DRY-ROT OF IXCENSE CEDAR. 
43 
Not only does the total number of wounds increase with age in a 
stand, but the number of severe wounds becomes proportionately 
greater. Each tree was given a wound rating (x) , x, xx, or xxx, the 
first symbol indicating very slight wounding and the last very 
severe. In Table IX trees with a rating of xx or xxx are con- 
sidered as severely wounded. In all cases the character as well 
as the extent of the wounding and its relation to inoculation by 
spores of the dry-rot fungus was carefully taken into account in 
applying the rating. 
In column 4 of Table IX it is seen that while in the age class of 
41 to 80 years .only 6.7 per cent of the wounded trees are severely 
wounded, an almost steady increase brings this figure to 68.5 per 
cent in the class of 321 to 360 years. This is to be expected, espe- 
cially since fire scars predominate, because large scars of this type 
are almost invariably the result of recurring fires, and in the past 
virgin stands in California have been fire swept time and again. 
The two oldest age classes can not be given much weight, owing to 
an insignificant basis. 
The above figures demonstrate the rather slight chance an incense 
cedar has of rounding out its life without a reduction in its normal 
increment through an injury interfering with the growth processes 
or a reduction in its actual content of merchantable timber, either 
directly from a wound or by a wound affording an entrance for a 
heartwood-destroying fungus, in this instance most probably the 
dry-rot fungus (Polyporus amarus). 
RELATION OF DRY-ROT TO MECHANICAL INJURIES. 
The intimate connection of various kinds of wounding, especially 
fire, with infection by the dry-rot are shown in Table X. The 
infections are grouped under their respective causes and percentages 
for each cause, figured on the basis of the total number of infections. 
Trees of uncertain ages are included in these figures, since it makes 
no difference in this table whether or not the absolute age of the 
tree is known. 
Table X. — Mode of entrance of dry-rot infections of incense-cedar trees. 
Number 
of infec- 
tions 
(basis). 
Means of entrance of infections (per cent). 
Locality. 
Fire 
scars. 
Knots. 
Wounds, 
cause 
un- 
known. 
Light- 
ning 
scars. 
Un- 
known 
causes. 
Frost 
cracks. 
Broken 
or dead 
tops. 
322 
334 
75. 8 
58.7 
19.3 
31.1 
0.6 
5.1 
2.5 
1.5 
0.9 
2.4 
0.6 
.9 
0.3 
Optimum area. 
.3 
Combined 
656 
67.1 
25.3 
2.9 
2.0 
1.7 
.8 
.3 
