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Identificaton of common buckthorn and other alternate hosts for crown rust
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Rhamnus cathartica is the principal alternate host for oat crown rust (Pucciniacoronata f. sp. avenae) in the U.S. R. cathartica is a common shrub native to Europe and western and northern Asia that has escaped from cultivation and is common throughout the northern U.S. (east of the Rockies).

Description : Shrub or small tree; leaves elliptic or ovate, 4 to 7 cm long, acute or obtuse, rounded or subcordate at the base, crenate-serrulate, dark green above, light green and usually smooth beneath with 3 to 5 pairs of prominent veins; petioles 6 to 25 mm long; flowers yellowish green, in 2- to 5-flowered clusters, in June; fruits black, subglobose, about 6 mm across, in September and October. (Excerpted from Trees and Shrubs for Northern Gardens by Leon C. Snyder).

Other Potential Alternate Hosts

Rhamnus frangula is native to Europe, western Asia, and northern Africa. However, in Europe it is more often a host of crown rusts of grasses than oats. R. frangula was introduced from Europe into North America in 1860. It escaped from cultivation in the U.S. and Canada. In the U. S., it is most often found in plantings around buildings.

Description: Shrub or small tree; young branchlets hairy; leaves oval or obovate-oblong, 3 to 7 cm. long, acute, rounded or broadly wedge-shaped at base, entire, dark shiny green above, lighter green and often slightly hairy beneath, with 8 or 9 pairs of veins; fall color golden yellow; petioles 6 to 12 mm. long; flowers in clusters of 2 to 10, smooth, in June and July; pedicels 8 to 12 mm. long; fruits globose, 6 mm. across, changing from red to dark purple, 2-seeded, in August and September. (Excerpted from Trees and Shrubs for Northern Gardens by Leon C. Snyder).


Rhamnus alnifolia is a native shrub found from New Brunswick to British Columbia and south to New Jersey and California. It is found in streams and flood plains and is thought to be associated with crown rust (short horn type) on Calamagrostis.

Description: Low, spreading shrub; young branchlets downy; leaves bright green, elliptic to ovate, 4 to 10 cm. long, acute, wedge-shaped at base, unequally crenate-serrate, smooth or slightly hairy on the veins beneath, with 6 to 8 pairs of veins; petioles 5 to 12 mm. long; flowers usually 2 to 3, apetalous, of 5 parts; fruits subglobose, 6 mm. across, black, 3-seeded, in September and October. (Excerpted from Trees and Shrubs for Northern Gardens by Leon C. Snyder).


Berchemia scandens is native to North America. It is rarely reported to be infected with P. coronata, the uredinial and telial hosts have not been determined. It is commonly known as supplejack or rattan vine. B. scandens is found in the Southeast U.S. In Georgia and Alabama it is often found in wet soils, while in Mississippi and Arkansas it is found in wooded uplands.

Description: A glabrous high-climbing shrubby vine, with slender tough terete branches. Leaves ovate or ovate-oblong, 1'-2' long, 1/2'-1' wide, acute, acuminate, or obtuse and cuspidate at the apex, obtuse or somewhat truncate at the base, dark green above, paler beneath, their margins undulate and sometimes slightly revolute; veins 8-12 pairs; petioles slender, 2"-5" long; flowers about 1 1/2" broad, mainly in small terminal panicles; petals acute; style short; drupe 3"-4" long, equaling or shorter than its slender pedicel, its stone crustaceous. (Excerpted from An Illustrated Flora of the Northern United States and Canada by Britton and Brown)


Shepherdia canadensis is native from Newfoundland to Alaska and south to Ohio and New Mexico. It is sometimes used in shrub borders to provide a color contrast. It is a host for pycnia and aecia of Puccinia coronata and P. caricis-sherpherdiae. Bromus ciliatus and B. latiglumis were found to be uredinial and telial hosts for P. coronata found on S. canadensis (Fraser and Ledingham, 1933).

Description: Spreading, unarmed shrub; branchlets brown, scurfy; leaves elliptic to ovate, 2 to 5 cm. long, obtuse, green and sparingly scurfy above, silvery mixed with brown scales beneath; flowers yellow, 4 mm. across, in April; fruits ovoid, 4 to 6 mm. long, yellowish red, insipid, in June and July. (Excerpted from Trees and Shrubs for Northern Gardens by Leon C. Snyder)


Elaeagnus commutata is native from eastern Canada to the Northwest Territory and south to Minnesota and Utah. It is heavily rusted in Canada and is also a host for pycnia and aecia of P. coronata and Puccinia caricis-sherpherdiae. An unidentified species of Calamgrostis was found to be a uredinial and telial host for P. coronata found on E. commutata (Fraser and Ledingham, 1933). Description: Upright stoloniferous shrub; branches reddish brown, thornless; leaves short-petioled, ovate to oblong or ovate-lanceolate, 2 to 10 cm. long, acute or obtuse, wedge-shaped at base, silvery on both surfaces, sometimes with scattered brown scales beneath; flowers 1 to 3, yellow, silvery outside, short-stalked, 1.2 to 1.5 cm. long, fragrant, in June; fruits broad-ellipsoid, 1 cm. long, silvery with dry mealy flesh, in September and October. (Excerpted from Trees and Shrubs for Northern Gardens by Leon C. Snyder)