Chestnut Blight and 
Resistant Chestnuts 
By Tue Section oF Fruir anp Nut Crops anp Disrases, HorvicutruraL Crops 
Researcu Brancu, AGRICULTURAL REsEARCH SERVICE! 
THE CHESTNUT BLIGHT EPIDEMIC 
CHESTNUT BLIGHT was first ob- 
served and recognized as a new dis- 
ease in this country at the New York 
Zoological Park in 1904. Later a 
fungus ? native to Japan, China, and 
Korea was proved to be the cause 
of this disease. Probably the blight 
fungus had entered this country on 
Asiatic chestnut nursery trees. Be- 
fore 1912 we did not have a plant 
quarantine law. Asis often the case 
with introduced pests, the blight 
fungus proved to be more virulent 
here than in the countries where it 
isnative. The infection spread rap- 
idly from its center at New York 
City. Soon it reached far into New 
England (fig. 1). Moving still more 
rapidly to the south, it advanced 
into the Allegheny Mountains and 
down through the Appalachians 
(figs. 1 and 2). 
Birds, insects, and wind carried 
the blight fungus from infected 
trees to healthy ones, both nearby 
and far away. Shipments of in- 
fected nursery stock, seed, bark- 
* Partially in cooperation with the Con- 
necticut Agricultural Experiment Sta- 
tion, New Haven, Conn., and the U. S. 
Forest Service. 
* Scientific names of trees and fungi 
are listed on pages 20-21. 
covered poles, and rough lumber 
also carried it. New infection cen- 
ters resulted, often many miles 
ahead of the main infected area. 
Advance spots rapidly enlarged and 
joined, forming continuous infected 
zones. Most of the early efforts at 
control by Pennsylvania and other 
States consisted in locating and cut- 
ting out advance infections. These 
efforts delayed the progress of the 
disease, but it soon became apparent 
that control was impracticable. 
Less than 50 years after the blight 
fungus was discovered in this coun- 
try, it had reached every part of the 
natural range of the American 
chestnut? (fig. 1). The chestnut 
killed is estimated to have been the 
equivalent of more than 9,000,000 
acres of forest stands of pure chest- 
nut. Isolated chestnut trees many 
miles from any other susceptible 
species were not safe from infection. 
Living old chestnut trees are now 
very rare. 
Blight infections have been found 
in orchards and ornamental plant- 
ings of the American and European 
chestnuts in Washington, Oregon, 
California, and British Columbia. 
A few new infections are still oc- 
curring each year in two of the 
1 
