ROSACEAE

Malus sp. - Flowering Crabapple

There are few other trees or shrubs that approach the beauty of a crabapple tree in full bloom.
Crabapples are valued for their foliage, flowers, fruit, and variations in size and habit.  By using
different varieties, the flowering period can be extended from early May to early June, with colors
ranging from white through purplish red.

The small fruits, borne in the fall, are also effective, with colors of red, yellow, and green.  Other
features of this group are the small size (most less than 25 feet in height) and the variation in growth
habit (rounded, horizontal, pendulous, fastigiate, and vase shaped).  Crabapples are suited for the
home grounds, schools, parks, commercial and public buildings, and highway plantings.

A. CHARACTERISTICS

1) Deciduous trees and shrubs, rarely half evergreen; most are between 15-25' in height at maturity.

2) Shape:  Range from low mound like plants, to narrow upright or pendulous types.

3) Branches:  Alternate, upright, horizontal, or drooping rarely with spinescent branches.

4) Buds:  Ovoid, with several imbricate scales.

5) Leaves:  Serrate or lobed, folded or convolute in bud, stipulate.

6) Flowers:  White to pink or carmine to red or rose.  Single flowers have 5 petals, semidouble 5-10
                   petals, and a double flower 10 or more petals.  Flowers occur in umbels or corymbs.
                   Petals are small suborbicular or obovate, stamens 15 to 20, usually with yellow anthers.
                   Ovary is inferior, 3 to 5 celled; styles present from 2 to 5, connate at the base.

7) Fruit:  A pome with persistent or deciduous calyx; colors range from red to yellow to green.
              If fruit is 2" in diameter or less, it is a crabapple.  If the fruit is larger than 2", then it is
              classified as an apple.

B. HABITAT

There exists more than 40 species of crabapples in the temperate regions of North America, Europe,
and Asia.  Currently, at least 100 types of crabapples are grown in North American nurseries, with at
least 134 additional types in arboreta and botanical gardens (roughly 250 types).
 

Origin of Selected Crabapple Seedlings:

Europe                                               North America                                                  Asia

Florentina                                             Coronaria                                                          Baccata (N.E. Asia to China)
Pumila                                                  Augustifolia                                                       Floribunda (Japan)
Sylvestria                                              Glabrata                                                           Halliana (Japan)
                                                            Glancescens                                                     Hupehensis (China)
                                                            Fusca                                                              Sargenta (Japan)
                                                            Lancifolia                                                         Sieboldi (Japan)
                                                            Platycarpa                                                        Spectabilis (Japan)
                                                            Bracteata
                                                            Ioensis
 

Hybrids

Malus arnoldiana - (Floribunda x Baccata)
Malus atrosanguinea - (Sieboldi x Halliana)
Malus micromalus - (Spectabilis x Baccata)
Malus purpurea - (Pumila Niedwetzkyana x Atrosanguinea)
Malus zumi - (Baccata mandschunica x Sieboldi)
Malus almey - (Redvein x Siberian)
Malus hopa - (Siberian x Redvein)
Malus Dorothea - (Halliana parkmani x Arnoldiana)
Malus Katherine - (Halliana x Baccata)
Malus Van Eseltine - (Amoldiana x Spectabilis)

C. GENERAL CULTURE

Crabapples are quite adaptable to varying soil conditions, but have been observed to do best in
heavy loam. The soil should be well drained regardless of type.  Crabapples do best when planted
in full sun for best development of flowers and fruits. The Asiatic forms are much more resistant
to insects and diseases than are the forms native to North America.

Generally, crabapples require little pruning, but if any is done, it should be completed before mid June.
Most crabapples initiate flower buds for the next season in late June - early June and pruning at
this time or later would result in decreased flower production the following year. Pruning may be
done, however, to remove sucker growth, open up the center of the tree to light and air, to cut off
out-of-place branches and to shape the tree.

D. PROPAGATION

Practically all flowering crabs are self-sterile and are propagated by budding, grafting, or some
softwood cuttings. Three crabapples are, however, commonly propagated from seed and come
entirely true to type; these include hupehensis, sikkimensis, and toringoides.

Crabapples are often grafted, using a whip graft, or are budded in mid to late August.  The
preferred understocks are the various types of native American species, but frequently common
apple seedlings are utilized.  In addition to grafting and budding, a few crabapples such as Arnold,
Carmine or Sargent are propagated from softwood cuttings taken from mid June through July.

E. INSECTS AND DISEASES
 

The Asiatic types are much more resistant to insects and diseases than species native to North America.

1) Borers: (Cultural control - keep the plants growing well with adequate fertilization and watering practices).
                For preventive control - use tree wrap impregnated with Dieldrin 2'-3' up the trunk of the tree
                from ground level.

2) Aphids: A serious problem generally only on native species.  Adequate control can be obtained by
                spraying the trees with malathion at the rate of 2 1/2-4 lbs. per 100 gallons of water.

3) Scale: Generally two types attack crabapples - San Jose and Oyster Shell and control can be by
              using a dormant oil as a spray before bud break or with malathion at the crawling stage of
              the scales.

4) Apple Scab: The native North American species and hybrids and the native apple (Malus pumila)
                      are quite susceptible to this disease.  Fruits show darkened, leathery spots with many small
                      cracks. The leaves also have darkened spots which may look black or velvety.

5) Fireblight: The diseased plants have the appearance of being scorched by fire. Generally, the first
                    visible signs of infection is often a drying up of the tips of young shoots and budclusters.
                    This disease is caused by bacteria which is spread by aphids, leaflioppers, and even bees.
                    Carelessness in handling diseased leaves and branches, and failure to adequately disinfect
                    pruning equipment contributes to the spread of the disease.

6)Cedar Apple Rust: (Asiatic varieties are resistant) This disease appears on apple leaves in May as yellow
                              leaf spots which subsequently enlarge, resulting in heavy leaf drop.  The disease has
                              an alternate host Red Cedars (Juniperus virginiana). Galls appear on Red Cedars in early
                              April, and spores produced by these galls later infect apple trees.
 

Malus x Zumi calocarpa - Calocarpa or Redbud Crabapple

             SPRING HABIT                                                             WINTER HABIT

                                                       FLOWER                                                                                                  FRUIT

                HABIT                                                                      FLOWER

             SPRING HABIT                                                                                     FLOWER                                                                                                         FRUIT

              SPRING HABIT                                                                FLOWER                                                                      FRUIT

              SPRING HABIT                                                         WINTER TEXTURE                                                             FLOWER

                     SPRING HABIT                                                                                                        FLOWER

              SPRING HABIT                                                               FLOWER