IIO 
Journal of Agricultural Research 
Vol. I,No. 2 
whitish heart-rot, piped in its earliest stages and common in the upper 
half of the trees, due to P . dryophilus; (4) a string and ray rot in 
the butts of the trees, due to P. berkeleyi; (5) a straw-colored rot 
caused by P. frondosus; (6) a white piped or pocketed rot caused by 
P. pilotae; (7) a brown, brittle rot, cause unknown; and (8) a tough, 
spongy, whitish rot caused by Fomes lobatus . 
Of these eight rots the bulk of the damage to the timber in the butts of 
the trees is caused by the following fungi, named in the order of their im¬ 
portance: Hydnum erinaceus, Polyporus pilotae , P. sulphureus, P. berke¬ 
leyi , and P. frondosus . However, P. dryophilus causes a most common 
and very injurious heart-rot of the upper trunk and limbs of oaks in the 
Ozarks. 
Although 64.8 per cent of the felled oak trees studied in the Ozarks 
were affected with butt-rots, the amount of merchantable timber actually 
destroyed by these fungi was comparatively small, owing to the fact 
that these rots do not ascend very high in the trees. More than 2,100 
felled oak trees were carefully studied by the writer, and extensive data 
concerning each tree were recorded. Of the entire number 1,938 were 
white oaks. 
Table I shows the various heights of each rot in the trees down to a cer¬ 
tain limit, together with the corresponding stump diameter, the diameter 
of the rot for each tree, and the number of trees for each recorded rot 
height. For example, the first line, reading across the page, shows 
the name of the rot—“hollow-producing rot”; cause— “Hydnum erina - 
ceus”; diameter of the stump—“26 inches;” diameter of the rot in the 
stump—“17 inches”; height of rot in the bole of the tree—“28 feet”; and 
the number of trees with this height of rot—“1.” Where more than one 
tree has a particular rot of a given height the diameters of the stumps 
and the diameters of the rot in the stumps are averaged, and the resulting 
numbers are shown in the proper columns. 
