correlation, however, between PAD and scab inci- 

 dence in the blocks. Also, there was no correlation 

 between scab on fruit in 1992 and PAD in 1993, 

 indicating the danger of trying to use fruit scab 

 incidence to predict scab inoculum in the orchard. 

 Summer fimgicide use was higher in the check 

 blocks than in the test blocks (Table 1), with check 

 blocks receiving about 0.8 DE more than the test 

 blocks. Flyspeck, however, was nearly twice as great 

 in the test blocks compared to check blocks, though 

 sooty blotch incidence was similar in both block 

 types (Table 3). There was no correlation between 

 the DEs of summer fungicide and flyspeck. The time 

 of harvest was critical to flyspeck incidence (Table 4). 

 Fruit harvested after September 15 were much more 

 likely to have flyspeck than those harvested before 

 that date. In fact, fruit harvested before September 

 15 (largely Mcintosh) had virtually the same fly- 

 speck incidence in either check or test blocks. In 

 fruit harvested later (Delicious, Cortland, and 

 Golden Delicious), the incidence of flyspeck was 



higher in test blocks than in checks, but the inci- 

 dence in either block far exceeded that in the early 

 harvest. From these results, two points stand out. 

 First, our major cultivar, Mcintosh, may get only 

 marginal benefit from summer fungicide sprays. 

 Second, minimal fungicide applications will control 

 sooty blotch. 



Fungicides present a particularly difficult prob- 

 lem to second-level IPM in apples. The nature of 

 scab, and its potential for severe damage, limit 

 options for further early season fungicide reduc- 

 tions; however, the potential for reducing summer 

 fungicides remains good. We will need to examine 

 the role that alternative hosts,such as brambles and 

 roses, play in providing inoculum for summer dis- 

 eases. Removing these hosts may make flyspeck 

 management much easier. Relatively little fungi- 

 cide is needed to control sooty blotch under our 

 conditions. It may be possible to spray late-season 

 cultivars selectively. Alternatively, if early fungi- 

 cide applications can be used to delay the epidemic, 

 even later season cultivars may be harvested before 

 flyspeck develops. Certainly, weather will also guide 

 fungicide applications in summer. There are many 

 unanswered questions, but the prospect for at least 

 reducing, and possibly eliminating, summer fungi- 

 cides in Massachusetts appears good. 



References 



Christie, M., R. J. Prokopy, K Leahy, J. Mason, A. 

 Pelosi, and K. White. 1993. Apple integrated pest 

 management in 1992: Insects and mites in second- 

 level orchard blocks. Fruit Notes 58(1):24-31. 



Cooley, D. R., W. R. Autio, and J. W. Gamble. 1992. 

 Second-level apple integrated pest management: 

 The effects of summer pruning and a single fungi- 

 cide application on flyspeck and sooty blotch. Fruit 

 Notes 57(1):16-17. 



Cooley, D. R. and R. S. Spitko. 1992. Using sterol 

 inhibitors. American Fruit Grower 112(l):30-32. 



Wisniewska, J., Y. Yang, and R. Prokopy. 1993. 

 Spiders in second-level and first-level apple IPM 

 blocks. Fruit Notes 58il):20-23. 



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Fruit Notes, Winter, 1994 



15 



