246 
Journal of Agricultural Research 
Vol. I, No. 3 
Four trees of Quercus alba were found affected with this disease in 
Maryland. All had been uprooted by the wind, two very recently, so 
that the character of the earlier stages of the rot and its progress in the 
roots was easily observed. In both of these trees the rot was only in 
the lower ends of the roots and had not reached the stool nor formed 
sporophores. Three of these uprooted trees were growing in dense 
stands and were much suppressed. 
Oaks which have been uprooted by the wind may be separated into two 
classes: (1) Those whose root system has been weakened by insect or 
fungous attack and (2) those with a very shallow root system, due to the 
presence of impermeable layers of rock in the subsoil or to the ground- 
water being constantly near the surface of the ground (within 1 to 2 feet). 
Trees uprooted by wind owing to rotten roots have very little soil adher¬ 
ing to the upturned stool of the tree, as most of the roots break off within 
1 to 2 feet of the base of the tree. On the other hand a tree with a sound 
root system brings with it when uprooted a large mass of earth several 
cubic yards in size. Bearing this in mind one can often distinguish, even 
at a distance, wind-thrown trees with sound roots from those overthrown 
on account of root-rot. 
In every instance where the sporophores of Polyporus dryadeus were 
found on trees the roots were diseased with the same type of root-rot. In 
wind-thrown trees where the disease was not far enough advanced to pro¬ 
duce sporophores the rot was identical with that obtained from the roots 
of trees which had sporophores of P. dryadeus . The rot in such uprooted 
trees evidently began at some point on the lower end of the roots and 
advanced up the roots toward the base of the tree, stopping, however, 
when it reached the surface of the ground. Roots lying very near the 
surface of the soil, especially large ones with their upper surfaces exposed 
to the air, are not entirely rotted or even killed by this fungus. Many 
instances of such superficial roots were found in which the part under¬ 
ground was rotted while the upper portion remained alive. The cross 
section of the root illustrated in Plate XXII, figure 6, shows the upper 
part alive, while the lower and more deeply buried portion is rotted. This 
root forked some 2 feet from the tree; one root, 10 inches in diameter, 
went down deep in the soil and was thoroughly rotten and dead; the other 
fork was 2 to 4 inches deep and was perfectly sound 2 feet from where the 
rotted root joined it. 
The inability of the fungus to rot exposed roots and the trunk above 
the surface of the soil, coupled with the further fact that the sporophores 
usually are attached to what superficially appears to be sound wood, 
probably explains why the connection between this rot and the fungus 
causing it has not been previously noted. Trees in all stages of this 
disease were seen; some were already dead, others dying, others on the 
decline, while some showed no evidence of the disease until they were 
overthrown by the wind and the decayed roots were exposed. Some of 
