DEATH OF CHESTNUTS AND OAKS. 5 
by lightning this disease was found following up and enlarging the 
wounds. Many of the white oaks killed by this fungus had been 
blown down. In every case the upturned roots were covered with a 
network of the black rhizomorphs (PI. I, fig.1). Several groups of 
two to four chestnut trees which had originated from sprouts around 
a common stump vere found killed by this root-rot. Plate II, figure 
2, shows two trees .com a common base, one being already dead 
and the other badly diseased. In the latter the bark and roots on 
the side adjacent to the dead tree were killed for about one-third of 
the distance around the base, and the rot had extended up the tree 
8 feet under the bark. : 
PERCENTAGE AND SIZE OF CHESTNUTS KILLED BY ARMILLARIA MELLEA. 
Of the 302 felled chestnut trees examined, 64, or 21 per cent, had 
been killed by the Armillaria root-rot. The average diameter of these 
killed trees was 12 inches; the largest chestnut killed was 26 inches 
and the smallest 3 inches in diameter. Trees of all diameters be- 
tween these limits were found diseased and killed. Of these trees, 
10 had a diameter of 3 to 5 inches, 13 of 6 to 10 inches, 22 of 11 to 
15 inches, and 19 of 16 to 26 inches. From this it follows that a 
greater percentage of the large chestnut trees was killed by this root- 
rot than of the smaller and younger trees. Of the 64 chestnut trees 
killed, 41, or 64 per cent, were over 10 inches in diameter. The 
average diameter of these 41 trees was 16 inches. In the white oak, 
just the reverse occurred; a greater percentage of the smaller and 
younger trees was killed than of the larger and older ones. 
PERCENTAGE AND SIZE OF OAKS KILLED BY ARMILLARIA MELLEA. 
Of the 477 oaks checked, 130, or 27 per cent, had been killed by 
the Armillaria root-rot. The average diameter of these killed trees 
was 7 inches, as compared with 12 inches in the chestnut. The 
largest oak killed was 18 inches and the smallest 2 inches in diameter. 
Trees of all sizes between these two extremes were affected. Of 
these white oaks, 39 ranged in diameter from 2 to 5 inches, 70 from 6 to 
10 inches, and 20 from 11 to 15 inches, with only 1 over 15 inches. 
Of these 130 white oaks which had been killed, 84 per cent were less 
than 11 inches in diameter and only 16 per cent were over 10 inches 
in diameter, as compared with 64 per cent in the case of the dead 
chestnut trees in the same locality. 
_ Of the white oaks killed by this root-rot, 46 had been overthrown 
by the wind, while only 2 of the dead chestnuts had been blown 
down. Of the wind-thrown oaks, 26 were from 6 to 8 inches in 
diameter, showing that the smaller as well as the larger sizes of white 
oaks were not as easily uprooted as those of medium diameter. 
34907°—14——2 
