BULLETIN No. 189 



ORCHARD SPRAYING PROBLEMS AND EXPERI- 

 MENTS: A REVIEW OF, AND A CONTRIBUTION 

 TO PREVIOUS DATA. 



W. W. BONNS. 



The spraying of economic plants for the control of insect and 

 fungous enemies has markedly increased within the past decade. 

 This is largely due to the work of experiment stations in demon- 

 strating the effectiveness of the operation and the profit attend- 

 ing it. Great improvements in spray machinery and materials 

 have helped much towards the adoption of spraying as an annual 

 farm operation, and especially is this true of the fruit growing 

 industry. The progressive orchardist today recognizes the ne- 

 cessity of timely, thorough and intelligent application of in- 

 secticides and fungicides in order to sell his fruit in the best 

 and most profitable markets. 



Spray Injury. 



The increase of spraying operations has, however, been ac- 

 companied by serious problems for the solution of which the 

 grower turns to the experimenter. The use of bordeaux mix- 

 ture, for many years the standard orchard spray, and even today 

 recognized as the best all-round fungicide known, has been ac- 

 companied by injury to fruit and foliage. 



Complaints of such injury have been increasing with each 

 season and are not confined to any section of the country. The 

 severity of the injury varies in degree and in different seasons. 

 It has long been known that bordeaux mixture cannot be used 

 with safety on the peach and Japanese plum when the tree is in 

 leaf, although Cordley and Gate report the use of 5-6-50 and 

 3-6-50 formulae on peach foliage without injurious results.* 



* Cordley, A. B. and Gate, C. C. "Spraying for Peach Fruit Spot." 

 Oregon Agric. Expt. Sta. Bulletin io6 (igog), p. ii. 



