Nov- io, 1913 
Heart-Rots of Hardwood Trees 
121 
Of the 1,938 white oaks studied in the Ozarks 408 trees had this rot. 
The average diameter of the rot per tree was 13.7 inches, the average 
diameter of the stump was 25.6 inches, and the average height was 3.86 
feet. The maximum diameter and height of the rot in these trees was 
found in a tree 400 years old. The diameter of the tree was 40 inches, 
the diameter of the rot was 36 inches, and the height of the rot was 24 
feet. The oldest rot was 280 years and was found in a tree 310 years old. 
The average age of the rot in 92 trees was 156 years. The average rate 
of growth of the rot was 1 foot in height and 3.5 inches in diameter for 
every 40 years of time. The youngest white oak found with this rot 
was 180 and the oldest 400 years old. 
The exact range of this fungus is not known. It is very common in 
oak and chinquapin in the Ozark National Forest and has been found in 
Virginia on scarlet oak. 
The writer has also examined authentic sporophores of this fungus on 
the following hosts and from the following localities: ‘ 
“On underside of log” (resupinate sporophore), Pennsylvania; “on 
log,” North Carolina; “in hollow oak log,” Ohio; “on rotten oak 
log,” Indiana; “on underside of old log” (resupinate sporophore), 
West Virginia; “on dead oak logs,” New York; “on oak,” North Caro¬ 
lina; from Iowa, no host given; “on punky chestnut log,” no locality 
given; from Florida, no host given; from South Carolina, no host given; 
from Tennessee, no host given; “on end of log,” Canada; “on oak,” 
Canada; “on old logs,” Canada. Three specimens were also seen from 
Europe, where it is known as Polyporus croceus (Pers.) Fries: “On 
living oak,” Sweden; “on old oak and chestnut,” apparently from 
France, no locality given; and “on old oak,” locality not given. It 
probably occurs east of the Rocky Mountains in the United States on 
oak, chinquapin, and chestnut wherever the hosts grow and also in 
Europe on oak and chestnut. It is by far the worst heart-rot found in 
chestnut timber, occurring in this host as both a butt and top rot. It 
stands second in destructiveness to white-oak timber in the Ozark 
National Forest, both as to number of trees infected and height attained 
in the tree. Hydnum erinaceus is the most destructive heart-rotting 
fungus of the oak found in the Ozark forests (see Table I, p. 111). The 
rot caused by P. pilotae was found associated with the rot produced by 
Hydnum erinaceus in 105 trees, with string and ray rot in 3 trees, with 
Polyporus sulphurous rot in 8 trees, and with both Hydnum erinaceus and 
Polyporus sulphureus rots in 5 trees. 
The sporophores of P. pilotae were in an actively growing stage during 
the month of September in the Ozark National Forest. This fungus 
usually enters the oak at the base of the tree, probably through fire 
scars in most instances. The rot was also found occasionally in the 
upper part of the tree, while the base was not infected. The fungus, 
13000 0 —13-3 
