Evening star., 1940-07-27
Controlling
Diseases of
COnifers
Constant Attention
And Regular Care
Are Called For
BY EDITH L. HOUGH.

The most common diseases o.
conlfers are environmental, as ar
artificial habitat sometimes causes
decay as well as makes the trees
dependent on other nutrition thar
that normally in the soil. Constant
care and attention is required tc
prevent or check diseases which re-
duce the trees vigor. depreciate
their ornamental value and otter
kill them outright.
The Norway spruce, Douglas fir
white pine, cedar and arbor- vitae
are affected by sun-scorch, caused
by hot and dry weather. The needles
turn yellow at the tips, then brown
and finally dark red, while the root
system dies. as more water is given
of by the leaves than is absorbed
by the roots. This is prevented BY
heavy watering, often with a light
mulch.
All wounds to the trees open the
way for fungus spores. Wood-rots
caused by fungi, are rare individual
ornamental specimens, as there is
less chance Of their spreading, but
the fir. spruce, larch and pine are
susceptible. Decay may begin in the
roots, wood or bark, the external
signs appearing one or more years
after the infection has set in. Some
species project from the trunk in
bracket-like bodies; some cause a
brown heart-rot, most common in
the juniper, hemlock and arbor-
vitae. All diseased wood should be
removed and all external fruiting
bodies destroyed. In case of a root
rot, the injured roots and bark at
the butt should be removed, the
wood then creosoted and tarred.
Rusts, also from fungus spores
attack the leaves, twigs, branches
and trunks. The blister-rust af-
fects particularly the white pine OF
all ages. It occurs in the vicinity
OF currant and gooseberry bushes,
from which the spores are blown
by the wind. The entrance is at
the bases of the leaf-fascicles or
directly through bark not more than
three years old. The spores pass
down the branch, even to the trunk,
where they grow in the bark. The
outward signs are slight swellings
in the bark. which become cream
colored blisters. When these break,
the spores are carried away by the
wind and return to currant and
gooseberry bushes, where they ap-
pear on the underside of the leaves.
Such bushes should be removed from
the vicinity of the pines. The twigs
and branches of the latter should
be cut, Z or more inches back of the
infected part; all diseased bark
should be removed with 2 inches
to the sides and 4 inches at the
ends into the healthy wood. Shellac
Is then applied and tar or a bark
colored paint. The gymnasporan-
gium fungus attacks jumpers and
cedars. For completion of its life
cycle, the apple. pear, ounce or
hawthorn trees are necessary. It
appears in swelling and witches
brooms, compact clusters of small
branches, and sometimes turns the
leaves to gals called "cedar-apples. "
All diseased parts should be care
fully removed.
In some localities, the larch and
spruce are commonly attacked by
the woolly aphid, which appears in
small, cottonlike spots on the larch
and as gals on the spruce. This
is treated by an application Of scale
side oil.
Oak rust, attacking the two and
three needle pines, occurs in the
vicinity Of oak trees, with large gall
like swelHngs on the branches.
Leaf-cast attacks the pine, larch,
fir, spruce and juniper. The leaves
turn yellow and then brown, the
fruiting bodies Of the fungi appear
ing in black spots along them. All
dropped leaves should be burned and
a. bordeaux mixture applied.