foliage and fruit within 10 to 20 inches of a trap was 

 removed. Response was significantly or numerically 

 less to baited spheres when spheres were hung in the 

 inner half of the canopy (foliage and fruit cleared to 10 

 or 20 inches) or when spheres in the outer half of the 

 canopy had foliage and fruit cleared to distances of 0, 

 30, or 40 inches. In contrast to baited spheres, unbailed 

 spheres performed about as well when hung in sub- 

 optimal position (either in the inner half of the canopy 

 with foliage and fruit cleared to 10 inches or in the 

 outer half of the canopy with foliage and fruit cleared 

 to 40 inches) as when in optimal position (in outer half 

 of the canopy with foliage and fruit cleared to 20 

 inches). Patterns of adult response to sphere treatments 

 were essentially the same during each phase of the 

 fruit development season. 



In our experiments, use of a five-component blend 

 of synthetic apple volatiles in association with red 

 spheres not only significantly enhanced attractiveness 

 of spheres but also significantly accentuated degree of 

 differential response to varying within-tree sphere 

 positions compared with response to unbailed spheres. 

 For example, adults responded equally to outer-canopy 

 spheres with foliage and fruit cleared to 20 inches and 

 inner-canopy spheres with foliage and fruit cleared to 

 1 inches when spheres were unbailed but significantly 

 favored the former over the latter when spheres were 

 baited. Causes underlying this and similar differential 

 response patterns found here are unknown but could 



involve an interaction between presence of synthetic 

 fruit odor and visual apparency of spheres that favors 

 discovery of baited spheres in positions where the 

 integrity of a synthetic odor plume and the 

 conspicuousness of a sphere are not compromised by 

 an overabundance of nearby foliage and fruit (e.g., as 

 at a distance of or even 10 inches) or an insufficient 

 amount of light (e.g., as at interior of canopy). Too little 

 nearby foliage and fruit, however, as for odor-baited 

 spheres having foliage and fruit cleared to 40 inches, is 

 just as unfavorable as too much nearby foliage and fruit, 

 possibly in part because AMF are less able to visually 

 detect 3.5-inch red spheres at a distance of 40 inches 

 compared with closer distances. 



In summary, our results suggest that maximal 

 success in using a red sphere for monitoring or 

 controlling AMF can be achieved by baiting a sphere 

 with a five component blend of attractive odor, 

 positioning the sphere in the outer half of an apple free 

 canopy, clearing away all foliage and fruit within 20 

 inches of the sphere, and allowing foliage and fruit 

 beyond that distance to remain. 



A ckn o wledgm ents 



This study was supported by funds from a USDA 

 Northeast Regional IPM grant, a USDA Crops at Risk 

 grant, and a Hatch grant. 



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20 



Fruit Notes, Volume 69, Spring, 2004 



