446 DISEASES OF ECONOMIC PLANTS 



destructive to a considerable number of small trees and in- 

 juring the lower branches of large trees; serious damage 

 from it, however, is not common. 



Fusariose, damping off (Fusarium sp.). — The general 

 characters are these mentioned under damping off. It is 

 serious in Vermont, New York, Missouri, and probably in 

 many other states, killing the seedlings in nurseries as 

 soon as they appear above ground. 



The beds should be given all ventilation possible. A top- 

 dressing of sterilized sand sprinkled over the beds immedi- 

 ately after germination resulted in 30 per cent of disease 

 against 42 per cent in the untreated part. Perhaps the best 

 results have been attained by the use of copper sulphate 1 

 pound and lime 10 pounds,' and by sulphuric acid 1 ounce 

 to 1 gallon of water, either of these applied to the soil of 

 the seed bed before planting and again after the plants 

 are up. 



Rust, peridermiose {Peridermium Cerebrum Peck of Cro- 

 nartium Quercus). — Swollen areas occur upon the branches 

 and young stems which are gradually killed. The gall-like 

 growth sheds an abundance of orange-colored spores each 

 spring. In some sections it kills many trees, chiefly by 

 its interference with the sap current. The swellings are 

 perennial and may last for many years. One stage of this 

 rust occurs upon the oaks. 



Peridermiose {Peridermium acicolum Und. & Earle, of 

 Coleosporium solidaginis (Schw.) Thiim.). — Another species 

 of Peridermium of no special significance occurs upon leaves, 

 producing small, sac-like, tubular outgrowths which contain 



' Spaulding, Perley, U.S. Dept. Agr. Bur. Plant Indus. Circ. 4, April, 

 1908. 



