SPRAY MANAGEMENT 



By Harry C. Woodworth and Cecil O. Rawlings 



The application of sprays to control the pests of apples is the or- 

 chardist's most difficult management problem. Effective control re- 

 quires the thorough covering of all the trees within very brief and definite 

 periods of time. Since insects and diseases must be destroyed at certain 

 definite stages in their development, changing weather conditions may 

 either hasten or delay the effective spraying so that only a fraction of 

 the control period is available for the operation. 



Under these conditions the operator must have expensive equipment 

 in good repair and skilled labor available for efficient operation to cover 

 the trees within the effective period and when weather is favorable. In 

 certain years this may mean only an hour or so a day. Equipment of 

 sufficient capacity to cover the orchard quickly will not be used many 

 days a year, yet adequate equipment is essential. In order to have skilled 

 labor available for these brief but definite periods, a plan for its utiliza- 

 tion productively in non-spray periods is often necessary. (See spray 

 time schedules, Figures 9 to 12.) Often the operator can use his own 

 time to advantage in orchard work for most of the year, but there are 

 periods during the season when it is difficult to employ the extra spray 

 help to advantage. Yet such help will not be available at critical spray 

 periods if the men are not employed full time. 



On account of the need for the expensive equipment and the skilled 

 help for short periods, the spray practice is one of the chief factors in 

 determining the most economical and practical size of orchard unit. 

 Efficiency and effective management procedure in connection with 

 spraying will enable the individual grower to handle a larger orchard. 

 For these reasons spray management is far more important than is in- 

 dicated by hours of man labor and cost per hour of equipment. It is the 

 crux of the whole field of orchard management. 



This project of studying in detail the management problems asso- 

 ciated with spraying was undertaken in order to guide orchardists in their 

 practices in this critical operation. Fifty farmers were selected as co- 

 operators; for two or more years 40 of them kept detailed spray records, 

 representing a total of 158 orchard years. The orchards were mapped, 

 inventories of equipment and supplies were taken, and the operators 

 were instructed in the keeping of spray records. 



Description of the farms 



The 40 farms include a wide range in size of orchards from several 

 part-time enterprises of 200 to 400 trees to large specialized apple farms 



ir rhis project was initiated as a joint project with the Departments of Agricultural Economics 

 and of Horticulture cooperating. The field work was undertaken by E. J. Rasmussen, at the 

 time a member of the Department of Horticulture. H. C. Woodworth, G. F. Potter, and C. O. 

 Rawlings co-operated in certain phases of the work. Mr. Rasmussen and Mr. Potter resigned to 

 take positions elsewhere. Mr. Woodworth and Mr. Rawlings completed the field work and made 

 the analysis. 



