Evening star. [volume] (Washington, D.C.) 1854-1972, 1908-12-30
ENEMY OF CHESTNUT TREES
GROWTH AND SPREAD OF A
NEW DEADLY FUNGUS.
No Remedy Known for the Parasite.
Lives Beneath the Bark.
Spraying Not Effective.
From Suburban Life.

From Suburban Life.
The chestnut tree. one Of the most
abundant and valuable trees of the east
ern United States, is being rapidly ex-
terminated in the vicinity Of New York
city and in the neighboring states by the
ravages of a parasitic fungus, known as
the chestnut canker.
This fungus attacks the active layers
OF the tree between the outer bark and
the wood, where the new tissues are form
ed and where food for all portions of the
tree is stored and distributed. Its pres
ence is at first indicated by the death OF
individual branches. whose leaves sud-
denly wilt and dry up as though scorched
by fire; while closer observation reveals
rough, discolored patches on the bark
srding the branch just below the part
that has been killed. The fruit of the
fungus is pushed up through the bark in
numerous small. yellowisR-brown warts
pustules containing the spores, which
are produced during the summer in deli
cate yellowish or brownish twisted threads
composed OF millions OF very minute
spores not larger than some bacteria.
On the smaller branches. where the
bark is thin and smooth and the lenticels
active, the fungus usually makes use or
these natural openings to reach the sur
face: but the older bark is much too thick
to penetrate, SO that on the trunk and
larger branches the pustues are to be
found in the cracks or burrows formed
where the older layers of bark have sepa-
rated. to accommodate themselves to the
increa sing size of the tree.
At the approach of winter the pustules
become darker and cease to produce the
coils of summer spores. which would be
unable to endure the cold; but they form
sacs containing much larger spores with
thick walls and rich in food content.
which pass the winter without injury and
aid in distributing the disease the follow
ing spring. The active portion of the
fungus the mycelium is very inconspicu-
Gus. consisting of minute whitish threads,
which penetrate the tissues extensively in
their search for food and increase at
rapid rate beneath the bark in all direc-
tons. even following the medullary rays
for some distance, to extract the stored
food which they contain.
Discovery of Disease.
This disease was first discovered in
Bronx Park, in 1905, by II. w. Merkel,
who called my attention to a number of
dead and dying chestnut trees at the New
York Geological Park, which, upon eX-
animation, showed the fungus actively
at work. Steps We're at once taken to
separate the fungus from all other asso-
ciated fungi. so that experiments might
be undertaken in incubation and treat
ment.
This parasite is probably the most de-
structive known in its effect on the host,
the parts attacked being SO vital and the
attack SO vigorous that young trees often
succumb in one or two years, and older
ones soon lose branches of such size that
the vigor of the tree is materially I'M
paired and its beauty and usefulness prac-
tically destroyed. Under favorable condi-
tons trees of large size may be killed In
two or three years by sirdling, when the
point of attack is on the main stem, the
IA of Ia tn
around the trunk in search of the currents
of food and water circulating up and
down the tree. Nursery trees are often
attacked near the surface of the ground.
where it is moist, and such infections usu-
ally cause death very quickly. The leaves
and tender green twiss are never at
tackled; it is only when the twig has be-
come brown that its food content is able
TO nourish the parasite.
After a branch of a tree has been killed
by girdling the fungus runs through 1t
very rapidly and extracts the stored food
IL contains, fruitinS abundantly in the
meantime. and then dying: 1t cannot use
the dead wood a source of food, as a
great many other fungi do. Areas killed
by the fungus at first appear pale brown,
then rough, with the numerous wart-like
fruit bodies. and finally blackish and much
cracked and distorted. A year or two
after the death of tree the bark peels
off and leaves the bare trunk compare
lively untouched by the disease and en-
tlrely unable 10 disseminate IL TO Otuef
trees. How long the spores will live in
the bark has not yet been determined.
No Cure Known.
There is no treatment known for the
chestnut canker. Since the fungus lives
beneath the bark. no ordinary spraying
solution can be applied. and in fruiting
it breaks through the bark and produces
spores so abundantly and continuously
that no amount of spraying could reach
a large percentage of them When these
spores are distributed to other trees, they
are powerless to enter and grow except
by means of a crack or abrasion Of some
kind; and. when this is formed, whatever
protective covering may have been APP
piled to the surface of the tree would
likewise be broken through, thus admit
ting the spores unframed. Strong poisons
that would reach the fungus. when
specially applied, would kill or seriously
injure the tree itself.
The only method of treatment that l
have ever been able to suggest is the
severe and careful pruning of affected
branches thus removing the fungus from
the tree. and closing the wounds against
new infections by covering them with
coal-tar. 1t has not proved successful.
however
Even if this method were theoretically
perfect, which is far from being the case,
the practical difficulties are jnsurmount-
able. In the first place. II involves the
discovery and complete eradication of
every particle OF the fungus in the tree
affected: and, secondly, the tree must be
sealed against all new infections, which
is manifestiy impossible.
The present distribution OF the canker
is very imperfectly known. although re-
ported from many localities, but the in
dications are that II exists along the
Atlantic coast from southern Massachu-
sets to Maryland, and west as far as
Poughkeepsie and central Pcnnsy lvaHia
ANTI-CoNSPICUoUSNESS.