Nov., 1922] KAUFFMAN AND KERBER HEART-ROT OF LOCUST 
495 
these branches were perforated with borer channels horizontally and 
vertically, and when present, either in apparently sound wood or in slightly 
rotten wood, these channels would be found to contain mycelium. The 
spread of the rot from these channels is shown in figure 2. 
Fig. 2. From a piece of diseased black locust, cut from the region of the sound wood 
of section VI. It is clearly shown that the points of infection throughout the diseased tree 
were the borer channels, a, area, of decay; b, borer channels; c, dark border zone of rot. 
Old borer channels in badly decayed wood were indistinct and were 
recognized by pellets of dead mycelium. 
Description of the Rot 
The diseased area of rot of Trametes rohiniopJiila may be divided into 
three stages : 
1. Black Border Zone. The apparently sound wood of the tree is 
sharply differentiated from the rotten area by a very fine, distinct, brownish- 
black zone, having a width that varies between 1/4 and 1/2 millimeter. 
This zone is very irregular in outline, but invariably tends to maintain the 
same color and width. 
2. Lesser Decayed Portion. There is a sharp differentiation between the 
apparently sound and the decayed wood immediately adjoining and outside 
the black zone. The decayed wood is of a light fawn color to a brownish 
white except where traversed by borer channels where it assumes a dark 
brown to reddish appearance. The borer channels are filled with old, 
dead mycelium. The decayed wood is of a solid texture, but very much 
softer and lighter in weight than the sound wood. This first stage of rotted 
wood cuts very easily without breaking. 
