22 BULLETIN 799, U. S. DEPARTMENT OY AGRICULTURE. 
number of dead branches on trees of the bottom sites. Site is ap- 
parently responsible for a greater percentage of sporophores de- 
veloping on the trees of the bottom sites. An average for the bot- 
tom sites gives a distribution of 11 sporophores to every 10 trees, 
while the slope sites have 8 sporophores to every 10 trees. The pro- 
portion of live and dead sporophores to the total sporophores is 
about equal on each type of site, 93 per cent alive and 7 per cent 
dead. The proportion of live and dead sporophores to the total, in 
the case of the largest sporophores, shows a percentage approaching 
that already given, also showing very little variation in respect to 
site. A greater number of sporophore-bearing trees are found upon 
the bottom sites. 
METHODS OF CONTROL. 
From the study of the data presented, it appears that the control 
of diseases in western white pine under the present stage of forestry 
in the Northwestern States will be a difficult matter and subject to 
extensive rather than intensive methods. The high economic value 
of the tree and the large amount of loss due to rot are two important 
factors which make it imperative that steps be taken at least to 
check the diseases and that attempts be made to reduce the annual 
loss of sound material brought about by the spread of the casual 
organisms. * 
There are two methods of control which present themselves as 
practicable under the present methods of forest management. These 
two methods work hand in hand. The first method is primarily 
based upon the rotation of the stand or the felling age. It is evident 
from a study of the data presented that if the stand is cut before any 
sporophores are produced, or before they are produced in any great 
numbers, the spread of the diseases will be effectively checked. The 
data show that a certain age class represents the period in the stand 
which develops a maximum of sporophores. This period in western 
white pine is represented by the 121 to 160 age class. This age 
class has 43 per cent of the total trees bearing sporophores for the 
bottom sites and 45 per cent for the slope sites. Both the next lower 
and the next higher age classes have smaller percentages for the two 
types of site than the 121 to 160 age class. If the felling age of west- 
ern white pine is kept within the 101 to 120 age class there is every 
reason to believe that the infected trees will be cut down before they 
reach the age of maximum sporophore production. Most of them 
will no doubt be cut down before airy fruiting bodies whatever 
appear. This is the most desirable result and is particularly true 
for the slope sites. 
The second method is fundamentally concerned in the strict appli- 
cation of proper pathological marking rules and the consequent re- 
