DistributionRead full entry
DistributionMore 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 ),, and soon after its introduction, common barrberry escaped from cultivation. Soon after its introduction and escape, common barberry was linked with failing wheat crops . 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 ). Some suggest that common barberry has been "virtually exterminated in the United States" , 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 . Large common barberry populations and infestations occur primarily in Ontario and Quebec in Canada  and are scattered through the northeastern United States [2,60,75]. Populations are especially persistent along the Atlantic Coast . 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 ). 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 ). Common barberry was considered a weed in Massachusetts by 1754 . 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 .
- Since at least 1821, common barberry occurred in Pennsylvania's Wyoming County (and perhaps others) .
- In 1850 in Iowa, common barberry was planted as an ornamental and as a hedge to contain livestock .
- In 1885, common barberry was considered abundant in Tottenville, New York .
- As of 1886, common barberry was reported in Summit County, Ohio .
- By 1902, common barberry was occasional along the Quinnipiac River sand plain from New Haven to Meriden, Connecticut .
- In a 1910 Nantucket flora, common barberry was noted along a roadside near Siasconset .
- By the early 1900s, common barberry was widespread in 13 north-central US states (Hutton 1927 cited in ).
- In 1914, common barberry was reported a "considerable distance from any habitation" in Rum Village woods in South Bend, Indiana .
- As of 1921 in Pennsylvania, common barberry was "thoroughly established" in "numerous natural areas"; escaped plants were "exceedingly numerous" in Susquehanna County .
- By 1925, common barberry was common throughout Michigan .
- In a 1937 flora of the Columbia Plateau, common barberry was listed, although not listed in earlier floras from 1892, 1901, or 1914 .
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 . 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 ). When common barberry grows near cereal crops (<330 feet (100 m) away) (Roelfs 1985 cited in ), it can support the development of new genotypes able to adapt and attack rust-resistant crops (Leonard 2001 cited in ). 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 , 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 . 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 .
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 . Between 1935 and 1950, there were 150,087,197 common barberry or American barberry (B. canadensis) shrubs destroyed in West Virginia . By 1956, nearly 500 million barberry shrubs were killed on 149,318 properties in 19 states . Widespread barberry eradication was "gradually phased out" by 1980 . 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 .
- Early USDA records reported common barberry scattered throughout Colorado, but by 1964, it was limited to the north-central part of the state ; as of 1996, common barberry occurred only on the Enchanted Mesa near Boulder because of "deliberate extermination" from wheat-growing areas .
- Although widely planted in the Great Plains, no common barberry plants were found by Stephens  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 .
- As of 1985, common barberry was considered "largely eradicated" from Michigan .
- Although reported from 20 Ohio counties prior to USDA eradication efforts, common barberry was uncommon in the state in 1961 .
- As of 1959, common barberry still occurred in "fair numbers" in Wisconsin; disturbances associated with eradication were considered beneficial to common barberry seedling establishment .
- 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 .
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 . 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" .