Minnesota Plant Diseases. 



215 



treated contain sufficient poison to injure cattle, if fed to them, 

 but in this case the potatoes are steeped in the solution. In 

 general, therefore, the sprays, when properly applied, do not 

 deposit upon the plants sufficient poison to injuriously affect 

 man or his domestic animals. 



SPRAYS. 



Bordeaux mixture. "All things considered, it is believed 

 that the best results will be obtained from the use of what is 

 known as the fifty-gallon formula of this preparation. This 

 contains : Water, fifty gallons ; copper sulphate, six pounds ; 

 unslacked lime, four pounds. In a barrel or other suitable ves- 

 sel place twenty-five gallons of water. Weigh out six pounds 

 of copper sulphate, then tie the same in a piece of coarse 

 gunny sack, and suspend it just beneath the surface of the 

 water. By tying the bag to a stick laid across the top of the 

 barrel no further attention will be required. In another vessel 

 slack four pounds of lime, using care in order to obtain a 

 smooth paste, free from grit and small lumps. To accomplish 

 this it is best to place the lime in an ordinary water-pail and 

 add only a small quantity of water at first, say a quart, or a 

 quart and a half. When the lime begins to crack and crumble, 

 and the water to disappear, add another quart or more, exercis- 

 ing care that the lime at no time gets too dry. Towards the 

 last, considerable water will be required, but if added carefully 

 and slowly, a perfectly smooth paste will be obtained, provided, 

 of course, the lime is of good quality. When the lime is 

 slacked, add sufficient water to the paste to bring the whole up 

 to twenty-five gallons. When the copper sulphate is entirely 

 dissolved and the lime is cool, pour the lime milk and the cop- 

 per sulphate solution slowly together into a barrel holding fifty 

 gallons. The milk of lime should be thoroughly stirred before 

 pouring. The method described insures good mixing, but to 

 complete this work the barrel of liquid should receive a final 

 stirring, for at least three minutes, with a broad wooden paddle." 



"It is now necessary to determine whether the mixture is 

 perfect that is, if it will be safe to apply to tender foliage. To 

 accomplish this, two simple tests may be used. First insert 



