Mugo Pine (Swiss Mountain Pine) - Pinus
General Information: Mugo Pine is a shrub or small, round or broad
pyramidal plant 4 to 10 feet tall which grows best in sun or partial shade
in moist loam. It comes from Alpine Europe. The dark green, 1 - 1 1/2
inches long, stiff needles of this two-needle Pine are held on the tree
for more than four years making this one of the more dense Pines suitable
for a screen planting. Most other Pines are not suited for screens since
they loose their inner needles and lower branches as they grow older.
Since there seems to be great variability in height among individual
trees, select nursery plants which have the form which you desire. When
selecting a Mugo Pine to grow into a tree, choose one with a central
leader; if looking for a more dwarf type Mugo Pine choose among the many
Lighting: Full sun.
Turn the tree from time to time so that all parts of the foliage receive
Temperature: Will tolerate freezing but roots need to be
Watering: May dry out
between waterings. Fast draining soil to avoid root rot. Spray the foliage
with water daily during the summer.
Feeding: Once a month in spring and autumn using
a slow-acting organic fertilizer. If you prefer to feed using chemical
fertilizers, feed the tree once every two weeks with a half-strength
solution of a fertilizer meant for acid-loving plants, such as Miracid.
Suspend feeding for two months during the hot part of summer (July and
August in the northern hemisphere). Do not feed if the tree is ailing or
has been repotted recently (2-4 weeks).
Pruning and wiring: Initial pruning should be carried out at the same time as
repotting. When repotting, be sure to leave a good root system. Subsequent
pruning can be carried out when wiring in the fall. Pinch by shortening
new shoots (candles) by two thirds in the spring, before the needles open.
Pinch the candles in two stages, pinching the most vigorous candles first
and a week later pinching the weaker candles. In the fall, reduce the
number of buds on each branch to two to encourage ramification. Also in
the fall, thin the needles by removing any needles that are too long or
that are growing downward. Thin more at the apex of the tree and less as
you work down the tree. This will allow light to reach the lower branches
and will slow the growth of the apex.
Wiring should be done in late fall or early winter,
and the wire removed 6-8 months later at most.
With healthy trees, it is possible to remove all the
new candles every other year, before they harden. The following fall, buds
will appear where the candles were removed. This serves to shorten the
internodes and encourage more dense foliage.
early spring or late summer, every 2-3 years for young specimens and every
3-5 years for older ones. Pines need deep, well drained soil, so plant in
a fairly deep container. Simon and Schuster's recommends 50% soil and 50%
coarse sand. Rémy Samson recommends 1 part leaf mould, 1 part loam, and 1
part coarse sand. Peter Chan recommends 1 part loam, 1 part peat, and 3
parts coarse sand.
Pines and other conifers grow in association with a
symbiotic fungus which grows in the root ball of the tree. If this fungus
is not present, the tree may die. For this reason, pines and other
conifers should never be bare-rooted, unless steps are taken to
re-introduce the fungus to the repotted plant, such as making a slurry
(thin mud) of the old soil and pouring it over the newly potted
Some experts feel that it is more important to be sure
that the tree always has a healthy root system with sufficient feeder
roots than to worry about symbiotic fungi. They feel that trees are more
likely to die from having their root systems reduced too much at once than
from not having the fungus present. Certainly it is good advice in any
case to be sure the tree has sufficient roots.
Pests and diseases:
Pests: Mugo Pine is a favored host for Pine sawfly and Pine needle
scale. Some adelgids will appear as white cottony growths on the bark. All
types produce honeydew which may support sooty mold. European Pine shoot
moth causes young shoots to fall over. Infested shoots may exude resin.
The insects can be found in the shoots during May. Pesticides are only
effective when caterpillars are moving from overwintering sites to new
shoots. This occurs in mid to late April or when needle growth is about
Spruce mites cause damage to older needles, and are
usually active in the spring and fall. Mites cause older needles to become
yellowed or stippled.
Zimmerman Pine moth larvae bore into the trunk. The
only outward symptoms may be death of parts of the tree or masses of
hardened pitch on the branches.
The larvae of Pine weevils feed on the sapwood of the
leaders. The leader is killed and the shoots replacing it are distorted.
First symptoms are pearl white drops of resin on the leaders. The leaders
die when the shoot is girdled as adults emerge in August. Prune out and
burn infested terminals before July 15.
Diseases: Diplodia tip
blight is a common problem and Mugo Pine is very sensitive. This pine is
susceptible to rusts. Canker diseases may rarely cause dieback of
landscape Pines. Keep trees healthy and prune out the infected branches.
Needle cast is common on small trees and plantation or forest trees.
Infected needles yellow and fall off.
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