DRY-ROT OF INCENSE CEDAR. 



39 



centage with open fire scars) shows that of the total number of trees 

 analyzed on the intermediate area, 38.3 per cent had open fire scars, 

 while on the optimum area the percentage is only 23.5. In other 

 words, these percentages of the total number of trees cut on the 

 areas under consideration were still exposed to infection by wood- 

 destroying fungi through fire scars alone. The last column indicates 

 that 72.2 per cent of the trees on the intermediate area and 49.3 per 

 cent of those on the optimum area have had open fire scars at some 

 period of their life history, thus exposing them to inoculation by 

 fungous spores. 



Table VI. — Incense-cedar trees found in the combined areas having fire scars. 





Number 

 of trees 

 (basis). 



Trees with Are scars (per cent). 



Locality. 



Open. 



Internal. 



Miscella- 

 neous. 1 



Total. 



Intermediate area 



509 

 566 



38-3 

 23.5 



33.2 

 25.4 



0.8 

 .4 



72.2 



Optimum area 



49.3 







Combined 



1,075 



30.5 



29.1 



.5 



60.1 







1 Includes wounds probably but not certainly caused by fire. . 



The internal scars on the intermediate area exceeded those on the 

 optimum area by less than 8 per cent, but there were 15 per cent more 

 open scars. This points to the fact that the intermediate area has 

 been visited by more serious fires than the other, since, as has already 

 L en pointed out, large catfaces are normally the result of repeated 

 fires. 



The combined figures for all the areas show that a total of 30.5 

 per cent of the trees had open fire scars, while 60 per cent suffered 

 fire injury at some time. The column headed "Miscellaneous" in- 

 cludes trees with scars not identified beyond all doubt as having been 

 caused by fire. These are so few that they need not enter into the 

 interpretation of the figures. 



Frost causes some injury in incense cedar but is not nearly as serious 

 in this respect as fire. Frost cracks as a rule extend for some dis- 

 tance up the tree and go deeply into the heartwood. A common place 

 for the cracks to commence is just at the apex of an open fire scar, 

 apparently a point of weakness in the tissues of the wood. Often 

 they are somewhat spirally twisted around the trunk, distinctly 

 reminding one of typical lightning scars. While frost cracks present 

 only a very narrow opening for the entrance of fungous spores, yet 

 in length those cracks or clefts are often quite extensive. In many 

 cases the wood around a frost crack is badly discolored, causing 

 considerable loss in the merchantable contents of the tree. 



