CHESTNUT BLIGHT 
By G. F. GRAVATT, Senior Pathologist, and L. S. Guu, formerly Associate 
Pathologist, Office of Forest Pathology, Bureau of Plant Industry 
CONTENTS 
: Page Page 
Tntre@uchion =. 2.ccexecun secs teeeess 1 | The causal organism.__.._._..-.------------- 7 
Spread of the blight _--...-------------------- 1 | Deterioration of wood__-_._____--.---------- il 
Present distribution-_-_----.-.--..-- — 2 | Utilization of blight-killed chestnut______.--- 13 
Symptoms of the disease 3 | Blight-resi hestnuts - - 15 
INTRODUCTION 
i are PARASITIC FUNGUS, E£ndothia parasitica (Murr.) A. 
and A., that causes the disease of chestnut known as the blight 
or bark disease, was brought into the United States from Asia before 
this country had enacted plant-quarantine laws. As is often the 
case with introduced plant and insect pests, the chestnut-blight 
organism proved to be more virulent in the home of its adoption 
than in its native habitat. Chestnut blight was first observed and 
recognized as a new disease in this country at New York City in 
1904, though it must have been present for some time previous to 
that date. The millions of acres of chestnut growth north of the 
Potomac River and east of the Allegheny Mountains have been 
killed by the blight fungus, and the remaining American chestnut 
stands of the southern Appalachian Mountains are heavily infected 
and face certain destruction. 
SPREAD OF THE BLIGHT 
The disease spread rapidly from its original infection center at 
New York City and later from other centers. It soon covered New 
England, but it made its most rapid advance in a southwesterly 
direction from New York City along the eastern slopes of the Blue 
Ridge and Allegheny Mountains. : 
The blight fungus not only spreads from infected trees to healthy 
ones near by, but often it is carried for long distances on shipments 
of chestnut poles or nursery trees and by birds or wind. Under 
favorable conditions such distribution of the fungus may result in 
new centers of spread, known as spot or advance infections. The 
rapid progress of the blight over the chestnut area is largely due to 
the fact that these advance infections become established many miles 
ahead of the main infection area, These advance spots rapidly en- 
large, run together, and form a continuous infected area. The plan 
of the early work in Pennsylvania and other States was to locate 
1 
