does require moisture to germinate - a litter layer aids this.³ Late season seeds require a period of after-ripening and therefore most seedlings are from the previous year's crop.³ Fall seedlings overwinter in a 'rosette' type stage and resume growth in the early spring. Spring germinated seedlings can be killed by a late frost in northern latitudes.³ It fruits and dies in the summer. All parts of the plant remain green while alive and then turns tan upon curing.
Japanese brome competes with native perennials for resources and its presence on reclamation sites can slow succession toward desirable perennials.³

Habitat

Grows in sandy and clay textured soils but is intolerant of alkaline oils. It prefers a mesic moisture regime. Sites with a good litter cover promote growth as it holds moisture.³

Identification:

Stems: Stems can be erect or spreading and grow up to 90 cm tall.¹ Stems are bent at base and the nodes are swollen and brownish.²
Leaves: Blades are up to 20cm long, .25 to .5 cm wide, usually densely hairy with a prominent midrib, and lax & spreading¹The sheaths are densely velvety pubescent,² Ligules are about 1.5 mm long, membranous and hairy with ragged edges.⁴
Flowers: Inflorescences have long branches and pedicels, are usually drooping to one side when mature, and each branch bears 1-5 spikelets at the tip.² Spikelets are oval to lance-oval shaped, and are 12 to 30 mm long the excluding awns. Awns are 8-10 mm long and straight to bent/twisted at maturity²

Prevention:

Most seeds fall near the parent plant, but can be spread as a contaminant of grain, hay, straw and soil, or seed caching by rodents. Japanese brome invades disturbed and undisturbed sites.

Control:

Except in wet years,
Grazing: Japanese brome can be grazed fall and early spring, but rapidly loses palatability. Production is good in wet years & bad in dry.³Invasive plants should never be considered as forage.
Cultivation: A healthy perennial plant community should be fairly resistant to Japanese brome invasion. Maintain a desirable plant community and remediate disturbance areas prone to brome invasion.
Mechanical: Disking followed by a second disking or herbicide treatment after the germination period reduced Japanese brome on the Texas Southern Great Plains.³Fire tends to reduce Japanese brome populations but the reduction usually lasts for only 1 or 2 years. Some seed is killed by fire, but seed bank reserves, reproductive capacity, and competitive ability of Japanese brome are usually sufficient to allow for repopulation of an area within 2 years unless the site is reburned.³
Chemical: Imazamox (in product combination with Bentazon or Imazapyr) and Pyroxsulam are registered for use on Japanese brome. Always check product labels to ensure the herbicide is registered for use on the target plant in Canada by the Pest Management Regulatory Agency. Always read and follow label directions. Consult your local Agricultural Fieldman or Certified Pesticide Dispenser for more information.
Biological: No biological control agents are currently available.

Selected Images

Maps

Invasive Listing Sources

• Alberta Weed Control Act
• California Invasive Plant Council
• Invasive Plant Species of West Virginia
• Kentucky Exotic Pest Plant Council - Significant Threat
• Pennsylvania Department of Conservation and Natural Resources Invasive Plants
• West Virginia Invasive Species Strategic Plan and Volunteer Guidelines 2014
• West Virginia Native Plant Society, Flora West Virginia Project, and West Virginia Curatorial Database System, September 3, 1999

References