290 GENERAL PLANT PATHOLOGY 



of Des Moines, Iowa, by A. L. Bakke,^ it. has been found that conifers 

 are more susceptible than deciduous trees. The direct injury is seen 

 in the deposit of the tarry matters of the smoke in the stomata of 

 nearby plants; leaves and leaflets are shed, or assume abnormal shapes, 

 and the formation of foodstuffs is hindered. The sulphur dioxide and 

 acetylene as constituents of smoke act toxically upon the plant. The 

 work which has been done in the United States may be summed up as 

 follows: Burkhart states that injury from gases is the result of the 

 chemical constituent of the smoke and is not due to the clogging of the 

 stomata. The investigation of J. K. Haywood^ in the vicinity of 

 the famous smelter at Anaconda, Mont., is of importance. He finds 

 that trees are injured at a considerable distance; that very small 

 amounts of SO2 are toxic to plant growth; that water used for irrigation 

 purposes often has sufficient copper in it to be toxic to plant growth 

 and that certain trees, as the juniper, are more resistant than others.^ 

 Officials of the Forest Service are watching with interest the develop- 

 ments in the matter of the fumes from copper smelters in the southern 

 Appalachian Mountains. The service has been interested for years, 

 but since the acquirement of land in that section under the Weeks law 

 for forestry and watershed protection purposes, it has been felt that 

 the destruction of forests by the action of the fumes should be stopped. 

 W. L. Hall, forest supervisor of the seventh forest district, has 

 recently submitted to the bureau a report upon the subject. It seems 

 that one or more of the purchase areas established in the southern 

 Appalachians are endangered by the fumes, which are of a sulphuric 

 nature. 



iBakke, a. L.: The Effect of City Smoke on Vegetation: Bull. 145, Agric. 

 Exper. Stat. Iowa State Coll. Agric. & Mech. Arts., October, 1913; The Effect 

 of Smoke and Gases on Vegetation. Proc. Iowa Acad. Sci., xx: 169-187, with 

 bibliography; also Anderson, Paul J.: The Effect of Dust from Cement Mills 

 in the Setting of Fruit. The Plant World, 17: 57-68, March, 1914. 



2 Die Beschadigung der Vegetation durch Rauch. Handbuch zur Erkennung 

 und Beurteilung von Rauchschaden von Professor Dr. E. Haselhofe, Vorsteher 

 der landwirtschaftlichen Versuchsstation in Marburg i. H., und Professor Dr. G. 

 LiNDAu, Privatdozent der Botanik und Kustos am Kgl. Botanischen Garten in 

 Dahlem. Mit 27 Textabb. 



3 Haywood, J. K.: Bull. 89, Bureau of Chem., U. S. Dept. Agric, 1905; In- 

 jury to Vegetation and Animal Life by Smelter Wastes. Bull. 113 revised, Bureau 

 of Chem., U. S. Dept. Agric, 1910. 



'' The Southern Lumberman, xxix: 27, Nov. 6, 1915. 



