Holcus lanatus

Holcus lanatus occurs widely in Eurasia and temperate parts of Africa; it is a widespread alien species in the Americas, producing significant ongoing ecological damage, partularly in North America. This grass occurs in overgrazed pastures, roadsides, meadows, rocky slopes and abondoned fields.

Also known by the common name of Common velvetgrass, this tufted perennial can attain a height of one to two meters. Quattrocchi reports that the species can produce hydrocyanic acid poisoning.

lanatus: woolly

Common velvetgrass is nonnative but widespread in North America. On the west and east coasts of North America and in Hawaii, common velvetgrass is a widespread nonnative species. Populations are less common in more inland states and provinces [70]. In southeastern Alaska, common velvetgrass was cultivated and had established outside cultivation by 1959 [3]. Common velvetgrass is common to abundant at low elevation sites in the Pacific Northwest [114,134]. In California, it occurs in all but the desert regions [125], and some have referred to it as a "new native" [67]. In Baja California, Nevada, and Arizona, common velvetgrass is likely restricted to northern habitats [79,80,141,165]. Common velvetgrass is essentially absent from the Great Plains [164] and may only occur in Missouri and eastern Kansas [57]. Scattered populations occur in Illinois [98]. In the northeastern United States and adjacent Nova Scotia, common velvetgrass is well established [53,134]. Populations are scattered in southern Quebec and Ontario [134] but common along the Atlantic Coast from North Carolina to Nova Scotia [37]. In Hawaii, common velvetgrass is widely distributed in all but the driest habitats [127] and is often found in pastures, wet disturbed areas, and on roadsides [153]. Grass Manual on the Web provides a distribution map of common velvetgrass in North America.

Common velvetgrass is native to Europe, western Asia, northwestern Africa, and the Canary Islands and is very common throughout temperate Europe [14,15]. A review reports that it was likely introduced several times to both the east and west coasts of North America as a contaminant or an intentional component of imported forage seed [113,134]. As of 1800, common velvetgrass occurred in many parts of North America [9]. Based on early North American floras, it occurred in Pennsylvania by 1755 and was frequent in 1814 [163]. In New England, common velvetgrass introductions probably occurred in the 17th century [92]. The first known collection of common velvetgrass from London, Ontario, occurred in 1879 [134]. In Hawaii, it was first collected in 1909 [153].

Notholcus lanatus (L.) Nash ex Hitchc.:
Bolivia (South America)
Canada (North America)
Ecuador (South America)
United States (North America)

Note: This information is based on publications available through Tropicos and may not represent the entire distribution. Tropicos does not categorize distributions as native or non-native.

Holcus lanatus L.:
Argentina (South America)
Australia (Oceania)
Bolivia (South America)
Brazil (South America)
Canada (North America)
Chile (South America)
Colombia (South America)
Costa Rica (Mesoamerica)
Ecuador (South America)
Mexico (Mesoamerica)
New Zealand (Oceania)
Panama (Mesoamerica)
Peru (South America)
Taiwan (Asia)
Uruguay (South America)
United States (North America)
South Africa (Africa & Madagascar)
Caribbean (Caribbean)
India (Asia)
Venezuela (South America)
China (Asia)

Note: This information is based on publications available through Tropicos and may not represent the entire distribution. Tropicos does not categorize distributions as native or non-native.

Canada

Origin: Exotic

Regularity: Regularly occurring

Currently: Unknown/Undetermined

Confidence: Confident

United States

Origin: Exotic

Regularity: Regularly occurring

Currently: Unknown/Undetermined

Confidence: Confident

Global Range: Velvet grass is of European origin, its center of origin thought to be the Iberian peninsula (Jacques and Munro 1963), and is a native of temperate areas of Europe and Asia (Scoggan 1978). It was probably introduced to North America either accidentally as a contaminant of forage seed or deliberately as a component of seed mixtures for meadow (Thompson and Turkington 1988). It has since spread and become locally abundant from British Columbia to Nova Scotia, Canada, south from Maine to Kansas and Colorado, south to Georgia and Louisiana and in primarily moist areas below 7500 feet along the Pacific Coast from British Columbia to California and to Montana and Arizona (Thompson and Turkington 1988).

Velvet grass is common throughout Europe except the extreme north and northeast where it is only casual (Thompson and Turkington 1988). In England, it is widely distributed in fields, partic- ularly on north-facing slopes (Grime and Lloyd 1973). The grass is now found throughout Asia, Africa, New Zealand, Australia, and sub- Antarctic islands. It has escaped cultivation and become a weed pest along roadsides, fencerows, ditch banks, in old pastures, and other disturbed sites, particularly in moist places (Muenscher 1955). In the Coast Ranges, it has become a weed of minor importance (Robbins et al. 1970).

Perennial, softly hairy. Culms tufted, erect or geniculate at base, 30–80 cm tall, pubescent, 4–5-noded. Leaf sheaths loose, tomentose with reflexed hairs; leaf blades flat, 6–18 cm, 3–9 mm wide, soft, both surfaces pubescent, apex acute; ligule 2–3 mm, truncate or toothed. Panicle lanceolate to oblong or ovate in outline, rather loose to very dense, 3–12 cm; branches narrowly ascending, pubescent. Spikelets oblong or gaping, 3.5–6 mm, pale grayish green or purplish; glumes lanceolate, keel and veins hispidulous, surface scabrid or puberulent to villous, lower glume apex acute, upper glume wider and sometimes slightly longer than lower glume, apex mucronate; florets subequal, 2–2.5 mm; rachilla ca. 0.5 mm; lower lemma awnless, anthers 1.8–2 mm; upper lemma with hooked 1–2 mm awn, anthers ca. 1.5 mm. Fl. and fr. May–Oct.

More info for the term: perfect

This description provides characteristics that may be relevant to fire ecology and is not meant for identification. Keys for identification are available (e.g., [69,73,115,152,153]).

Common velvetgrass is typically a pubescent, tufted, perennial grass. However, in the Carolinas and Atlantic Coastal regions, common velvetgrass behaves as an annual [37,115]. European studies revealed that life span and life history can vary with environmental conditions. Plants grown from seed collected from dry, southern European habitats flowered in their first year and died within 2 to 4 years. Plants grown from seed collected in northern Europe failed to flower in their first year and were longer lived. Plants grown from seed collected in exposed maritime habitats displayed a low, spreading growth form and produced leaves that were only 13 inches (32 cm) long, but plants from seed collected from continental habitats were erect and reached 28 to 35 inches (70-90 cm) tall [19].

Aboveground description: Common velvetgrass stems are generally erect, hollow, and grow to 12 to 39 inches (30-100 cm) tall [3,9,73,114,153]. At the base, stems may be somewhat prostrate and produce roots at the nodes [9,31,85]. Leaf blades are flat and measure 4 to 12 mm wide and 2 to 8 inches (5-20 cm) long [31,69,114,153]. Common velvetgrass produces a dense, compact panicle that can reach 6 inches (15 cm) long [3,114,153]. Spikelets are generally 2-flowered. Upper florets are staminate with fairly robust awns that become hooked when dry. Lower florets are perfect [149,153,164]. Common velvetgrass seeds measure 1.5 to 2.5 mm long [115,149].

Belowground description: The common velvetgrass root system is fibrous and concentrated at shallow depths. Boogie and others (1958, as cited in [134]) indicated that, while common velvetgrass roots may reach 35 inches (90 cm) deep, most roots occur in the top 4 inches (10 cm) of soil. In a heavily grazed pasture in Germany, 51% of common velvetgrass roots were in the top 4 inches (10 cm) of soil, and 16%, 18%, 11%, and 4% of the roots occurred in the subsequent 4-inch (10 cm) depth intervals (Klapp 1943, as cited in [14]).

Site conditions may affect root development. When widely spaced, common velvetgrass may produce "a dense network of fine, whitish, surface roots" on the ground beneath the shading of its own canopy. When water tables are high, root penetation is limited [14]. During a field experiment in the University of York experimental garden, shading reduced common velvetgrass root number and root dry biomass [42].

On Hartz Mountain in Germany, a researcher reported that common velvetgrass produced "subterraneous, elongated creeping rhizomes". Soils on this site had high metal concentrations. While this characteristic was not mentioned elsewhere in the literature, the researcher's examination of herbarium specimens revealed rhizomes on other European collections not associated with heavy metal concentrations (abstract in [40]).

Perennials, Terrestrial, not aquatic, Stolons or runners present, Stems nodes swollen or brittle, Stems erect or ascending, Stems geniculate, decumbent, or lax, sometimes rooting at nodes, Stems caespitose, tufted, or clustered, Stems terete, round in cross section, or polygonal, Stem nodes bearded or hairy, Plants conspicuously hairy, grayish, or wooly, Stem internodes hollow, Stems with inflorescence less than 1 m tall, Stems with inflorescence 1-2 m tall, Stems, culms, or scapes exceeding basal leaves, Leaves mostly cauline, Leaves conspicuously 2-ranked, distichous, Leaves sheathing at base, Leaf sheath mostly open, or loose, Leaf sheath hairy, hispid or prickly, Leaf sheath and blade differentiated, Leaf blades linear, Leaf blades lanceolate, Leaf blades 2-10 mm wide, Leaf blades mostly flat, Leaf blade margins folded, involute, or conduplicate, Leaf blades more or less hairy, Ligule present, Ligule an unfringed eciliate membrane, Ligule a fringed, ciliat e, or lobed membrane, Inflorescence terminal, Inflorescence a contracted panicle, narrowly paniculate, branches appressed or ascending, Inflorescence solitary, with 1 spike, fascicle, glomerule, head, or cluster per stem or culm, Flowers bisexual, Spikelets pedicellate, Spikelets laterally compressed, Spikelet less than 3 mm wide, Spikelets with 1 fertile floret, Spikelets with 2 florets, Spikelets solitary at rachis nodes, Spikelets all alike and fertille, Spikelets bisexual, Spikelets disarticulating below the glumes, Rachilla or pedicel glabrous, Glumes present, empty bracts, Glumes 2 clearly present, Glumes equal or subequal, Glumes equal to or longer than adjacent lemma, Glume equal to or longer than spikelet, Glumes keeled or winged, Glume surface hairy, villous or pilose, Glumes 1 nerved, Glumes 3 nerved, Lemma coriaceous, firmer or thicker in texture than the glumes, Lemma 3 nerved, Lemma 5-7 nerved, Lemma glabrous, Lemma apex truncate, rounded, or obtuse, Lemma dis tinctly awned, more than 2-3 mm, Lemma with 1 awn, Lemma awn less than 1 cm long, Lemma awn subapical or dorsal, Lemma awn once geniculate, bent once, Lemma margins thin, lying flat, Lemma straight, Palea present, well developed, Palea about equal to lemma, Palea 2 nerved or 2 keeled, Stamens 3, Styles 2-fid, deeply 2-branched, Stigmas 2, Fruit - caryopsis.

HOLCUS LANATUS is rarely mistaken for any other species with the possible exception of H. MOLLIS. H. LANATUS can be distinguished by the purplish coloration on the panicles and veins of the sheaths, soft hairs all over, and lack of rhizomes. The two species may be able to hybridize (Jones 1954).

Avena lanata (Linnaeus) Koeler; Notholcus lanatus (Linnaeus) Nash ex Hitchcock.

More info for the terms: adventitious, fresh, litter

In North America, common velvetgrass habitats include pastures, cultivated fields, meadows, ditch banks, lawns, roadsides, and other disturbed sites [9,31,73,79,114,153].

Climate: A review reports that common velvetgrass tolerates a wide range of moisture conditions within temperate climate regimes. While common velvetgrass grows best in moist areas, it grows well in very wet conditions and tolerates "moderate" periods of drought [134]. The northern limit for common velvetgrass is near the January isotherm of 28.4 °F (-2 °C). The 80 °F (26.7 °C) July isotherm approximates common velvetgrass' southern boundary in Europe and the Mediterranean. Beyond this southern boundary, precipitation from May to October is typically less than 5 inches (130 mm) and is likely the reason for common velvetgrass' absence [14].

Climates are similar in common velvetgrass' nonnative North American habitats. In British Columbia, common velvetgrass is common in temperate cool semiarid and mesothermal climates. Evaporation exceeds transpiration and the average annual temperature is less than 64 °F (18 °C) in semiarid habitats. In mesothermal habitats the average temperature in the warmest month is less than 73 °F (23 °C) and fewer than 4 months see temperatures below 39 °F (4 °C) [83]. Common velvetgrass is common in the Willamette Valley, where winters are cool and wet, and summers are warm and dry. Temperatures in January and July average 46 °F (8 °C) and 82 °F (27.5 °C), respectively. Based on 30 years of records, annual precipitation averages 43 inches (1,100 mm) [126]. In Pacific coastal areas, environmental conditions are more harsh and include wind, salt spray, and fog [8]. On the Bodega Marine Reserve, in Sonoma California, annual precipitation, most of which occurs from November through March, averages 34 inches (860 mm). Frequent fog moderates drought conditions [13], and common velvetgrass utilizes fog as a water source [29]. Humid climates prevail in the montane rain forest zone in Hawaii Volcanoes National Park, where common velvetgrass is common. Annual precipitation averages 98 inches (2,500 mm) at high elevations and 59 inches (1,500 mm) at low elevations [4].

Climate change: Common velvetgrass may experience increased growth with elevated CO2 levels. In a controlled study, common velvetgrass monocultures grown in elevated CO2 produced significantly more biomass than when grown in ambient conditions (P<0.001). After 2 months at elevated CO2 levels, aboveground biomass of common velvetgrass increased by 44% and belowground biomass increased by 135%. Researchers also noted changes in nitrogen cycling, which, depending on native species responses to elevated CO2, could affect competitive outcomes in mixed communities [10,11]. Increases in common velvetgrass biomass were also noted by Jongen and Jones [77]. When common velvetgrass was grown with 3 other grasses at elevated CO2 levels, increases in common velvetgrass biomass exceeded those of the other grasses. Common velvetgrass tillering increased by 25% with elevated CO2.

Elevation: Throughout North America, common velvetgrass occurs from sea level to 7,500 feet (2,300 m) [9]. In British Columbia, occurrence of common velvetgrass decreases with increasing elevation [83].

Common velvetgrass elevation range by state State Elevational range (feet) Arizona 4,500-7,000 [80] California below 7,500 [69,101] Hawaii 2,500-10,700 [153] Nevada 3,500-6,800 [79] northern New Mexico 5,000-6,000* [93] Utah 4,990 [164] *As of 1981, common velvetgrass was not described in New Mexico; this is an expected distribution.

Soils: Although common velvetgrass tolerates a wide range of soil conditions [9], it is often described as occurring on moist sites [125,149]. In British Columbia, common velvetgrass is most common on fresh to very moist soils [83]. In California, common velvetgrass is found in all but the desert regions and grows best in moist, rich soils [125]. In the coastal prairies of California, common velvetgrass is rare on hilltop or steep sites that dry out early in the season (Thomsen, personal observation, cited in [140]). In the eastern United States, common velvetgrass often occurs on damp, moist, or poorly drained sites [149]. In controlled studies, as the water table height increased, common velvetgrass growth decreased. However, on sites with elevated water tables, common velvetgrass developed fine roots at the soil surface and adventitious roots at the plant base, suggesting a possible long-term adaptation to a high water table [160].

Native habitats: A review reports that although common velvetgrass may be absent from shallow soils in areas that experience severe drought, a wide range of soil types is tolerated. Coastal areas that receive salt-spray are occupied by common velvetgrass [14]. In waterlogged soils, growth of common velvetgrass is often reduced [44]. Near Sheffield, England, common velvetgrass grew on soils with pH levels of 3.5 to 8 but was most abundant where the pH was 5 to 6 (Grime and Hodgson, personal communication, cited in [157]).

Nonnative habitats: In North America, soils vary in common velvetgrass habitats. In one review, common velvetgrass is reportedly frequent on poor, moist soils [113]. In a review from Canada, common velvetgrass is considered most common in infertile grasslands [134]. In British Columbia, common velvetgrass often occurred on nitrogen-medium and exposed mineral soils [83]. Sandy or gravelly soils were preferred habitat in Baja California [165]. After analyzing the vegetation and environmental data for 184 plots in Oregon white oak savannas in the Cowichan Valley of southeastern Vancouver Island, researchers found that common velvetgrass occurred most often on sites with shallow soils, 4 to 8 inches (10-20 cm) deep [91]. The common velvetgrass-sweet vernalgrass community type in Oregon was most common on deep soils with thick litter layers that averaged 2.6 inches (6.5 cm) deep. Soil pH averaged 5.7, and soil depth averaged 57 inches (146 cm). Soils averaged 13% clay, 31% silt, 56% sand, and 15.5% organic matter [119].

More info for the terms: cover, mesic, restoration, shrub

In both its native and nonnative ranges, common velvetgrass occupies a wide
range of habitats. In Europe common velvetgrass occurs in pastures, grasslands,
wet to mesic meadows, and open forests and woodlands [14,161].
Pacific Coast: Most of the
information about North American common velvetgrass populations comes from the
Pacific Coast states, British Columbia, and Hawaii. In the Pacific
Coast states, common velvetgrass occurs in the north coastal shrub cover type
that is discontinuous from Washington's Olympic Peninsula to Santa Cruz,
California, and in the coastal prairie cover type that occurs from Oregon to
Monterey, California [8,12,67,107]. In Washington's Puget Trough,
common velvetgrass is a typical understory species in Douglas-fir–Pacific
madrone/pink honeysuckle (Pseudotsuga menziesii-Arbutus menziesii
/Lonicera hispidula) forests if grazed or near a disturbed or developed
area [25]. In the Oregon Coast ranges, common velvetgrass is often dominant in
the understory of red alder (Alnus rubra) stands before the understory
becomes shrub dominated (Henderson 1970, as cited in [49]). In the Willamette
Valley, common velvetgrass is frequent in Oregon white oak (Quercus garryana)
woodlands and tufted hairgrass (Deschampsia caespitosa) grasslands
(review by [49]).
Common velvetgrass is recognized in the following vegetation classifications:

• common velvetgrass-Queen Anne's lace (Daucus carota) community type on
  moderately disturbed sites in Seattle, Washington's Montlake wildlife area [72]
• common velvetgrass-sweet vernalgrass (Anthoxanthum odoratum)
  community type in Oregon coastal grasslands from northern Tillamook to southern
  Curry County [119]
• redtop (Agrostis gigantea)-common velvetgrass community
  type on the Salmon River Estuary in Lincoln County, Oregon; restoration
  of a high water table resulted in high common velvetgrass mortality. For more
  information, see Flooding/salinity [97]

Hawaii: Common velvetgrass is often
associated with grazed areas or sites with feral pig activity. The following vegetation
types are potential common velvetgrass habitat in Hawaii: koa-māmane
(Acacia koa-Sophora chrysophylla) forests, koa-`ōhi`a
(Metrosideros polymorpha) montane mesic forests, `ōhi`a montane wet
forests, Hawaii blackberry (Rubus hawaiensis) shrublands, pūkiawe-`ōhelo `ai
(Styphelia tameiameiae/Vaccinium reticulatum) shrublands, and alpine
hairgrass (Deschampsia nubigena) grasslands [153].
Atlantic Coast: In Massachusetts,
common velvetgrass occurs in little bluestem (Schizachyrium scoparium)
and "weedy" sandplain grasslands [39]. In West Virginia, it is
common in maintained hay meadows [48]. In the southern Appalachians
of North Carolina, common velvetgrass cover was 17% in old fields
dominated by common cinquefoil (Potentilla simplex) [27].

Comments:

HOLCUS LANATUS exhibits a wide climatic tolerance of temperate regimes over a wide range of altitudes (0-1500m). It is killed by severe frost (Watt 1978b). Optimal growth occurs under moist conditions; however, it grows well in very wet conditions and can survive moderate periods of drought (Watt 1978a).

In Britain H. LANATUS occurs on a wide range of soil types including those of rich-fen and fen-meadow communities, poorly drained, waterlogged, low to moderately fertile, and nutrient-rich soils. It occurs independent of soil phosphorous content and grows well in potassium- and/or nitrogen-poor soils. It tolerates a wide range of soil pH, growing best between pH 5.0 and 7.5 (Thompson and Turkington 1988). Studies in Oregon (Hart and McGuire 1963) indicate an increase in the abundance of velvet grass under mildly acidic conditions.

Open ground, meadows, moist places; an adventive occasionally cultivated as a meadow grass. Jiangxi, Taiwan, Yunnan [native to Europe].

In Great Britain and/or Ireland:
Plant / epiphyte
fruitbody of Athelia decipiens grows on dead stem of Holcus lanatus

Foodplant / parasite
Blumeria graminis parasitises live Holcus lanatus

Plant / associate
adult of Bruchidius villosus is associated with flower of Holcus lanatus

Plant / resting place / within
puparium of Cerodontha denticornis may be found in leaf sheath of Holcus lanatus
Other: major host/prey

Plant / resting place / on
puparium of Cerodontha flavocingulata may be found on leaf of Holcus lanatus
Other: major host/prey

Foodplant / spot causer
amphigenous acervulus of Colletotrichum coelomycetous anamorph of Colletotrichum holci causes spots on fading leaf of Holcus lanatus
Remarks: season: 7-8

Foodplant / saprobe
often buried under desne layers of decayed grass leaves fruitbody of Coprinopsis urticicola is saprobic on decayed leaf of Holcus lanatus
Remarks: season: summer

Foodplant / saprobe
colony of Helminthosporium dematiacous anamorph of Drechslera triseptata is saprobic on dead leaf (basal) of Holcus lanatus

Foodplant / parasite
sorus of Entyloma dactylidis parasitises live leaf of Holcus lanatus
Other: major host/prey

Foodplant / gall
stroma of Epichlo causes gall of stem of Holcus lanatus

Foodplant / parasite
numerous sorus of Jamesdicksonia dactylidis parasitises live leaf of Holcus lanatus
Remarks: season: 8-9
Other: major host/prey

Plant / resting place / on
puparium of Liriomyza phryne may be found on leaf of Holcus lanatus
Other: major host/prey

Foodplant / saprobe
fruitbody of Marasmius curreyi is saprobic on dead, decayed stem of Holcus lanatus
Other: major host/prey

Foodplant / saprobe
fruitbody of Melanotus phillipsii is saprobic on dead, decayed leaf of Holcus lanatus
Other: major host/prey

Foodplant / feeds on
adult of Oulema melanopus/rufocyanea agg. feeds on leaf of Holcus lanatus
Remarks: season: 1-12

Foodplant / parasite
hypophyllous telium of Puccinia coronata parasitises live leaf of Holcus lanatus
Remarks: season: mid 8-

Foodplant / parasite
amphigenous uredium of Puccinia hordei parasitises live leaf of Holcus lanatus

Foodplant / spot causer
colony of Ramularia anamorph of Ramularia holci-lanati causes spots on live leaf of Holcus lanatus
Remarks: season: spring, autumn

Foodplant / parasite
colony of Ramulaspera anamorph of Ramulaspera holci-lanati parasitises live Holcus lanatus

Foodplant / pathogen
embedded sorus of Tilletia holci infects and damages ovary of Holcus lanatus
Remarks: season: 6-9

Foodplant / saprobe
fruitbody of Typhula incarnata is saprobic on dying stem of Holcus lanatus

Foodplant / spot causer
long, linear, erumpent sorus of Ustilago striiformis causes spots on live, blistered leaf of Holcus lanatus
Other: major host/prey

Known Pests: GAEUMANNOMYCES GRAMINIS, PLASMODIOPHORA BRASSICAE

More info for the terms: cover, fire frequency, fire severity, frequency, prescribed fire, severity, succession, top-kill

Potential for postfire establishment and spread: If common velvetgrass occurs in or around a burned area, it is possible in the postfire plant community. Studies described above suggest that common velvetgrass is often present and can be abundant in early postfire succession. This pattern does not appear to be affected by location, fire severity, fire frequency, fire season, or associated disturbances. Common velvetgrass abundance typically decreases with time since fire, although long-term studies are lacking. See FIRE ADAPTATIONS AND PLANT RESPONSE TO FIRE for details.

Common velvetgrass establishes on burned sites from off-site or seed bank sources, and may sprout from surviving basal plant parts. Common velvetgrass seeds often occur in the soil even when mature plants are absent or occur in low abundance on the site. Seeds are readily dispersed by a number of vectors (see Seed dispersal). Germination from the seed bank on burned sites is possible, since germination was not affected by up to 10 minutes of exposure to temperatures of 180 to 230 °F (80-110 °C) [120]. Buried seed may also survive on severely burned sites. A review reports that viable common velvetgrass seed was collected from a maximum depth of 20 inches (50 cm) [136]. Anecdotal accounts from Hawaii [127] and Argentina [51] suggest that common velvetgrass may sprout following top-kill. Postfire sprouting was not reported in the majority of reviewed literature.

Minimizing soil disturbances and maintaining high cover of native plants may help prevent or minimize common velvetgrass establishment and spread after fire. For more detailed information on preventing postfire establishment and spread of invasive species, see the following publications: [6,22,55,147].

Use of prescribed fire as a control agent: Fire is not likely useful in the control of common velvetgrass because becaue it is likely to establish, persist, and/or spread after fire (see FIRE ADAPTATIONS AND PLANT RESPONSE TO FIRE). Cover of common velvetgrass typically exceeds that of native Hawaiian grasses after fire, so prescribed fire is not recommended in common velvetgrass habitats in Hawaii [128]. Integrating mowing or grazing and prescribed fire treatments, however, may decrease common velvetgrass dominance [113].

More info for the terms: fire regime, frequency, fuel, fuel continuity, litter

FIRE REGIMES in the native range of common velvetgrass were not described in the reviewed literature. Given that common velvetgrass persists on sites in Washington that have burned almost annually for the last 50 years [145,146], frequent fire is likely tolerated. Lack of fire is more likely to reduce the abundance and/or persistence of common velvetgrass than frequent fire.

While common velvetgrass could potentially increase fine fuel loads in many of its nonnative US habitats, this is described only in Hawaii and California. Establishment of common velvetgrass may reduce the frequency and/or size of gaps in subalpine vegetation and increase fire potential through increased fuel continuity [128]. In coastal grasslands of Sonoma, California, litter accumulations are often greater in common velvetgrass communities than in annual grasslands [13], which may affect fire probability and/or behavior. This topic is also addressed in Litter accumulation. The Fire Regime Table provides fire regime information for many vegetation types and plant communities in which common velvetgrass may occur.

More info on this topic.

More info for the terms: cover, density, frequency, hardwood, indicator value, litter, nonnative species, phase, severity, shrubs, succession, tiller, tree, vine

While often a component of newly disturbed, open communities, common velvetgrass may also occur in stable savannas or heavily shaded mid- and late-seral forest types. In a review, Beddows [14] reported that common velvetgrass "readily colonizes bare soil and disturbed ground", but that plant size and abundance often decrease with increasing severity of common velvetgrass defoliation. Grime [58] classified common velvetgrass as a "competitive ruderal" that is often present as a seedling in the colonization of bare ground but is typically most abundant when disturbances are "less immediate or catastrophic". Researchers in British Columbia described common velvetgrass as "scattered to plentiful" in early-seral communities and/or disturbed sites [83]. In the Puget Trough of Washington, common velvetgrass is typical in Douglas-fir–Pacific madrone/pink honeysuckle vegetation if grazed in the past or near a severely disturbed area [25]. In grasslands and savannas of Hawaii Volcanoes National Park, common velvetgrass established soon after and was often abundant on recent pig digs and artificially created disturbances [129]. Disturbance-related succession is discussed below.

Shade relationships: Although some consider common velvetgrass shade intolerant [83] and studies have shown that shade may decrease seedling growth and plant biomass [52,63], common velvetgrass may occur in heavily shaded woodlands with high tree density [90], especially with soil disturbance.

Field studies in western Oregon revealed that increasing shade reduced common velvetgrass seedling growth and survival [63,64]. For details, see Shade effects. In dune grasslands in the Newborough Warren National Nature Reserve of Wales, the density of common velvetgrass was 0.6 plants/200 cm² in plots shaded by surrounding vegetation and 2.6 plants/200 cm² in plots where vegetation was held back. Total common velvetgrass biomass was 0.02 g/200 cm² in shaded plots and 1.1 g/200 cm² in unshaded plots [52]. When the vegetation and environmental data were analyzed for 184 plots in Oregon white oak savannas in Vancouver Island's Cowichan Valley, common velvetgrass was most frequent on partly shaded sites. On a scale from 0 (completely shaded) to 1 (completely unshaded), common velvetgrass' shade preference ranked near 0.3 [91]. On the Hoh River in Washington's Olympic National Park, common velvetgrass cover and frequency were 4.4% and 30%, respectively, in 14-year-old red alder stands; less than 1% and 3% in 24-year-old stands; and common velvetgrass was absent from 65-year-old stands. Shading was heaviest and tree density greatest in 14-year-old stands; canopy openness increased with increasing stand age [90].

Hydrarch succession: Common velvetgrass is typically found in the last and driest stages of hydrarch succession of temporary ponds in the Willamette Valley. Common velvetgrass occurred in the "grassland-composite" stage that appeared only after water levels decreased with root and litter accumulations of submerged and emergent vegetation [89].

Old-field succession: Pastures and abandoned fields are important common velvetgrass habitats. As succession proceeds to shrublands, woodlands, and forests, common velvetgrass may become less frequent. On pastures near Aldergrove, British Columbia, common velvetgrass cover was 9.5% on a 2-year-old pasture, 20.6% on a 21-year-old pasture, 37.9% on a 40-year-old pasture, and 15.1% on a 65-year-old pasture (Aarssen 1983, as cited in [134]). In the northeastern United States, common velvetgrass decreased in frequency with increased time since last disturbance. On an abandoned agricultural field that was last cultivated in 1945 and last grazed in 1951, the frequency of common velvetgrass was 60% in 1954, 48% in 1960, 10% in 1973, and was absent after that. Vegetation of the old field changed from an open perennial meadow in 1954 to a shrub-dominated thicket in 1973 and to a young hardwood forest or woody vine community by 1992 [45].

Forest Succession: Common velvetgrass is possible in heavily shaded, shrub- or hardwood-dominated seral forests but rarely occurs in old-growth forests without disturbance. Many studies from Oregon and Washington indicate that common velvetgrass is typical in the understory of red alder stands and thickets. In these studies, red alder stands with common velvetgrass ranged from 2 to 75 years old ([47,61,68], Henderson 1970, as cited in [49]). While common velvetgrass occurred in the understory of red alder and Scouler willow (Salix scouleriana) thickets on recent river terraces of the Hoh River in Olympic National Park, it did not occur in forest-dominated terraces [47]. In the lower Fraser Valley and southern Vancouver Island, British Columbia, common velvetgrass was frequent in western hemlock/goose neck moss (Tsuga heterophylla/Rhytidiadelphus loreus) forests logged less than 5 years previously and in stages prior to closure of the sapling canopy. Frequency was lower in the closed-canopy sapling phase, and common velvetgrass was lacking in late immature pole stands, mature stands, and old-growth stands [84].

Disturbance-related succession: Common velvetgrass is often more abundant on disturbed than undisturbed sites. As time since disturbance increases, common velvetgrass abundance often decreases.

Logging: An increased occurrence of common velvetgrass is common following forest logging operations. Increases may be greater on more heavily disturbed sites. Soil scarification may be more important to common velvetgrass establishment and growth than canopy removal. Common velvetgrass was more common in the understory of thinned than untreated Douglas-fir forests on Washington's Ft. Lewis Military Reservation. One year after thinning, the indicator value of common velvetgrass was 36 on the thinned site and 0 on the untreated site. Three years after thinning, the indicator value of common velvetgrass was 59 on thinned and 2 on untreated sites. Average cover of native woody species was not much different on thinned (41.9%) and untreated (45.8%) stands 3 years after thinning [142]. Common velvetgrass occurred in Douglas-fir/western sword fern-redwood-sorrel (Polystichum munitum-Oxalis oregana) habitat types in the southern Oregon Coast Range 4 to 25 years after clearcutting. Common velvetgrass cover was greater on severely disturbed than on relatively undisturbed clearcuts. Severely disturbed sites experienced soil disturbances from skid trails and other operations [7]. Common velvetgrass frequency was much greater on unburned clearcut sites than on burned clearcut sites in other Douglas-fir forests in the Oregon Coast Range. Unburned sites were evaluated 3 years after clearcutting, and burned sites were evaluated 2 years after slash burning. More on this study is presented in Fire adaptations and plant response to fire [30].

Grazing: Reviews report that common velvetgrass is susceptible to trampling [158] and that plant size and abundance often decrease with increasing defoliation severity. In an England pasture, common velvetgrass seedling establishment and survival were much lower on clipped sites than on undisturbed sites or sites with mechanically disturbed soils [74]. In several western US studies, common velvetgrass abundance or growth was less on grazed or clipped than on ungrazed or unclipped sites [1,65,66,124,144].

Although susceptible to trampling [158], decreases in common velvetgrass abundance may be short-lived. When common velvetgrass in a North Carolina old-field was trampled up to 500 times by people wearing lug-soled boots, relative cover of common velvetgrass was 32% two weeks after trampling but was 85% a year after trampling [28].

When 42 paired grazed and ungrazed sites were compared in central coastal California prairies, common velvetgrass cover was substantially less on cattle-grazed than ungrazed sites. On sites visited in 2000, common velvetgrass cover averaged 10.8% on grazed and 23.7% on ungrazed sites. For sites visited the next year, common velvetgrass cover averaged 8.4% on grazed and 36.5% on ungrazed sites. Differences were significant on sites visited in 2001 (P<0.01). Precipitation levels were slightly below normal for the study period [65,66]. On the Tomales Point Elk Reserve in Marin County, California, elk grazing reduced abundance of common velvetgrass in open grasslands, but abundance was not reduced when plants grew beneath coyote bush (Baccharis piluaris). Poor accessibility was likely the reason for reduced grazing beneath shrubs [75]. In perennial grasslands of northwestern California, the cover of common velvetgrass was 0.1% in perennial grasslands grazed by cattle for 8 months of the year and 1.7% in grasslands grazed for 4 months of the year. Cover was nearly equal on Oregon oak woodland sites grazed for 8 and 4 months [124]. In a greenhouse study, increased exposure to grazing appeared to improve common velvetgrass' regrowth following clipping. Plants were collected from 2-year-old, 21-year-old, and 40-year-old pastures in the lower Fraser Valley of British Columbia. In general, biomass production was lower for clipped than unclipped plants, but clipped plants produced more tillers than unclipped plants. Total biomass, shoot biomass, and tiller number of clipped plants from the oldest pasture were significantly greater (P<0.05) than those of clipped plants from 2- and 21-year-old pastures. Common velvetgrass from the oldest pasture was exposed to grazing pressure for the longest time. Differences in common velvetgrass regrowth between the oldest and younger pastures suggest that plants developed a tolerance to grazing on the oldest pasture [1].

Other: A variety of disturbances can impact the establishment and spread of common velvetgrass. Generally open sites with favorable moisture provide for the best common velvetgrass establishment and growth; however, establishment and growth vary in their response to shading, disturbance, and fertility. In a British Columbia field experiment, researchers found that common velvetgrass growth was greatest in undisturbed plots with low-nutrient levels. Monoculture and mixed stands were established from seed collected in pastures. Seedlings were grown for 11 months before applying treatments and evaluated after 5 months of nutrient additions and/or clipping treatments. Common velvetgrass cover was greatest in undisturbed monocultures with low-nutrient levels. Clipping to 0.4-inch (1 cm) heights each week was the highest level of disturbance tested and severely depressed common velvetgrass growth. Cover of common velvetgrass was lowest in high-disturbance, low-nutrient, mixed-species treatments [144].

Studies conducted in Derbyshire, United Kingdom, suggest that common velvetgrass establishment and abundance may increase with increased disturbance and fertility. Five years after common velvetgrass was seeded along fertility and disturbance gradients, researchers indicated that common velvetgrass "appeared to respond positively to both increased fertility and disturbance". Disturbances involved turf removal [137]. At the conclusion of this experiment, 3 years after 3 years of treatments, common velvetgrass cover differences were greatest between fertile, disturbed plots (30.3%) and infertile, undisturbed plots (9.0%) (P=0.001). Researchers reported that common velvetgrass went into "relatively steep" decline after treatments were discontinued [23].

Common velvetgrass appeared early after debris flows in the Coast Range of central Oregon and on Mount St Helens in Washington. On the more severe Mount St Helens debris flows, common velvetgrass increased consistently with time since flow [35]. On the less severe debris flow in Oregon, common velvetgrass increased until about the 4th year after the flow [102].

In alpine hairgrass grasslands and koa savannas in Hawaii Volcanoes National Park, common velvetgrass established soon after and was often abundant on recent pig digs and artificially created disturbances. Researchers concluded that pig digging could "greatly enlarge" the abundance of nonnative species in mostly native communities [129]. However, in the montane rainforest zone of Hawaii Volcanoes National Park, common velvetgrass was not associated with feral pig disturbances. Researchers suggested that common velvetgrass establishment and growth may have been so rapid that disturbances were not recognized as recent [4].

In coastal prairie vegetation in Sonoma County, California, common velvetgrass establishment and growth were greater in canopy gaps created in sweet vernalgrass patches than in common velvetgrass patches. Gaps in the canopy were created by killing individual bunchgrasses; standing dead vegetation remained. By the second year after gap creation in sweet vernalgrass, common velvetgrass cover was 100%. Common velvetgrass leaf area was 1,000 times greater in sweet vernalgrass than in common velvetgrass patches [109].

More info for the terms: rhizome, tiller, top-kill

Common velvetgrass clumps expand through tillering or the growth and development of prostrate rosette shoots (Tansley 1949, as cited in [14]). In reviews, vegetative growth of common velvetgrass has been described as producing a "blanket of runners or stolons" on the soil surface [158] and as "aggressive tillering" that allows clumps to "enlarge rapidly" [149]. Claims of rhizome production [40] and sprouting following top-kill [51] were not substantiated by the available literature.

While vegetative growth commonly occurs, recruitment of seedlings is typically the primary method of common velvetgrass reproduction. In field and greenhouse studies conducted in British Columbia, seedlings grew more rapidly and resisted invasion better than tillers collected from 11- and 49-year-old pastures. In the greenhouse, common velvetgrass was least abundant in patches grown from tillers collected in the 49-year-old pasture and most abundant in seeded patches. Common velvetgrass seedling patches were the most difficult to invade by other nonnative pasture grasses, but patches grown from tillers collected in the 11- and 49-year old pastures were invaded easily. In the field, common velvetgrass tiller patches expanded at a rate of 8.28 cm²/week, while seedling clumps expanded at a rate of 16.0 cm²/week [143].

In frequently mowed habitats, the importance of tillering increases. In the North Wales Treborth Botanic Garden, nearly all species, including common velvetgrass, colonized cleared patches through vegetative growth in frequently mowed grassland (1-2 times/2 weeks). Seedlings (of any species) were extremely rare [5]. At 4 weeks old, common velvetgrass tillers can survive apart from the parent plant. Researchers collected common velvetgrass plants from a pasture in Cheshire, United Kingdom, potted them in a greenhouse and evaluated the survival of severed tillers. Four-week old tillers survived, but 1- and 2-week old tillers did not [24].

More info for the terms: cover, fen, natural, presence, resistance

In its nonnative range, common velvetgrass is known as a rapid growing seedling. Late-fall sowing dates and shading can decrease seedling growth and survival, but spring moisture can increase seedling establishment and survival. While common velvetgrass establishment is often associated with disturbances in both its native and nonnative ranges [7,45,102,142], the bulk of information about seedling establishment and survival on disturbed sites comes from native habitats.

Seedling growth: Common velvetgrass seedlings develop rapidly, making them competitive at this early stage. After 20 weeks of growth in a greenhouse, common velvetgrass produced the greatest overall root biomass and root:shoot biomass of 6 coastal prairie species grown from seed collected in Marin County, California. Species included in this experiment were bulbous canarygrass (Phalaris aquatica), tall fescue (Schedonorus phoenix), red fescue (Festuca rubra), Oregon bentgrass (Agrostis oregonensis), and purple needlegrass (Nassella pulchra). In the first 5 weeks of growth, common velvetgrass' estimated growth rate exceeded that of any other species. When grown in the presence of others, common velvetgrass seedlings were considered the "least responsive to the presence of a neighbor". The relative yield/neighbor plant was significantly smaller for plants grown with common velvetgrass than with any other species (P<0.05) [140]. In greenhouse and field experiments conducted in British Columbia, common velvetgrass grew most rapidly, was most abundant, and resisted invasion best as a seedling. When transplanted as tillers from 11-year-old and 49-year-old pastures, common velvetgrass growth, abundance, and resistance to invasion were lower [143].

Associated vegetation effects: While the growth of common velvetgrass can decrease in the presence of associated vegetation, decreases may not occur at the seedling stage. After the 1st year of growth in a California coastal prairie field study, common velvetgrass produced the greatest shoot biomass of any species when grown in a monoculture and when grown with an equal proportion of native grasses. Aboveground biomass of common velvetgrass decreased in the 2nd and 3rd years of the experiment (Corbin and D'Antonio, in preparation, cited in [140]). In the Danebo Wetlands of West Eugene, Oregon, the relative performance of common velvetgrass was lower in mixed species field plots than in monoculture field plots. Two years after seeding, average common velvetgrass biomass in a monoculture was 10.2 to 19.6 g/plant and in mixed plots was 0.45 to 1.33 g/plant. Biomass values reported are only for those plots in which common velvetgrass established [36].

Germination date: In both native and nonnative habitats, earlier germination dates are associated with increased seedling establishment, growth, and survival of common velvetgrass. In the United Kingdom, earlier sowing dates related to increased common velvetgrass establishment in the field. Sowing began on 19 July and continued at weekly intervals (Mortimer 1974, as cited in [157]). In field studies conducted in western Oregon, common velvetgrass growth and survival were best at the earliest fall planting date [63,64].

Common velvetgrass survival and growth at different planting dates [63,64] Sowing date Sept. 26 Oct. 7 Oct. 16 Oct. 25 Nov. 8 Seedlings surviving
to mid-March (%) 96a 67b 71b 64b 41c Seedling dry weight
in mid-March (mg) 314a 168b 73c 27c 7c Within a row, values followed by different letters are significantly different (P<0.05).

Shade effects: Increasing shade reduced seedling growth and survival during field studies in western Oregon. In 0%, 33%, 53%, and 78% shade, 5- to 6-week-old common velvetgrass seedlings had dry weights of 9.2 mg, 3.8 mg, 2.5 mg, and 2 mg, respectively. Shading of 33% or greater significantly reduced seedling growth (P<0.05) [63,64].

Moisture: While moisture may increase seedling survival and establishment, both drought and long periods of inundation can decrease seedling establishment. Added spring moisture increased seedling establishment and survival in an annual coastal prairie in the University of California's South Meadow in Mendocino County. Control, winter-irrigated, or spring-irrigated plots (each 900 cm ²) were seeded in fall. Irrigation treatments added 17 inches (42 cm) of water. Common velvetgrass seedling establishment was 80% on spring-irrigated plots, 55% on winter-irrigated plots, and 30% on control plots. Of the 28 common velvetgrass seedlings that survived most of the subsequent summer drought and growing season, 1 occurred on the control plot, 4 on the winter-irrigated plot, and 23 on the spring-irrigated plot. On spring-irrigated plots, 17 common velvetgrass plants flowered and were described as "large" and "robust" [139]. In field experiments in the Danebo Wetlands common velvetgrass established in plots inundated for 12 to 14 weeks from January to June but failed to establish in plots inundated for 24 to 27 weeks during the same period [36].

Herbivory and disturbance effects: In native habitats, studies indicate that disturbances can increase common velvetgrass seedling establishment and survival, but the effects of simulated and natural herbivory on seedling establishment and survival were mixed. Mechanical soil disturbances may increase establishment more than canopy removal. In a fen meadow and a rush (Juncus spp.) pasture in Devon, southwestern England, common velvetgrass seedling emergence and survival generally increased with disturbances that involved inversion of the top 2.8 inches (7 cm) of soil. In the pasture, clipping dramatically decreased common velvetgrass seedling surival but in the fen, seedling survival was not affected by clipping. Common velvetgrass seedling survival was greatest in the fen with soil disturbance alone and in the pasture with soil disturbance and irrigation and without clipping. Field conditions were "exceptionally dry" in June and July [74].

Emergence and survival of common velvetgrass seedlings on treatment plots with and without irrigation, canopy vegetation, and soil disturbance [74] Treatment Seedling emergence (%) Seedling survival May-October* (%) Irrigation Clipping Soil disturbance Fen Pasture Fen Pasture - - - 18 16 97 75 - - + 12 21 100 96 - + - 12 2 70 0 - + + 21 25 58 35 + - - 17 18 93 98 + - + 20 23 98 100 + + - 11 1 60 0 + + + 23 19 90 0 *Researchers noted that conditions were "exceptionally dry" in June and July.

The absence of vegetation cover reduced the probability of successful seedling establishment in a field study in the Treborth Botanic Garden of North Wales. The fate of 275 common velvetgrass seeds was tracked for 8 months on a plowed plot, an herbicide-treated plot, and a relatively undisturbed plot. Just 37% of the seeds developed into seedlings. The probability of survival to adulthood was much lower. Probablity of establishing an adult was 0.0329 on the plowed plot, 0.0333 on the undisturbed plot, and 0.0048 on the herbicide-treated plot when small mammals, birds, and invertebrates were not excluded. Probablity of establishing an adult increased to 0.0518, 0.0592, and 0.0148 on plowed, undisturbed, and herbicide-treated plots, respectively, when small mammals, birds, and invetebrates were excluded [100].

Four years of rabbit exclusion increased common velvetgrass cover, flowering, and seedling emergence but not seedling survival in an acidic, species-poor grassland in Silwood Park, Berkshire, United Kingdom. Common velvetgrass cover, flower production, and seedling emergence from soil samples in rabbit-exclusion plots were more than double that of unfenced plots; however, the proportion of common velvetgrass seedlings surviving from fall 1995 to mid-winter 1997 was 0.18 in exclusion plots and 0.32 in unfenced plots. All differences were significant (P<0.01) [43].

Additional information on common velvetgrass seedling establishment, plant growth, and spread is available in Impacts.

More info for the term: litter

Greenhouse and field studies indicate that common velvetgrass germinates best in full light conditions and fluctuating temperatures. Low temperatures, dry conditions, and burial can decrease or delay germination. In a review, Beddows [14] reports that common velvetgrass germinates "readily". In the laboratory, 100% of common velvetgrass seeds collected from an encina (Quercus ilex subsp. rotundifolia) woodland in central-western Spain germinated [112]. Germination rates of common velvetgrass seeds collected from a permanent pasture in England ranged from 90% to 99% after up to 48 weeks of dry storage [167].

Light requirements: While full light and exposed conditions are typically best for common velvetgrass germination, some germination also occurs when seeds are buried and/or in the dark. Large temperature fluctuations may increase germination in dark conditions. At nearly constant temperatures of 54 °F (12 °C) and 75 °F (24 °C), common velvetgrass germination percentages in the dark were 48% and 30%, respectively [44]. After conducting numerous laboratory studies on common velvetgrass seed germination, Thompson and others [135] found that common velvetgrass germination was greater than 75% when temperatures fluctuated from 0 to 22 °F (0-12 °C). Emergence rates and germination percentages of common velvetgrass seed in the greenhouse were not different between shading levels of 0%, 33%, 53%, and 78% [64].

Depth of burial: Increasing depths of burial beneath soil or litter typically decrease common velvetgrass germination. In the greenhouse, maximum common velvetgrass germination was 89% under 0.4 inch (1 cm) of soil, 75% under 1.2 inches (3 cm) of soil, and 26% under 2 inches (5 cm) of soil [167]. In cleared coastal prairie plots in northern Marin County, California, common velvetgrass germinated at nearly 90% on sites without litter. Under 0.4 inch (1 cm) of litter, germination decreased to about 50% but was still significantly greater than that of 4 native prairie grasses (P-value not reported). Germination of common velvetgrass was about 30% under 1.2 inches (3 cm) of litter, which was not different than germination of the native species [117]. This study is also discussed in Litter accumulation.

Temperature, moisture: Cold temperatures and dry conditions can reduce or delay common velvetgrass germination. Common velvetgrass seed collected from a California coastal prairie had the lowest germination (nearly 30%) when growth chamber temperature fluctuatations were slight, between 37 and 48 °F (3-9 °C). At higher and greater fluctuations of temperatures (46 to 68 °F (8-20 °C)), germination was near or just below 50% [117]. In the greenhouse, common velvetgrass seeds from a grassland in Oxford, England, germinated best when temperatures alternated below and above 68 °F (20 °C). Germination percentages were lowest at a constant temperature of 68 °F (20 °C) [166]. Diurnal temperature requirements may function as a "gap-detecting mechanism", allowing common velvetgrass seeds to sense gaps in the canopy through temperature changes (Thompson and others 1977, as cited in [166]). When common velvetgrass was exposed to high temperatures of 180 to 230 °F (80-110 °C) for up to 10 minutes, germination was not affected. Germination was inhibited after 10 minutes at 300 °F (150 °C), although seeds were not "destroyed". Smoke exposure did not affect germination [120].

Common velvetgrass emergence was affected by sowing date, which was related to temperature and moisture field conditions in Oxford, England. Generally seedlings emerged 1 to 2 weeks after sowing. When temperatures were low or conditions were dry, emergence was delayed. Emergence was evaluated in each month of the year and was lowest for seeds sown from April to July. Mild winter and hot, dry summer conditions prevailed during this experiment [156]. In nonirrigated western Oregon pastures, common velvetgrass typically germinates with fall rains. In a field study, emergence was delayed when fall moisture was low [64].

More info for the terms: cover, frequency, natural, succession

Studies from native and nonnative ranges indicate that common velvetgrass produces an abundant seed bank that is important to population persistence. A review of studies conducted in northwestern Europe reported that common velvetgrass seed may remain viable in the soil for more than 12 years. In one study, a maximum number of 16,900 common velvetgrass seeds/m² occurred in a sample of the top 2 inches (5 cm) of soil from a natural habitat. Another study reported collecting viable common velvetgrass seeds from a depth of 20 inches (50 cm) [136]. In other reviews, 5% of common velvetgrass seed reportedly germinated after 12 years of storage in a laboratory [14], and at the Welsh Plant Breeding Station, 14% of common velvetgrass seeds germinated after 10 years of burial beneath 5 inches (125 mm) of mineral soil [157].

Native habitats: Common velvetgrass seed banks can be extensive in disturbed and undisturbed habitats. A review reports that 70,000 common velvetgrass seedlings/acre emerged from the top 7 inches (20 cm) of soil collected in an undisturbed bentgrass-fescue (Agrostis-Festuca spp.) grassland in Kerry Hills, United Kingdom. No seedlings emerged from soil samples collected at depths below 7 inches (20 cm) [14]. When seed banks from 38 western European sites were compared, common velvetgrass was most common in the "extensively managed" grasslands [16]. Field and greenhouse studies conducted in Norfolk, United Kingdom, showed that common velvetgrass colonized artificially created gaps from soil-stored seed. Although common velvetgrass cover was less than 0.3% in the field, an average of 150 common velvetgrass seedlings/m² emerged from soil samples taken to 2-inch (5 cm) depths. Three common velvetgrass seedlings/m² emerged from soil samples collected from 12- to 14-inch (30-35 cm) depths. When gaps were created, common velvetgrass establishment was lowest on sites where vegetation was removed and soil was inverted to a depth of 14 inches (35 cm) [103].

Nonnative habitats: There is little evidence that seed bank dynamics are different between native and nonnative common velvetgrass habitats. If common velvetgrass is present in the aboveground vegetation, banked seed is nearly certain. On the University of British Columbia research forest, common velvetgrass seed was not recovered from seed traps or soil in old-growth mixed-conifer forests. In recent clearcuts, however, the frequency of common velvetgrass was 21.9% in the aboveground vegetation, 6.3% in seed trap collections, and 3.1% in the seed bank [81]. Although clipping reduced common velvetgrass seed set by 97% in a coastal prairie in Van Damme State Park, California, common velvetgrass seedlings emerged at a high rate, suggesting germination of soil-stored seed. On clipped plots, about 29 common velvetgrass seedlings/m² emerged, and on unclipped plots about 5 common velvetgrass seedlings/m² emerged [17]. It is possible that removal of aboveground vegetation improved germination and establishment conditions on clipped sites. In coastal prairies of Sonoma County, California, common velvetgrass emergence occurred with and without seed rain. On plots where seed rain was allowed, 1.8 common velvetgrass seedlings/m² emerged from soil collected in a common velvetgrass-dominated patch type and 12.0 seedlings/m² emerged from a Pacific hairgrass (Deschampsia holciformis)-dominated patch type. In the Pacific hairgrass patch, cover of common velvetgrass was almost 85% lower than in the common velvetgrass patch. When seed rain was excluded, 2.6 and 3.9 seedlings/m² emerged from soils collected in the common velvetgrass patch and the Pacific hairgrass patch, respectively. The researcher suggested that common velvetgrass may be invading Pacific hairgrass patches as succession proceeds [107].

There are many potential common velvetgrass seed dispersal vectors. Seeds are easily shed [14], and a large spikelet surface area encourages wind dispersal [14,134]. In a field study in northern California coastal grasslands, 90% of common velvetgrass seeds dispersed within a 17-foot (5.2 m) radial distance from the parent plant. Half of all seeds fell within a 5.6-foot (1.7 m) distance [110]. Water dispersal may be possible, and human and other animal vectors likely aid in seed dispersal.

Water: Buoyancy of comon velvetgrass seed suggests that it may be dispersed by water. In stagnant water, 54% of common velvetgrass seeds remained floating after 25 days and 9% after 90 days. In moving water, 47% remained floating after 25 days and 2% after 90 days. Germination of floating seeds was not tested [150].

Human activities: Mowing equipment was likely an important dispersal vector for common velvetgrass in the Netherlands. After mowing in common velvetgrass-dominated grasslands, 86% of seeds removed from equipment were common velvetgrass [132].

Animals: Worms, birds, rabbits, and cattle are possible dispersers of common velvetgrass seed. McRill (1974, as cited in [121]) reported that common velvetgrass seed was a major component of earthworm castings collected from grasslands in North Wales. Worms are likely important in the burial and unearthing of common velvetgrass seed (McRill 1974, as cited in [156]). Not all birds are likely to disperse common velvetgrass seed. Common velvetgrass seeds that passed through the digestive tract of sparrows were killed, but seeds passing through the digestive tract of rooks had only slightly reduced viability (Krach 1959, as cited in [157]). A small number of common velvetgrass seedlings emerged from rabbit pellets collected from an acidic grassland in Norfolk, United Kingdom. Although field and greenhouse studies indicated that the seed bank was most important to the colonization of bare patches, dispersal and establishment from rabbit pellets was possible [103]. For more on this study, see Seed banking. Common velvetgrass also germinated from cattle dung collected from heather (Calluna spp.) moorland in northeastern Scotland [162].

Predation: In a coastal prairie in Sonoma County, California, predation of common velvetgrass seed was low. When petri dishes of common velvetgrass seed were left out for 3 weeks in an annual grassland, only 6% were removed [107].

More info for the terms: cover, vernalization

A review reports that although seed is generally only produced by lower florets, common velvetgrass is "notoriously a prolific seed producer".

Studies conducted in native and nonnative habitats indicate that common velvetgrass seed production can vary by vegetation type and sowing date. In Britain, common velvetgrass produced 63 to 611 spikelets/panicle in a greenhouse setting [15]. In a "closed" common velvetgrass-dominated grassland in Bangor, United Kingdom, the average number of common velvetgrass seeds/panicle was 270 but ranged from 100 to 380. Average seed production was 19,000 seeds/m² (Mortimer 1974, as cited in [157]). In coastal prairies of Sonoma County, California, common velvetgrass seed rain was 82,300 seeds/m² in a patch type where 91% of the relative cover was common velvetgrass. Seed rain was less than 6,000 seeds/m² in a patch where the relative cover of common velvetgrass was 4.6% [107]. For more on common velvetgrass seed production on newly colonized sites, see Impacts.

During field experiments in Oxford, England, sowing date affected common velvetgrass panicle and seed production. Plants from seed sown in November or December failed to flower. Plants from seed sown from January to June produced large numbers of panicles and seeds/plant. Panicle/plant production decreased from 759 on plants from June-sown seed to 184 on plants from July-sown seed. The greatest number of seeds produced per plant was 240,000 on plants from March-sown seed. The summer was very hot and dry and the winter very mild during these field experiments [156].

Seeds are generally viable soon after they are produced. When researchers tested seed germination at increasing time since anthesis, they found viable seeds 9 days after seed shed. Twenty days after anthesis, germination was 100% [14]. Another review notes that successful flowering depends on vernalization, and that longer cold periods often translate into a longer flowering period [134].

More info for the term: breeding system

Common velvetgrass reproduces primarily from seed, but tillering is also common and can be important to clump size increases.

• Pollination and breeding system
• Seed production
• Seed dispersal
• Seed banking
• Germination
• Seedling establishment and plant growth
• Vegetative regeneration

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More info for the terms: hemicryptophyte, therophyte

Raunkiaer [116] life form:
Hemicryptophyte
Therophyte

More info for the term: graminoid

Graminoid

Follow this link to the U.S. Forest Service Fire Effects Information Service to see a table with fire regime information that may be relevant to habitats in which this species occurs

A review reports that common velvetgrass flowers are cross pollinated by wind [14]. Experiments have shown that common velvetgrass is "highly self-sterile" [15].

Little research has been done on HOLCUS LANATUS in North America. In Europe, it is an adaptable, competitive species that tolerates a wide range of habitats, particularly acidic, low nutrient sites (Watt 1977).

GROWTH, PRODUCTIVITY, AND COMPETITION

In the Soviet Union, Trapaidze and Gogiya (1981) report that HOLCUS species have an exceptionally long growing season. Germination occurs from seed or as sprouts from roots in late autumn, with flowering between May and July. In a Dutch experiment (van Andel and Jager 1981), velvet grass leaf area peaked 15 weeks after sowing, and maximum dry weight was attained two weeks later. In the later stages of growth, root mass increased dramatically, reaching half of the total plant weight. Nitrogen levels also showed a marked increase after 15 weeks of growth. Nitrogen availability may be the limiting factor in HOLCUS LANATUS growth (Watt 1978). HOLCUS LANATUS normally occurs on soils of moderate to low fertility, but fertilization appears to improve its competitive ability (Remison and Snaydon 1980).

High water table levels reduce the productivity of velvet grass. HOLCUS manages to persist on these wet sites by producing a large number of fine roots on the soil surface where aeration and nutrient levels are higher (Watt and Haggar 1980b). Grootjans (1979) noted that a lowered water table increase the N-mineraliza- tion rate and the nitrate content leading to a strong site dominance by HOLCUS LANATUS. Severe winter weather and high ground water can kill the grass, perhaps by lowering the N-mineralization rate (Bakker et al. 1980). Velvet grass can tolerate soils with a pH range of 3 to 8.1 (Grime and Lloyd 1973) but does best on sites with a pH of 4.5 to 5.5 (Roberts 1982).

Like other weeds from disturbed but productive habitats, HOLCUS LANATUS is able to grow rapidly. The mean recorded growth rate is 1.56 g/g.week while the maximum growth rate exceeds 2 g/g.week (Redosevich and Holt 1984). This rapid growth may indicate a high potential competitive ability among crop and weed species (Redosevich and Holt 1984). This aggressiveness is shown in the dominance of velvet grass in English pastures (Turkington et al. 1979). HOLCUS also does well in both high and low levels of light (Anonymous 1976).

In an English study, Remison and Snaydon (1980) found that HOLCUS LANATUS outcompeted DACTYLIS GLOMERATA (orchard grass) under a wide variety of conditions. Velvet grass yield increased by 50% on sites with competition over sites where it was grown alone. Similar results are reported for competition between HOLCUS LANATUS and LOLIUM PERENNE (ryegrass). Velvet grass is particularly aggressive in root competition due to its higher proportion of roots than other British pasture species (Watt and Haggar 1980a).

In a Dutch grassland study (Bakker et al. 1980), HOLCUS LANATUS became dominant when the grass was mowed following maturation and seed dispersal. When earlier cuts were made, HOLCUS LANATUS survived but became less dominant. HOLCUS LANATUS responds well to cutting, even when cut back to only 2 cm above the ground. On unharvested sites, velvet grass gradually forces other plants out, reducing species diversity. This process is particularly apparent on unfertilized sites. Allelopathy may also play a role in the dominance of HOLCUS LANATUS over other grasses (Remison and Snaydon 1978).

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Common velvetgrass flowers are possible from May to September in California, Nevada, and Baja California [79,101,165]. In the northeastern United States common velvetgrass typically flowers from June to August [149]. Along the Atlantic Coast, common velvetgrass flowers are possible from May to October [37,115,131]. Anthesis and flowering progress from the apex of the common velvetgrass panicle downwards. Flowering along the entire panicle is typically complete in 4 to 6 days [15]. At the end of the growing season, nutrients are relocated and stored below ground [21].

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 20
Specimens with Barcodes: 22
Species With Barcodes: 1

Information on state-level noxious weed status of plants in the United States is available at Plants Database.

Canada

Rounded National Status Rank: NNA - Not Applicable

United States

Rounded National Status Rank: NNA - Not Applicable

Rounded Global Status Rank: GNR - Not Yet Ranked

Global Short Term Trend: Increase of 10 to >25%

Comments: HOLCUS LANATUS is present on Oregon and Washington westside grassland preserves and the Northern Califoria Coast Range Preserve. It is apparently not a major problem species on Nature Conservancy lands in California, but where it occurs, control may be difficult due to its prolific seeding ability and its possible allelopathic effect on native grasses. It has, however, become a major problem on western Oregon and Washington grassland preserves.

More info for the terms: cover, fire management, fuel, litter, natural, nonnative species, prescribed fire, radicle

In many of its nonnative habitats, common velvetgrass is not described as a serious weed; however, many studies indicate that common velvetgrass' allelopathic potential, rapid early development, litter accumulation, response to disturbances, and nutrient additions can negatively impact associated native vegetation.

Impacts: Common velvetgrass is referred to as a problematic species in Hawaii but is often considered a species of lesser concern in other parts of its nonnative North American range. In reviews from the Hawaiian Islands, common velvetgrass is considered "disruptive" and described as "forming dense stands that appear to inhibit recruitment of natives" [34]. Establishment on disturbed sites in Hawaii is often rapid [127]. Invasiveness ratings of common velvetgrass are likely relative; when associated with more invasive weed species, it is less likely to be described as a problem.

Throughout most of its nonnative range, common velvetgrass is either not listed on invasive plant lists [56,94] or is referred to as a "minor weed" [134], not a "major problem species" [113], moderately invasive [151], or "not readily invading natural areas" [82] as of this writing (2009). Although prevalent in Oregon and Washington, common velvetgrass is absent from many invasive species lists for the area [56]. Common velvetgrass is not listed in the Invasive Plant Atlas of New England [94], although it is well established in the area. Potentially problematic common velvetgrass growth characteristics are discussed below; these may result in impacts that affect a local scale in the nonnative range.

Allelopathy: In laboratory tests, common velvetgrass showed possible allelopathic properties. When common velvetgrass and garden sorrel (Rumex acetosa) seedlings were grown in sand that was collected beneath a common velvetgrass monoculture, growth of both species was "markedly depressed" as compared to controls, even when nutrients were added (Al-Mashhadani and Grime, personal communication, cited in [158]). Germination and radicle extension were significantly lower for bulbous canarygrass (Phalaris aquatica) and orchardgrass (Dactylis glomerata) seeds kept moist with water containing common velvetgrass leaf extracts than for those kept moist with deionized water (P=0.001) [154].

Rapid early growth: Rapid germination and seedling growth may allow common velvetgrass establishment and spread in a variety of habitats. In a greenhouse experiment, the maximum relative growth rate of common velvetgrass was 2.01/week. Soon after seedling establishment, 4 weekly harvests were made to calculate this growth rate, which was high compared to other species evaluated [59]. In another greenhouse experiment, growth rates of common velvetgrass were 42 mg and 65 mg/g/day in low- and high-nitrogen environments, respectively. Growth rates were calculated from 10 weekly harvests [20].

Early germination and rapid seedling growth may allow for the development of stable common velvetgrass stands that limit the growth of associated species. Fifty days after seeding, common velvetgrass seedlings produced the greatest dry weights of 6 western Oregon pasture species grown in the greenhouse [64]. When seeds collected from coastal prairie in northern Marin County, California, were monitored in growth chambers, common velvetgrass germinated more rapidly than red fescue. However, the final germination rate of red fescue was 60% higher than common velvetgrass [117]. Common velvetgrass biomass was significantly greater than that of Hawaii's alpine hairgrass after 6 months of growth in low-light/low-nutrient, high-light/low-nutrient, and low-light/high-nutrient treatments (P<0.05). In high-light/high-nutrient conditions, alpine hairgrass biomass was greater than that of common velvetgrass, but not significantly. Common velvetgrass allocated more biomass to roots than did alpine hairgrass [50].

In greenhouse and field experiments, common velvetgrass was most abundant, had the highest growth rate, and, as a seedling, was the most resistant to invasion when compared to other British Columbia pasture species. In the greenhouse, common velvetgrass was most abundant in patches established from seed. Seedling patches resisted invasion most. Based on comparisons made with common velvetgrass tillers collected from older pastures, researchers characterized common velvetgrass as an "r-type" species that likely requires repeated colonization opportunities to maintain a viable population in pastures [143]. In patchy coastal prairie vegetation in California, patches of common velvetgrass inhibited establishment of other species when seed was introduced. Although some seedlings emerged in common velvetgrass patches, none of these produced seed within 2 years of establishment. In patches of nonnative annual grasses, common velvetgrass establishment was successful. An input of 12,442 common velvetgrass seeds/0.25 m² produced 39.2 common velvetgrass seedlings/0.25 m². Newly established individuals in annual grass patches produced up to 21 seeds/0.25 m² and 5.1 seedlings/0.25 m². Common velvetgrass also had some establishment in perennial grass patches, but none of these plants produced seed within 2 years [108].

A common velvetgrass monoculture established in the field near Bristol in the United Kingdom severely restricted the growth of European white birch (Betula pendula) seedlings. One year following planting, the diameter of European white birch seedlings averaged 2.8 mm when grown with common velvetgrass and 8.4 mm in the absence of common velvetgrass. Seedling heights averaged 8.7 inches (22.2 cm) with and 24.7 inches (62.7 cm) without common velvetgrass [168].

Litter accumulation: In California grasslands, high productivity and reduced litter decomposition in common velvetgrass grasslands may affect regeneration potential and species composition. On the Bodega Marine Reserve in Sonoma County, California, common velvetgrass stands (aboveground biomass 836 g/m²) were more productive than annual grassland stands (aboveground biomass 534 g/m²). Standing litter accumulations in common velvetgrass stands were 1,537 g/m² and in annual grasslands were 766 g/m². From exclusion experiments, researchers learned that the dominant detritivore in the area, Porcellio scaber, did not consume common velvetgrass litter. Increased litter in common velvetgrass stands could affect seedling recruitment as well as fuel loads, fire potential, and fire behavior [13]. In field studies in coastal prairie in northern Marin County, California, common velvetgrass litter decreased germination of native grasses more than that of common velvetgrass. Under 0.4 inch (1 cm) of litter, common velvetgrass germination was about 50% lower than germination on bare soil; however, germination of common velvetgrass was still significantly greater than that of Pacific hairgrass, red fescue, Pacific reedgrass (Calamagrostis nutkaensis), and purple needlegrass (Nassella pulchra) (P-value not reported). Under 1.2 inches (3 cm) of litter, common velvetgrass and native grass germination were not different [117].

Control: While several methods may be useful to control common velvetgrass, it is likely that severe defoliation and repeated treatments may provide the best control. Evaluation of associated vegetation and potential increases in these species may affect management decisions. In a greenhouse study using monocultures of 6 grasses and 4 legumes, researchers found that introduced thistle seed (Carduus nutans and Cirsium vulgare) emergence was lowest in common velvetgrass stands [155]. Management decisions in common velvetgrass' nonnative habitats may involve making value judgments between nonnative species.

Some researchers suggest that marking common velvetgrass treatment areas in the early morning when dew is trapped in its velvety hairs may help to focus control efforts and minimize nontarget effects [46].

Photo taken in Maui, HI,
©Forest and Kim Starr

Flooding/salinity: Common velvetgrass experienced high mortality when partial dike removal occurred in a 15-year-old pasture on the Salmon River Estuary in Lincoln County, Oregon. Cover of common velvetgrass was up to 70% in the pasture before dike removal. In the 1st growing season after dike breaching, common velvetgrass suffered high mortality and averaged less than 5% cover. By the 2nd growing season, common velvetgrass was essentially absent. Before dike removal, salinity in the pasture was 0 to 3 ppt and after breaching was 11 to 39 ppt [97].

Fire: For information on the use of prescribed fire to control this species see Fire Management Considerations.

Prevention: Methods that may limit the establishment of common velvetgrass in lawn or pasture plantings are discussed by Fitzsimmons and Burrill [46].

Physical and/or mechanical: Some suggest that hand-pulling and hoeing, while labor intensive, can decrease common velvetgrass abundance [113]. A review reports that intense grazing or mowing may limit common velvetgrass establishment and spread [161]. Mechanical methods to control common velvetgrass are described by Fitzsimmons and Burrill [46].

It is important to note that mowing equipment has the potential to disperse common velvetgrass seed. After mowing in a common velvetgrass-dominated grassland in the Netherlands, 86% of the seeds removed from the mower were common velvetgrass seeds [132].

During controlled studies conducted outdoors and in a greenhouse, short cutting heights and increased cutting frequencies decreased common velvetgrass yield. When plants were cut between mid-March and early May, regrowth produced panicles by July 8, but when cut in early June, no panicles were produced on regrowth [159].

In the Willamette Valley, mowing and cutting led to increased common velvetgrass inflorescence production. Plants were mowed short, cut to the base twice, or burned twice in the fall. Mowing and cutting increased the reproductive potential of common velvetgrass. Fire generally decreased inflorescence production; details are discussed in the Western United States section of Fire Ecology [26]:

Changes in the number of common velvetgrass inflorescences/plant between pretreatment and first growing season after 1st and 2nd treatments [26] Treatment Mowed to 8-12 cm heights Cut at base Fall fire Control Difference between pretreatment and 1st year after single treatment +4.45 +1.34 -0.7 -0.38 Difference between pretreatment and 1st year after 2 treatments +11.50 +5.46 -0.7 -0.80

Biological: No information is available on this topic.

Chemical: Herbicides potentially useful in common velvetgrass control are discussed in the following reviews: [46,134,161]. McHenry (1985, cited in [113]) suggests herbicide treatments may be most effective in the spring or when the first seed head appears because translocation to the roots is likely at that time.

Integrated management: A review suggests that mowing or grazing combined with prescribed fire treatments may decrease common velvetgrass dominance [113].

Restoration Potential: With the right combination of control measures, it should be possible to eliminate velvet grass from selected areas. Constant monitoring of previously infected sites will be necessary since it can quickly become dominant on a site.

Management Requirements: Control of velvet grass requires active management once it becomes established in an area.

MECHANICAL CONTROL

Hoeing or hand pulling HOLCUS LANATUS plants are effective, albeit time-consuming, control methods. Intensive mowing or grazing suppresses the establishment and spread of velvet grass on a site (Grime and Lloyd 1973). However, low intensity grazing may allow invasion of pastures (Thompson and Turkington 1988). Haggar and Elliot (1978) found that H. LANATUS increased from 18 to 43% of the total herbage over four years at a low stocking rate. The effects of grazing on velvet grass can be influenced by associated species and nutrient status (Thompson and Turkington 1988). HOLCUS LANATUS is also susceptible to damage from heavy treading by stock (Roberts 1982).

Control of the grass is most effective when it is cut prior to seed dispersal (Bakker et al. 1980). Elimination of the plant will be difficult, however, due to its perennial nature and ability to regenerate from decumbent tillers (Watt and Haggar 1980a) even when cut to only 2 cm above the ground surface (Anonymous 1976). The enormous HOLCUS LANATUS seed bank means that the grass can quickly re-establish itself after any disturbance, so careful monitoring is needed (Roberts 1982).

HOLCUS LANATUS is considered a "low-fertility species" (Scott and Hardacre 1974). Studies in Oregon (Hart and McGuire 1963) showed that nitrogen application reduced relative abundance. However, Haggar (1976) and Elliot et al. (1974) documented a positive response to nitrogen fertilization.

Lack of irrigation (Watt and Haggar 1980b), burning (Grime and Lloyd 1973), and ploughing (Beddows 1961) have reduced relative abundance of H. LANATUS in pastures.

PRESCRIBED BURNING

Burning has a deleterious effect on velvet grass under some condi- tions. It is particularly effective in controlling the grass when combined with grazing (Grime and Lloyd 1973).

BIOLOGICAL CONTROL

Very little research has been done on controlling HOLCUS LANATUS with insects or phytotoxins. Most insect predators of the weed also attack other, more desirable grass species (Charles Turner 1985). No list of insects preying on HOLCUS LANATUS exists for Canada (Thompson and Turkington 1988). However, Beddows (1961) has compiled one for British populations which includes various species of leafhoppers, butterflies, and flies.

HOLCUS species are hosts to the fungus GAEUMANNOMYCES GRAMINIS which also infects wheat and barley, so it is unlikely to be used to control HOLCUS (Roberts 1982). HOLCUS LANATUS is a host to the club-root disease PLASMODIOPHORA BRASSICAE which also infects several important vegetable crops (Webb 1949). Toms (1964) and Conners (1967) listed the following plant virus and fungus parasites from Canada: twist (DILOPHOSPORA ALOPECURI), leafsmut (ENTYLOMA DACTYLIDIS), crown rust (PUCCINEA CORONATA), rust (P. RECONDITA), stripesmut (USTILAGO STRIIFORMIS), EPICHLOE TYPHINA, and HELMINTHOSPORIUM TRISEPTUM. A list of fungi that infect velvet grass in Britain are compiled in Beddows (1961).

CHEMICAL CONTROL

HOLCUS LANATUS is susceptible to a variety of herbicides (Fryer and Makepeace 1978, Kirkham et al. 1982, and Watt 1983), but not all are safe or legal to use. Near streams or lakes, particular caution should be taken when using herbicides. Prior to using any herbicide, check with the County Agricultural Commissioner to determine which chemicals are legal to use in a given situation. The labels should also give more precise information on proper mixing and safety precautions. A certified Pest Control Applicator should be hired for large jobs or those requiring nonselective her- bicides.

Dr. Jim McHenry (1985) of the University of California, Davis, recommends the use of dalapon (Dowcon) to control HOLCUS LANATUS on California preserves. For perennials such as velvet grass, spraying should be done in spring when the seed head first appears. This results in better translocation of the herbicide into the root system. Dalapon will also kill other grasses and can kill some broadleaf species. It should be applied at a rate of 1 quart/100 gallons. Haggar and Elliot (1978) suggest biennial application of dalapon to control HOLCUS LANATUS. Dalapon is cleared for use on rights-of-way and for spot treatment of grazed areas. It is lethal to 50% of tested animals (LD50) at 9330 mg/kg of body weight but is classified as being of "relatively no hazard." The herbicide will persist in the soil for up to 8 weeks.

There are several petroleum oils used for weed control. The herbicidal use of oils depends on their chemical and physical properties. Most contact oils evaporate slowly and owe their plant toxicity to their high content of aromatic compounds. Spraying oil on HOLCUS LANATUS will be effective only if the entire plant is coated.

Herbicides can be applied uniformly over an area of large infesta- tions or by spot spraying individual plants. Dr. McHenry recommends using a flat-fan nozzle (Spraying Systems Co. #8003 or #8004 nozzle tip), rather than the cone nozzles available on most garden sprayers. Cone sprayers produce greater atomization of the chemicals and increase the chance of drift into unwanted areas. Spraying should be done on calm days to dry plants, as dew or rain will tend to dilute the herbicide reducing its effectiveness. When spraying large areas, a horizontal boom (6-8 feet long) made from aluminum tubing will improve herbicide coverage.

Management Programs: HOLCUS LANATUS is present on the Northern California Coast Range Preserve (NCCRP). It is not a major problem species but is present along roads in wet portions of several of the meadows. Hand pulling of the plants and removal of the flowering heads has decreased the size of some of the infestations. Prescribed burning has not been used due to potential fire control problems.

Contact: Peter Steel, Caretaker NCCRP 42101 Wilderness Lodge Road Branscomb, CA 95417 (707) 984-6653

Monitoring Programs: Monitoring programs are ongoing at the following Oregon TNC preserves: Willow Creek, Cascade Head, Wren Prairie, and Camassia Plateau. For further information, contact:

Cathy Macdonald, Land Steward The Nature Conservancy Oregon Field Office 1205 25th Avenue Portland, OR 97210 (503) 228-9561

Management Research Needs: Much additional research is needed on obligate parasites and pathogens of HOLCUS LANATUS before any viable biocontrol measures can be developed. Prescribed burning is a relatively effective control technique in Europe, but more information should be obtained on its use as a control method.

Stewardship Overview: HOLCUS LANATUS is a perennial grass, native to Europe, that was brought into California as forage. It escaped from cultivation and has become a weed species, particularly in the California Coast Ranges. Velvet grass frequently occurs on poor, moist soils. It is a prolific seeder and can exist in the seed bank in large numbers. It can also reproduce from decumbent tillers. HOLCUS LANATUS is an aggressive weed and can become dominant if not controlled. The most effective control measure is physical removal by hand pulling or hoeing. Mowing or grazing used in combination with prescribed burning may also reduce the plant's dominance.