Table 3. For each cultivar at each interval before or at harvest, 

 estimated percentages of all emerging larvae that could have 

 been prevented by picking up all drops at designated times.* 



Estimated emerging larvae prevented 

 by picking up all drops (%) 



Four weeks Two weeks At 



Cultivar before harvest before harvest harvest 



Jersey Mac 1 



Mcintosh 9 



Cortland 7 



Golden Delicious 13 



39 

 50 

 58 

 55 



60 

 41 

 35 

 32 



*Each vallue here was derived from (a) multiplication of values 

 given in Tables 1 and 2 for that cultivar at that time interval, (b) 

 addition of all multiplied values for that cultivar, (c) setting "b" 

 equivalent to 100%, and (d) calculating the value given here for 

 each time interval as a percentage of "c". 



vars such as Jersey Mac that 

 ripen in August, drop removal 

 would be most effective at har- 

 vest. For mid-ripening culti- 

 vars such as Mcintosh and 

 Cortland, drop removal would 

 be most effective about two 

 weeks before harvest. The 

 same would be true for later 

 cultivars such as Golden Deli- 

 cious. 



moval either by having already exited dropped fruit 

 before pick up or by being present in infested fruit 

 still hanging on the tree (these fruit would eventu- 

 ally drop, but after the optimum drop removal time). 



Conclusions 



Even at the most effective 

 time of drop removal for each 

 cultivar, however, only about 

 half of apple maggot larvae in- 

 festing that cultivar would be 

 removed. The remainder could 

 exit fallen fruit and form pu- 

 paria in the soil. Therefore, we 

 seriously doubt that the mod- 

 est gain in terms of preventing 

 within-orchard apple maggot 

 buildup would justify the extra cost of labor to re- 

 move drops specifically for that purpose. Hence, 

 for the future, we plan to place increased emphasis 

 upon optimizing patterns of odor-baited red sphere 

 trap deployment for controlling the adults to pre- 

 clude the need for removing drops. 



Results of our two-year study indicate foremost Acknowledgments 

 that little is to be gained in terms of preventing 

 within-orchard buildup of apple maggot flies by pick- 

 ing up drops two weeks after harvest. By that time, 

 larval exit from drops is nearly complete. For culti- 



This work was supported by the USDA North- 

 east Regional IPM Competitive Grants Programs 

 and State/Federal IPM Extension funds. 



*T# *X^ *T# *T* vL* 



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Fruit Notes, Spring, 1996 



