FOREST DISEASE SURVEYS. i) 
basis and figuring in all the economic and silvicultural factors con- 
cerned, a cutting age can be computed, aimed to secure the greatest 
amount of sound material at a minimum of cost. No definite rule 
can be given as to the value of the ratio between the total volume and 
the volume of rot required in determining the cutting age. Too 
many factors are concerned even to generalize, and each stand must 
be judged according to the conditions present at the time it is under 
consideration. But it is unquestionably true that data giving the 
relation between the sound and the decay increment in a stand, as 
well as giving an approximation of the rate of increase in decay to 
be expected, will aid 
greatly in solving the 
question. of the proper 
cutting age for that 
stand. 
Forest management 
of this kind can _ be 
practiced to a profitable 
end provided intensive 
methods are employed 
in making a_ special 
disease survey of the 
areain question. Sure- 
‘ly this would be a step 
toward more intensive 
and more economic for- 
est management and 
would aid in solving 
many of the perplexing 
- problems hinging upon 
the decay in timber. 
; 
Whe cost of such a sur- |Be yu ae 
etric "system 2! 
vey would not be pro- | 
hibitive by any mean»ns, Fig. 10.—Typical rot of the sulphur fungus in larch. 
even in case the stand 
were composed of more than one age class, since sample plats of 
small dimensions could be successfully used in securing the necessary 
data upon the decay. To supplement these and aid in the diagnosis 
of the stand, such available data previously secured for similar tree 
species, age classes, sites, etc., could be used te advantage. 
Aside from the advantage secured in arriving at a more accurate 
rot percentage for a stand,.a disease survey accompanied by a patho- 
logical map would be extremely useful after the sales are closed, the 
brush burned, and preparations made for the reforestation of the 
cut-over area. Looking into the future is the forester’s basic prin- 
39732°—18—Bull. 658 
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