203 



added. -^ Lime should be added until iieitber reaction occurs. 

 A slight excess of lime, however, is desirable. 



The following precautious should be obsen^ed: never mix 

 the concentrated solutions together and then dilute, or never 

 mix the two together while warm. The properly prepared 

 mixture should be fine in texture, and very slow to settle. 

 (See illustration.) The Bordeaux mixture is the best when 

 first prepared, and it is hardly advisable to use it when more 

 than a few months old. 



One of the standard mixtures is as follows : — 



4 pounds copper sulphate (blue vitriol), 

 4 pounds of lime (unslaked). 

 25 gallons of water. 



This is known as the 4-4—25 formula, the half-strength 

 mixture being 4—4-50 ; other formulas frequently used are 

 6-4-25 or 50, 2-2-50, 3-6-50, 3-9-50, etc., the weaker 

 mixtures being useful for tender foliage, such as the peach. 



Speaying Methods. 



One of the frequent drawbacks in not obtaining the "best 

 results from spraying is due to the methods employed in 

 applying the spray. Quite often sufficient attention is not 

 given to spraying those parts of the plants which become 

 afi^ected. Then, again, the time to apply the spray is not 

 always well chosen, and considerable depends upon the man- 

 ner in which the spray is applied to the plant. The essential 

 feature in a spray is fineness, which is determined by the 

 type of nozzle employed and the pressure behind it. A pump 

 capable of maintaining 100 pounds pressure is better than 

 one with a limited capacity of 40 or 50 pounds ; and a spray 

 from a nozzle with 100 pounds pressure back of it is quite 

 difl:'crent from one obtained by 25 pounds pressure. 



Fig. 2 shows some typical results obtained by different 

 nozzles with a pump maintaining an approximate pressure 



> A simple test for excess of lime can be made as follows: put a little of the mixture in a 

 flat dish and blow into it for half a minute. If an excess of lime is present, a thin coating 

 of carbonate of lime will be formed upon the surface, caused by the chemical action of the 

 carbonic acid in the breath upon the lime. 



