246 



Effective Farming 



146. Spraying of fruit-trees. Like pruning, spraying is 

 an important detail of orchard management. Fruit-trees are 

 subject to many insect and fungous pests and it is necessary 

 to combat these successfully if profitable crops are to be pro- 

 duced. 



Materials used for spraying. Insecticides and fungicides 

 are used as spray materials to fight the pests. An insecticide 

 is any substance that kills insects and a fungicide is any sub- 

 stance that kills 

 fungi. Insecticides 

 are of two general 

 classes poisonous 

 and contact. The 

 former contain poi- 

 son and are used 

 to kill insects with 

 biting mouth parts. 

 Those most used are 

 arsenate of lead, 

 paris green, arsenite 

 of lime, london pur- 

 ple, and hellebore. 

 All these, except 

 hellebore, contain 

 arsenic in some 

 form. Hellebore is made from the roots of the white hellebore. 

 A contact insecticide is a substance used to kill insects by 

 coming in contact with their bodies. Insects with sucking 

 mouths cannot be killed by means of poison and must, there- 

 fore, be combated with contact insecticides. Plant-lice and 

 the scale insects are usually killed in this way. The chief con- 

 tact insecticides are boiled lime sulfur, self-boiled lime sulfur, 

 miscible oils, distillate oils, kerosene emulsion, and tobacco 

 preparations. 



The fungicides used in combating the fungi of fruit-trees 



FIG. 101. 



Sprayed trees in same orchard as 

 shown in Fig. 102. 



