2 BULLETIN 658, U. S. DEPARTMENT OF AGRICULTURE. 
OBJECT OF FOREST DISEASE SURVEYS. 
Timber surveys have as their prime object the gathering of such 
data upon proposed sales areas as will be of use in the appraisal and | 
administration of the sales, and it is this survey which makes the 
sale possible. The collection of valuable data on the board-feet con- 
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Fic. 1.—Pathological map of sections 22, 23, 24, 25, 26, and 27, T. 2 N., R. 15 W., 
the Big Hole area, based upon the map of the timber survey of that area in 
the Deerlodge National Forest, Mont., showing timbered areas infected with disease. 
The rot percentages are indicated for heart-rot (Trametes pini (Brot.) Fr.) and - 
butt-rot (Polyporus schweinitzii Fr.) only. Crosshatching indicates infection areas. 
Other symbols on the map are part of the Forest Service map legend, such as Spr. 
200, which indicates Engelmann spruce, 200-year age class; L. P. 60, 0.7 equals 
lodgepole pine 60-year age class, density 0.7; Gr. equals grassland ; Br. equals brush. 
A, Pine rust (Cronartium coleosporioides (D. and H.) Arthur), gall and blister 
forms, on lodgepole pine (Pinus contorta) ; B, smelter-smoke injury, principally of 
alpine fir (Abies lasiocarpa) and Douglas fir (Pseudotsuga tazxifolia) ; C, honeycomb 
rot (Trametes pini (Brot.) Fr.), principally on Engelmann spruce (Picea engel- 
manni); D, porcupine injury—peeling of bark and girdling of lodgepole pine; 
E, cubical butt-rot (Polyporus schweinitzii Fr.) on lodgepole pine and white-bark 
pine (Pinus albicaulis) ; F, mistletoe (Razoumofskya americana (Nutt.) Kuntze) 
on lodgepole pine. 
tents of the stand, cull percentages, forest types, age classes, topog- 
raphy, and logging factors is followed by an accurate map portray- 
ing the topography, types, density, age classes, and timber estimates. 
A careful stumpage appraisal of the area based upon these available 
data and upon the various economic and topographic factors forms 
the final step before contracts are let. 
