Malus

Apple, Crab Apple, Culinary Apple, Eating Apples, Wild Apples

Crabapple tree (Malus) is a woody plant. Moreover, the tree shape of crabapple tree is relatively large, and the yield is relatively large in the later stage. Crabapple tree planting technology is not very mature. Today, we will briefly explain the planting conditions and propagation methods of crabapple trees.

I. Appearance and Characteristics 

Malus ( or ) is a genus of about 32–57 species of small deciduous trees or shrubs in the family Rosaceae, including the domesticated orchard apple, crab apples and wild apples.

The genus is native to the temperate zone of the Northern Hemisphere.

Apple trees are typically 4–12 metres (13–39 feet) talI at maturity, with a dense, twiggy crown. The leaves are 3–10 centimetres (1+1⁄4–4 inches) long, alternate, simple, with a serrated margin. The flowers are borne in corymbs, and have five petals, which may be white, pink, or red, and are perfect, with usually red stamens that produce copious pollen, and a half-inferior ovary; flowering occurs in the spring after 50–80 growing degree days (varying greatly according to subspecies and cultivar).

Many apples require cross-pollination between individuals by insects (typically bees, which freely visit the flowers for both nectar and pollen); these are called self-sterile, so self-pollination is impossible, making pollinating insects essential.

A number of cultivars are self-pollinating, such as ‘Granny Smith’ and ‘Golden Delicious’, but are considerably fewer in number compared to their cross-pollination dependent counterparts.

Several Malus species, including domestic apples, hybridize freely.

The fruit is a globose pome, varying in size from 1–4 cm (1⁄2–1+1⁄2 in) in diameter in most of the wild species, to 6 cm (2+1⁄4 in) in M. sylvestris sieversii, 8 cm (3 in) in M. domestica, and even larger in certain cultivated orchard apples. The center of the fruit contains five carpels arranged star-like, each containing one or two seeds.

The seeds contain cyanide compounds.

II. How to Grow and Care

Sunlight

Malus thrives in temperate regions where it can access full sunlight for ideal growth and health. Optimal lighting for malus involves direct exposure to at least 6-8 hours of sunlight daily. This strong light is crucial for robust photosynthesis, necessary for energy production, and supports healthy flowering and fruiting cycles. In settings where natural light is insufficient, such as indoors or in greenhouses, supplemental lighting systems can provide the high light intensity malus required. Ensuring malus receives ample light is essential for optimal growth and crop yield.

Watering

Once established, your crabapple tree should not need extra watering unless there is an exceptionally dry season. They tend to be drought-tolerant, but if the rainfall for your area is particularly low, give your tree a deep watering at the base of the tree, in the morning or evening once a week, to keep it healthy. About 1 inch of water per week, through a combination of rainfall and irrigation, is ideal for these trees.

Excessive rainfall can harm the tree’s growth cycle and productivity. You can place a tarp or other barrier over the tree’s roots during rainy periods to keep the soil from getting too soggy.

Soil

When planting, be sure to add plenty of organic soil amendments to give your tree roots a good start. Rich soil with good drainage is ideal, and they prefer a slightly acidic soil pH.

Crabapples do well with natural mulch. If turf lawns surround them, this can make the tree somewhat more susceptible to fungus or pests. Mulch also helps to keep the roots cool and moist in summer if a heatwave arrives.

Fertilizing

Most apple trees don’t need much in the way of fertilizer. A good rule of thumb is to put a small amount of compost around the tree’s roots in the spring and a light application of composted manure in the late fall. Using natural mulch (wood chips or pine bark) can help keep nutrient-rich soil intact.

Pruning

All crabapple trees benefit from regular annual pruning. Dead branches, water sprouts, and smaller new growth can be trimmed at any time, but you may want to wait until after blossom season. If you want to prune branches larger than 1 inch in diameter, it’s best to wait until late fall and use a pruning saw. Pruning during the active growing season can open the tree up to bacteria and insect damage.

An old adage regarding applet tree pruning says you should be able to throw a cat through the branches without hitting any of them. Kindness to cats notwithstanding, this kind of spacious pruning practice allows for good air circulation, which helps reduce disease risks.

Never prune away more than about 20 percent of a tree’s canopy in a single season; with a neglected tree, you should gradually prune it back into shape over the course of several years. Branches that are crossed, or heading in that direction, should be pruned away. The more sunlight that reaches into the center of the tree, the more blooms the tree will produce.

Applewood is fragrant when burned and can also be used for barbecue cooking or smoking to impart flavor.

Propagation

Most named crabapple cultivars are grafted trees, produced by skilled nursery professionals who meld branches from ornamental varieties onto hardier rootstocks. Such a procedure is not practical for most amateurs. While it is certainly possible to take softwood cuttings from your crabapple tree, root them, and grow them into trees, the resulting specimen may not have the hardiness or performance of the parent tree.

Cuttings

The exception to this rule is if you happen to have a pure ungrafted crabapple species, such as Malus floribunda (Japanese crabapple) or Malus mandshurica (Siberian crabapple). If you wish to try propagating your crabapple tree from cuttings, here’s how to do it:

  • During the early growing season, use sharp pruners to clip 8- to 12-inch cuttings from flexible green growth at the tip of the crabapple’s branches.
  • Strip off the lower leaves, then use a sharp knife to scrape off the bark on the bottom 3 inches of the cuttings.
  • Dip the stripped end in rooting hormone, then plant each cutting in a pot filled with moist, coarse sand.
  • Place the cutting in a loosely secured plastic bag to hold in moisture, then set the pot in a sunny location. Keep the cutting moist until roots form, which generally takes about 4 weeks. Check periodically to add moisture, if necessary.
  • When roots have developed, remove the plastic bag and continue to grow the cutting in full sunlight. After another few weeks, you can transplant the sapling into a larger container filled with commercial potting soil.
  • Continue growing the tree in the pot until it is large enough to transplant into the garden. A cutting started in spring should be ready to plant in the garden by fall.

Seed

After crabapple’s seeds mature, there is still a period of dormancy. Crabapple seeds can be stored in wet sand for 80 ~ 100 days, and crabapple seeds can be sown in the early spring of the next year. The seedbed can be sunny, slightly higher and fertile. After applying enough base fertilizer, it can be deeply turned into a fine furrow, which can also be filled with mountain soil and rotten leaf soil; During crabapple tree propagation from seed, we can screen out the seeds, sow them on demand, cover the seedbed with fine sand, spray water through with a fine hole watering can, and cover the seedbed with a thin layer of straw to keep the matrix moist.

Repotting

When we are doing crabapple tree repotting, we first separate the basin soil of the old basin. After taking out the plants, leave a soil ball. The depth of the flower pot for changing the pot of crabapple tree should not be too deep, and then put the plant with a soil ball into the new flower pot and add the prepared soil. The soil should be mixed with garden soil, river sand and rotten leaf soil, which is more suitable for the growth of crabapple tree. After changing the basin, pour water once and keep it in the semi shade for a week.

Overwintering

Within its hardiness range, a crabapple tree generally requires no winter protection, though you may want to shield the trunks of young trees with metal hardware cloth or fencing to prevent damage from rabbits or deer. Young trees can be susceptible to winter sunburn, and the trunks should be wrapped with a commercial-grade tree wrap for their first few years.

The ground beneath a crabapple should be raked clean of leaf and fruit debris before winter sets in, to prevent fungi and insect larvae from overwintering. A thin layer of well-decomposed manure applied in late fall will help enrich the soil for the following spring.

Pests and Diseases

Like other apples in the Malus genus, crabapples are quite susceptible to several diseases, including:

  • Fireblight is caused by the Erwinia amylovora bacterium. Its symptoms are oozing wounds in the tree’s bark and blackened, burned-looking leaves. Good sanitation is key to preventing the spread of the disease, for which there is no cure. Make sure to plant cultivars that are resistant to fireblight, and avoid fertilizing with high-nitrogen fertilizers on lawn areas beneath the tree, which can encourage the bacteria.
  • Rust is caused by several different fungi that cause orange-yellow spots on the leaves. Mild disease usually doesn’t require treatment, but fungicides can be used on severely diseased trees.
  • Apple scab is a fungal disease that causes olive-black spots on the leaves and fruits of the tree. Symptoms usually begin in May or early June. Infection is hastened by prolonged wet weather and sometimes will completely defoliate the tree by late June. Keeping ground areas well-tended can prevent the fungi from overwintering. Properly timed application of fungicide can also help treat the disease.
  • Powdery mildew is a fungal disease that causes a coating of grayish-white powder to cover leaves. Though unattractive, powdery mildew usually does no lasting harm. Regular pruning to improve air circulation often helps prevent powdery mildew.

These are the most common insect pests:

  • Mites are most often identified by the reddish appearance created on the twigs, followed by withering leaves. Smothering the insects and eggs with horticultural oil is the best remedy.
  • Aphids are tiny insects that feed on leaf juices. They are most often identified by the sooty black mold that grows on the sticky honeydew excretions left by the insects. Spraying with horticultural soaps or oils is an effective treatment.
  • Japanese beetles chew holes between the veins of leaves, often giving them a skeletonized look. While carbaryl insecticide will kill beetles, its use often encourages intense mite infestations, so it’s best to ignore Japanese beetle damage unless it is very severe. Beetle infestations are cyclical, and populations do not necessarily persist year after year.
  • Appletree borer is the larval stage of the Chrysobothris femorata beetle. These worms often attack young or sickly trees, boring into the trunk and main branches. Cracks may appear in the bark of the tree. Eventually, the damage can girdle the limb or trunk, killing major branches or the entire tree. There is no control for this pest, other than keeping your tree healthy so it can fight off the damage.

III. Uses and Benefits 

  • Culinary uses

Crabapple fruit is not an important crop in most areas, being extremely sour due to malic acid (which like the genus derives from the Latin name mālum), and in some species woody, so is rarely eaten raw. In some Southeast Asian cultures, they are valued as a sour condiment, sometimes eaten with salt and chilli or shrimp paste.

Some crabapple varieties are an exception to the reputation of being sour, and can be very sweet, such as the ‘Chestnut’ cultivar.

Crabapples are an excellent source of pectin, and their juice can be made into a ruby-coloured preserve with a full, spicy flavour. A small percentage of crabapples in cider makes a more interesting flavour. As Old English Wergulu, the crab apple is one of the nine plants invoked in the pagan Anglo-Saxon Nine Herbs Charm, recorded in the 10th century.

  • Other uses

Applewood gives off a pleasant scent when burned, and smoke from an applewood fire gives an excellent flavour to smoked foods. It is easier to cut when green; dry applewood is exceedingly difficult to carve by hand. It is a good wood for cooking fires because it burns hot and slow, without producing much flame. Applewood is used to make handles of hand saws; in the early 1900s 2,000,000 board feet of applewood were used annually for this purpose.

Malus Details

Common name Apple, Crab Apple, Culinary Apple, Eating Apples, Wild Apples
Botanical name Malus
Plant type Native Plant
Hardiness zone 3a, 3b, 4a, 4b, 5a, 5b, 6a, 6b, 7a, 7b, 8a, 8b, 9a, 9b
Growth rate Medium
Harvest time Fall
Height 14 ft. 0 in. - 44 ft. 0 in.
Width 14 ft. 0 in. - 44 ft. 0 in.
Sunlight Full sun (6 or more hours of direct sunlight a day)
Soil condition Clay
Flower color Pink
Leaf color Green