Long; Western Red Rot in Pinus ponderosa 179 
Western red rot is exceedingly common throughout the western 
yellow pine regions of Arizona and New Mexico. Specimens 
of the fungus have also been examined from Vermont, New 
Jersey, Washington, and Idaho, while a photograph of the rot in 
western yellow pine has been seen from South Dakota. It is 
therefore highly probable that the fungus is widely distributed 
throughout the western states and to a limited extent at least in 
the northeast. 
The western red rot fungus enters the living tree through the 
heartwood of dead branches in the crown. It first attacks the 
sapwood of the dead branch, then the heartwood ; it then travels 
down the dead branch into the heartwood of the living tree. 
In order to throw some light on the presence of western red rot . 
in western yellow pine and its probable influence on the rotation 
period, studies were conducted on certain areas in the Santa Fe 
National Forest, N. Mex., where both tie trees and sawtimber 
were being cut. These areas were especially suitable for a study 
of this character, since an unusually large percentage of the black 
jack (30 to 50 per cent.) and nearly all of the yellow pine (85 to 
100 per cent.) were being cut. A marked difference was found 
in the percentage of black jack (young western yellow pine be- 
fore it reaches the age of 125 to 150 years) and of yellow pine 
affected by western red rot on these areas. Of 1815 felled mer- 
chantable black jacks examined, only 29 or 1.59 per cent, had 
this rot, while out of 563 yellow pines, 77 or 13.6 per cent, were 
attacked by it. The above data show that during the black jack 
period, the trees are practically free from western red rot but as 
they grow older, the increasing number of dead branches make 
them more subject to the attacks of the fungus. 
On the areas examined, western yellow pine trees up to 125 to 
150 years old were rarely attacked by western red rot, while trees 
over 200 years old showed a much higher percentage of rot than 
the younger trees (black jack). It therefore follows that a short 
rotation will be better for the future health of the forest as far 
as heart rots are concerned than a long one. It is a fundamental 
fact that the older a tree is, the more liable it is to be attacked by 
heart-rotting fungi. 
