THE ROTS OF WESTERN WHITE PINE. 19 
On the bottom sites it is observed that sporophores are recorded for 
all the age classes, including that of 61 to 80 years. In the slope sites 
both the 61 to 80 and the 81 to 100 age classes have no sporophores 
recorded. The first sporophores appear in the 101 to 120 age class. 
They increase in number in the 121 to 160 age class and decline in the 
161 to 200 and the 201+ age classes. The column indicating the 
average number of sporophores per tree indicates this very clearly. 
The column recording the number of sporophore-bearing trees shows 
a similar increase, reaching a maximum in the 121 to 160 age class, 
and a rapid decline is noted in the two succeeding age classes. These 
data indicate a maximum of sporophore production attained in 
the 121 to 160 age class and show the rapidly decreasing numbers of 
sporophores present on the trees of the two oldest age classes. Two 
factors are responsible for the decline — first, the fact that the fungus 
in the tree has reached and passed its maximum development and so 
produced fewer new sporophores, and second, the fact that in the 
old-age classes the old sporophores are observed to have died, be- 
come loosened from the trunk, and dropped off. The relation of rot 
percentage to sporophores is evident when compared on a basis of 
site. On the bottom sites the rot percentage is nearly 8 (7.8, Table I) , 
and an average of 1.1 sporophore per tree or 11 sporophores to every 
10 trees is recorded. In the slope site the rot percentage is over 6 
(6.1, Table I), and the average number of sporophores per tree is 
0.8 or 8 sporophores to every 10 trees. The bottom sites show a 
greater rot percentage and a greater average number of sporophores 
per tree. 
Another interesting point brought out by the table is the fact that 
on both types of site the smallest groupings of sporophores were 
found on the southeast side of the trees. 
DISCUSSION OF RESULTS. 
From the foregoing data it appears that age is the important factor 
in determining the amount of rot to be expected in a western white- 
pine stand. This factor of age is significant in the application of 
proper silvicultural methods to the care and disposal of the timber. 
From the forester's point of view two things stand out in consider- 
ing the stand in relation to rots. The one is the age of earliest infec- 
tion of the stand, or the period when infection by fungi can first be 
expected. This is undoubtedly controlled by the formation of heart- 
wood and the appearance of injuries susceptible to infection. This 
infection age is found to be approximately 50 years for western white 
pine, and it indicates the period when the young stand is in need of 
the utmost protection against infection by fungous spores. Infection 
takes place in this tree earlier than at 50 years in certain individuals, 
