Follow-Up Work 501 



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as the percentage of wormy apples was concerned, this ranging, 

 for plots in the case of the former, from 13 to 14 per cent, and 

 for the latter from 27 to 34 per cent on the sprayed trees, and 

 on the check or unsprayed trees from 67 to 69 per cent. By far 

 the greater portion of this infestation — 9 to 12 per cent in one 

 case and 25 to 33 per cent in the other — was dne to ''side 

 injury." This latter is a peculiar condition that appears to be 

 closely related to evening temperatures, and is a type of injury 

 much more marked in the western part of the state than in the 

 Hudson Valley. 



The characteristic mark or blotch produced by the codling moth 

 and termed by us " side injury " is frequently referred to by fruit 

 growers as " side worm " or " second brood " codling moth, though 

 an investigation of conditions has satisfied us that this damage is 

 produced by young caterpillars hatching from late-deposited eggs 

 laid by moths developing from apple worms or larvae that have 

 lived through the winter. This latter is of great practical import- 

 ance, since it is obvious, if such be the case, that the condition of 

 the fruit, especially in sections where there may be considerable 

 of this side injury, depends to an appreciable extent upon the 

 work of the preceding year. On account of the young larvae, 

 which hatch from eggs deposited upon the fruit, feeding on the 

 comparatively unprotected, growing surface of the apple, the prob- 

 ability of destroying these young apple worms at the outset and 

 before they have inflicted the characteristic blemish, is by no 

 means good. This is borne out by a summary of all the plots, 

 which shows a reduction in side injury of oiily a little over 

 1 per cent as a result of the second spraying for the codling moth, 

 and of approximately I/3 of 1 per cent additional from the third 

 treatment. There is a possibility that a spraying, given just as 

 many of the young caterpillars that hatch from eggs deposited upon 

 the fruit commence feeding, would be of considerable value in 

 checking side injury, though this is by no means proved. 



There are orchards in the western fruit section — and one of 

 the experimental orchards belongs in this class — which are com- 

 paratively free from codling moth, the total infestation being 

 approximately 5 per cent or less, and, in the case of the check or 



