-14- 



In 1981, we investigated (1) the comparative efficacy of 

 different AMF traps and (2) the effect of within-tree trap 

 positioning (relative to surrounding fruit and foliage) on AMF 

 captures on red sphere traps. The study was conducted in 4 

 commercial apple orchards located in Middlesex, Worcester, and 

 Hampden Counties in Massachusetts. 



Efficacy of Different Traps 



We compared 5 different AMF traps: (1) unbaited wooden spheres, 

 8.5 centimeters (cm) in diameter, painted red (Tartar Red Dark enamel- 

 Sherwin Williams Corp., Cleveland, Ohio); (2 § 3) baited and unbaited 

 Pherocon ICYTM yellow rectangular traps (Zoecon Corp., Palo Alto, 

 Calif.); (4 ^ 5) baited and unbaited Pherocon ICYTM yellow rectangular 

 traps with a red disc, 8.5 cm in diameter, painted at the center 

 of each side of the trap. All traps received an initial coating of 

 Tangle Trap (The Tanglefoot Co., Grand Rapids, MI). A 0.5 gram 

 mixture of equal parts of ammonium acetate and enzymatic yeast hydro- 

 lysate was added to the Tangle trap for each side of the baited traps 

 tested. All traps were hung 25-50 cm from the nearest foliage or 

 fruit. They were emplaced during the first week of July (when the 

 earliest flies were found entering commercial orchards) and remained 

 there for 8 weeks. 



TABLE 1 



ry r Mean number captured AMF per trap 



^^ First sample date Combined sample dates 



^^^P (July 21) 



Red sphere 1.2 14.8 



Baited yellow rectangle 0.3 1.8 



(with red disc) 



Unbaited yellow rectangle 0.5 1.2 



(with red disc) 



Baited yellow rectangle 0.2 1.4 



(plain) 



Unbaited yellow rectangle 0.0 1.4 



(plain) 



z 

 15 replicates per treatment. 



Table 1 shows that early in the season as well as throughout, 

 red sphere traps were far more effective in capturing AMF than any 

 of the yellow rectangle traps. In fact, by the first sample date, 

 81^ of the sphere traps had captured at least one AMF, compared with 

 values of 0-31% for the rectangle traps. Previous studies in commer- 

 cial apple orchards have shown the red sphere trap to range from being 



