362 



PEAR GROWING IN CALIFORNIA. 



importance of the ant as a blight spreader and the necessity for its 

 control. One of the most practical methods of preventing ants from 

 getting into the trees is to apply a band of the sticky tanglefoot prepa- 

 ration to the trunks. For years the 0. & W. Thum Company have been 

 manufacturing this material for insecticidal purposes. It is safe to 

 apply direct to the trunks of trees, as years of experience have proven, 

 and while fresh, at least, no insect can cross over it. Some difficulty is 

 experienced in keeping it fresh enough for any length of time to pre- 

 vent the ants, which are very strong, from crossing over. Consequently, 



FIG. 157. Tree tranglefoot around the trunk of a blighted tree to prevent ants 

 from crawling up the trunk and thus distributing pear blight organisms. 



when used to control ants it should be freshened every few days by 

 adding a new supply or by disturbing the surface of that already 

 applied so that it possesses its original sticky characteristics. 



Another very important group of insects bearing a close relation to 

 the spread of blight, are the aphids. Spraying with a good contact 

 insecticide, e. g., nicotine sulphate, to control these pests is important 

 during a season of severe blight infestation. The various species of 

 mites which feed on the pear are no doubt also responsible for spreading 

 blight and should therefore, if for no other reason, be controlled. Since 

 the blight is due to a bacterial organism and can not become started in 

 a tree unless the organism is placed there by some outside agent, and 

 since the insects have been proved to be the agents most general^ con- 

 cerned in the work of carrying the germs and inoculating the trees, 

 every effort should be made to reduce the numbers of injurious species 

 to a minimum in the orchards. 



144 



