Diseases and Pests of the Apple and Their Control 235 



the western orchard section is unquestionably the codlin- 

 moth. The dry arid climate in nearly all the irrigated 

 sections seems particularly favorable to its development. 

 The long hot seasons increase the number of broods and 

 seem to stimulate the activities of this pest. Furthermore, 

 the close grading of the fruit emphasizes the loss from 

 worm injury. Eastern growers are justified in feeling 

 that they have worked out a satisfactory spray program 

 against codlin-moth and are inclined to believe that the 

 western grower is deficient in his spraying methods for con- 

 trolling this insect. Yet in many instances growers on 

 the western slope of Colorado and the Yakima Valley, 

 Washington, have found it difficult to avoid excessive cod- 

 lin-moth loss even after spraying much more thoroughly 

 and frequently than is necessary under eastern conditions. 

 Fire-blight epidemics have been more or less serious in 

 the West and have been particularly injurious in the 

 Yakima Valley, Washington and the Rogue River Valley, 

 Oregon. In the Rogue River and Hood River valleys, 

 Oregon, the apple-scab has been serious in years when the 

 climatic conditions were favorable to its development. 

 However, elsewhere in the West fungous troubles are in 

 the main inconspicuous. 



California. The Watsonville apple-grower in the 

 Pajaro Valley must devote considerable attention to the 

 control of the tussock moth. The leaf-roller is also rather 

 prevalent and the powdery-mildew causes more or less 

 injury. 



DUSTING 



Dusting, as a substitute for the liquid spray method in 

 controlling insects and disease, has been brought to the 

 recent attention of fruit-growers by the extensive experi- 



