16 The Bulletin. 



through the nozzle. Whatever style of pump is used, it should be 

 fitted with three or four feet of hose and three or four feet of ex- 

 tension pipe (Fig. 4), curved elbow (Fig. 5) and vermorel nozzle 

 (Fig. 6). The extension pipe and curved elbow enables one to 





l 



Fig. 6.— Vermorel Nozzle. (Courtesy of the Dem- 

 ing Co.) 



reach all parts of the plant easily, and especially the underside of the 

 leaves. With an outfit of this kind one man could easily spray two 

 acres of full-grown tobacco per day, provided his solutions had been 

 prepared the evening before. "No attempt need be made in spraying 

 tobacco in the field to cover every leaf on both sides. The plant should 

 simply be covered in a general way. 



Spraying Materials. 



Spray mixtures may be divided into two classes : First, those that 

 kill by coming in direct contact with the insect, and which corrode 

 and eat away its body walls or stop its breathing pores. Insecticides 

 of this class are known as "contact insecticides." These mixtures 

 cannot be applied in advance of the insect with the hope that when 

 it comes along it will devour enough to kill. Contact insecticides 

 must be applied directly to the insects themselves, and they kill only 

 those insects with which they come in direct contact. The second 

 class of insecticides are known as "stomach poisons." They are 

 used against insects that chew their food, and they kill because 

 they are real poisons, and should be handled accordingly. But there 

 is really no occasion to avoid the use of these substances on tobacco 

 for this reason. This subject is dealt with more in detail below 

 under the heading, "Danger from the Use of Arsenates on Tobacco" 

 (page 19). These insecticides may be placed upon the plants ahead 

 of the appearance of any insect in anticipation of their attacks. 

 The insect appearing later secures a small portion of the poison and 

 dies. These poisons are usually well retained by the tobacco leaf 

 owing to the presence of minute hairs which secrete a sticky sub- 

 stance. 



Arsenate of Lead. — Arsenate of lead should be the chief spraying 

 material used by tobacco farmers. It has but a single objection. 



