53 JOURNAI. OF FORESTRY 



rid of the undesirable trees,^ and this will leave little or none for use 

 in disposing of the remaining infected slash. 



Young trees left upon an area following an improvement cutting 

 are open to infection by spores liberated from the sporophores pro- 

 duced on the slash on the area, the standing trees at the edge of the 

 cutting and the trees forming the denser forest surrounding the area. 

 There is greater danger of infection from the first two sources than 

 from the last. This is due in part to the forest itself, which acts as 

 a screen, preventing the wide distribution of spores liberated within 

 the denser stand, and to the freer circulation and greater dispersion of 

 the spores produced in the more open stand of the cut-over area. 



In the young growing stands, A^ and Ag, of the western white pine 

 type,^^ where improvement cuttings are proposed by the Forest Service, 

 there is a maximum need for forest sanitation. This is due to the 

 danger of infection to which the young trees of the future crop are 

 subjected. In such areas every means possible consistent with eco- 

 nomic conditions should be employed to destroy or prevent from 

 developing, all sporophores of the more harmful, wood-destroying 

 fungi. 



In mature stands,^^ Bj, B^, and Bg, where reproduction cuttings 

 or clean-cutting methods are proposed, and where the only trees left 

 upon the area are seed trees, the greatest danger to the reproduction 

 is from mistletoe,^^ ^^ and rust infections. The removal of all mistletoe, 

 rust-infected and otherwise diseased standing trees upon the sale area 

 should be provided for in the special marking rules. ^^' This would 

 greatly reduce the danger to the reproduction. The danger from 

 such fungi as Annillaria mellea, which attacks seedlings and young 

 trees, should not be overlooked, and such attacks prevented, if possible, 

 by the burning or thorough drying of infected material on the area, 

 such as infected stumps or butt logs. The importance of the disposal 

 of infected slash in the mature stand is not so great as in the young 

 growing stands,^^ since between 50 and 60 years (in the case of 

 heart-rotting fungi in western white pine) would elapse before the 

 reproduction on the area reached the age of earliest infection.^- The 

 diseases would be carried over this period of years more readily by 

 the trees in the surrounding infected stand than by the infected slash 

 left upon the cut-over area. At the same time consideration must be 



a This practice not only covers the removal of undesirable species but in 

 most cases removes trees heavily infected with fungi and also makes light avail- 

 able for the relatively intolerant seedlings of such spec'es as western white pine 

 and western larch. 



