52 BULLETIN 380, U. S. DEPARTMENT OF AGRICULTURE. 
SOIL CONDITIONS. 
Greater opportunity for infection seems to be an important factor 
in the greater abundance of Endothia in the South. By far the most 
favorable places of infection, especially for Endothia gyrosa, are 
bruised or broken but still living roots. Soil, cultural, and climatic 
conditions combine to make these many times more abundant in 
the Southern States than elsewhere. The more sandy and easily 
eroded soil, usually without turf, subject throughout the winter to 
the action of wind and rain, leaves innumerable oak roots exposed, 
which are readily injured by vehicles and the tramping of horses and 
cattle, leaving wounds suitable for the entrance of Endothia. In the 
Fig. 4.—Map of the United States, showing the distribution of Endothia perasitica in 
December, 1915. The solid portion shows the area in which EL. parasitica is generally 
present. The dots indicate scattered infections. The heavy line shows the limits of 
the range of Castanea dentata, 
North, the more rocky soil, frequently covered with sod, protected 
through much of the winter by snow, makes exposed roots much less 
common, and the roots so exposed are rather less subject to mechani- 
cal injury. In the writer’s experience the most favorable localities 
for collecting EZ. gyrosa are the unfenced public squares of Southern 
towns, where partial grading, erosion, and constant traffic have left 
hundreds of oak roots exposed, and the pastures of southwestern In- 
diana, where the roots of Fagus are often found injured by cattle. 
COMPETITION AMONG FUNGI. 
The writers’ extensive field studies and observations have con- 
vinced them that competition among fungi must be considered as a 
a 
