could yield such information, it was decided to test its usefulness by making 

 a preliminary extensive tree examination. 



Since the work of this first season was regarded as preliminary and had 

 for its broad objective an evaluation of the problems and possible methods of 

 approach, it was decided to make these examinations in two readily accessible 

 areas of known decadence, a 161-200 year old stand on the south-facing head 

 of Hoodoo Creek, a tributary of east-facing Deception Creek within the De- 

 ception Creek Experimental Forest; and a 101-140 year old stand in the south- 

 west-facing upper reaches of Clay Creek about 13 miles distant, a tributary 

 of south- facing Steamboat Creek, Coeur d'Alene National Forest. Timber volumes 

 of these stands averaged about 25,000 board feet per acre. Topography of 

 both areas is steep, slopes ranging from 15 to 60 percent. 



Western white pine trees on the two areas were sampled by arbitrarily 

 located lines running as nearly as possible at right angles to the contours. 

 Along these lines, one tree every chain (66 feet) was chosen for examination, 

 the chosen tree being the dominant or codominant individual closest to the 

 chain mark and within a radius of half a chain. If no suitable tree stood 

 within this radius, a tree was chosen a chain farther along the line. On 

 the two areas, 180 trees were examined along 11 lines. 



Preparation consisted in digging away enough soil to bare the root 

 collar and every lateral root within 2 feet of the root collar and not more 

 than about 1 foot below the ground line. Sufficient bark was removed to 

 observe the character and extent of infection in the inner bark, cambium, and 

 sapwood (plate 1-C). With an increment borer, two cores at least 3 inches 

 long were taken from the bole of each infected tree at a point approximately 

 1 foot above the ground line. One of these cores was taken above the root 

 with greatest percentage of bared surface infected, and the other above the 

 root showing the least infection or one without infection. Each main lateral 

 root was separately numbered and described and the cores were indelibly marked 

 with numbers corresponding to the tree and root numbers. 



Results and Conclusions 



1. Prevalence of Root Diseases 



One ultimate objective of an extended investigation of root diseases 

 is, of course, an evaluation of their role in the decadence of merchantable 

 stands and the formulation of rules for economically feasible control 

 through modifications of forest practice. Before their role can be evaluated, 

 it must be ascertained whether they are capable of killing sound trees, 

 whether they merely hasten the death of trees weakened or retarded by other 

 agencies, or whether they are merely accompaniments of death due to other 

 causes. The preliminary investigation of 1938 was not expected to supply 

 the answer to this question, but to furnish information suggestive of the 

 answer. Of first interest is the prevalence of root diseases as indicated 

 by incidence and cause, degree, and duration of root infection. 



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