Introduction
Large, leathery, medium to light green, highly lustrous leaves and clusters of extremely fragrant, small, white flowers, completely covering the plant in springtime, make Awabuki sweet viburnum a plant with great potential. The shiny leaves are quite distinctive from the dull, dark green, blunt-tip leaves of the species. For some reason, the species has fallen out of favor as a small tree in recent years, but it is often used as a screen or clipped hedge. Its dense, spreading, evergreen habit makes sweet viburnum suitable for use as a small tree, reaching only about 15 to 20 feet at maturity, with an open, multibranched, rounded canopy. The flowers are often followed by small, showy red berries which are highly ornamental and turn black when ripe. This is a small tree which should be tried, and some nursery operators are beginning to grow it. Thirty-year-old plants grow to about 18 feet tall and wide.
General Information
Scientific name: Viburnum odoratissimum var. awabuki
Pronunciation: vye-BER-num oh-duh-ruh-TISS-ih-mum variety aw-wah-BOO-kee
Common name(s): Awabuki sweet viburnum
Family: Adoxaceae
USDA hardiness zones: 9A through 11 (Figure 2)
Origin: Taiwan and Japan
UF/IFAS Invasive Assessment Status: not considered a problem species at this time, may be recommended
Uses: screen; hedge; specimen; deck or patio; street without sidewalk; container or planter; sidewalk cutout (tree pit); tree lawn 3–4 feet wide; tree lawn 4–6 feet wide; tree lawn > 6 ft wide; highway median; parking lot island < 100 sq ft; parking lot island 100–200 sq ft; parking lot island > 200 sq ft
Description
Height: 15 to 20 feet
Spread: 15 to 20 feet
Crown uniformity: symmetrical
Crown shape: round
Crown density: dense
Growth rate: slow
Texture: coarse
Foliage
Leaf arrangement: opposite/subopposite
Leaf type: simple
Leaf margin: serrate
Leaf shape: elliptic (oval)
Leaf venation: pinnate, bowed, brachidodrome
Leaf type and persistence: broadleaf evergreen, evergreen
Leaf blade length: 3 to 6 inches
Leaf color: dark green wax, thick, and shiny on top, paler green and smooth underneath
Fall color: no color change
Fall characteristic: not showy
Flower
Flower color: white/cream/gray
Flower characteristics: showy; funnel shaped; emerges in clusters on cymes
Flowering: spring to summer
Fruit
Fruit shape: round
Fruit length: less than .5 inch
Fruit covering: fleshy drupes
Fruit color: red, black
Fruit characteristics: attracts birds; showy; fruit/leaves not a litter problem
Trunk and Branches
Trunk/branches: branches droop; not showy; typically multi-trunked; no thorns
Bark: green and reddish, becoming brownish gray with age
Pruning requirement: needed for strong structure
Breakage: resistant
Current year twig color: green
Current year twig thickness: thick
Wood specific gravity: unknown
Culture
Light requirement: full sun, partial sun or partial shade
Soil tolerances: clay; sand; loam; alkaline; acidic; well-drained
Drought tolerance: moderate
Aerosol salt tolerance: unknown
Other
Roots: not a problem
Winter interest: no
Outstanding tree: yes
Ozone sensitivity: unknown
Verticillium wilt susceptibility: susceptible
Pest resistance: resistant to pests/diseases
Use and Management
Sweet viburnum grows quickly in full sun or partial shade on a wide variety of soils. Relatively maintenance-free, sweet viburnum grown as a tree will require only occasional pruning to control size and shape. This would be a good tree for planting along a street where power lines or other obstructions limit overhead space.
The cultivar 'Emerald Lustre' has larger leaves and `Nanum' is a dwarf form.
Propagation is by cuttings or layerings.
Pests
This tree is usually free of pests.
Viburnum aphid is gray to dark green and feeds in clusters at the tips of the branches, causing leaf curl. 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.
Caterpillars eat holes in the new foliage. This may be more troublesome in the nursery than in the landscape.
Thrips, mites, white-fly, bagworms, and sooty mold are also problems, but none are normally serious.
Diseases
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.
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.
Downy mildew and powdery mildew cause a white powdery growth on the leaves.
Reference
Koeser, A. K., Hasing, G., Friedman, M. H., and Irving, R. B. 2015. Trees: North & Central Florida. Gainesville: University of Florida Institute of Food and Agricultural Sciences.