There are approximately 25 species and hundreds if not thousands of named cultivars of deciduous fruit bearing trees and shrubs. Some cultivars are developed to suit warmer or cooler climates, though generally speaking apples do mest in temperate climates. Apples are distinguished from pears by the softer, sometimes hairy, leaf surface. Some are grown mainly for their edible fruit, and others mainly for decorative flowers and smaller coloured fruits that are used for making preserves.
Rarely grown in pots, however there are new dwarf cultivars available that are ideal for small gardens and large tubs (i.e. the ‘Ballerina’ range of apples).
Most prefer a sunny position with some protection from winds, and are best grown in temperate climates. They may grow, but not fruit well in the sub-tropics.
They do best in full sun but will take light shade. Adapts to all but very poor soils, provided drainage is good.
Often planted on a slope in heavier soils, never in a gully.
Mulch plants in sandy soils. Soils should not be subject to water logging and minor nutrient deficiencies may develop on highly alkaline (ie. lime) soil.
Prune annually to shape, maintain vigour and regulate fruiting. Many pruning and training techniques have been tried and used with apples. Hard pruning has long been advocated to help stimulate the development of fruiting spurs. The Central Leader and Modified Central Leader techniques avoid this need for heavy pruning and make use of the tree's natural growth habit to encourage spurs. In this case, pruning is only carried out to control the general size, shape and vigor of the tree. Most can be readily espaliered.
Important pest and disease problems to watch for include: Codling Moth, Woolly Aphis, Light Brown Apple Moth, Apple Scab and Black Spot. Propagated generally by budding/grafting onto seedling rootstocks.
Thousands of named cultivars (both crop and ornamental species) have been developed over the centuries. Most grow around 4-5m tall, though some are lower and others taller.
Cropping cultivars have been bred for their large edible fruits; whereas ornamental varieties have been bred for their flowers or colourful fruits (which are usually smaller, but in large numbers). Crab apples are any species or hybrids which are bred and grown for their decorative fruits rather than for eating. Dwarfing rootstocks are sometimes used to keep otherwise taller trees from growing too large (e.g. a cultivar that normally grows to 6m may only grow to 4m on a dwarfing rootstock).
Apples are extremely versatile and will grow under a wide range of conditions. They do best in cooler temperate climates but will fruit in warmer areas provided the winters are cold. Apples require 1200 to 1500 hours of cold weather for good fruit set. Tropical varieties have been bred which will bear fruit in places that have milder winters (eg. some parts of the subtropics); though the results cannot be expected to be as good as in temperate climates. If the winter is cold enough, a lot of fruit will set, and thinning may be needed to prevent fruit drop during the growing season. Summer pruning and thinning of clusters may be necessary with red varieties for the development of proper skin colour.
ORNAMENTAL APPLE TREES
Origin: Europe, Asia, North America; 35 species.
Appearance: Deciduous trees and shrubs, attractive bowl-shaped mildly fragrant flowers in whites through to pinks and reds, five petals and yellow stamens, edible fruits, mostly small trees.
Culture: Grows in most freely draining soils, full sun or part shade, mulch and fertilise young trees in late winter. Prune over winter to encourage spur systems and strong young growth (flowers and fruit occur here), cut back straggly trees after flowering.
Propagation: Named cultivars are commonly grafted on seedlings; Seed needs stratification (period in cold) to induce germination
Health: Hardy; crab apples are largely pest-free, but can be attacked by problems that affect fruit apples, including: leaf hoppers, red spider mites, caterpillars, capsid bugs, aphids, codling moth and apple sawfly. Likewise, diseases include: apple mildew, apple scab, and mosaic virus. Honey fungus may kill trees.
Uses: Shade tree, ornamental feature tree for flowers (some are doubles) or attractive fruits, autumn foliage, edible fruit production, shrub border, standard.
Many named cultivars exist of both ornamental and fruiting types; varying in flower appearance, fruit size, colour and taste; and in foliage effect.
M. floribunda: To 8 metres tall, rose to carmine coloured flowers.
M. ioensis: To 9 or 10 metres tall, white or pinkish flowers.
M. pumila (syn. M. domestica): Most commercial eating apples developed from this species. It is similar to M. sylvestris but not thorny.
M. sylvestris: Cultivars vary from 2 to 12 metres tall, often thorny stems.
(Note: At times, some authorities have considered Malus to be a subgenus of Pyrus).
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