6 CONTROL OF THE CHESTNUT BARK DISEASE. 
Depression in the value of real estate, especially suburban or near- 
suburban, owing to the death of the chestnut trees, must be taken 
into account in an estimate of this kind, as well as the loss of the 
trees themselves. 
CAUSE AND SYMPTOMS. 
The chestnut bark disease is caused by a fungus parasite known 
under the technical name of Diaporthe parasitica Murrill. When 
any of the microscopic spores (reproductive cells) of this fungus gain 
X 
Fic. 1.—Map of the northeastern part of the United States, showing the distribution 
of the chestnut bark disease. The horizontally lined part shows the approximate 
area wherein the majority of chestnut trees are already dead from the bark disease. 
The part marked by vertical lines shows the approximate area wherein infection is 
already complete. The round dots show the location of advance infections of the 
disease. Many of these have already been eradicated. The map has been compiled 
from both observations and correspondence. The writers are under especial obligations 
to Dr. Perley Spaulding, Prof. A. H. Graves, Mr. I. C, Williams, Mr. W. H. Rankin, 
Mr. J. I’. O'Byrne, Mr. F, W. Besley, Dr. Ernest S. Reynolds, and Mr. H. G. MacMillan, 
for data along this line. According to Dr. G. P. Clinton (Connecticut Agricultural Ex- 
periment Station, Report of the Botanist, 1909 and 1910) there are Many more points 
of infection in Connecticut than are shown on this map. 
entrance into any part of the trunk or limbs of a chestnut tree they 
give rise to a spreading “sore” or lesion, which soon girdles the tree. 
If the part attacked happens to be the trunk, the whole tree in con- 
sequence is killed, perhaps in a single season. If the smaller branches 
are attacked, only those branches are killed, or only those portions of 
branches beyond the point of attack, and the remainder of the tree 
may survive for several years (fig. 2). 
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