FUNGICIDES 37 



used in greenhouses and elsewhere, where, for reasons 

 already stated, Bordeaux mixture could not be applied. It 

 is especially useful against the large group of parasitic fungi ^ 

 having superficial mycelium Perisporiaceae including 

 such pests as rose mildew (Sphaerotheca pannosa), and 

 hop mildew (Sphaerotheca castagnei). It may also be 

 generally used where the object is to check the spread of 

 a disease extending by means of conidia. 



POTASSIUM SULPHIDE SOLUTION 



Water .... 2^ gallons. 



Potassium sulphide . i ounce. 



Dissolve the potassium sulphide, popularly known as 

 liver of sulphur, in a quart of hot water, then make up to 

 2\ gallons with cold water. This is also a clear liquid, 

 and like the former can be easily used without any clogging 

 at the nozzle of the sprayer. It is useful for checking the 

 spread of an epidemic, and has proved successful against 

 the chrysanthemum rust (Pucdnia hieracii). 



IRON SULPHATE SOLUTION 

 Water . . . 50 gallons. 



Sulphuric acid . . . . i pint. 

 Iron sulphate . . . 25 pounds. 



Pour the sulphuric acid upon the iron sulphate, and 

 then add by degrees the 50 gallons of water. A metal 

 vessel must not be used for the preparation of this mixture, 

 as it would be acted upon by the sulphuric acid ; a barrel 

 is the best to use. 



This preparation may be used with great advantage in 



