442 Diseases of Economic Plants 



required and to pour them together into a separate con- 

 tainer, usually the tank of the sprayer. The colloidal sus- 

 pension obtained by this method of mixing settles very 

 slowly and can be applied with the maximum uniformity. 

 To make 200 gallons, the content of the usual power sprayer, 

 by this method, an elevated platform, or a series of elevated 

 platforms, is required. The diluted lime and copper sulfate 

 are run simultaneously from 100-gallon wooden contain- 

 ers standing on the platform into the sprayer, or into an 

 elevated 200-gallon tank, where the resulting Bordeaux 

 mixture is held in readiness to supply the power sprayer 

 while the smaller containers are being refilled. 



The above method is open to improvement because of the 

 large amount of apparatus and labor involved. 



Hawkins claims "a Bordeaux mixture in which the sus- 

 pension of the copper compound settles out slowly may 

 be prepared by adding the concentrated calcium hydroxid 

 to the diluted copper sulfate solution or vice versa, pro- 

 vided the mixture is sufficiently agitated." He states that 

 "the agitation necessary for preparing Bordeaux mixture 

 with a low rate of subsidence by this method could hardly be 

 obtained in practice except by means of a power outfit pro- 

 vided with a good agitator." This method can be used to 

 advantage with the tank-filler, a jet pump, with which 

 any power sprayer can be equipped, which permits the rapid 

 filling of the spray tank by means of the spray pump. The 

 construction of a platform and the expense of pumping water 

 into the elevated containers are thereby obviated. Sixteen 

 gallons of stock copper sulfate or lime is first diluted in the 

 spray tank to within sixteen gallons of the final volume, the 

 stock solution of the other component is poured in, and the 

 mixture is thoroughly agitated. A method very similar to 

 this has proved satisfactory in the field and is in common use 

 in Illinois. 



Wooden containers should always be used for the copper 

 sulfate solutions, and the lime or Bordeaux mixture should 

 always be strained before it enters the tank. 



