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experiments, all bags were removed from the beginning to the end of bloom to 

 permit pollination. For the last 3 years (1984-1986), we conducted a third 

 experiment in which we used a single approach to bagging buds. We emplaced 280 

 bags before silver tip (half on Mcintosh, half on Delicious). At the start of 

 each of 7 bud development stages (silver tip, green tip, half-inch green, tight 

 cluster, early pink, late pink, and petal fall) we removed 40 bags (20 per 

 cultivar) but replaced the bags at the end of that stage, thereby exposing the 

 buds to TPB only during that stage. In addition, 40 check terminals were not 

 bagged. As before, all bags were removed during bloom for pollination. In all 

 experiments, bagged and check terminals were examined in July or August for TPB 

 injury to fruit. 



To acquire information on the abundance of TPB adults in these 

 experimental blocks during each tree development stage, each year at silver tip 

 we hung 20 sticky-coated, white visual monitoring traps (half on Mcintosh, half 

 on Delicious) in trees immediately adjacent to the trees with bags. TPB adults 

 were counted and removed from traps at each tree development stage. 

 To compare time of fruit injury initiation and time of TPB abundance with time 

 of pesticide treatment against TPB, each year in another block adjacent to the 

 above we applied pesticide to 8 randomly-positioned trees (all Mcintosh) at 

 each of 4 different tree development stages. On each tree, 60 fruit were 

 examined in August or September for TPB injury. 



Results 



Over the 6 years in which flower bud terminals were bagged with cloth to 

 assess the time at which TPB fruit injury was initiated, 6904 bagged and check 

 fruit were examined for injury. Normally, 6 years of research involving nearly 

 7000 experimental fruit is sufficient to gain a detailed impression of any 

 insect interaction with tree fruit. In this case it was not. The data (Table 

 1) reveal inconclusive, even conflicting trends. Thus, the results of 

 Experiment 1 (in which terminals were bagged at silver tip and bags were 

 removed permanently at successive stages beginning at tight cluster) suggest 

 that progressively less injury to fruit was initiated at successive stages 

 after tight cluster. Conversely, the results of Experiment 2 (in which 

 terminals were bagged permanently at successive stages beginning at tight 

 cluster) suggest that progressively greater injury to fruit was initiated at 

 successive stages after tight cluster. The results of Experiment 3 (in which 

 terminals were bagged permanently except during a given developmental stage) 

 suggest lack of a consistent trend in time at which injury to fruit was 

 initiated . 



The visual trap capture data (Table 2) suggest TPB adults were on average 

 most abundant in the unsprayed experimental block from half-inch-green until 

 late pink. Comparatively few were captured before half-inch-green and after 

 pink. Time of peak captures varied considerably from year to year. We should 

 add that the consistent decline in trap captures from pink onward may have been 

 due only partly to decreasing TPB populations. It may have been due also to 

 declining ability of the traps to compete as visual stimuli with developing 

 foliage and blossoms. 



The pesticide timing experiments (Table 3) reveal no clear picture of the 

 most effective time of treatment for preventing TPB injury to fruit. The only 



