RESISTANCE of CHESTNUT to the BLIGHT 
(Endothia parasitica (Murr.) Ander. and Ander.) 
History:—Chestnut blight was brought into this country apparently 
on nursery stock imported from the orient a few years before 1900, and 
first attracted attention at the New York Zoological Park, New York City, 
in 1904, when it was discovered killing native chestnut trees. In 1913 the 
ceswel fungus was found in China under conditions which left no doubt 
that its original home was in Asia. 
Host trees:—All species of Castanea are hosts of the fungus. The 
most susceptible species is the American chestnut, C. dentata. 
Symptoms:—During the growing season, the yellow or brown leaves 
of a killed branch stand out in strong contrast to the green foliage, and these 
dead leaves may remain on. the diseased parts throughout the following win- 
ter and spring. On the affected stem a canker may be found located usually 
below the lowest killed foliage, with sprouts commonly developing below 
the canker. Young cankers on smooth-barked stems have a yellowish brown 
color, contrasting strongly with the olive-green color of normal bark. Can- 
kers may be either sunken or swollen. Later, longitudinal splits often ap- 
pear in the bark of cankers. Small yellow, orange or reddish-brown fruit- 
ing pustules about the size of a pinhead break through the cankered bark. 
On large stems with thick, fissured bark the disease is difficult to detect un- 
til finally the longitudinal splits appear or fruiting pustules develop in the 
bark fissures. (Fig. 1) ‘ 
Description of the Disease:—The fungus responsible for the blight en- 
ters the trunk or branches through a dead branch, a broken branch stub, or 
through dead or dying areas resulting, e. g., from winter injury. Living and 
growing in the bark, the fungous mycelium gradually extends the radius 
of its operations until the branch or trunk becomes girdled. Then, or 
before, spores are produced in tiny pustules breaking through the surface 
of the bark. The spores are of two kinds: (1) conidia, tiny one-celled 
spores produced in enormous numbers, in moist weather oozing forth from 
the pustules and cemented together in long, thread-like formation, and (2) 
ascospores, 2-celled spores which are ejected forcibly from their spore-cases 
into the air from the pustules. Both kinds of spores are capable of reprod- 
ucing the disease when carried to a suitable host, or to another part of the 
same host. <= 
Extent of Damage:—Without doubt this easwel fungus has proved to 
be the most destructive fungous parasite on forest trees that we have thus 
far known in this country. From an economic standpoint the chestnut was 
one of our most valuable timber trees; prized for its tall, straight, durable 
timber, its ease of coppicing, its bark used in tanning leather, its edible sweet 
nuts, and its beauty and dignity as an ornamental tree. At the present time 
all marketable chestnut within the natural range of the tree has been vir- 
tually killed out. No definite figure or the amount of loss sustained can be 
given, but it must run into many millions - perhaps billions - of dollars. 
Blight Resistance:—Certain of the oriental species of chestnut, e.g. 
Castanea crenata, the Japanese, and C. mollissima, the Hairy Chinese chest- 
nut, offer varying degrees of resistance to the attack of the fungous parasite. 
