spray dried on trie foliage in about twenty minutes and the temperature was 

 between 55° and 67° F. These conditions are not such as are popularly regarded 

 as conducive to spray injur>'. Nevertheless, spray injury as above described 

 did occur when lime-sulfur-lead arsenate spray was applied. 



Another type of spray injury, also practically confined to trees sprayed with 

 lime-sulfur, consisted in the killing of leaf tissue under and around scab lesions. 



Spray injury to the fruit as revealed at picking time. — Fruit russeting was 

 much more severe on Gravenstein than on Mcintosh or Baldwin. (See Table 



in.) 



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

 resulted, in the case of Gravenstein, in a reduction of about 50 per cent in the 

 amount of russet. When this spray was used without spreader, 16.0 per cent 

 of the apples were russeted; when used with spreader, 8.4 per cent of the 

 apples were russeted. The addition of the spreader was evidently of very 

 considerable benefit but by no means did it prevent all russeting; for there 

 was nearly four times as much injury, even where the spreader was used, as 

 there was on the check plot. On Mcintosh plots sprayed with lime-sulfur there 

 was so little russeting, either Math or without the spreader, that no benefit 

 from the use of the spreader was evident. 



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

 pink applications resulted in more russeted fi-uit than when lime-sulfur was 

 used for all applications. In the Gravenstein orchard there was 13.1 per cent 

 russeted fruit where Bordeaux mixture was used and 8.4 per cent on the plot 

 on which lime-sulfur was used for all four applications. Similarly, in the 

 two Mcintosh orchards there were 14.7 and 13.5 per cent russeted apples on 

 plots receiving the preblossom applications of Bordeaux mixture, and 0.2 and 

 0.4 per cent russeted apples, respectively, on plots where lime-sulfur was used 

 for all applications. 



With the substitution of copper dust for sulfur dust for the preblossom 

 applications in the two Mcintosh orchards, there were 11.1 per cent and 5.0 

 per cent russeted fruit. The percentages of russeted fruit in these two orchards 

 in plots dusted with sulfur for all applications were 0.8 per cent and 0.6 per 

 cent respectively. In the Baldwin orchard the difference was not as great: 

 there was 2.2 per cent russet where sulfur dust was used, and 4.0 per cent 

 russet where copper dust was substituted for the prepink and pink applications 

 But on Mcintosh, especially, there is evidence that even for preblossom appli- 

 cations copper dust is more likely to result in russeted fruit than is sulfur dust. 



There was practically the same percentage of russeted fruits on plots sprayed 

 four times with lime-sulfur as on plots which received a fifth application of 

 lime-sulfur (about the middle of July). 



Apparently, late applications of sulfur dust are as safe as the earlier ones, 

 for there were no consistent or significant differences in the amount of russeting 

 of fruit on plots dusted four, five, six or seven times. 



Black-Rot and Frog-Eye Leaf-Spot. 



In April and May large numbers of the pycnospores of the causal fungus 

 were found on the surface of the bark of cankered limbs. Such limbs were 

 sprayed in the laboratory with Bordeaux mixture or with lime-sulfur, and 

 spores so treated would not germinate although 95 to 100 per cent of spores 

 from limbs not sprayed germinated. This means that the preblossom applica- 

 tions must have disinfecting values, in that they kill such of the spores of this 

 fungus as are at that time exposed on the surface of the bark of cankered twigs 

 and limbs. 



The first frog-eye leaf -spot was observed June 9. There was a slight increase 

 in the number of these leaf -spots up to July 25, but there was no increase after 

 that, at least on the marked branches used for earlier counts. On July 21, in 

 the Baldwin orchard, 9.0 per cent of the accessible leaves on check trees, and 

 an average of 3.0 per cent of the accessible leaves on all dusted plots had frog- 

 eye leaf -spot. 



In neither of the Mcintosh orchards or in the Gravenstein orchard was there 

 more than 0.5 per cent black-rot on fruits in cheek plots at picking time. Only 



