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False Brome

Posted by cahnrs.webteam | November 13, 2013

Also Known As: slender false brome, wood false brome

False Brome is a Class A (or still proposed?). Non-native species that is limited in distribution in Washington. State law requires that these weeds be eradicated.

False brome (Brachypodium sylvaticum (Huds.) P. Beauv.), is a perennial bunch grass native to Eurasia and North Africa that has spread extensively in areas of western Oregon and has begun to spread to other parts of the Pacific Northwest. This tufted perennial grass forms “squatty” clumps or bunches that stand 1 ½ to 3 ½ feet Image_002tall. Its culms (stems) are hollow and soft-hairy at the nodes (where the leaves attach to the stems) and sometimes also soft-hairy between lower nodes. The leaves are broad, flat, floppy, and bright green, often retaining their color through the fall and into the winter. Leaf margins and lower leaf stems are hairy; the leaf sheath (the lower part of the leaf that surrounds the stem or culm of the grass) is open and freely releases the stem when pulled back. The ligules (strap-shaped structures located at the junction of the sheath and the blade) are membranous. False brome blooms between June and September. Its flowers are located on short, pale-green spikelets that noticeably droop and have short or no stalks.

False brome can be confused with native perennial grasses though it has several distinguishing features. First, false brome has open leaf sheaths and spikelets on short stalks, while other Bromus species have closed leaf sheaths and spikelets on long stalks. It also has small hairs or “fuzz” covering the leaves and stems, making the tops of the leaves feel almost velvety. In addition, false brome retains its bright green color long after most other grasses and natives have gone dormant.

False brome reproduces by seed, producing a few to a couple hundred seeds per plant. Seeds are thought to be viable for only one year although research on seed viability has yet to be done. While plants do not spread by rhizomes, false brome can resprout from small stem or root fragments when cut. By growing closely together, individual plants form dense, monotypic stands that can overwhelm other vegetation.

False brome can tolerate a wide range of conditions, from shade to sun and dry to moist soils. It is highly invasive in forest understories and open grasslands where it can out-compete native vegetation; it is also found in riparian forests, forest edges, upland prairies, and roadsides. In addition to displacing native plants, false brome ruins pasture, suppresses forest regeneration, degrades wildlife habitat, and increases fire risk by building up heavy layers of thatch (false brome itself will resprout within 2 weeks of a burn). False brome may also be toxic to livestock. The endophyte fungus Epichloe sylvatica has been identified in North American false brome populations. Existence of endophyte fungi in forage grasses has been linked to negative health effects in sheep and other livestock.

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Control Methods

The identity of plants thought to be false brome should be verified by a weed specialist before control efforts are undertaken as this species can be easily confused with native grasses.

Prevention: Because seeds of false brome can be carried by people, animals and vehicles, extra care should be taken to clean potential carriers before they leave an area infested with the plant.

Physical/Mechanical Control: Isolated plants or small infestations can be hand pulled or dug out, preferably in spring but in any event before the plants produce seed. Care should be taken to remove the entire root system to avoid resprouting. Repeated mowing may eliminate seed production. A combination of mowing in early July followed with a fall herbicide treatment is also effective.

Chemical Control: Herbicide applications are currently the most effective technique known for controlling false brome. Non-selective herbicides such as those containing glyphosate or grass- specific herbicides such as Poast® can be applied from mid-summer through fall or after the rainy season in fall (with the exception of Poast®).

Attempts to control this species at the Oregon State University Research Forests with the herbicides hexazinone and glyphosate formulation were effective. Application of glyphosate at a rate of 5 liters/ha (2 quarts/acre) with surfactant, followed in the next year by hexazinone at 9 liters/ha (1 gallon/acre), provided good control.

More information can be found in the PNW Weed Management Handbook

Use pesticides with care. Apply them only to plants, animals, or sites listed on the label. When mixing and applying pesticides, follow all label precautions to protect yourself and others around you. It is a violation of the law to disregard label directions. Store pesticides in their original containers and keep them out of the reach of children, pets, and livestock.

Biological Control: No biological control agents are known or available. Intensive grazing may be used to suppress false brome, although the plant’s palatability and toxicity place into question its desirability as forage.

After control efforts are made, continue to monitor the site in the spring and early summer to find and destroy any new growth. Revegetation may be necessary in order to restore the disturbed site and create a healthy plant community that can withstand weed invasion.

Questions: contact Steve Van Vleet or phone (509) 397 – 6290

Photo credits included in PDF

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