FOREST DISEASE SURVEYS. 13 



upon all such areas in which the newly transplanted seedlings are 

 subject to infection by fungi or mistletoe. Many of the plantation 

 sites of this region are located upon burned-over areas, and the 

 majority of these are so badly fire swept that very little has been 

 left in the form of coniferous hosts for forest-tree diseases. How- 

 ever, to review the succession of plant life on a burned-over area, 

 after a fire which has been sufficiently intense to destroy every vestige 

 of humus and litter, is to find that the alternative hosts of some viru- 



Fig. 14. — Typical rot of brown-cedar poria in butt and roots of cedar. Xote 

 the laminations of the rot and (on the left) the fruiting of the fungus. 



lent needle or twig diseases have invariably appeared. In many cases 

 the new plant succession carries with it alternate host plants of im- 

 portant forest-tree rusts which soon bear their parasitic fungi, and 

 some of these are found to menace the young tree growth upon the 

 area. A disease survey of such a site is very necessary, especially 

 if the site is to be used as a plantation area for susceptible seedlings. 



DISEASE-SURVEY METHODS. 



The most practicable methods only are to be applied by unit 

 erews in gathering forest-disease data. These methods should be ap- 

 plied with a reasonable knowledge of the principal destructive disease 



