5 



likely to occur before that time. Because a prepink application is proved necessary 

 or unnecessary one year, it does not follow that the reverse may not be true the 

 next year. A prepink application made in the absence of information as to the 

 development and condition of the winter spores is to be regarded as insurance. 



Ivrout (2) in 1922 tested the addition of a prepink application to the spray sched- 

 ule. In the fu-st orchard, the addition of the prepink application was not followed 

 by a decrease in the percentage of scab but rather by an increase of 3 per cent. In 

 each of two other orchards the prepink spray apparently reduced the scab 1 per 

 cent. It is evident, therefore, that in 1922 no real benefit from the use of the pre- 

 pink spray was shown, as compared with a schedule which included only a pink 

 application before the flowers opened. 



In 1923, spray schedules with and without a prepink application were tested in 

 two orchards. In the Frost orchard trees sprayed with lime-sulfur beginning with 

 the pink application yielded 7.06 per cent scabby fruit and when this material 

 was used beginning with the prepink application, there was only 1.2 per cent scab, 

 a significant reduction. Where Bordeaux mixture was used for the pink applica- 

 tion, followed by hme-sulfur for the later applications, there was 1.7 per cent scabby 

 fruit, and on the plot where this schedule was modified by the addition of a pre- 

 pink appUcation of Bordeaux mixture, only 0.6 per cent scabby fruit was produced. 

 Here again there was a reduction in the percentage of scab, although such a smaU 

 one as to be probably without significance. 



In the Knights orchard, trees sprayed with dry lime-sulfur 4-50 beginning with 

 the pink application, yielded 1.7 per cent scabby fruit, and where dry lime-sulfur 

 3-50 was appUed beginning with the prepink spray, there was 4.8 per cent scabby 

 fruit. Since the strength of the material was different the addition of a prepink 

 appUcation was not the only changed factor affecting the control of the disease. 

 When the cost of the material and the cost of the labor for each application are 

 considered, however, it is evident that three appUcations of dry lime-sulfur 4-50 

 beginning with the pink were a more profitable treatment than four applications 

 of dry lime-sulfur 3-50 beginning with the prepink. There was 1.06 per cent 

 scabby fruit on the trees sprayed with Bordeaux mixture beginning with the pink 

 application and dry lime-sulfur 4-50 for the later applications. As compared with 

 this there was 4.9 per cent scabby fruit on trees sprayed with Bordeaux mixture 

 for the prepink and pink appUcations foUowed by liquid lime-sulfur for the later 

 appUcations. Since, as is shown elsewhere in this report, we may regard Uquid 

 lime-sulfur as of equal fungicidal efficiency with dry lime-sulfur 4-50, it is evident 

 that the addition of a prepink appUcation did not reduce the percentage of scab; 

 instead, it was foUowed by an increase of 3.84 per cent. The need of a prepink 

 appUcation is not shown by the data of either 1922 or 1923. 



When we consider dusting, however, the case may be entirely different. In the 

 two orchards where the dusting schedule began with a prepink appUcation, a good 

 control of scab was secured. In the orchard where only one appUcation, the pink, 

 was made before the flower buds opened a much poorer control resulted. Satis- 

 factory experimental evidence on this point, however, would necessitate that the 

 two schedules, with and without a prepink appUcation, be used in adjoining parts 

 of the same orchard with one check for the two. 



The Use of Dry Lime-Sulfur. 



Arguments for and against the use of dry Ume-sulfur as compared with the liquid 

 form include, of course, considerations of the relative costs, convenience in handling, 

 and effect on the pump. But the first question to consider is, does it control scab? 

 For if it does not, further consideration is needless. In the experiments here de- 

 scribed, trees sprayed with dry lime-sulfur 4-50, beginning with the pink appUca- 

 tion, produced an average of 1.3 per cent scabby apples as compared with 60.7 

 per cent on the unsprayed trees. In the same orchards, on trees sprayed with 

 Uquid lime-sulfur, the percentage of scabby apples was 2.7. The conclusion from 

 this is that dry lime-sulfur is fuUy as dependable for the control of apple scab as is 

 Uquid lime-sulfur. 



In two successive years, Krout (2) secured as good control of apple scab with 

 dry lime-suLfur as with the Uquid. Gardner (6) found dry lime-sulfur as effective 



