A DISEASE THREATENING THE CHESTNUT TREES 
A new disease of remarkably destruc- 
tive character has attacked the native 
American chestnut, and has gained a 
foothold and attained proportions which 
threaten the extinction of these trees 
in and about New York, writes G. G. 
Capp in a recent issue of the Scientific 
American. The same disease is known 
to exist among the chestnuts of New 
Jersey, Maryland and Virginia, but to 
what extent can only be ascertained by 
•extensive and painstaking work in the 
respective fields. 
The attention of George W. Merkel, 
forester and engineer at the New York 
Zoological Park, was first attracted by 
the immense number of dead and dying 
chestnuts in the park. He suspected 
the presence of a destructive fungus. 
He found that the disease was also cre- 
ating havoc among the young chestnuts 
in the park nursery. He sprayed the 
young trees with Bordeaux mixture, 
and extended the treatment to the 
larger trees in the park. At best this 
treatment could be called' only partially 
successful, and he appealed to Dr. W. 
A. Murrill, mycologist and first as- 
sistant in the New York Botanical 
Garden. This occurred last year, since 
which time Dr. Murrill has devoted all 
the time he could spare from other im- 
portant duties to the careful study of 
the disease and to a long series of ex- 
periments as to its nature, cause, and 
cure. His investigations are not yet 
completed, but the ravages of the dis- 
ease have now become so apparent that 
the subject is one of great economic 
importance. 
As Mr. Merkel suspected, the disease 
is of fungous origin. Pure cultures 
were made by Dr. Murrill from affected 
chestnut sprouts in the Botanical 
Garden last autumn, and were trans- 
ferred to agar and sterilized bean- 
stems and chestnut twigs. In each of 
these situations the fungus grew rap- 
idly and fruited abundantly. Living 
chestnut twigs were infected and placed, 
with their ends in water, and bell jars 
for inspection and study of the fungous 
growth and action as a preliminary to 
•experiments in the field. 
FIG. 1. TRUNK OP AN INFECTED 
CHESTNUT NURSERY TREE 
A. point of infection; B, area killed 
last year; C, development 
early last May. 
FIG. 2. FRUITING PUSTULES AND 
SPORE MASSES PROM CHESTNUT 
CULTURES 
A, pustules in stages of development; 
B, C, D, spore discharges in moist air 
This year, as soon as actual spring 
growth had begun, numbers of young 
chestnut trees in the Garden propagat- 
ing houses were infected with active 
fungus transferred from bean stalks to 
the young trees. As Dr. Murrill had 
been led to expect by results obtained 
in his preliminary experiments, the 
fungus attacked the trees vigorously, 
and soon caused their death by girdling. 
Experiments with cut twigs, covered 
with glass tubes, were made on one 
tree. Attempts were made to intro- 
duce the fungus into various buds and 
young twigs near the top of this tree 
without wounding the bark, but none 
of them was successful. 
Another tree was treated on April 5 
in the same way, several buds and 
young twigs from one to five inches 
in length being covered with the fun- 
gus for some time under glass: but all 
these attempts failed. The dead branch 
at the top was inoculated through a 
wound. 
The work of observation was next 
carried into the open, where the rav- 
ages of the disease among the older 
trees throughout Bronx Park were 
watched, as they also were among 
young trees transferred from the nur- 
sery of the Zoological Park. In these 
instances infection had occurred nat- 
urally, and the fungus was found to be 
exceedingly active at the beginning of 
the season of growth, before the open- 
ing buds were able to utilize the large 
quantity of nourishment at hand. 
The fungus works beneath the cor- 
te.x in the layers of inner bark and 
cambium. Its presence is first indi- 
cated by the death of the cortex and 
the change of its color to a pale brown, 
resembling that of a dead leaf. Later 
the fruiting pustules push up through 
the lenticels and give the bark a rough, 
warty appearance; and from these nu- 
merous yellowish-brown pustules mil- 
lions of minute summer spores emerge 
from day to day in elongated reddish- 
brown masses, to be disseminated by 
the wind and other agencies, such as 
insects, birds, squirrels, etc. In late 
autumn the winter spores arc formed, 
which are disseminated from the dead 
branches the following spring. The 
present supposition is tliat infection 
