Journal of Agricultural Research 
Vol. I, No. 2 
114 
to enter either at the butt or in the top of the tree, such as Hydnum erina- 
ceus t Polyporus sulphur eus, and P. pilotae; (3) those which enter the 
upper portion of the tree and work in both directions from the point of 
entrance, but rarely, if at all, enter through fire scars at the butt, such 
as P. dryophilus and Fomes everhartii. 
THREE UNDESCRIBED TYPES OF HEART-ROTS 
In a later article the writer expects to discuss a large number of heart- 
rots of the oak, limiting this paper to a detailed description of the following 
rots: A pocketed or piped rot of the oak, chestnut, and chinquapin caused 
by Polyporus pilotae; a string and ray rot of the oak caused by P. 
berkeleyi; and a straw-colored rot of oak caused by P. frondosus . 
A POCKETED OR PIPED ROT CAUSED BY POLYPORUS PILOTAE 
The rot produced by P. pilotae has been found by the writer directly 
associated with the sporophores of this fungus in the following species of 
trees: Quercus alba L., Q . velutina Lam., Q. texana Buck!., Q . coccinea 
Muenchh., Castanea pumila (L.) Mill., and C. dentata (Marsh) Borkh. 
A Pocketed or Piped Rot in White Oak 
The description of the pocketed or piped rot which follows was made 
from the diseased wood of a white-oak tree ( Quercus alba) which was cut 
on July 23, and on August 27 the sporophores of Polyporus pilotae shown 
in Plate VII, figure 1, were found fully developed on the end of the log. 
There could be no question as to the identity of the fungus producing 
the rot in this case, as less than 30 days had intervened between the 
felling of the living tree and the formation of the sporophore of P. pilotae . 
The first indication of this rot in white oak is a slight browning of the 
heartwood. Later white, oval, or circular cellulose patches from deligni- 
fication appear in this discolored wood. These white areas by dissolution 
of the fibers often become holes, which show in both radial and cross 
section (PI. VII, fig. 2). The delignification seems to originate in the last 
layers of the summer-wood fibers and spreads in a very irregular manner. 
In later stages long strings of white cellulose fibers are found. This is 
especially true where an abundance of air and rain water can reach 
the rotting area, especially in old dead logs or in trees with cracks or in 
hollow, open butts. The delignification and absorption of the fibers 
do not follow the spring wood as closely as they do in the scarlet oak 
(1 Quercus coccinea ). 
Another type of cavity may be formed which seen in radial view is 
0.5 to 1 mm. by 1 to 2 mm. in size. These cavities are lined with the 
ends of the white cellulose fibers and usually occur in and at right angles 
to the large spring vessels, but they may also extend radially from one 
annual ring to the next in a more or less winding or interrupted course. 
