FOREST DISEASE SUKVEVS. 



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 

 area in 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. 

 The cost of such a sur- 

 vey would not be pro- 

 hibitive by any means, 

 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 to 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 2 



Fig. 10. — Typical rot of the sulphur fungus In larch. 



