Methods of Control 407 



Principles Involved in Spraying 



It should be remembered that to destroy chew- 

 ing insects, such as caterpillars, etc., the stomach 

 poison must be evenly distributed all over the plant. 

 This thorough spraying should be done as soon as 

 the presence of the pest is suspected. Intelligent 

 and observant growers will remember the time of 

 appearance of the pest every year, although this date 

 depends somewhat on the climate of each season.' 

 In destroying the green aphids, the contact poison, 

 should be distributed as evenly as possible on the 

 insect itself. It is, therefore, best to spray for aphids 

 when they are actually found working on the plants. 

 To check chewing insects and fungous pests, how- 

 ever, the applications are made before the parasites 

 appear. Before spraying it is necessary to have 

 well in mind which organism is to be destroyed, 

 and the proper ingredients to be used. To keep 

 fungous pests in check it is necessary to have the 

 plant covered with the fungicide all the time infec- 

 tion is feared or suspected. This spraying is preven- 

 tive, protecting the plant from becoming infected. 

 When the parasite has penetrated the host, spraying 

 is of little value in saving the infected plant, al- 

 though it will protect others which are as yet 

 healthy. It is essential that the gardener be always 

 ready to spray. Sometimes delay for even a day 

 may prevent the attainment of positive results. The 

 timely destruction of one insect, or of one spore, 



