|Crab Apple||(Malus sp.)||%*|
| fertilize once in the spring; if you fertilize during the summer it could dehydrate the plant; might show a little windburn on the leaves; needs a winter chill to do well and develop flower buds; the flowers develop out of last year’s growth; needs full-day filtered sun; water only when showing wilt: watering every day unnecessarily can quickly kill the plant due to root rot; prefers being in a deeper pot for cool roots; needs a period of freezing weather to stay healthy and look its best; keep soil away from direct contact with the bark of the trunk; can be a very fast grower; keep upwind from junipers or keep as far away as possible from junipers — bonsai or landscape specimens — because junipers can spread rust infection to crab apples. [Rosaceae; Rosales]
General information: Apples and Crabapples are best grown in a sunny location with good air circulation and have no particular soil preferences, except soil should be well-drained. Root pruned trees transplant most easily. Tree size, flower color, fruit color, and growth and branching habit vary considerably with the cultivar grown but many grow about 20 feet tall and wide. A few Crabapples have good fall color and double-flowered types hold blossoms longer than single-flowered cultivars. Some Crabapples are alternate bearers, blooming heavily only every other year. Crabapples are grown for their showy flowers and attractive, brightly-colored fruit.
Apples and crabapples come in a profusion of varieties, most bearing lovely flowers and attractive, sometimes edible, fruit. They have alternate, toothed leaves, bear flowers in early to mid spring, and set fruit in late summer to early fall.
Malus is a very popular traditional bonsai due to its flowers of seemingly infinite variety and lovliness. Crabapple is much loved for its attractive fruit and small leaves. Apples make excellent, if rarely seen, bonsai, but are only suitable for large sized trees.
Lighting: Full sun or semi-shade; needs protection from full summer sun.
Temperature: Zones 4 through 8A.
Watering: Moderate – do not allow the soil to dry out completely. Requires plenty of water when fruiting, or the apples will shrivel and drop. Do not mist, as this encourages mildew.
Feeding: Resnick says weekly in spring-early fall, using dilute manure tea or general purpose fertilizer. Tomlinson recommends discontinuing feeding from the beginning of flowering until the fruits are set, to discourage leafy growth that will occur at the expense of fruits and flowers. Most texts encourage heavy feeding to provide nutrients for fruit and flower production. Simon and Schuster’s and Murata disagree with this practice, preferring to feed sparingly to reduce the rapid growth of the tree. Feeding is recommended at 20-30 day intervals for M. halliana and every 15-20 days for M. pumila. A good sprinkling of bonemeal in the fall promotes fruiting.
Pruning and wiring: Prune sub-branches by mid-August, if you wish to encourage flower bud formation instead of leaf and stem growth. Tips can be pruned as needed, reducing new shoots to two buds. In general, wiring can be done from spring to autumn, protecting the bark. Simon and Schuster’s recommends wiring M. pumila from spring to summer only. It is wise to wait a few months to wire crabapples after repotting. Suitable for all sizes, but for shohin, pick varieties with especially small fruit. Does not work well styled as cascade or broom.
Fruiting puts stress on crabapple bonsai. Fruit should be thinned out considerably, and Owen recommends allowing the bonsai to rest one year in three, removing all the fruit.
Propagation: From seed (requires cold pre-treatment) or air- layering. Crabapples are commonly propagated by grafting, but for bonsai use, care must be taken that a specimen does not exhibit an ugly graft scar. Crabapples can be grown from root cuttings (see “Creating Crabaple Bonsai from Root Cutings,” in “International Bonsai” 1994/issue 1.) Many crabapples also sucker up from the roots, and the suckers may be seperated from the roots in the fall or in the following spring from their formation. Brent provides extensive information on cuttings from young crabapple growth, which is quote directly:
Repotting: In early spring after flowering, or in early autumn. Repot every 1-2 years; M. halliana may require yearly repotting. Crabapples need root space, so a deep pot should be used. Likes well-drained, slightly alkaline soil.
Pests and diseases: Pests: Aphids infest branch tips and suck plant juices, and are quite common. They can deform newly emerging foliage and secret honey dew creating a sticky mess beneath the tree, but will not kill the tree.
Fall webworm makes nests on the branches and feeds on foliage inside the nest. Small nests can be pruned out or sprayed with Bacillus thuringiensis. Controlling severe infestations may require other chemicals.
Scales of various types are controlled with horticultural oil.
Borers can be a problem on stressed trees.
Mites are too small to see easily so they can cause much foliage discoloration before being detected. Mites can be controlled to a degree with horticultural oil, but other chemicals are often required by the time mites are detected. The mite infestation can also be severe by the time foliage chlorosis or bronzing is evident.
Eastern tent caterpillar builds tents or nests in trees in early summer or late spring. Feeding occurs on foliage outside the nest. Defoliation can be extensive if infestation is severe, and repeated defoliations for several years can weaken trees. Small nests can be removed by pruning them from the tree. Spray with Bacillus thuringiensis or other approved chemical. Do not burn nests while they are still in the tree.
Diseases: Many selections are fairly susceptible to disease. Select from the disease-resistant ones.
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. Infected fruits have black, slightly raised spots. Use resistant varieties to help avoid this severe problem.
Fire blight susceptible trees have blighted branch tips, particularly when the tree is growing rapidly. 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 since severe infections on susceptible trees can kill the tree.
Powdery mildew coats leaves with white fungal growth resembling powder.
Cedar apple rust causes brown to rusty-orange spots on the leaves. Badly spotted leaves fall prematurely, and defoliation can be heavy. Redcedars (Juniperus virginiana) are the alternate host. Crabapples are subject to several canker diseases. Prune out infected branches, avoid unnecessary wounding, and keep trees healthy.
Some species suitable for bonsai:
Compiled by Sabrina Caine