DRY-ROT OF INCENSE CEDAR. 27 



the same tree, each one, however, the result of a separate and distinct 

 inoculation. As soon as an infection causes a measurable amount of 

 cull it becomes a cull case and is so termed. Hence, every infection 

 is not a cull case, but every cull case is an infection. Only loss of 

 merchantable timber through dry-rot is considered; cull from 

 wounds, knots, limbs, insect borings, or crook is disregarded, since 

 these have no bearing on the loss from dry-rot except when the 

 decay is directly traceable to a wound. In such cases loss from the 

 wound is included with the volume of rot. 



For figuring from the field notes and measurements the cull caused 

 by dry-rot, the amount and degree of damage with relation to the 

 resulting loss in merchantable lumber was carefully taken into 

 account, just as it is hi scaling. For example, a cull case might 

 have considerable linear extent but consist only of a few scattered 

 pockets in a straight line, resulting in little or no loss in merchantable 

 volume. The same number of dry-rot pockets, shorter in linear 

 extent but radially scattered throughout the heartwood, probably 

 would cause considerable cull. Again, a number of pockets close to 

 the sapwood, mostly slabbing out when the log is sawed, would have 

 far less weight than the same pockets in the center heartwood. 

 Meinecke's method (16, p. 37) of considering the entire bole of the 

 tree over the linear extent of decay as cull, while justifiable with the 

 commercially inferior white fir, could not be applied to the distinctly 

 more valuable incense cedar. Here the lateral extent of the decay 

 also had to be taken into account. This could be readily determined 

 from the field notes and diagrams. For example, if the decay occu- 

 pied one-fourth of the area as seen on cross sections and had a linear 

 extent of 10 feet, the volume outside the bark of this 10-foot frustum 

 (the tree being considered as a cone, see p. 26) was first secured 

 and then one-fourth of it was considered as the volume of the decayed 

 portion of the tree. Below one-fourth the decay was usually treated 

 as negligible except when it had a linear extent of several feet. The 

 volume was then computed as before. 



Separate tables containing the above figures were worked up for 

 the four areas, the trees being arranged progressively by ages, begin- 

 ning with the youngest. It does not seem necessary to present these 

 tables, since they were merely preliminary. 



In considering the trees on the intermediate area it was found that 

 the first infection which resulted in cull occurred in a tree 98 years 

 old. However, infection can take place at a much earlier age than 

 this. For example, in a tree 104 years old there was a light cull case 

 traced to a healed lightning wound. The tree was injured at the 

 age of 50 years and the wound completely healed when the tree was 

 63 years old; hence, the tree could not have been older than 63 years 

 at the time of infection. Again, in a tree 146 years old there was 9, 



