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Commonwealth of Pennsplbania

DEPARTMENT OF FORESTRY

A REPORT

ON

THE CHESTNUT TREE BLIGHT

THE FUNGUS, DIAPORTHE PARASITICA, MURRILL

By JOHN MICKLEBOROUGH, Pu. D.
MAY, 1909

HARRISBURG:
C. E. AUGHINBAUGH, PRINTER TO THE STATE OF PENNSYLVANIA

1909

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(2)

LETTER OF TRANSMITTAL.

Hon. Robert 8S. Conklin,
Commissioner of Forestry:

a

Sir: I have the honor to present my report on the deadly fungus,
Diaporthe parasitica, that has caused the destruction of many chest-
nut trees within the borders of the State of Pennsylvania. The in-
vestigations have been carried on to ascertain the presence of this
disease in the valleys of the Delaware and Susquehanna rivers. Ac-
companying the report of its geographical distribution is an account
of its life history, its prolific propagation, the damage already done,
and suggestions for remedial treatment.

Thanking you ahd your associates for many courtesies, I have the
honor to be,

Most respectfully yours,

JOHN MICKLEBOROUGGH, Ph. D.

(3)

THE CHESTNUT TREE BLIGHT.

BY JOHN MICKLEBOROUGH, PH. D.

The devastation produced by the chestnut tree fungus, Diaporthe
parasitica, is arousing the attention of State authorities and deeply
concerns the owners of woodland, also the owners of chesinut groves
and chestnut orchards. Nothing more serious has ever appeared in
the forests of this country than the destructive work of this parasite.
Its presence is known by the writer from personal examinations to
extend from near the northern boundary of Maryland, through south
eastern Pennsylvania, across New Jersey and New York. ‘The line
of inspection covers a distance of nearly two hundred and fifty miles.
On Long Island the disease has spread for fifty or sixty miles with
great rapidity, and is most prevalent and its ravages the most deadly.

In December, 1908, I was invited by Dr. Jane Baker, the physician
in charge of Chester County Insane Hospital, to speak before an
Educational Conference at Embreeville, Pa. On this visit several
infested chestnut trees were found. The disease was not prevalent.

The inspection of forests to ascertain the presence of the blight,
under the direction of the Department of Forestry, began March 29th,
1909. The counties first to receive attention were, Dauphin, Leba-
non, Berks (west), Cumberland, and Franklin. This is a rich agri-
cultural section of the State lying between South Mountain and
North Mountain or the Blue Ridge. The Lebanon and Cumberland
valleys are a limestone formation and very few chestnut trees are to
be found until the mountain slopes are reached where the chestnut
growth is abundant. A careful inspection of the forests was made on
each side of the Susquehanna where the river cuts through the Blue
Ridge to the north of Harrisburg, and at Middletown where it wends
its way bevond the broken ridges of South Mountain. An examina-
tion of chestnut forests was made at Wernersville in Berks County,
and as far west as Mont Alto in Franklin. Examinations were
made along South Mountain at Hunters Run, Mt. Holly Springs, and
farther south at Idaville. The Chestnut tree blight was not found
to the north and west of South Mountain. It becomes an interest-
ing question whether the valley from twelve to twenty miles or more
in width between North and South Mountains may not act as an
effective barrier to the progress of the disease into the interior of the
State. At Mont Alto, the State Forestry Academy was visited. This
institution is doing most excellent work. The instructors are able
and practical men, and the students are enthusiastic lovers of nature.

3)

The value of having trained men in the service of the Department
can nut be too highly estimated. The next region of the State to be
inspected was to the south and east of South Mountain. From the
city of Lancaster three trips were made by trolley, first to Ephrata,
second to Quarryville, and the third to Gap. At each of these places
the blight was found. Specimens of bark were taken from .trees
six and eight inches in diameter. Infected sprouts or coppice about
stumps were obtained. Under the microscope spores of the deadly
fungus in uncountable millions were shown. The disease was most
prevalent at Gap. Ephrata in Lancaster is south of South Mountain
and is only twelve miles from Wernersville in Berks county where
the forests of South Mountain furnished no evidence of the disease.

At Gap, Mr. Levi Wise has a chestnut grove of one hundred trees,
consisting of Paragon and Spanish grafts. A distinction is made
between a chestnut grove and a chestnut orchard. When the stock
is a native chestnut and the scion for grafting is a foreign variety or
species, such as Paragon, Spanish, Japanese, Numbo, Ridgely, Alpha,
eic., it is termed a grove. When young seedlings are set out in rows,
‘whether grafted or not, it is called an orchard. The blight had in-
vaded Mr. Wise’s grove. Infected spots were found on the native
stock and also on grafts. The following note was made at the time
of the inspection: “The Paragon and Spanish grafts are unusually
healthy considering the number of infected native trees in the imme-
diate vicinity.” On these trips in Lancaster county it was my good
fortune and very great pleasure to have the company of Deputy
Commissioner of Forestry, Mr. Irvin C. Williams. It was decided
at once to make an Experiment Station at Gap and to plant twenty-
five Japanese chestnut trees and to start with one hundred grafts
of the same species. Surrounded by natural woodland in which the
disease is quite prevalent, here was an opportunity to test the im-
munity or resisting power of three foreign chestnut growths side by
side.

Through the generosity of Mr. Isaac Hicks, a nurseryman at West-
bury, Long Island, twenty-five Japanese chestnut trees were donated
for the experiment and all the Japanese scions that could be used.
Three of these Japanese trees will probably bear this year, and all
should begin to bear next year. Mr. Wise had made one hundred
new grafts this season, using Paragon scions on native stocks.
Within half a mile of Mr. Wise’s grove there is another small grove
of Paragons on the property of Mr. Thomas J. Bitzer. Seven of
the Japanese trees were given to Mr. Bitzer. During the past win-
ter, the writer has had in his laboratory specimens of bark and limbs
and sprouts of native chestnut, Paragon and Japanese, all infected.
And yet from the examination of hundreds of trees of each kind,

6

and nine chestnut groves in widely separated localities it is firmly
believed these chestnut groves and orchards may be protected from
the ravages of this fungus growth.

Since the blight was found at three places on the east side of Lan-
caster county, an inspection was made at two points on the western
border. At Martic Forge, or Marticville, the blight was found on
native chestnut trees in the immediate vicinity of, and in the grove
of the Paragon Nut Co. The grove contains nearly four hundred
acres. About two hundred infected trees had been removed from
the grove. The wood was on a pile at the woodshed. Many of the
sticks on the wood pile were infested with living spores. The blight
is a bark disease and when a tree is felled the bark should be burned
at once. When the bark has been removed, the wood may be used
for various purposes. The bark on the stump should be burned for
two or three inches below the surface of the ground. Spores will be
developed and propagated many months after the tree has been cut
down. Specimens of infected bark have been kept in sealed test tubes
for more than nine months and on examination the spores were
alive and as active as on the day when selected for the experiment.
Martic Forge is thirteen miles directly south of the city of Lancas-
ter and about four from the Susquehanna river. The next inspec-
tion was made at Marietta, located on the Susquehanna and about
sixteen miles directly west of Lancaster. At this place Mr. John G.
Engle has a grove of one hundred and twenty-five trees, chiefly Para-
gon. His grove is in excellent condition. There was no evidence
of the blight and no indications that it has ever existed on his
property. The grafting which had been done by him several years
ago is as perfect in the union between scions and stocks as can well
be obtained. Infected trees on other property were found at
Marietta. Specimens of bark and branches showing the disease were
taken from native growth and also from Paragon grafts from two
small groves in the vicinity which had been seriously infected. In
Lancaster County the disease was found at three places on the east-
ern border and at two places on the west. In Adams county, at
Gettysburg, there is no chestnut growth to speak of, but in the north-
ern part of the county at Idaville the forests are chiefly chestnut and
oak. This village is on the south side of South Mountain. Much
care was exercised in the inspection at this place and hundreds of
trees on several lots were examined. No evidence could be obtained
of the presence of the disease at Idaville.

The next county to receive attention was Montgomery. Specimens
showing the infection were obtained from the trees on the campus
of Haverford College. Three estates near Haverford were examined.
The chestnut was the prevailing tree in this portion of the State. In

7

one case all the chestnut trees had been carefully treated by cutting
off all dead limbs and each wound covered with tar or paint. All
the trees, several hundred in number, on the estate of Mr. Harold
Pierce were in a fine healthy condition. On two other estates, dead:
trees had been felled during the winter, but in one instance the pile
of cordwood contained abundant evidence that the fungus parasite
had done its deadly work, and in the other all the wood and brush
had been burned, but an examination of the bark on the stump re
vealed the fact of the existence here of enough living spores to in-
fect all the trees of the neighborhood, should they find a lodgment on
their favorite hosts, the chestnut trees.

The next trip was to follow up the valley of the Susquehanna to
the north of Harrisburg. At Sunbury in Northumberland county,
the North Branch and the West Branch unite to form the Susque
hanna river. At this point the forests for a distance of ten miles,
along the river and its two main branches, were examined. The
chestnut growth was not so abundant as along the slopes of South
Mountain. No evidence could be obtained of the presence of the
blight. A side trip was taken up the Shamokin valley. This gave
an opportunity to examine the Paragon grove of Mr. C. K. Sober,
situated about twelve miles in a direct line from Sunbury. This
famous grove contains about four hundred acres and all the trees
bearing fruit. Here is a demonstration that waste mountain land,
on which the native chestnut grows, may be redeemed and become
a profitable investment. One year Mr. Sober had two thousand
bushels of Paragon chestnuts to sell. And since the selling price
has ranged from $5 to $12 per bushel, one can estimate the income
from this source. In his nursery, he had approximately three hun-
dred thousand seedlings and about one hundred thousand of these
were to be grafted in the spring of 1909. In large banks or mounds
of sand there were one hundred bushels of nuts which would be
planted early in May. The object on all trips was primarily to in-
spect the natural woodland. The native growth of chestnut on
Herndon Knob was examined and also the opposite ridge two miles
away across the valley. There was no sign of the blight in Shamokin
valley nor in any other portion of Northumberland county that was
visited.

At Sunbury an inspection was made to the east and south of the
Susquehanna, and at Bloomsburg it was to the north or on the op-
posite side of the river. No sign of the blight could be found in Col-
umbia county. With Mr. S. C. Creasy a drive was taken to Mill-
ville, twelve miles from Bloomsburg on the Susquehanna. The chest-
nut trees are very abundant in certain parts of Columbia county. ;
Mr. Creasy is well informed on all subjects pertaining to forestry in |

8

its practical bearing and his company was a great delight. The
next stop was made at Wilkes-Barre. In company with Mr. J. E.
Patterson a trip was taken to Glen Summit Springs, about nine miles
south of Wilkes-Barre. In these trips frequent stops were made and
a dozen or more investigations were undertaken. Luzerne county
did not furnish a single specimen that gave any indication of the
presence of the blight.

At Scranton on the Lackawanna river, a tributary of the Susque-
hanna, there is little or no chestnut growth. Valuable information
was obtained from Mr. T. J. Snowden, a lumber dealer, as to the
character of what little forest growth remains in that part of the
State. In his lumber yard there were four hundred chestnut posts
from six to eight feet in length. These had been cut at Hawley near
the border of Pike county. Having been recently cut, the bark which
was on the posts would have given evidence of the disease had it
existed. There was no sign of the blight on any of these posts.

The next stop was made at Carbondale in the northeasterly part of
Lackawanna county. Here as at Scranton, the lack of forests in gen-
eral, and especially of chestnut trees, precluded an extended investiga-
tion. Guing eastward over the divide between the Lackawanna river
and the Lackawaxen creek or in a broader sense over the highland
which separates the watershed of the Susquehanna from that of the
Delaware river, the work was taken up at Honesdale. No chestnut
growth could be found within ten miles of Ionesdale, was the in-
formation received from Mr. Kreitner of that town. Since the writer
had found the blight at Milford on the Delaware, in Pike county it
became an important question to ascertain if it had spread westward
and been carried into the upper portions of the Susquehanna valley.
The disease exists at Milford and farther north to within three miles
of Matamoras, Pa., opposite Port Jervis, N. Y. With Mr. E. T
Riviere of Milford, infected trees were found to the west and again
to the south of Milford. Specimens of the blight were taken about
one mile from the Camp of the Yale Summer School of Forestry on
the estate of Mr. Gifford Pinchot, Chief of the U. S. Forest Service.

To sum up for the Susquehanna valley. The chestnut tree blight
was nut found north of South Mountain. It was found in several
localities south of South Mountain along the Susquehanna and on
the watershed lying to the east of the river.

In the Delaware valley infected chestnut trees were found at Em-
breeville in Chester County, on the Brandywine, a tributary of the
Delaware river; at Haverford in Montgomery county; at Trenton,
N, J., and across the river at Morrisville in Bucks county: near Eas-
ton, i in Northampton county; and at Milford and Matamoras in Pike
county, ;,, Nowhere in Pennsylvania has the blight become so virulent

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9

and malignant as in New York, especially on Long Island. In the
winter of 1908, over eleven hundred chestnut trees were felled in
Prospect Park in Brooklyn, N. Y. Many of them were dead and the
others so infected that removal was the best course to pursue. For-
est Park, is another large park in Brooklyn. It contains 536 acres
of which about 350 acres are natural woodland. The Park Commis-
sioner reports fifteen thousand or more chestnut trees in Forest Park.
At this date, May, 1909, these trees are standing, but greater havoc
from blight or insect pest on forest trees has probably never been ex-
celled in deadly malignity. The disease is so prevalent, that it is
proposed to cut every chestnut tree in the Park. On many estates
on Long Island similar conditions exist.

THE LIFE HISTORY OF THE BLIGHT.

Neither insect pests nor blights can be dealt with successfully
until the life history is known. It is almost useless to strike at one
of these supposed antagonists in the dark. Is it much better to
know your antagonist, where it lives, and how and when it is pro-
pagated. As to the chestnut blight, its general appearance should
be known at different stages of growth and for each season of the
year. Does it have the same appearance in the resting stage of
winter as in the rapidly growing condition of summer?

The first scientific description of the chestnut blight was given in
1906 by Dr. Wm. A. Murrill of the Bronx Botanical Garden, New
York City. After a year or more of study and experiment the fungus
was proved to be a new species. It belongs to the class known as
the sac-fungi and to the genus Diaporthe of which more than one
hundred species are known to science. The scientific name of this
blight is Diaporthe parasitica.

Many of the fungi derive their nourishment from decayed vegeta-
tion. Such are the common brackets or shelves on stumps and logs
and are properly called saprophytes. Other saprophytes live on de-

‘cayed animal matter. When one looks at a pulf-ball, mushroom, or

bracket on a log, it is the fruiting body of the fungus that is under
observation. Besides this there are hundreds of fine threads a yard
or more in length penetrating the mould or decayed log. These
threads or mycelia take up the nourishment and produce the fruiting
body. Some fungi, however, derive their nourishment from living
plants or animals, and are consequently called parasites. Ringworm
that attacks man is a fungus parasite, Trichophyton tonsurans. The
deadly chestnut blight is also a fungus parasite. The ringworm
burrows beneath the skin and the chestnut blight lives in the bark
and derives nourishment from the new cells of the cambinm. The
other hundred or more species of Diaporthe live, as a general rule,

10

on decayed wood and do not attack the living. They are saprophytes
and not parasites. This distinction should be kept in mind.

The saprophytes are found on dead limbs and trunks of the locust,
mountain maple, hickory, ironwovud, ash, chestnut, basswood, elm,
walnut, oak, red maple, beech, willow, sassafras, golden rod, aster,
and many other plants. After a forest fire many forms of saprophytes
may be found on the dead limbs and trunks of various trees.

What are fungi? They are plants produced by spores and in this
respect differ from seed-bearing plants. The ferns and the mosses
are also spore plants and are higher in the scale of plant life than
the fungi. The fungi include the moulds on bread, cheese, and pre-
served fruits; mildews, as the downy mildew causing the rot of the
Irish potato; rusts on wheat; black-knot on the plum and cherry;
mushrooms, edible and poisonous; yeasts; puff balls, etc.

The total number of plants of all kinds known to science is about
two hundred thousand species. There are about fifty thousand
species of fungi, and of this number about fifteen thousand belong
to the sac-fungi (Ascomycetes). The sac-fungi are a very destructive
fornr of fungus growth and produce a number of diseases on ac-
count of the fact that many of the species have the parasitic habit.
In this division of fungi, there are the leaf-curl of the peach; the
black-knot of the plum and cherry; many of the powdery mildews;
the large morels, prized for food; the yeast plant, known to make-s
of bread and beer; the green mould on cheese, as well as the deadly
chestnut blight. After the chestnut trees or sprouts have been killed
by the blight. numerous other fungi will attack the dead wood. These
must not be charged with the destruction of the tree or sapling.
These are the scavengers that come to feed upon the dead and are
known as saprophytes. Between thirty and forty different species of
fungi are known to attack dead chestnut limbs, stumps, and logs.

PROPAGATION OF THE CHESTNUT BLIGHT.

The Diaporthe parasitica is propagated by at least two kinds of
microscopic spores. One kind of spore is developed in minute sacs.
Hach sac contains eight spores and nature fills each tiny sac with the
eight spores as uniformily as one finds four legs on a dog and two”
on a bird. These are sometimes called the winter spores. These
spore-sacs are developed in minute flasks resembling carafes or long
necked water bottles and are formed abundantly in the autumn. In
this way the fungus tides over the winter. Another kind of spore
more minute than the winter spore may be found in thread like masses
in early spring and during the summer. These are called summer
spores, or conidial spores. Conidial is derived from the Greek word
meaning dust. Sometimes the thread mass or spores is more than
half an inch in length. Such a thread will furnish millions of spores.

11

These two kinds of spores are different in origin but the same in
power in producing the young plant. For the benefit of the micro-
scopist it may be well to state, the winter or sac spores are sexual
spores and the conidial or suminer spores are non-sexual. It would
take from five to six hundred of the tiny sacs placed end to end to
measure one inch and about three thousand of the sac spores end
to end to measure an inch, and of the minute summer spores eight
to nine thousand. Both kinds of spores are produced by countless
millions. A section of a limb twelve inches in length and one inch
in diameter will furnish an ample supply of spores to infect all the
chestnut trees in a county. The minute spores are carried by the
wind, on the feathers of birds and the fur of squirrels, and find a
lodgment where the bark is abraded and especially in the fork of the
limbs or more tender branches. The spore immediately sprouts, and
procures its nourishment from the new wood or cambium layer.
These newly formed wood cells have very thin delicate walls and are
full of sap. Thus the cambium furnishes the parasite with ample
nourishment. The walls of the new wood cells are broken down by
the growing parasite and the bark begins to change color from a
healthy olive green on twigs and slender branches to a reddish brick
color, and the parasite shows a tendency to girdle the limb or trunk.
As soon as the girdle is complete, all nourishment is cut off from the
parts beyond the infected portion. The result is the same whether
the girdling is done with an axe, a saw, or by a parasite. Large
trees are girdled and killed in two or three years. During the sum-
mer of 1908 many branches of chestnut trees showed signs of decay
and the green leaves of spring withered long before the frosts of
autumn had touched the foliage. So far we have spoken only of the
growing fungus. Its work during this stage is carried on in and be-
neath the bark. It is technically speaking a hypophloeous disease.
The next stage is known as the fruiting period. As the fungus grows
it finally matures and develops the fruiting body, or rather fruiting
bodies. Its growth is now outward, through the pores in the bark.
In old trees the fruiting or spore producing bodies are in the long
crevices or fissures of the bark. A piece of a limb kept in the lab-
oratory where the changes in the weather will not affect it, will soon
be thickly beset with small yellow pustules, resembling little yellow
cushions of velvet. These are fruiting bodies of this parasite. Run-
ning through the pustule are some dark lines. These are the necks
of the flasks or perithecia at the base of the pustule and are situated
just beneath the outer layer of the bark. These flasks are lined with
the eight-spored sacs. In early spring and during the summer the
thread masses consisting of the summer or conidial spores will be
found. These threads are dissolved and washed away by the rain
and the spores are blown about by the wind. These developments

2
may be seen best on specimens in the laboratory. A .ommon fruit
jar, in which is placed a four or six inch piece of an i: fected limb,
will, in thirty-six or forty-eight hours show signs of the fruitii 5
bodies. First put the stick into water for two or three minites then
transfer it to the jar in which there is less than half an inch of
water. The jar is closed and kept at summer temperature. A warm
cellar is most convenient, since the fungus grows in the dark as
well as it does in the light. In this way the writer has had an
abundant supply during the past winter of fruiting pustules on
limbs of the native chestnut, Castanea dentata; on the Japanese chest-
nut, Castanea crenata; and on the Paragon, which is probably a
variety of the Spanish or sweet chestnut, Castanea vesca. From these
specimens the two kinds of spores were at hand during the entire
winter.

Foreign chestnut treés sometimes attain an immense size, and are
quite common in the south of Europe, in Spain, Italy, Switzerland,
and Germany. The fruit or nut which is two or three times the
size the American nut is much used as an article of food. The large
kernel is frequently ground into meal and is used to thicken soups,
and even bread is made of the chestnut flour. The largest foreign
chestnut tree is on the slope of Mt. Etna, in Sicily, and has a cir-
cumference of 190 feet, and is known as the “Castagno di cento
eavalli,” the chestnut of one hundred horses.

There is no lack of opportunity for spores to find an entrance be-
neath the bark of a chestnut tree, large or small. The wood is brit-
tle and the storms of winter leave many broken twigs and limbs. The
small boys and older nut gatherers have clubbed the trees and left
many a scar. Insect borers and woodpeckers have made openings in
the bark in many places. The forks of the branches seem to be
favorite places for the lodgment of spores. In a young tree ten or
more points of infection have been observed at the break of the bark
in the forks of the limbs.

The propagation is readily carried on wherever there is a supply
of spores. _The transportation and ready access to the cambium wood
cells are well provided. On Long Island an isolated tree, more than
a mile distant from any chestnut growth was infected.

IMMUNITY OF OTHER TREES.

All the other forest trees seem to be immune. There are fungus
growths of the saprophytic type on all forest trees. Abundant spores
of another species of fungus were found upon the branches of several
_ oak trees. The trouble was limited to the under side of the branches,
and there was no tendency on the part of the fungus to invade the
new cells of the cambium or to girdle the branch. An examination of

THE CHESTNUT BLIGHT AS FULLY
DEVELOPED BY INCUBATION.

(from a Color Photograph.)

13

the locality revealed the fact that it had been swept by fire a year or
more ago and the under side of the limbs had been injured. ‘The
fungus was merely doing scavenger work, and living upon decayed
vegetable tissue. Many times questions have been asked about the
horse chestnut, AEsculus hippocastanum. The common horse chest-
nut or buckeye is a near relative of the maple and is quite unlike the
oak, chesinut, and beech, belonging to the same natural order, Cupuli-
ferae, from the fruit being contained in a cup or burr. Another
question,—is the chestnut oak immune? It is just as immune as any
other oak. Up to this date the writer has not found the deadly chest-
nut fungus on the chestnut oak,sometimes called rock oak, or Quercus
Prinus, L. Hundreds of the chestnut oaks have been examined and
although growing side by side with diseased chestnut trees, no case
of an infected oak has been discovered.

The variety of chestnut called the Paragon, is quite susceptible to
the disease. While the Japanese variety or species is not immune,
it is certainly more resistant than the native or the Paragon. In
one locality eleven Japanese chestnut trees were in a perfectly healthy
condition and bore abundance of fruit in the summer of 1908, although
in the immediate vicinity there were many native trees all badly in-
fected. Within one hundred yards of these eleven trees there was a
Taragon infected in several different places. Ina nursery of twelve or
fifteen hundred young Japanese chestnut trees, there were many
young native chestnut seedlings from five to ten feet in height. It
was almost impossible to find a native tree free from the infection.
On the other hand many of the Japanese were immune, yet on an cx-
tended examination some five or six of the Japanese were infected,
and under hothouse treatment developed a rich supply of spores.
Evidently an orchard of Japanese or Paragon chestnut trees can be
made profitable and the trees kept in a healthy condition with rea-
sonable care.

ESTIMATED VALUE OF PROPERTY DESTROYED.

The statistics furnished by the United States government show
that for the year 1907 over 600,000,000 board feet of chestnut lumber
were cut. Valued at $17 per 1,000 the total value would be about
$10,000,000 for one year. lLesides, there were over $3,000,000 for
chestnut cross-ties. Much timber is used in the mines, and also
for fence posts and telegraph and telephone poles, and by cabinet
makers. The tanneries also use many cords of chestnut wood. The
market value of the nuts is no inconsiderable item. In 1908 it would
appear, the output of all kinds from the chestnut forests of the United
States would aggregate $22,000,000. Should the chestnut blight be-
come as prevalent and virulent as on Long Island, and advance as

14

rapidly over the country as it has moved eastward on the Island, it
is only a matter of a few years when this source of income will be
reduced many millions per annum.

The number of chestnut trees on an acre of natural woodland has
been counted in New York, New Jersey, and in Pennsylvania. In
some counts there were from forty to fifty chestnut trees to the acre
disregarding any tree under two or three inches in diameter. In
Somerset and Morris counties, N. J., an average of thirty chestnut
trees to the acre would be a low estimate for many pieces of wood-
land. The damage already done by the chestnut blight in the States
of New York, Pennsylvania, and New Jersey would not be less than
$12,000,000; and when the special value from location on lawns and
the aesthetic value in landscape features are considered, two or three
millions could be added to this estimate.

REMEDIAL TREATMENT.

Let us notice the conditions in the life history of the chestnut
blight. It is a vegetable growth and in its development, the threads
penetrate the delicate cells of the newly forming cambium. Summer
spores are produced from early spring to late autumn. On the ap-
proach of winter, the winter spores are developed in sacs and the
sacs line the Hasks or perithecia, and in this way tide over the sever-
est cold in the resting stage.

In the care of a large tree, if it is infected at several points it
would be advisable to cut it down at once. AJ] the branches and the
loose bark s! ould be burnt. The wood may be used for various pur-
poses. If al‘!owed to stand, it furnishes millions of spores, and the
wood is greatly injured on acount of the attack of saprophytic fungi
of vatious kinds and also certain insect pests. Young trees are de-
stroyed in one or two years after becoming infected. The girdling
process is soon accomplished and the cutting and burning of such
growth is recommended. First, all undergrowth about the chestnut
trees should be removed. An examination of the trunk will soon re-
veal the healthy or living condition of the new wood beneath the
bark. If the layer beneath the bark is destroyed, the extent of in-
jury up and down and around the trunk can be ascertained. If only
a limited area has been destroyed, the dead portion, bark and dead
wood should be cut away and the wound covered with tar. If only a
few limbs are attacked, their removal should not be delayed, if the
tree is considered worth treatment. Cover all wounds with tar. The
two discouraging features about any treatment arise, first from
the difficulty of finding all infected spots on a large tree, and second,
mnany owners of woodland will not give attention to the matter.

A few neglected trees will supply enough spores to infect all the

15

trees for miles around. When the spore has found a lodgment in the
layer of new growing cells beneath the bark, only the greatest care
will prevent the growth and maturity of the fungus. No forest tree
develops sprouts or coppice more abundantly than the chestnut, unless
it is the basswood. If the tree is much infected almost invariably the
blight will be found on the coppice about its base. A chestnut stump
will aid the investigation, for it is sure to be surrounded with aa
ample supply of sprouts. The bark of an old tree has deep crevices or
fissures. In these fissures in the bark of old trees the fruiting bodies
are found. If the layer beneath the bark is dead, the deepest part of
the fissure should be examined for rows of little red tubercles. Here
is where the microscopist finds the sacs with their eight spores, as
well as masses of summer spores. By tapping on the thick bark with
« hammer, the muffled sound will indicate where the bark is dead.
If the area is small it can be cut away and the place tarred.

Many suggestions have been made about injecting some chemical
that would enter into the circulation and destroy the fungus. So far
nothing of, practical value in this line has been accomplished. There
are fungicides but if used in sufficient strength to kill the growing
fungus, the treatment is about as injurious to the tree‘as is the dis-
ease. Trees kept free from undergrowth and frequently inspected
and by cutting as soon as the infection is observed, may be saved and
kept in a healthy condition. Chestnut groves and orchards may be
protected by careful inspection and prompt treatment. If a tree is
badly infected its removal is advised. All bark should be burned at
once. The bark of the stump well down into the ground must not be
forgotten.

While spraying hundreds of forest trees is out of the question, yet
grafted trees in groves or orchards may be benefited by spraying,
and a limited number of young chestnut trees on a lawn may be so
treated. In the Zoological Bulletin, Oct. 1, 1907, page 190, Prof.
H. A. Surface says of the Lime-Sulphur Wash; “It is a fungicide as
well as an insecticide and cleans up many of the disease germs, such
as those causing leaf curl, leaf spots, rusts, mildews, apple scab, and
other diseases of leaves or fruits.” The Bulletin of March 1, 1909,
contains all necessary information on spraying. Many spores may be
washed away, but this infection is protected because it grows beneath
the bark and is scarcely touched by spraying. .

Trees have been treated by using cotton saturated with Bordeaux
mixture. Small bunches of raw cotton saturated with Bordeaux and
wrapped in burlap have been tied in the forks of the limbs. To be
effective, it would be necessary to treat every fork of the limbs and
twigs in this manner and also abraded bark on any part of the tree.

Whether the blight will spread inland must remain a problem for

16

further investigation. At present it appears to be following the
coast. On woodland in several localities in Pennsylvania its existence
can be shown, yet it can not at present be considered a discouraging
menace. On the other hand should the disease spread from tree to
tree as is now the case in certain localities in New York and New
dersey, every available measure should be adopted to prevent the
propagation of spores by cutting the trees and burning all infected
bark.

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