Amur maple - Acer
General information: Amur maple is an excellent, low-growing tree
for small yards and other small-scale landscapes. It can be grown as a
multi-stemmed clump or can be trained into a small tree with a single
trunk up to four to six feet tall. The tree grows about 20 to 30 feet
tall and has an upright, rounded, finely branched growth habit which
creates dense shade under the crown. Due to excessive branchiness, some
pruning is required early in the life of the tree to create dominant
major branches. Amur maple can grow rapidly when it is young if it
receives water and fertilizer, but it is well-suited for planting close
to power lines since it slows down and remains small at maturity.
Amur maple has only started to attain popularity as
a bonsai. It is certain to become widely used as it is an attractive,
fuss-free maple. It shares the three-lobed leaves of trident maple, but
is much more frost resistant. In fact, it is more tolerant of adverse
conditions than most other maples. Amur maple also has its brilliant
autumn coloration to recommend it. 'Durand's Dwarf' is an especially
desirable cultivar for bonsai.
Lighting: Full sun,
part sun, but part shade in midsummer and in very hot climates to
prevent leaf burn.
Temperature: Very weather resistant -
may be grown in somewhat hotter areas if
care is taken to prevent leaf-burn or dehydration.
Watering: Moderate -
increase watering during the summer heat, and keep fairly dry in
Feeding: Weekly for
the first month after leafing out, then every two weeks through summer.
Use bonsai fertilizer or half strength plant food.
Pruning and wiring:
Acer ginnala takes well to bonsai techniques. It buds back rapidly on
old wood, and thus can be cut back quite hard. Its leaves will reduce to
under one inch if it is defoliated once every two years in midsummer.
New shoots should be pruned through the growing season. Acer ginnala may
be wired, but like other maples, may require some protection of the
Propagation: Cuttings, seed, air-layering.
tolerances include clay, loam, sand, acidic, alkaline, well-drained.
Repot in early spring, before bud burst, using a fast-draining soil mix.
Young trees may need to be repotted annually. Otherwise, repot every two
years, but not in the same year that the tree is defoliated.
Pests and diseases: Pests: Amur maple is usually pest-free. Aphids infest maples,
usually Norway Maple, and may be numerous at times. High populations can
cause leaf drop. Another sign of heavy aphid infestation is honey dew on
lower leaves and objects beneath the tree. Aphids are controlled by
spraying or they may be left alone. If not sprayed, predatory insects
will bring the aphid population under control. Scales are an occasional
problem on maples. Perhaps the most common is cottony maple scale. The
insect forms a cottony mass on the lower sides of branches. Scales are
usually controlled with horticultural oil sprays applied in spring
before growth begins. Scales may also be controlled with well-timed
sprays to kill the crawlers. If borers become a problem it is an
indication the tree is not growing well. Controlling borers involves
keeping trees healthy. Chemical controls of existing infestations are
more difficult. Proper control involves identification of the borer
infesting the tree then applying insecticides at the proper
Verticillium wilt symptoms are wilting and death of branches. Infected
sapwood will be stained a dark or olive green but staining can't always
be found. Ifstaining can not be found do not assume the problem is not
verticillium wilt. Severely infected trees probably can't be saved.
Lightly infected trees showing only a few wilted branches may be pulled
through. Fertilize and prune lightly infected trees. This treatment will
not cure the problem but may allow the tree to outgrow the infection.
Girdling roots will cause symptoms which mimic verticillium wilt. Scorch
occurs during periods of high temperatures accompanied by wind. Trees
with diseased or inadequate root systems will also show scorching. When
trees do not get enough water they scorch. Scorch symptoms are light
brown or tan dead areas between leaf veins. The symptoms are on all
parts of the tree or only on the side exposed to sun and wind. Scorching
due to dry soil may be overcome by watering. If scorching is due to an
inadequate or diseased root system, watering may have no
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