DRY-ROT OF INCENSE CEDAE. 35 



Table V. — Combined data relating to dry-rot found in incense cedars of the combined areas. 



Age class. 



(years). 



Number 

 of trees 

 (basis). 



Percentage of- 



Dry-rot 

 volume. 



Severe 

 cull 

 cases. 



Cull 

 cases. 



Infec- 

 tions. 



to 40 years 



41 to 80 years... 

 81 to 120 years.. 

 121 to 160 years. 

 161 to 200 years. 

 201 to 240 years. 

 241 to 280 years. 

 281 to 320 years. 

 321 to 360 years. 

 361 to 400 years. 

 401 to 440 years. 



Combined 



40 

 60 

 105 

 141 

 180 

 223 

 259 

 296 

 334 

 370 

 436 



1 

 51 



185 



284 



233 



118 



94 



49 



19 



4 



2 





 4 

 20 

 29 

 42 

 61 

 79 

 88 

 90 

 100 

 100 





 6 

 38 

 46 

 61 

 73 

 83 

 92 

 90 

 100 

 100 



1,040 



Table V strikingly demonstrates the cumulative risk to incense 

 cedar from dry-rot with advancing age. Starting at 1 per cent of 

 cull in the age class of 41 to 80 years it mounts to 67 per cent in 

 the class of 321 to 360 years. With a very gradual increase up to 

 160 years it then becomes rapid. The figure of 82 per cent in the 

 class of 361 to 400 years, even though on an insignificant basis, is 

 not without significance when considered in relation to the general 

 previous progression. That this figure should drop to 5 per cent in 

 the last age class need not cause concern, since the basis is only two 

 trees. Even though infected, a tree may escape extensive decay 

 throughout its life. This is a rare occurrence, however. The percent- 

 age of severe cull cases closely follows the percentage of cull throughout 

 until the last two age classes with their small bases are reached. 

 These two sets of figures show beyond doubt the high percentage of 

 loss through dry-rot that may be expected in overmature cedars and 

 clearly prove that the presence of such trees in our stands of the pres- 

 ent and the future can be nothing but an economic loss. 



That the percentages of cull cases and of infections do not follow 

 the same form as the two others just discussed was shown in previous 

 tables, but is more clearly brought out here. The reasons for this 

 have been touched upon. However, these two figures are of interest 

 when compared. It is seen that with advancing age the percentage 

 of cull cases becomes increasingly higher at a more rapid rate than 

 does the percentage of infections, until finally in the class of 321 to 

 360 years the two coincide. To be more explicit, the infections 

 gradually begin to cause more and more measurable decay, until 

 finally every infection has resulted in a cull case, no matter how slight. 

 In the last two age classes both cull cases and infections have reached 

 100 per cent; but again we are confronted by the small basis and this 

 figure can not be accepted. There is no doubt that a tree by rare 

 chance may escape infection throughout its life, but there is hardly 



