252 VEGETABLE FOES AND DISEASES 



night or by the time the plants are showing or coming 

 into flower. For general crops one application should 

 be made towards the end of June and another towards 

 the end of July. The effect of the spraying is to ( i ) 

 prevent infection to a great extent, if not entirely ; 

 (2) render the plants more impervious to the attacks of 

 the fungus where it has made its appearance ; and (3) 

 arrest the disease in a considerable degree after the 

 plants show signs of the infection. Thus the plants 

 remain longer in growth and yield a heavier crop of 

 better-matured tubers and freer from disease than would 

 otherwise be the case. 



The Bouille Bordelaise has the following composi- 

 tion : 



Sulphate of copper . . . . 20 Ib. 



Lime unslaked . . . . . 20 Ib. 



Water . . . . . . 100 gallons. 



The sulphate of copper is dissolved in a tub con- 

 taining about twenty-five gallons of water, being first 

 placed in a bag of coarse sacking suspended over the 

 edge. The lime is slaked in another vessel, and after 

 forming into a paste free from grit and small lumps, 

 add sufficient water to make up twenty-five gallons. 

 When the copper sulphate is entirely dissolved and the 

 lime is cool pour the lime milk and copper solution 

 slowly together, stirring the milk of lime well before 

 pouring out. Add the remainder of the water and stir 

 with a broad wooden paddle for at least three minutes 

 and the mixture is ready for use, 



