Author: Mandy Tu, Global Invasive Species Team, The Nature Conservancy
Latin Names: Brachypodium sylvaticum (Huds.) P. Beauv., Festuca sylvatica Huds.
Common Names: slender false-brome, false-brome
The genus Brachypodium is derived from the Greek "brachys" for short, and "podion" foot, in reference to its short (or non-existent) pedicels (Hitchcock et al. 1969). The species epithet sylvaticum refers to woods, groves, or forests (from the Latin "silva"). There are numerous synonyms for B. sylvaticum, but the most commonly used is Festuca sylvatica Huds. (TROPICOS 2001).
The common name of false-brome indicates that B. sylvaticum is often misidentified or mistaken for a brome (genus Bromus).
Brachypodium sylvaticum is a perennial bunchgrass native to North Africa and Eurasia, and has recently been reported as rapidly invading coniferous forest understories in western Oregon. Occasionally cultivated for ornamental purposes, B. sylvaticum was first collected as an escaped invader in North America near Eugene, Oregon in 1939 (Chambers 1966). By 1966, it was well-established in two large colonies near Corvallis, Oregon and since then has been quickly increasing in cover and range. It is now spreading into closed-canopy coniferous forests, riparian forests, forest edges, and upland prairies in full sun in Oregon's Willamette Valley and into the Cascade foothills (Kaye 2001). Brachypodium sylvaticum has the potential to spread throughout low elevation forests in the Pacific Northwest (Oregon, Washington, Idaho, British Columbia), and could spread into northern California too.
Brachypodium sylvaticum is a caespitose (tufted) perennial grass that typically grows 5 to 7 dm tall. It tends to form large clumps or bunches, but is apparently not rhizomatous. The hollow culms (stems) are pilose (i.e. bearing soft, spreading hairs) at the nodes and sometimes over the lower internodes. Its broad flat leaves are 4 to 10 mm wide, pilose, open-sheathed at the base, and do not have auricles. The ligules (1 to 2.5 mm long) are membranous, and are more or less erose-ciliolate (Hitchcock et al. 1969).
Flowers of B. sylvaticum are located on pale green spikelets that are semi-spicate (i.e. the pedicels very short or lacking). Spikelets tend to be few (5 to 10), are 2 to 4 cm long, and are 7 to 17-flowered. The awns are straight, 10 to 15 mm long, and the unequal glumes are shorter than the florets that each one subtends. The lemmas are strongly ciliate and 2-nerved (2-veined) (Hitchcock et al. 1969). Brachypodium sylvaticum can be easily distinguished from Bromus species, in that the former has open leaf sheaths and spikelets which are either subsessile or short-pedicellate, while Bromus species have closed leaf sheaths and spikelets on long pedicels (Kaye 2001).
Brachypodium sylvaticum is native to North Africa, northern and Mediterranean Europe, and Asia (Kaye, pers. comm.; Hitchcock et al. 1969). In its native range, B. sylvaticum is most commonly found in forests and woodlands, but may also occur in open habitats (Tutin et al. 1980).
As an invader in North America, B. sylvaticum is documented as invasive only in the state of Oregon (USDA, NRCS 2001). It occurs at sites ranging in elevation from sea level to about 1,200 m(4,000 ft) and it occupies a variety of aspects and light conditions. Within Oregon, B. sylvaticum is present in and around the Willamette Valley, and as far south as Josephine County (southwest Oregon near the California border). It currently covers thousands of acres in Oregon State University Research Forests near the city of Corvallis, and there are unconfirmed reports of this species in Colorado and Utah (T. Kaye, pers. comm.).
Analysis of the sites it already occupies in Oregon and its native range suggest B. sylvaticum has the potential to spread throughout low elevation forests in the Pacific Northwest (Oregon, Washington, Idaho, British Columbia), and could spread into northern California too (Kaye 2001).
Brachypodium sylvaticum is listed on the Pacific Northwest Exotic Pest Plant Council list B, indicating that it is a wildland weed of lesser invasiveness (PNW-EPPC 1997). This classification, however, may underestimate the threat it poses to native vegetation.
Brachypodium sylvaticum reproduces rapidly from seed, and although reportedly not rhizomatous, can resprout from small stem or root fragments when cut. It has also been suggested that B. sylvaticum does not maintain a persistent (longer than 1 year) seed bank in soils, but this is not yet confirmed in North America (T. Kaye, pers. comm.).
Control methods for B. sylvaticum have not been well-studied. Tom Kaye reports that removal of the entire plant by digging/hand removal is effective for small infestations, but is extremely time and labor-intensive. He also cautions that if enough of the root system is left in the soil, the plant will resprout.
Mowing or grazing treatments may control B. sylvaticum, if repeated for some time. In Europe, B. sylvaticum was absent in heavily grazed sites, indicating that repeated aboveground removal may eventually eliminate this species. Burning, however, seems ineffective, as B. sylvaticum is frequently found in recently burned sites (Fitzpatrick 2001; Kaye 2001). Repeated mowing, grazing, or burning treatments that are carried out before seed set may benefit control efforts by eliminating seed production each year, eventually exhausting the seed bank (if present). These methods may also increase the efficacy of subsequent herbicide treatments by forcing the plants to produce new shoots that are more likely to take up and be killed by herbicides.
Herbicide applications are currently the most effective technique known for controlling B. sylvaticum. Attempts to control this species at the Oregon State University Research Forests with the herbicides hexazinone (tradename Velpar®) and one glyphosate formulation (tradename Accord®) were effective. Application of Accord®; (which is often used in forestry practices) at a rate of 5 liters/ha (2 quarts/acre) (with surfactant Activar 90®), followed in the next year by Velpar® at 9 liters/ha (1 gallon/acre), provided good control (T. Kaye, pers. comm.). Surprisingly, treatment with another formulation of glyphosate (tradename RoundUp®) met with little success as did treatment with sulfometuron methyl (tradename Oust®).
Note: Monsanto representative Ron Crockett states that there is little difference between the formulations of RoundUp®; or Accord®; although the former contains a surfactant and the latter does not. Thus it is surprising that treatment with RoundUp®; was unsuccessful while treatment with Accord® was successful. Ron speculates that the difference reported by the OSU Research Forests for Brachypodium control may have been the result of different application rates or in the timing of application.
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