106 



Chapter VIII. 

 INSECTICIDES AND FUNGICIDES FOR THE APPLE. 



H. T. FERNALD AND A. V. OSMUN. 



Insecticides and fungicides for use by apple growers are few 

 in number, many which were formerly on the list having now 

 been discarded. Insecticides are of two classes, viz., the 

 stomach poisons and the contact insecticides. Where the in- 

 sect bites off and swallows solid food, such as leaves, the best 

 material to use is a stomach poison sprayed or dusted onto 

 the tree. The insect eating this substance on its food is 

 poisoned and dies. If, on the other hand, the insect sucks 

 the sap from the tree, no stomach poison put on will reach 

 it, and materials applied so as to actually hit it must be re- 

 sorted to. These contact insecticides, as they are called, kill 

 the insects they touch, and only those. As many of the 

 sucking insect pests of the apple are extremely small, it is 

 difficult to reach them all by the spray, so very thorough 

 spraying must be done with these materials if all the insects 

 are to be reached and destroyed. 



Fungicides are applied only for the control of diseases known 

 to be caused by fungi which at some stage in their life cycles 

 grow on the surface of the host where the spray or dust can 

 come in contact with them. Fungicides are toxic to the fungi 

 for which they are applied. 



Insecticides. 

 Stomach Poisons. 

 Arsenate of Lead. — This is the standard stomach poison for 

 orchard use. It comes both as a paste and as a powder. The 

 latter is for spraying and also for dusting the trees, using an 

 air gun or bellows, a number of forms of which are on the 

 market. In dusting, the powder should be thoroughly mixed 



