THE FUNGICIDAL PROPERTIES OF CERTAIN 

 SPRAY-FLUIDS. II. 



By J. VARGAS EYRE, E. S. SALMON and L. K. WORMALD. 

 (Research Department, South-eastern Agricultural College, Wye, Kent.) 



Introductory 



In a previous communicatioti^ we have adduced evidence to show that 

 solutions of alkaline sulphides are probably of fungicidal value owing 

 to the polysulphides which they contain. 



This work has been continued along similar lines, and the following 

 account gives the main results obtained during the past three years 

 1916-18. During the first two years a number of ammonium poly- 

 sulphide solutions were made according to different methods, and the 

 fungicidal value of each determined with a view of ascertaining whether 

 a relationship existed between the polysiUphide sulphur content and 

 the fungicidal action of these solutions. 



During this period evidence accumulated that the death-point of 

 the mildew (Uphaerotheca Humuli (DC.) Burr.) varied according to its 

 stage of development. 



In 1918 by the selection of suitable material a method was adopted 

 whereby any two solutions could be very strictly compared with regard 

 to their fungicidal action. Thus it could be determined whether the 

 nature of the polysulphide was of importance. 



Methods. 



While the general methods used in our experiments in 1915, which 

 have been described in detail^, were adopted in our work in 1916-18, 

 it was found necessary to pay closer attention to the stage of development 

 of the mildew-patch sprayed. On this point we wrote in 1915: 'The 

 plant used for spraying was carefully selected as bearing on a number 

 of its leaves young and vigorously-growing patches of the mildew in 

 its conidial stage. In order to make the experiments as strictly com- 

 parable as possible only those patches of mildew were used where the 



^ J. Vargas Eyre and E. S. Salmon, "The Fungicidal Properties of Certain Spray 

 fluids," Journ. Agric. Science. 7, 473-507 (1916). 



^ J. Vargas Eyre and E. S. Salmon, lor. cil., p. 477. 



