|Southern Black Haw - Viburnum rufidulum|
Family Adoxaceae. Also called rusty
blackhaw, bluehaw, rusty nannyberry.
USDA hardiness zones: 5B through 9
|A native of the well-drained, upland woods of southeastern North America, Rusty Blackhaw forms a multiple or single-trunked small tree or large shrub, reaching 25 feet in height with an equal spread. Trunks usually grow no thicker than six inches and arch away from the tree, forming a pleasing, vase-shaped crown. Leaves are dark green, three inches long, leathery, and extremely glossy. The tree is covered in springtime with striking five-inch-wide clusters of small, white blooms. These flowers are followed by clusters of dark blue, waxy, one-half-inch-long fruits that are extremely popular with wildlife and will occasionally persist on the plant from September throughout the autumn, if not eaten by wildlife. In fall, Rusty Blackhaw puts on a brilliant display of scarlet red to purple foliage.|
Height: 20 to 25 feet / Spread: 20 to 25 feet / Crown uniformity: irregular outline or silhouette / Crown shape: vase shape / Crown density: moderate / Growth rate: slow
Viburnum is a genus of about 150-175 species of shrubs or small trees that were previously included in the family Caprifoliaceae. Genetic tests by the Angiosperm Phylogeny Group showed that they are correctly classified in the family Adoxaceae. They are native throughout the temperate Northern Hemisphere, with a few species extending into tropical mountain regions in South America and southeast Asia. In Africa, the genus is confined to the Atlas Mountains.
The leaves are opposite, simple, and entire, toothed or lobed; cool temperate species are deciduous, while most of the warm temperate species are evergreen. Some species are densely hairy on the shoots and leaves, with star-shaped hairs. The flowers are produced in corymbs 5-15 cm across, each flower white to cream or pink, small, 3-5 mm across, with five petals, strongly fragrant in some species. The gynoecium has 3 connate carpels with the nectary on top of the gynoecium. Some species also have a fringe of large, showy sterile flowers round the perimeter of the corymb to act as a pollinator target. The fruit is a spherical, oval or somewhat flattened drupe, red to purple, blue, or black, and containing a single seed; some are edible for humans (though many others are mildly poisonous to people). 
Rusty Blackhaw will grow and look nice in full sun or partial shade on any reasonably fertile, well drained soil. The tree grows in a shady spot but forms a more open habit. Flowering is significantly reduced in the shade. although tolerant of drought, it will not tolerate compacted soil. This would be a good tree for planting beneath power lines and in other limited space areas. Useful as a hedge, specimen, or border tree, this deciduous tree adapts well to urban areas. Shoots arise from the root system, sometimes as far out as the dripline. This could be a maintenance problem when planted in a bed of mulch. But sprouts would be routinely cut with regular mowing when planted as a street tree in a lawn. Propagation is by seed or cuttings.
This tree is usually pest-free. Viburnum aphid is gray to dark green and feeds in clusters at the tips of the branches, causing leaf curl. Viburnum opulus is especially susceptible. The insects can be dislodged with high pressure water spray from the garden hose. Inspect the stems of unhealthy-looking plants for possible scale infestations. If found, spray with horticultural oil for some control.
Bacterial leafspot causes round, water-soaked spots on leaves and young stems. These develop into shrunken, brown areas about 1/8-inch in diameter. Destroy infected leaves, if you wish. This is not a problem to be concerned about. Bacterial crown gall forms galls on the lower stems. Do not replant in the same spot. Shoot blight causes grayish to brown decayed spots on the leaves. The spots first appear at the leaf margins, then spread to the rest of the leaf. Infected flower clusters or twigs are killed. A number of fungi cause leaf spots. Rake up and destroy infected leaves. These are usually not a serious problem. Powdery mildew causes a white powdery growth on the leaves, but this Viburnum is usually not affected .
1. Edward F. Gilman and Dennis G. Watson, Univ of Florida ENH-819/ST662 Siebold Viburnum
2. Wikipedia, the free encyclopedia, Viburnum
3. The Arbor Day Foundation, Viburnum
4. USDA, ARS, National Genetic Resources Program. USDA Fact Sheet ST-661 October 1994
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