Introduction
One of the many selections of flowering crabapple, Siberian crabapple is a deciduous tree with a rounded canopy of spreading branches, ultimately reaching 20 to 50 feet in height. The very fragrant blooms appear in great abundance, and the single, 1.5-inch-diameter flowers are pink when in bud but open up to white. The blooms are followed in fall by long-lasting, bright red, or yellow fruits which are very popular with the birds or can be used to make a delicious jelly. Some selections make a mess of a walk or driveway as the fruit falls in the fall and winter.
General Information
Scientific name: Malus baccata
Pronunciation: MAY-lus back-AY-tuh
Common name(s): Siberian crabapple
Family: Rosaceae
USDA hardiness zones: 2A through 7B (Fig. 2)
Origin: not native to North America
Invasive potential: little invasive potential
Uses: espalier; street without sidewalk; specimen; container or planter; trained as a standard; parking lot island < 100 sq ft; parking lot island 100-200 sq ft; parking lot island > 200 sq ft; tree lawn 3-4 feet wide; tree lawn 4-6 feet wide; tree lawn > 6 ft wide; highway median; bonsai
Availability: not native to North America
Description
Height: 20 to 35 feet
Spread: 15 to 25 feet
Crown uniformity: symmetrical
Crown shape: round, spreading
Crown density: dense
Growth rate: moderate
Texture: medium
Foliage
Leaf arrangement: alternate (Fig. 3)
Leaf type: simple
Leaf margin: serrate, serrulate, crenate
Leaf shape: elliptic (oval)
Leaf venation: pinnate, brachidodrome
Leaf type and persistence: deciduous
Leaf blade length: less than 2 inches, 2 to 4 inches
Leaf color: green
Fall color: yellow
Fall characteristic: not showy
Flower
Flower color: white/cream/gray
Flower characteristics: very showy
Fruit
Fruit shape: round
Fruit length: less than .5 inch
Fruit covering: fleshy
Fruit color: red, yellow
Fruit characteristics: attracts squirrels/mammals; showy; fruit/leaves not a litter problem
Trunk and Branches
Trunk/bark/branches: branches droop; not showy; typically multi-trunked; thorns
Pruning requirement: little required
Breakage: resistant
Current year twig color: brown
Current year twig thickness: thin, medium
Wood specific gravity: unknown
Culture
Light requirement: full sun
Soil tolerances: sand; loam; clay; acidic; alkaline; well-drained; occasionally wet
Drought tolerance: moderate
Aerosol salt tolerance: low
Other
Roots: not a problem
Winter interest: yes
Outstanding tree: no
Ozone sensitivity: sensitive
Verticillium wilt susceptibility: resistant
Pest resistance: resistant to pests/diseases
Use and Management
Pruning should be completed by late spring to ensure next year's flower buds are not removed. Trees normally branch low, but train to develop a central trunk if planting along a street or other area where pedestrian or vehicle clearance is required. Some low branches will probably need removing as the tree grows to allow for clearance. Crabapples need occasional thinning to eliminate water sprouts or crossed-branches and to open up the crown, to help prevent leaf diseases. The crown is normally full of foliage creating dense shade.
Crabapple selections with upright branches make great street trees where a small tree is needed. Do not plant those with a low-branching, spreading form along a street or in a parking lot as the tree will require regular pruning and will not be able to develop properly. But the low-branching types make wonderful specimens where there is adequate room for horizontal spread, or in a wide highway median.
Siberian crabapple grows in moist, well-drained, acid soil in full sun locations for best flowering and disease resistance. It is not extremely drought tolerant and not really adapted to alkaline soil, and not for extreme west Texas. Grows very well on the Texas panhandle, where there are a number of apple orchards.
The cultivar 'Columnaris' grows in USDA hardiness zones 4 to 8a, has single white blooms, upright columnar growth, 30 feet high and eight feet wide, yellow fruit blushed red, reportedly very susceptible to scab and fireblight; 'Jackii', USDA hardiness zones 2 to 7, upright-spreading, grows 20 to 30 feet high and 15 feet wide, has pink-tinged white buds, purplish or maroon-red fruit, is reportedly disease-resistant.\ There are many cultivars—be sure to select those which are disease-resistant. Contact the Ornamental Crabapple Society, Morton Arboretum, Lisle, Illinois 60532 for more information on Crabapples.
Trees produced on their own roots are preferred. Grafted or budded trees are more uniform in habit and performance than seedling trees.
Pests
Aphids infest branch tips and suck plant juices.
Fall webworm makes nests on the branches and feeds inside the nest. Small nests can be pruned out or sprayed with Bacillus thuringiensis.
Scales of various types are usually controlled with horticultural oil.
Mites are too small to see easily so can cause much foliage discoloration before being detected. Mites are usually controlled with horticultural oil.
Tent caterpillar builds tents or nests in trees in early summer or late spring. Feeding occurs outside the nest. Small nests are pruned out or simply pull the nest out of the tree and crush the caterpillars. Do not burn nests while they are still in the tree since this can cause severe damage to the tree and could start an uncontrolled fire.
Diseases
Siberian crabapple is susceptible to scab. Infection takes place early in the season and dark olive green spots appear on the leaves. In late summer the infected leaves fall off when they turn yellow with black, spots. Infected fruits have black, slightly raised spots. Use resistant varieties.
Fire blight susceptible trees have blighted branch tips. Leaves on infected branch tips turn brown or black, droop, and hang on the branches. The leaves look scorched as by a fire. The trunk and main branches become infected when the bacteria are washed down the branches. Cankers form and are separated from adjacent healthy bark by a crack. The infected bark may be shredded. Use resistant cultivars when available, and do not over-fertilize.
Powdery mildew is a fungus which coats leaves with mycelia resembling white powder.
Rust causes brown to rusty-orange spots on the leaves. Badly spotted leaves fall prematurely. Redcedars are the alternate host.
Crabapples are subject to several canker diseases. Prune out infected branches, avoid unnecessary wounding, and keep trees healthy.
