42 BULLETIN 614, U. S. DEPARTMENT OF AGRICULTURE. 



SPRAYING. 



Spraying is an annual practice. The need of careful and systematic 

 spraying is felt by practically all the growers of the valley, for it is 

 realized that only by persistently following such practice can the 

 production of marketable apples be guaranteed. The average spray- 

 ing cost of labor and material for all of the orchardists considered 

 in this study is $25.14 per acre, or 7.27 per cent of the net cost of 

 production. 



The orchardists considered in this investigation make an average 

 of four sprays per year. Some make as many as seven applications, 

 the number varying with the abundance of insect pests and the 

 prevalence of fungus diseases. The majority of growers make a 

 dormant or lime-sulphur spray and three lead-arsenate sprays. 



The codling moth is one of the worst pests with which the orchard- 

 ists in the valley have to contend. For this reason a few of the orchard- 

 ists practice making two calyx sprays, one immediately following 

 the other. This is done because of the irregularity in blossoming of 

 the different varieties and also to make a more thorough application 

 of material for protection against the codling-moth larvae. 



It is the practice of most growers to make lead-arsenate sprays 

 only on trees which promise to yield part or the whole of a crop. 

 Often small strips of rags, or markers, are tied to the trees. which are 

 to be sprayed. In this way considerable time can be saved. How- 

 ever, this practice may result in the survival of a number of codling- 

 moth larvse in the unsprayed trees. 



On account of the appearance of the apple powdery-mildew, a few 

 of the orchardists are beginning to use atomic sulphur for its control. 

 In some years also the apple aphids cause consid arable damage. A 

 few of the growers use tobacco extract, whale-oil soap, and other 

 contact sprays for their control, but a spray of this kind was not 

 general at the time of this study. 



Since so few growers were making an annual practice of applying 

 any material for the control of apple powdery-mildew or aphis, no 

 discussion is made of methods practiced. However, the cost of these 

 sprays is taken into account where they are made and is given in 

 Table XXXVI. 



It would seem from conditions prevalent at the time of the study 

 that the growers of the valley will find it necessary to use some pre- 

 ventive measures against both the apple powdery-mildew and the 

 aphis. 



The spraying crew usually consists of three men and two horses. 

 In the North Yakima district 55 of the 64 orchardists used such a 

 crew, 7 used a crew of two men and two horses, 1 a crew of two men 

 and one horse, and 1 man used a stationary engine and pump. In 

 the last case the orchard contained 3 acres and the operator himself 

 did all the spraying. 



