J. V. Eyre and E. 8. Salmon • 481 



Sodium carbonate. 



Hops. 1915. 



Ex'per. 1. Solution containing 0-3 % carbonate of soda (crystallised) 



and 1 % soft soap. 

 2)id daij. The mildew scarcely checked ; all the patches with numerous immature 

 conidiophores. 



'ird day. All the patches now densely powdery. 



Sodium thiosulphate . 



Hops. 1915. 



Exper. 1. Solution containing 1 % sodium thiosulphate and 1 % 

 soft soap. 



'2)}(1 day. The mildew but little checked; some patches almost "powdery." 

 8//f day. All the patches as "powdery" as on the controls. No injury to the 

 leaf. 



Summary of Observations. I. 



None of the following substances — soft soap^, 1 % soltition ; 

 saponin, 0-25 % ; sodium carbonate^, 0-3 % and soft soap, 1 % ; 

 sodium thiosulphate^, 1 % and soft soap, 1 % — had any fungicidal 

 value. 



II. Caustic Soda. 

 Hops. 1915. 



Exper. 1. Solution containing 0-3 % caustic soda and 1 % soft soap. 



2>id day. All the patches much checked, with conidiophores all collapsed. Slost 

 of the patches with dark rims round them ; otherwise no injury to the leaves. 



3rd day. All the patches greatly checked, mostly dormant and sterile; a few 

 with, here and there, isolated conidiophores bearing chains of spores. 



&h day. Some of the patches with fairly numerous small groups of conidiophores 

 near the centre; most with only a very few scattered conidiophores; some of the 

 patches dead. 



1 See above, p. 478. 



- G. Dorogin has stated (Zeitschr. f. Pflanzenkraiilch. xxm. p. 33.5 {ll»13)) that a 

 solution of 0-25 % or 0-5 % of carbonate of soda or carbonate of potash is efficacious 

 against the American Gooseberry-mildew. Hector, J. M. and Auld, S. J. M. (Gardeners' 

 Chronicle, Aug. 7, 1915, pp. 79-80) beUeve that they obtained some evidence in field 

 experiments that a 0-3 % solution of carbonate of soda was detrimental to the American 

 Gooseberry mildew. 



^ HoUrung, loe. cit. p. 50, mentions that Hitchcock and Carleton (Kansas Exper. 

 Station, Bull. 38) state that the germinating capacity of uredospores is weakened by pro- 

 longed treatment with a 1 % solution of sodium thiosulphate. 



Journ. of Agrio. Sci. vn 32 



