70 BULLETIN 380, U. 8. DEPARTMENT OF AGRICULTURE. 
observations leave no doubt that the tree was girdled and killed by 
E. parasitica. 
Endothia parasitica in exceptional cases undoubtedly attacks other 
hosts than Castanea, producing cankers and sometimes causing the 
death of the host. The results of the inoculations just recorded 
appear to indicate that some unusual conditions of host or parasite 
must obtain in such cases. Whether such a combination of conditions 
or factors will ever become sufficiently frequent to lead to serious 
destruction of Quercus or other forest trees remains to be determined. 
ENDOTHIA PARASITICA ON CASTANEA SPP. 
Although found occasionally on species of other genera, Endothia 
parasitica is dangerously pathogenic only on members of the genus 
Castanea. The parasitism of this fungus on the American chestnut 
(Castanea dentata) was first proved by Murrill (57) and has since 
been demonstrated by numerous investigators. : 
When Endothia parasitica was discovered in the United States it 
was considered by some investigators to be a native fungus which 
had suddenly become parasitic, and various theories were advanced 
to account for the supposed unusual susceptibility of the host. As 
enumerated by Clinton (18, p. 391), the factors suggested include 
winter injury, drought injury, fire injury, weakened condition due 
to continued coppicing, and reduced amounts of tannic acid due 
perhaps to weather conditions. 
Continued study by many investigators in different localities has, 
however, fully confirmed the observation originally made by Met- 
calf and Collins in 1910 (53) that “a debilitated tree is no more 
subject to attack than a healthy one” and that Endothia parasitica 
is actively parasitic on the healthiest specimen of Castanea dentata 
in case there is opportunity for wound infection. The writers have 
personally made over 1,200 inoculations of 2. parasitica on Castanea 
dentata without finding a single individual that showed any re- 
sistance. 
CASTANEA ON LIMESTONE SOILS. 
Not only are all trees susceptible, but_so far as is known no con- 
dition of soil, altitude, or moisture renders them more resistant to 
the disease. The idea has been held by some writers that chestnuts 
grown on limestone soils were immune to the disease, and the plant- 
ing of chestnut orchards on such soils was advocated. This view 
is held by Gulliver (38, p. 53), who sums up his observations in two 
regions in Pennsylvania as follows: 
In every series of tracts taken from limestone to overlying shale soils, the 
percentage of blight is least at a comparatively short distance * * * from 
the edge of the limestone. Tracts on soils derived from limestone which 
show the highest percentage of blight seem to be those where the soil has 
