The protection aflEorded by lime-sulfur without the calcium caseinate spreader 



is so nearly complete that it is not surprising to find the use of the spreader 

 without benefit in scab control. In fact, at both Harvard Fruit Farm and Pine 

 Crest Orchard there was slightly less scab where no spreader was used than 

 on plots where it was used. It is certain that the addition of the spreader to 

 lime-sulfur-lead arsenate does not increase the efficiency of the fungicide in 

 preventing apple scab. 



A fifth application of lime-sulfur solution was applied to certain plots the 

 middle of July because black-rot as well as scab was under observation, although 

 neither the weather conditions nor the prevalence of scab indicated any neces- 

 sity for it. This application followed six weeks of dry weather, and there was 

 less than 2.0 per cent scabby fruit on the trees. The fifth application did 

 not prove necessary since the protection given by four applications, as revealed 

 at picking time, could hardly be excelled. In August, 1924, there was rain on 

 a greater number of days than is normal for the month, and we may conclude 

 that the necessity for a late application for scab control is affected less by the 

 rainfall of August than by the degree of scabbiness attained by the tree in June 

 and July, 



Dry-mix sulfur-lime did not control scab as thoroughly as did lime-sulfur. 

 In one orchard, in the plot sprayed with dry-mix sulfur-lime 8.8 per cent of 

 the apples were scabby, and in the plot sprayed with lime-sulfur there were 0.2 

 per cent scabby apples. In another orchard there was 3.5 per cent scabby fruit 

 in the dry-mix sulfur-lime plot, and 0.2 per cent scabby fruit in the lime-sulfur 

 plot. Evidently on varieties as susceptible to scab as Mcintosh, dry-mix sulfur- 

 lime is not equal to lime-sulfur in protecting against scab. 



The substitution of Bordeaux mixture for lime-sulfur for the prepink and pink 

 applications gave practically perfect protection against scab, but the use of lime- 

 sulfur for all applications gave protection essentially as good. Since, as is 

 brought out elsewhere in this report, Bordeaux mixture costs somewhat more than 

 lime-sulfur, and since Bordeaux mixture, even when used only for the prepink 

 and pink applications, is more likely to cause fruit russeting than is lime-sulfur, 

 the use of Bordeaux mixture at all seems to be a practice of rather doubtful 

 value. 



Besults in the dusted plots. — In both Mcintosh orchards the percentage of 

 scabby apples was slightly less in the plots on which copper dust was substi- 

 tuted for sulfur dust for the first two applications, than in the plots dusted with 

 sulfur at all applications. But this difference was too small to be important. 



In each orchard there were four plots dusted with sulfur four, five, six and 

 seven times respectively. The increase in the number of applications beyond 

 four or five did not result in any consistent increase in protection against scab. 

 The average percentage of scabby apples on plots dusted with sulfur four, five, 

 six or seven times was as follows: Baldwins 6.9, Mcintosh (Pine Crest Orchard) 

 3.2, Mcintosh (Harvard Fruit Farm) 3.8. When the fifth application was 

 made, about June 30, 10.0 to 15.0 per cent of the leaves were scabby. The in- 

 frequency of rains thereafter made later apx^lications unnecessary. 



Injury to Leap and Fruit by Sprays and Dusts. 



Leaf Injury. — Leaf injury was more pronounced on Mcintosh than on Graven- 

 stein or Baldwin. Leaves on cheek trees, which of course received no spray 

 or dust except arsenate, were all large, flat, and uniformly green with no pale 

 margins. Leaves on trees dusted with sulfur had practically the same appear- 

 ance as leaves on cheek trees, that is, they were entirely uninjured and showed 

 no tendency to curl or for the leaf margin to become pale. Leaves on trees 

 sprayed with lime-sulphur-lead arsenate were somewhat curled, spoonshaped, or 

 cupped. Many had pale yellowish-green margins, with some marginal burning . 



The addition of calcium caseinate spreader to lime-sulfur-lead arsenate spray 

 did not reduce the injury to the leaves. 



The foliage of trees sprayed with dry-mix sulfur-lime was not injured as 

 much as that on trees sprayed with lime-sulfur. In fact, there was practically 

 no visible injury on leaves sprayed with dry-mix sulfur-lime, 



A fifth application of lime-sulfur resulted in no more leaf injury than was 

 present on plots sprayed four times. Injury occurred when the calyx and 

 fourth summer sprays were applied. When these applications were made, the 



