SOIL TREATMENTS AND SEED GERMINATION 37 



if applied to the surface of the soil immediately after seeding, for they are then 

 more concentrated near the seeds. 



Crucifers were more often injured by acetic acid and by formaldehyde than 

 were most of the other plants used. 



Too little vinegar to prevent damping-off was injurious if applied after the 

 emergence of seedlings. 



Damping-ofT was well controlled b)' p>Toligneous acid (from pine wood) and 

 this was not injurious when applied to soil immediately before seeding. 



Acetaldehyde was less toxic both to plants and to fungi than was formaldehyde 

 and, in infested soil, sweet pea grew better with it. Sweet pea, germination and 

 growth, was apparent!}- benefited by ethyl alcohol also. 



Calcium hypochlorite is not a chemical which, in effective quantities, may be 

 used safel>' with most species immediately before seeding. The interval of time 

 between soil treatment with calcium hypochlorite and seeding with safety is not 

 likely to be short. 



Heavy applications of potassium permanganate did not control damping-off, 

 and its occasional recommendation for this purpose is not justified. 



Inorganic salts, such as those of copper, may have a use in protecting seeds 

 and seedlings of such species as germinate so slowly that a volatile chemical 

 would be gone from the soil long before protection is most needed. Seeds of a 

 species which required three months to germinate were not well protected by 

 acetic acid, but were by copper oxalate. 



Copper-lime dust, with other species, gave as good results as did any copper 

 salt, but all salts of copper were too toxic to many species of plants, with hollyhock 

 showing the greatest tolerance. 



Aluminum sulfate in quantities injurious to many other species was perfectly 

 safe with Dianthus. Species of Dianthus and species of Rhododendron were 

 notably tolerant of sulfuric acid also. There was no evidence that sulfur is a soil 

 disinfectant. 



LITERATURE CITED 



1. Anonymous. The germination of seeds. New Flora and Silva 8:64-69. 1935. 



2. Anonymous. Editorial, New Flora and Silva 8:1-2. 1935. 



3. Abdel-Salam, M. M. Damping-off and other allied diseases of lettuce. 



Jour. Pomol. and Hort. Sci. 11:259-275, illus. 1933. 



4. Albrecht, W. A., and Jenny, Hans. Available soil calcium in relation to 



damping-off of soy bean seedlings. Bot. Gaz. 92:263-278, illus. 1931. 



5. Alexander, L. J., Young, H. C, and Kiger, C. M. The causes and control 



of damping-off of tomato seedlings. Ohio Agr. Expt. Sta. Bui. 496, 

 38 p., illus. 1931. 



6. Anderson, P. J. Pythium damping-off and rootrot in the seed bed. Conn. 



Agr. Expt. Sta. Bui. 359:336-354, illus. 1934. 

 '7. Andes, J. O. Tobacco bed soil disinfection. (Abs.) Phytopath. 25:972. 1935. 



8. Beach, W. S. Formaldehyde and other disinfectants in the control of 



lettuce diseases. Penn. Agr. Expt. Sta. Bui. 202, 28 p., illus. 1926. 



9. Bewley, W. F. Diseases of glasshouse plants. 208 p. London. 1923. 



