for all tree sizes. Although more AMF were caught by 

 interior traps in IPM blocks in comparison to control 

 blocks of each tree size, injury was slightly lower for 

 fruit sampled in IPM blocks composed of small trees. 

 Our results for wild AMF suggest that the level of con- 

 trol provided by red sphere traps increases when traps 

 are placed on small trees. This view is further sup- 

 ported by the fact that we recovered more marked AMF 

 on traps in blocks of small trees. Perhaps this was be- 

 cause those traps were more apparent to fruit-scarch- 

 ing AMF on trees that have less leaf canopy volume. 

 As a consequence, flies immigrating into IPM blocks 

 will have a higher probability of being intercepted by 

 traps placed on small trees when compared to the prob- 

 ability of being intercepted by traps on large trees. 



Together, our results suggest that the trend among 

 New England growers in adopting smaller tree sizes 

 aids in maximizing the effectiveness of odor-baited 

 spheres for controlling AMF. 



A ckn o wledgnt en ts 



We are thankful to William Broderick, David 

 Chandler, David Cheney, Dana Clark, David Shearer, 

 Joseph Sincuk, Timothy Smith, and Mo Tougas for gen- 

 erously allowing us to use their orchards. This work 

 was supported by grants from the Massachusetts De- 

 partment of Food and Agriculture, the USDA CSREES 

 Pest Management Alternatives Program, USDA NRI 

 grant 95-37313-1890, and the USDA SARE program. 



20 



Fruit Notes, Volume 64 (Number 4), Fall, 1999 



