European barberry (Invasive Plants of Maryland)

European barberry

Berberis vulgaris

Summary ⁸

Berberis vulgaris, also known as common barberry, European barberry or simply barberry, is a shrub in the genus Berberis. It produces edible but sharply acidic berries, which people in many countries eat as a tart and refreshing fruit.

Distribution ⁹

More info for the terms: natural, shrubs

Common barberry is a nonnative plant in North America. Its native range is Asia's middle and western mountains, and it is widely introduced throughout Europe [44,77]. Common barberry was brought to North America in the 1600s by early New England settlers (Josselyn 1672 cited in [55]),[44], and soon after its introduction, common barrberry escaped from cultivation. Soon after its introduction and escape, common barberry was linked with failing wheat crops [27]. Programs to eliminate and restrict planting of common barberry in North America began in the 18th century, but large-scale cooperative eradication did not occur until the early 1900s. Widespread eradication led to a dramatic decline in common barberry abundance, and common barberry's distribution today is largely the result of successes and failures in eradication (Roelfs 1982 cited in [27]). Some suggest that common barberry has been "virtually exterminated in the United States" [77], but populations persist in the eastern Great Plains, Great Lakes states, northeastern United States, and southeastern Canada. Populations also remain in Idaho, Montana, British Columbia, and Colorado [27]. Large common barberry populations and infestations occur primarily in Ontario and Quebec in Canada [77] and are scattered through the northeastern United States [2,60,75]. Populations are especially persistent along the Atlantic Coast [62]. Flora of North America provides a distributional map of common barberry.

Introduction and spread in North America: European settlers likely brought common barberry to New England because of its ornamental, food, and medicinal uses [44,57]. Common barberry was growing in early New England settlements by 1671 (Josselyn 1672 cited in [55]). In the 18th and 19th centuries, common barberry was commonly planted as a hedge and as a source of jam and yellow dye. Plants frequently escaped cultivation and established in natural areas in eastern North America (Roelfs 1982 cited in [27]). Common barberry was considered a weed in Massachusetts by 1754 [77]. Below is a sporadic timeline that provides information about the spread of common barberry in North America:

19th-century catalogs offering common barberry seeds or cuttings were available in New York, Massachusetts, Pennsylvania, Maryland, North Carolina, Ohio, Illinois, Indiana, Wisconsin, and California; common barberry was sold in the United States by at least 1841 [56].
Since at least 1821, common barberry occurred in Pennsylvania's Wyoming County (and perhaps others) [44].
In 1850 in Iowa, common barberry was planted as an ornamental and as a hedge to contain livestock [22].
In 1885, common barberry was considered abundant in Tottenville, New York [39].
As of 1886, common barberry was reported in Summit County, Ohio [19].
By 1902, common barberry was occasional along the Quinnipiac River sand plain from New Haven to Meriden, Connecticut [9].
In a 1910 Nantucket flora, common barberry was noted along a roadside near Siasconset [6].
By the early 1900s, common barberry was widespread in 13 north-central US states (Hutton 1927 cited in [57]).
In 1914, common barberry was reported a "considerable distance from any habitation" in Rum Village woods in South Bend, Indiana [68].
As of 1921 in Pennsylvania, common barberry was "thoroughly established" in "numerous natural areas"; escaped plants were "exceedingly numerous" in Susquehanna County [44].
By 1925, common barberry was common throughout Michigan [100].
In a 1937 flora of the Columbia Plateau, common barberry was listed, although not listed in earlier floras from 1892, 1901, or 1914 [54].

Eradication efforts and effects on local distributions: Soon after the introduction and escape of common barberry in New England, colonists determined it was responsible for dramatic reductions in wheat crop yields [28]. Common barberry is an alternate host for cereal stem rust (Puccinia graminis). As a host, common barberry provides an inoculum source and a sexual reproduction site for stem rust (Leonard 2001 cited in [71]). When common barberry grows near cereal crops (<330 feet (100 m) away) (Roelfs 1985 cited in [71]), it can support the development of new genotypes able to adapt and attack rust-resistant crops (Leonard 2001 cited in [71]). Earlier reports suggested that common barberry in urban areas was also able to spread stem rust to other grasses that eventually passed it on to wheat crops [80], suggesting there was no safe distance between common barberry and cereal crops. During epidemic stem rust outbreaks, wheat yield losses up to 70% were reported [71]. In 1916, stem rust was considered the principal reason for a 200 million bushel reduction in wheat yields for Minnesota, North Dakota, South Dakota, and Montana [80].

In the 18th century, the New England colonists of Connecticut, Massachusetts, and Rhode Island wrote laws restricting the planting and spread of common barberry. Over time many other states developed laws against the sale, transport, and planting of new barberry (Berberis spp.) plants and for the removal of established plants. It was not until 1918, after "devastating" wheat losses to stem rust, that federal laws and funding were devoted to eradication. Eradication projects and funding between 1918 and 1942 led to the destruction of 309,645,502 landscape, escaped, and nursery plants from the 964,000 mile² (2,497,000 km²) eradication area that included nearly all of the North American spring-wheat growing areas [28]. Between 1935 and 1950, there were 150,087,197 common barberry or American barberry (B. canadensis) shrubs destroyed in West Virginia [84]. By 1956, nearly 500 million barberry shrubs were killed on 149,318 properties in 19 states [12]. Widespread barberry eradication was "gradually phased out" by 1980 [71]. It is important to note that scattered common barberry populations persist in several areas of North America, and the potential for long-distance seed dispersal by birds makes monitoring and early detection of common barberry important to long-term control.

General effects of eradication efforts on common barberry distribution in North America are summarized below:

In New Mexico in 1997, common barberry was far less common than it once was because of the USDA eradication program [15].
Early USDA records reported common barberry scattered throughout Colorado, but by 1964, it was limited to the north-central part of the state [35]; as of 1996, common barberry occurred only on the Enchanted Mesa near Boulder because of "deliberate extermination" from wheat-growing areas [97].
Although widely planted in the Great Plains, no common barberry plants were found by Stephens [82] while conducting plant surveys for a North Central Plains flora (covering North Dakota, South Dakota, Nebraska, and Kansas); common barberry was not reported in the Flora of the Great Plains printed in 1986 [31].
As of 1985, common barberry was considered "largely eradicated" from Michigan [96].
Although reported from 20 Ohio counties prior to USDA eradication efforts, common barberry was uncommon in the state in 1961 [8].
As of 1959, common barberry still occurred in "fair numbers" in Wisconsin; disturbances associated with eradication were considered beneficial to common barberry seedling establishment [20].
In the 1970s, common barberry was planted on acidic surface-mine spoils on 2 sites in eastern Kentucky; bareroot stock was obtained from an unidentified nursery [73].

Although common barberry populations were often reduced or eliminated by eradication efforts, some post-eradication surveys indicate substantial spread from untreated or surviving plants. In Minnesota, researchers surveyed 72 sites treated by federal eradication teams. Surveyed sites had a "high potential" for reemergence, once supported large common barberry populations, and/or occurred in major grain production areas. Of the 72 sites, 32 had common barberry populations supporting 1 to 300 individuals [71]. In eastern Ontario and western Quebec, a 20-year eradication program (initiated in 1964) did not eliminate all common barberry. In the first 5 years of the program, population decreases of 90% or more were common. Eradication was successful at only a few sites where shrubs were initially rare and/or herbicide treatments were repeated for several successive years. Since 1980, there have been few treatments, and common barberry populations have increased "considerably" [18].

Impacts and control ¹⁰

More info for the terms: fire management, invasive species, natural, prescribed fire, rhizome, shrubs

Impacts: The most widespread and commonly described impact of common barberry's invasion is its ability to act as an alternate host for cereal stem rusts. As an alternate host, common barberry can support the development of new genotypes able to attack rust-resistant crops (Leonard 2001 cited in [71]). The wheat rust (Puccinia graminis) can severely reduce the yield of wheat, oat, and barley crops [77]. Once common barberry was removed from oat production areas of Pennsylvania and wheat production areas of Virginia, crop yields increased by an average of 123% and 68%, respectively [12]. For more on stem rust and common barberry eradication, see Eradication efforts and effects on local distributions.

Discussions and studies on the impacts of common barberry populations in natural areas were generally lacking as of 2009. The Massachusetts Invasive Plant Advisory Group reports that common barberry has a high potential for spread [60], and Vermont's Agency of Natural Resources suggests that common barberry could displace native vegetation on a localized or widespread scale [94]. See the following sections for additional information on common barberry's potential for spread: Seed dispersal, Seedling establishment, and Vegetative regeneration.

Studies conducted in Ontario indicate that common barberry is often spread along fence rows, throughout pastures, and along river corridors. During a 1951 survey of southwestern Ontario, large and spreading common barberry populations were reported in Elgin, Grey, Kent, Waterloo, and Wellington counties. In Waterloo and Wellington counties, thousands of common barberry shrubs occurred along the Grand and Eramosa rivers, respectively. Along the Grand River, populations were scattered along a 30-mile stretch. In Grey County, populations were spreading "rapidly" in "rough pasture land". In these pastures, common barberry stands covered several hundred acres [52]. During a 1952 survey in eastern Ontario, large common barberry populations occurred in Grenville, Lanark, Leeds, and Prescott counties. Common barberry populations were most common in pastures, along fence rows, along the St Lawrence and Ottawa rivers, and in open woodlands [67]. Dispersal of common barberry seeds by birds and cattle is likely important to the distribution of shrubs in pastures, along fence lines, and in open woods and riparian areas (see Seed dispersal).

Control: With widespread eradication efforts targeting common barberry, well established and successful control methods may be expected. However, many of the early methods used to reduce common barberry populations were time consuming, labor intensive (see Physical or mechanical control), and/or involved chemical experimentation. Most early eradication methods are not feasible or legal today.

In all cases where invasive species are targeted for control, no matter what method is employed, the potential for other invasive species to fill their void must be considered [11]. Control of biotic invasions is most effective when it employs a long-term, ecosystem-wide strategy rather than a tactical approach focused on battling individual invaders [58].

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

Prevention: It is commonly argued that the most cost-efficient and effective method of managing invasive species is to prevent their establishment and spread by maintaining "healthy" natural communities 58,78 and by monitoring several times each year [41]. Managing to maintain the integrity of the native plant community and mitigate the factors enhancing ecosystem invasibility is likely to be more effective than managing solely to control the invader [38].

Weed prevention and control can be incorporated into many types of management plans, including those for logging and site preparation, grazing allotments, recreation management, research projects, road building and maintenance, and fire management [90]. See the Guide to noxious weed prevention practices [90] for specific guidelines in preventing the spread of weed seeds and propagules under different management conditions.

Physical or mechanical control: Digging and hand-grubbing were used extensively in early eradication efforts. Effective control using these methods required complete root and rhizome removal. If root and rhizome removal was not done carefully and meticulously, sprouts were "almost sure to develop". Roots or rhizomes 1 foot (0.3 m) or more below ground rarely sprouted, but those near the surface sprouted "readily" [86]. Because sprouting was often abundant in areas where barberry was cut, pulled, or dug, eradication officials poured salt in and around the treated areas, which minimized sprouting, but high levels of seedling production often occurred in treated sites (review by [72]).

Common barberry sprouts following cutting [86], and berries from cut stems can still produce seedlings (Atwood 1930 [72]).

Biological control: Currently (2009) there have been no insects or pathogens released to control common barberry. Control by mammalian herbivores (especially cattle) is unlikely, since common barberry seed is dispersed in feces (see Seed dispersal).

Biological control of invasive species has a long history that indicates many factors must be considered before using biological controls. Refer to these sources: [93,98] and the Weed control methods handbook [88] for background information and important considerations for developing and implementing biological control programs.

Chemical control: Herbicides are effective in gaining initial control of a new invasion or a severe infestation, but they are rarely a complete or long-term solution to weed management [13]. See the Weed control methods handbook [88] for considerations on the use of herbicides in natural areas and detailed information on specific chemicals.

In eastern Ontario and western Quebec, a common barberry eradication program using primarily herbicides was initiated in 1964. After 20 years, common barberry was not eradicated. Eradication occurred at only a few sites where shrubs were scarce initially and herbicide treatments were repeated for several years. There have been few herbicide treatments since 1980, and populations have increased "considerably" [18]. In earlier eradication programs, researchers suggested that chemicals applied to the base of the plant where fine, fibrous roots were concentrated would be most effective [86]. However, the effectiveness of this practice in the field was not reported.

Integrated management: Although using a combination of control methods often produces better results, integrated management in common barberry populations was rarely described in the available literature (2009) (see Use of prescribed fire as a control agent).

Sources and Credits

(c) Werner Witte, some rights reserved (CC BY-NC), http://www.flickr.com/photos/43577957@N04/7885875386/
(c) Owen Clarkin, some rights reserved (CC BY-NC), uploaded by Owen Clarkin
(c) Erika Mitchell, some rights reserved (CC BY-NC), uploaded by Erika Mitchell
(c) aabram, some rights reserved (CC BY-NC)
(c) Xavier Béjar, some rights reserved (CC BY-NC-SA), https://www.flickr.com/photos/xbe/19162368626/
(c) Tom Norton, some rights reserved (CC BY), uploaded by Tom Norton
Adapted by Kate Wagner from a work by (c) Wikipedia, some rights reserved (CC BY-SA), http://en.wikipedia.org/wiki/Berberis_vulgaris
Public Domain, http://eol.org/data_objects/24634907
Public Domain, http://eol.org/data_objects/24634924

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