FOREST DISEASE SURVEYS. 



21 



Schroeder and Reuss in 1883. x Other works by Schroeder and 

 Schertel in 1884 2 and Borggreve in 1893 3 also give maps in connec- 

 tion with studies of smoke, the latter maps being uncolored. No 

 references were found which contained colored maps of the dis- 

 tribution of forest-tree diseases. 



In the making of timber-survey maps, type boundaries are indi- 

 cated by continuous dotted lines inclosing within the areas so 

 formed the figures 

 indicating type 

 mixture, density, 

 and age class, the 

 age class also being 

 separated by dotted 

 lines. Very often 

 these areas are col- 

 ored by the use of 

 wash inks or cray- 

 ons, so as to make 

 a greater distinc- 

 tion between them. 

 A number of stand- 

 ard colors are used 

 and are applied 

 upon white prints, 

 which are found to 

 give the best re- 

 sults. A similar 

 method is proposed 

 for use in rm^king 

 pathological -mlups, 

 the only variation 

 being the addition 

 to the type -sheet 

 maps of boundary 

 lines indicating the 

 infected areas and 

 a special set of col- 

 ors indicating va- 

 rious diseases. In the pathological maps only those colors denoting 

 the various infections should be used, leaving the type areas uncolored. 



1 Schroeder, Julius von, and Reuss, Carl. Die Beschadigung der Vegetation durch 

 Rauch ujnd die Oberjiarzer niittenrauchschiiden. 333 p., 2 maps (colored). Berlin, 18S3. 



2 Schroeder, Julius von, and Schertel, A. Die Rauchschiiden in den Wiildern der 

 umgebungder physikalischen Hiittemverke bei Freiberg. Separat-Abdruck Jahrb. Berg. w. 

 Hiittenw. Konigr. Sachsen, 1884, p. 93-120, map (colored). 1884. 



3 Borggreve, B. Rauchbeschiidigung in ' dem von Tiele Winkler'schen Forstreviere 

 Myslowitz-Kattowitz. 236 p., 2 maps. 1S93. 



Fig. 21. — Cronartium coleosporioidcs, pine rust, gall form, 

 on young lodgepole pine. The two galls on the main stem 

 are fruiting. Note the small white cups scattered over the 

 surface of these two galls. 



