Table 1. Of the total number of apple maggot larvae emerging from samples of drops removed 

 beneath each cultivar at bi-weekly intervals from four weeks before harvest until two weeks after 

 harvest in 1993 and 1994, the number of larva that could have been prevented from emerging by 

 picking up drops at indicated times. 



Cultivar 



Total number 



of emerging 



larvae 



Emerging larvae prevented by picking up drops (% of total) 



Four weeks 

 before harvest 



Two weeks 

 before harvest 



At 

 harvest 



Two weeks 

 after harvest 



Jersey Mac 159 



Mcintosh 82 



Cortland 49 



Golden Delicious 100 



9 

 21 

 18 

 26 



43 

 49 

 52 

 48 



38 

 29 



28 



20 



10 

 1 

 2 

 6 



enough fruit remained on the trees following har- 

 vest to provide a two-week postharvest sample. 



Each batch of 100 sampled drops was placed on 

 the ground beneath the canopy of a large non-bear- 

 ing apple tree. Weekly, beginning on the day of 

 acquisition, each batch of drops was examined care- 

 fully for evidence of larval exit holes. An exit hole 

 has a characteristic appearance of torn apple skin 

 surrounding the hole. To confirm that an apparent 

 exit hole was in fact an exit hole, we cut the flesh 

 beneath the skin and examined it for evidence of 

 characteristic larval trails. All suspected exit holes 

 were confirmed, following which apples containing 

 an exit hole were removed from the batch. 



Results 



no new drops after harvest. Our estimates are that 

 35 to 40% of all drops up to and including harvest 

 fell between four and two weeks before harvest, with 

 45 to 60% falling between two weeks before harvest 

 and at harvest. 



Values in Table 3 represent for each cultivar at 

 each interval before or at harvest, an estimate of 

 the proportion of all larval exit holes that could have 

 been prevented by picking up all drops at intervals 

 before or at harvest. These values indicate that the 

 most effective time to pick up Jersey Mac drops 

 would be at harvest whereas the most effective time 

 to pick up drops of Mcintosh, Cortland and Golden 

 Delicious would be about two weeks before harvest. 

 Even at the optimum drop removal time for each 

 cultivar, 40to 50% of larvae would have escaped re- 



Data in Table 1 show per- 

 centages of larval exit holes that 

 could have been prevented by 

 picking up drops at various in- 

 tervals before, during, and af- 

 ter harvest. The pattern is simi- 

 lar for each cultivar. Peak lar- 

 val exit occurred about two 

 weeks before harvest. Only 1 

 to 10% of larval exit holes oc- 

 curred two weeks after harvest. 



Values in Table 2 represent, 

 for each cultivar, estimated per- 

 centages of the total number of 

 fruit which dropped that fell be- 

 fore or at harvest. For purposes 

 of this table, we assumed com- 

 plete harvest of all fruit on the 

 tree at harvest time and hence 



Table 2. Of the total number of fruit beneath each cultivar that 

 dropped up to and including harvest, estimated percentages 

 that dropped between the previous and the designated time 

 interval.* 



Estimated drop (% of total drop) 



Cultivar 



Four weeks Two weeks At 



before harvest before harvest harvest 



Jersey Mac 5 



Mcintosh 15 



Cortland 15 



Golden Delicious 15 



35 

 35 

 40 

 35 



60 

 50 

 45 

 50 



*For purposes of this table, we assumed complete harvest of all 

 fruit on the tree at harvest time. 



Fruit Notes, Spring, 1996 



