28 BULLETIN 1118, U, S. DEPARTMENT OE AGRICULTURE. 



The spraying experiments of the writer were interrupted by the 

 freeze of February, 1917, and later by circumstances resulting in part 

 at least from war conditions. During several seasons no scab de- 

 veloped in the orchards where spraying experiments were conducted. 

 Nevertheless, a great many careful studies made of spray schedules 

 em.ployed in commercial groves in Florida and Alabama where scab 

 was successfully controlled, together with the results of inoculation 

 tests and of definite orchard spraying experiments, and of demon- 

 strations, lead the writer to feel confident that the above-m.entioned 

 general conclusions are correct and that the disease can be controlled 

 satisfactorily and economically. Good judgment must be used in 

 selecting and applying the fungicide and in following it with insecti- 

 cides if necessary. 



In addition to these field studies and observations, critical spraying 

 experiments were conducted in a nursery of sour-orange and rough- 

 lemon seedlings at Orlando, Fla., during 1919 and 1920. This 

 nursery was set out in the spring of 1918 and was not sprayed that 

 year, resulting in a very general infection on leaves and twigs to 

 serve as sources of early infection the following year. 



During the progress of this spraying experiment for citrus-scab 

 control in the nursery the following materials were used: 



Formula 1: Bordeaux mixtm'e, 3-3-50, prepared in the usual way. 



Formula 2 : Bordeaux mixture, 3-3-50, plus 0.5 per cent oil in emulsified form. 



The Bordeaux mixture was prepared in the usual manner to which sufficient 



oil emulsion was added to make 0.5 per cent oil in solution. 

 Formula 3: Bordeaux mixture, 2-2-50, plus 0.5 per cent oil in emulsified form. 



Prepared in same manner as formula 2. 

 Formula 4; Bordeaux mixture, 1-1-50, plus 0.5 per cent oil in emulsified form. 



Prepared in same manner as formula 2. 

 Formula 5: Commercial Bordeaux paste (6 per cent metallic copper), 12f pounds in 



50 gallons of water, the equivalent of 3-3-50, plus 0.5 per cent oil in emulsified 



form. 

 Formula 6: Homemade Bordeaux paste, in proportions to equal 3-3-50 Bordeaux 



mixture, plus 0.5 per cent oil in emulsified form. 

 Formula 7 : Burgundy mixtiu"e, 3-3 J-50, prepared in the usual manner. 

 Formula 8: Copper soap (Pritchard and Clark's (16) formula). Prepared by adding 



3 poimds of dissolved resin-fishoil soap to one-half poimd bluestone dissolved 



in 50 gallons of water. 

 Formula 9: Lime-sulphur solution, 32° B. diluted 1 to 40. 



Formula 10: Lime-sulphm- solution, 32° B. diluted 1 to 40 plus stabilized oil emul- 

 sion, 0.5 per cent. 



The oil emulsion used in these spray materials was prepared 

 according to Yothers {32, p. 19) by emulsifying 2 gallons of mineral 

 oil with 2 pounds (1 quart) of fishoil soap and 1 gallon of water. 

 To dilute 3 quarts of this emulsion to 50 gallons gives a proportion 

 of 1 per cent oil. 



In 1919 the sprays were applied at weekly intervals, beginning in 

 March and continuing thi'oughout the growing season. The applica- 



