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Bulletin 396 



different kinds of scars, and so a series of photographs was made for each 

 variety. The work of redbugs on standard varieties is here presented, 

 with a few cases of particular interest found on odd varieties. 



GROWTH OF FRUIT IN RELATION TO TIME OF INJURY A FACTOR IN 

 THE TYPE OF SCAR DEVELOPED 



The amount of redbug injury in an orchard, as measured by the pro- 

 portion of injured fruits at picking time and the types of scars produced, 

 depends on several factors. When there is a heavy set of fruit it is always 

 the weak and the injured fruits that drop first ; the fruits that get a strong 

 start and are free from injury are the ones that survive. In years when 

 there is a heavy set, therefore, the redbugs may actually help to thin 

 the fruit without leaving a noticeable proportion of scarred fruits, since 



Y 



\ 

 \ 



Fig. 23. YOUNG apples in section (JULY 13), showing the effect OF CORE PUNC- 

 TURES BY REDBUGS 



it is the injured apples that drop in the thinning process. If the season 

 is favorable to very rapid growth following the blooming period, a larger 

 proportion of injured fruits will recover and grow to maturity than in a 

 year when growth is slow following the bloom. In a year when there 

 is a light set of fruit and the period of growth is favorable to rapid 

 development, the conditions are right to produce the largest proportion 

 of scarred fruit at picking time, since by forced growth many weak and 

 injured fruits are able to develop that otherwise would have dropped. 

 Any condition that tends to force the growth of the tree will enable more 

 of the injured and weak fruits to grow and recover. The writer soon 

 learned to thin the fruit on limbs on which he was tagging apples that 

 were being injured by an insect; if this were not done, it was found that 

 about ninety-five per cent of the fruits tagged would drop and the experi- 

 ment would be lost. 



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