18 



As shown in Table 5, about 90 per cent of the crop from the sprayed 

 trees remained free from the apple-blotch disease, while about 75 per 

 cent of the crop of the unsprayed trees was destroyed by it. This 

 fairly represents the conditions as they existed throughout the block, 

 as shown by the comparative commercial yield of the sprayed and 

 unsprayed trees given later (p. 33). It will be noted, however, that 

 in spite of the spraying nearly 10 per cent of the crop was affected, 

 but the diseased spots were, as a rule, very small, and in many cases 

 scarcely noticeable. They were mainly on apples that were on low- 

 hanging branches, well in toward the trunk and protected from the . 

 spray by the outer branches. In cases where only one side of an 

 apple w^as reached by the spray, owing to some obstruction, the spots 

 developed on the unsprayed side. This emphasizes the importance 

 of driving the mixture into all parts of the tree in order to spray every 

 apple thoroughly. Since the period of infection is about the same as 

 that of bitter-rot, it appears that the same treatment is applicable to 

 both diseases. In connection with some bitter-rot experiments con- 

 ducted in the same orchard, it developed that the early applications 

 were not necessary for the control of apple blotch. In fact, trees that 

 were sprayed May 4, May 8, June 12, and June 27 had 46.6 per cent 

 of the crop affected with apple blotch, showing that these applications 

 gave only slight protection against this disease. 



RECOMMENDATIONS. 



Make four applications of Bordeaux mixture at intervals of two 

 weeks, beginning about six weeks after the petals fall. This corre- 

 sponds exacth^ with the treatment for bitter-rot, and the two dis- 

 eases may, therefore, be controlled with the same applications. 

 However, as apple blotch seems rather more difficult to control than 

 bitter-rot, in sections where severe outbreaks occur treatment should 

 perhaps begin a week earlier and be continued later, making five appli- 

 cations in all. So far as the writers know, these are the first experi- 

 ments in which this disease, when occurring on the fruit, has been 

 successfully controlled. 



LEAF-SPOT DISEASES. 



There are several species of fungi that attack apple leaves, produc- 

 ing brown, circular spots that range from mere specks to spots one- 

 fourth of an inch in diameter and in some cases much larger, as shown 

 in figure 3. The disease may begin to appear in the spring soon after 

 the young leaves unfold, but the spots are usually more prominent 

 between midsummer and the end of the season. This diseased con- 

 dition causes the leaves to drop prematurely, frequently leaving the 

 trees denuded in early autumn, six weeks or two months before the 



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