THE CHESTNUT BARK DISEASE. 
By Haven MEtcatr, 
Pathologist in Charge of Investigations in Forest Pathology, 
Bureau of Plant Industry. 
HISTORY AND DISTRIBUTION. 
To Mr. H. W. Merkel, forester of the New York Zoological Park, 
belongs the credit of first clearly recognizing, in 1904, the potential 
seriousness of the disease now known as the chestnut bark disease or 
chestnut blight. Observations reported later by other persons indi- 
cate that the disease was present on. Long Island some years earlier. 
Apparently the disease has spread from this general vicinity; at 
least no centers of infection have been found elsewhere which are as 
old as these about New York City. 
The disease is now distributed from Merrimack County, N. H., and 
Warren County, N. Y., on the north, to Albemarle County, Va., on 
the south. In New York the western border of distribution, so far 
as known at present, is sharply delimited by an area without chestnut 
trees—a natural “immune zone”-—-which extends southward along 
the eastern borders of Fulton, Montgomery, and Schoharie Counties 
nearly to the Pennsylvania line in Delaware County. Consequently 
in New York the range of the disease is at present practically limited 
to the valley of the Hudson. In Pennsylvania the western limit of 
general infection is roughly along a curved line extending from the 
northwest corner of Susquehanna County to the eastern border of 
Clearfield County and on to the southwest corner of Fulton County. 
West of this line the advance infections have been cut out by the 
Pennsylvania Chestnut Tree Blight Commission. The disease has 
not yet been found in Ohio or North Carolina. The infections 
farthest west, most of which have now been cut out, are those in 
Livingston County, N. Y., Warren and Somerset Counties, Pa., and 
Randolph County, W. Va. All of these appear to owe their origin 
to diseased chestnut nursery stock. 
It is difficult to estimate the financial loss which the above dis- 
tribution represents, as we have no exact statistics on the value of 
363 
