Spraying Materials 119 



and the other a plunger pump, either of which is capable 

 of handling 30 to 40 gallons of spray mixture per minute. 

 Where bordeaux mixture is used, however, there is some 

 danger from the rotary pump becoming more or less worn 

 by the friction with, the gritty particles in the lime, and 

 priming will be necessary in order to get the pump to work- 

 ing satisfactorily. For use with supply tanks, plunger 

 pumps are probably the most effective and satisfactory, 

 since it is necessary in this case, to pump the prepared 

 mixture with them. 



Spraying Materials 



Since the discovery of effective means of controlling 

 insect and fungous diseases of plants a great number of 

 preparations have been devised for the control of special 

 diseases on certain crops. Such a formidable list of these 

 preparations have been published that it would seem at 

 first glance that one would need an elaborate chemical 

 laboratory in order to prepare the materials. However, 

 the years of scientific and practical experimentation along 

 this line have eliminated many of these spraying materials 

 so that the plantsman of today needs know how to prepare 

 less than a dozen different sprays in order to control any 

 of the diseases for which a remedy is known. 



There are two distinct groups of these spraying ma- 

 terials, one of them, called insecticides, is for the control 

 of insect diseases, and the other, called fungicides, for the 

 control of fungous diseases. Of these materials there are 

 three groups of insecticides, suph as (1) food poisons, (2") 

 contact poisons, and (3) suffocating poisons. Which of 

 these poisons to use will depend altogether on the kind of 

 insect and the plant upon which it is feeding, so that for ef- 

 fective use of any insecticide, it is important that the 

 plantsman know something of the habit of the insect, and 

 just in what stage of its life it is most easily reached with 

 the poison. 



(O Food Poisons. These materials are composed of 

 substances which must be eaten by the insect as it chews 



